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1
Kamler, Jan F., Warren B. Ballard, Eric M. Gese, Robert L. Harrison, and Seija M. Karki. "Dispersal characteristics of swift foxes." Canadian Journal of Zoology 82, no. 12 (December 1, 2004): 1837–42. http://dx.doi.org/10.1139/z04-187.
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From 1997 to 2001, we monitored movements of 109 adult and 114 juvenile swift foxes, Vulpes velox (Say, 1823), at study sites in Colorado, New Mexico, and Texas to determine patterns of dispersal. Significantly more male (93%) than female (58%) juveniles dispersed, and both sexes had similar bimodal dispersal patterns with peaks in September–October and January–February. Adult dispersal occurred more evenly throughout the year, and significantly more male (32%) than female (5%) adults dispersed. Adult males tended to disperse after the death of their mate. Of dispersing foxes with known fates, settlement percentages in new territories were similar between juvenile males and females (40% overall), but they were significantly lower than for adults (89%). All other dispersing foxes with known fates died. Among juvenile females with known fates, similar percentages of philopatric and dispersing foxes reproduced as yearlings (50% overall), so the benefits of dispersal versus philopatry were not clear. Although rarely reported for other species, adult males were an important dispersal cohort in swift foxes (43% of male dispersals and 25% of all dispersals). Because of the female-biased philopatry among swift foxes, dispersal of adult males likely decreased the chances for inbreeding (e.g., father–daughter breeding).
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Brody, Alison K., and Kenneth B. Armitage. "The effects of adult removal on dispersal of yearling yellow-bellied marmots." Canadian Journal of Zoology 63, no. 11 (November 1, 1985): 2560–64. http://dx.doi.org/10.1139/z85-381.
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The relative importance of adult–yearling interaction and individual behavioral phenotypes on dispersal of yearling yellow-bellied marmots was investigated. Two marmot colonies near Gothic, Colorado, were studied; one was treated as an experimental colony from which all adults were removed, while the second was left undisturbed. Analysis of dispersal patterns and behavioral observations indicated that agonistic behavior between adults and yearlings is not necessary for dispersal to occur. Dispersal of male yearlings appears to be independent of adult–yearling interactions, although dispersal of female yearlings probably is mediated by social interactions. Individual behavioral phenotypes could not be used to predict which animals dispersed nor the relative timing of their departure. Dispersal can be viewed as an important mating strategy; for yearling males it is likely to be the only option available for reproductive success.
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McLellan, Bruce N., and Frederick W. Hovey. "Natal dispersal of grizzly bears." Canadian Journal of Zoology 79, no. 5 (May 1, 2001): 838–44. http://dx.doi.org/10.1139/z01-051.
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We studied natal dispersal of grizzly bears (Ursus arctos), a solitary nonterritorial carnivore with a promiscuous mating system, between 1979 and 1998. Dispersal distances for 2-year-olds did not differ between males and females, but by 3 years of age, males had dispersed farther than females, and farther still by 4 years of age. Dispersal of both sexes was a gradual process, occurring over 14 years. From the locations of death, or last annual ranges, it was estimated that 18 males dispersed 29.9 ± 3.5 km (mean ± SE) and 12 females dispersed 9.8 ± 1.6 km. Eleven of these males dispersed the equivalent of at least the diameter of 1 adult male home range, whereas only 3 of the females dispersed at least the diameter of 1 adult female home range. The longest dispersals recorded were 67 km for a male and 20 km for a female. Because the social system consists of numerous overlapping home ranges of both sexes, long dispersal distances may not be required to avoid inbreeding or competition with relatives. Simple models suggest that 61% of the ranges of brother and sister pairs would not overlap, but the home range of every daughter would overlap her father's range. The home range of an estimated 19 ± 4 (mean ± SD) adult males, however, would overlap at least a portion of each female's range, thereby reducing the chance of a female mating with her brother or father. Understanding the dispersal behaviour of grizzly bears is essential for developing conservation strategies. Our results suggest that meta-population reserve designs must provide corridors wide enough for male grizzly bears to live in with little risk of being killed.
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Valenta, Kim, Mariah E. Hopkins, Melanie Meeking, Colin A. Chapman, and Linda M. Fedigan. "Spatial patterns of primary seed dispersal and adult tree distributions: Genipa americana dispersed by Cebus capucinus." Journal of Tropical Ecology 31, no. 6 (August 28, 2015): 491–98. http://dx.doi.org/10.1017/s0266467415000413.
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Abstract:The spatial distribution of adult trees is typically not expected to reflect the spatial patterns of primary seed dispersal, due to many factors influencing post-dispersal modification of the seed shadow, such as seed predation, secondary seed dispersal and density-dependent survival. Here, we test the hypothesis that spatial distributions of primary seed shadows and adult trees are concordant by analysing the spatial distributions of adult Genipa americana trees and the seed shadow produced by its key primary disperser, the capuchin monkey (Cebus capucinus) in a tropical dry forest in Costa Rica. We mapped the dispersal of G. americana seeds by the capuchins during focal animal follows (mean = 463 min, n = 50) of all adults in one free-ranging group over two early wet seasons (May–July, 2005 and 2006). We mapped the locations of all G. americana trees within a 60-ha plot that lay within the home range of the capuchin group. We conducted multiple spatial point pattern analyses comparing degrees of clustering of capuchin defecations and G. americana trees. We found that adult tree distributions and primary dispersal patterns are similarly aggregated at multiple spatial scales, despite the modification of the primary dispersal patterns and long dispersal distances.
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Chapman, Colin A., and Lauren J. Chapman. "Frugivory and the fate of dispersed and non-dispersed seeds of six African tree species." Journal of Tropical Ecology 12, no. 4 (July 1996): 491–504. http://dx.doi.org/10.1017/s026646740000972x.
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ABSTRACTThe relationship between seedling recruitment (under and away from parent trees) and the behaviour of seed dispersers and predators, was explored in a three-year study in Kibale National Park, Uganda. On the basis of 1261 hours of observation, the foraging activity of the diurnal frugivores which fed on fruit from six tree species was quantified. The fate of dispersed and non-dispersed seeds and seedlings was examined experimentally. The findings suggest that a trade-off exists between factors that promote seedling growth in areas with high seedling density and factors that promote dispersal by frugivores. For example, dispersal ofMimusops bagshaweiincreases both seed and seedling survival; seeds placed away from adult conspecifics had a 8% lower probability of disappearing than seeds placed under adults and seedlings away from adults had a 30% greater probability of surviving than seedlings grown under adults. In contrast, forUvariopsis congensis, dispersed seeds had a 56% greater probability of disappearing than seeds directly under a parent tree, while the survival of dispersed and non-dispersed seedlings was similar. Non-dispersed seed and seedling disappearance were correlated with the percentage of the fruit crop removed from focal trees, suggesting that the ability to survive under an adult maybe related to other aspects of the tree's life history.
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Caughlin, T. Trevor, Jake M. Ferguson, Jeremy W. Lichstein, Pieter A. Zuidema, Sarayudh Bunyavejchewin, and Douglas J. Levey. "Loss of animal seed dispersal increases extinction risk in a tropical tree species due to pervasive negative density dependence across life stages." Proceedings of the Royal Society B: Biological Sciences 282, no. 1798 (January 7, 2015): 20142095. http://dx.doi.org/10.1098/rspb.2014.2095.
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Overhunting in tropical forests reduces populations of vertebrate seed dispersers. If reduced seed dispersal has a negative impact on tree population viability, overhunting could lead to altered forest structure and dynamics, including decreased biodiversity. However, empirical data showing decreased animal-dispersed tree abundance in overhunted forests contradict demographic models which predict minimal sensitivity of tree population growth rate to early life stages. One resolution to this discrepancy is that seed dispersal determines spatial aggregation, which could have demographic consequences for all life stages. We tested the impact of dispersal loss on population viability of a tropical tree species, Miliusa horsfieldii, currently dispersed by an intact community of large mammals in a Thai forest. We evaluated the effect of spatial aggregation for all tree life stages, from seeds to adult trees, and constructed simulation models to compare population viability with and without animal-mediated seed dispersal. In simulated populations, disperser loss increased spatial aggregation by fourfold, leading to increased negative density dependence across the life cycle and a 10-fold increase in the probability of extinction. Given that the majority of tree species in tropical forests are animal-dispersed, overhunting will potentially result in forests that are fundamentally different from those existing now.
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Hanson, Thor, Steven Brunsfeld, Bryan Finegan, and Lisette Waits. "Conventional and genetic measures of seed dispersal for Dipteryx panamensis (Fabaceae) in continuous and fragmented Costa Rican rain forest." Journal of Tropical Ecology 23, no. 6 (October 29, 2007): 635–42. http://dx.doi.org/10.1017/s0266467407004488.
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The effects of habitat fragmentation on seed dispersal can strongly influence the evolutionary potential of tropical forest plant communities. Few studies have combined traditional methods and molecular tools for the analysis of dispersal in fragmented landscapes. Here seed dispersal distances were documented for the tree Dipteryx panamensis in continuous forest and two forest fragments in Costa Rica, Central America. Distance matrices were calculated between adult trees (n = 283) and the locations of seeds (n = 3016) encountered along 100 × 4-m transects (n = 77). There was no significant difference in the density of seeds dispersed > 25 m from the nearest adult (n = 253) among sites. There was a strong correlation between the locations of dispersed seeds and the locations of overstorey palms favoured as bat feeding roosts in continuous forest and both fragments. Exact dispersal distances were determined for a subset of seeds (n = 14) from which maternal endocarp DNA could be extracted and matched to maternal trees using microsatellite analysis. Dispersal within fragments and from pasture trees into adjacent fragments was documented, at a maximum distance of 853 m. Results show no evidence of a fragmentation effect on D. panamensis seed dispersal in this landscape and strongly suggest bat-mediated dispersal at all sites.
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KOVATS, ZSOLT, JAN CIBOROWSKI, and LYNDA CORKUM. "Inland dispersal of adult aquatic insects." Freshwater Biology 36, no. 2 (October 1996): 265–76. http://dx.doi.org/10.1046/j.1365-2427.1996.00087.x.
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Getzin, Stephan, Thorsten Wiegand, and Stephen P. Hubbell. "Stochastically driven adult–recruit associations of tree species on Barro Colorado Island." Proceedings of the Royal Society B: Biological Sciences 281, no. 1790 (September 7, 2014): 20140922. http://dx.doi.org/10.1098/rspb.2014.0922.
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The spatial placement of recruits around adult conspecifics represents the accumulated outcome of several pattern-forming processes and mechanisms such as primary and secondary seed dispersal, habitat associations or Janzen–Connell effects. Studying the adult–recruit relationship should therefore allow the derivation of specific hypotheses on the processes shaping population and community dynamics. We analysed adult–recruit associations for 65 tree species taken from six censuses of the 50 ha neotropical forest plot on Barro Colorado Island (BCI), Panama. We used point pattern analysis to test, at a range of neighbourhood scales, for spatial independence between recruits and adults, to assess the strength and type of departure from independence, and its relationship with species properties. Positive associations expected to prevail due to dispersal limitation occurred only in 16% of all cases; instead a majority of species showed spatial independence (≈73%). Independence described the placement of recruits around conspecific adults in good approximation, although we found weak and noisy signals of species properties related to seed dispersal. We hypothesize that spatial mechanisms with strong stochastic components such as animal seed dispersal overpower the pattern-forming effects of dispersal limitation, density dependence and habitat association, or that some of the pattern-forming processes cancel out each other.
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Tomkins, A. R., D. J. Wilson, C. Thomson, and P. Allison. "Dispersal by passionvine hopper (Scolypopa australis) adults." New Zealand Plant Protection 53 (August 1, 2000): 185–89. http://dx.doi.org/10.30843/nzpp.2000.53.3632.
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Passionvine hopper (Scolypopa australis) (PVH) is a serious pest in some Bay of Plenty kiwifruit orchards with large numbers of PVH adults flying in from adjacent scrub A series of field experiments investigated their dispersal abilities Adult PVH released into an open area were recaptured on sticky traps up to 70 m downwind two hours later When released inside a kiwifruit orchard PVH gradually dispersed throughout a block of vines Sticky traps at different heights along an orchard border caught PVH up to 2 m above ground Different shaped (rectangle square or triangle) traps caught similar numbers of PVH adults
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Kankam, Bright Obeng, and William Oduro. "Frugivores and fruit removal ofAntiaris toxicaria(Moraceae) at Bia Biosphere Reserve, Ghana." Journal of Tropical Ecology 25, no. 2 (March 2009): 201–4. http://dx.doi.org/10.1017/s0266467409005835.
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In tropical forests, most individual fruit-bearing trees depend on frugivores for seed dispersal (Howe & Smallwood 1982, Wilson 1992). Seed dispersal enhances germination potential, provides an opportunity for seeds to escape predation under the parent plants, and reduces seedling numbers under parent trees (Şekercioğluet al. 2004). The way frugivores handle seeds and process them may influence the seed fate of many plants (Janzen 1971). The quantity of seeds dispersed and the quality of dispersal provided by frugivores impact plant fitness (Herrera & Jordano 1981). Schupp (1993) defined the effectiveness of seed dispersal by frugivores as an empirical measure of quantity of seeds dispersed and quality of dispersal from the parent plant to a suitable microsite. Seed dispersal by frugivores increases the chances for seedling survival away from the vicinity of the parent plant because in tropical forests seed predation is concentrated under adult trees that prevent seedlings from establishing near parent trees (Howe & Miriti 2004).
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Cilimburg, Amy B., Mark S. Lindberg, Joshua J. Tewksbury, and Sallie J. Hejl. "Effects of Dispersal on Survival Probability of Adult Yellow Warblers (Dendroica Petechia)." Auk 119, no. 3 (July 1, 2002): 778–89. http://dx.doi.org/10.1093/auk/119.3.778.
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Abstract Annual survival probability estimates for songbirds are generally biased low because dispersal is not differentiated from mortality. Presently, knowledge of between-year breeding dispersal is lacking for most songbirds. To assess adult survival probabilities and dispersal, we color-banded and resighted 436 Yellow Warblers (Dendroica petechia) over five breeding seasons at 11 study sites in the Bitterroot Valley, Montana. During the last two of those seasons, we searched extensively for marked warblers between and surrounding those sites. We compared survival probabilities estimated with and without this added dispersal information and assessed the effectiveness of adjusting survival probabilities with transient-type models. Survival probabilities were calculated using open population models, and model selection was based on Akaike's Information Criterion (AIC) within program MARK. The best model indicated that survival probabilities differed between males and females and varied among years. We found that dispersal off the study site was common (in 1999, 30% of resighted birds were found off their original study site), and survival probabilities increased by 6.5–22.9% (0.02 ± 0.07−0.106 ± 0.06) with the inclusion of dispersed birds. We suggest that emigration can have substantial effect on survival probabilities and advise against the use of return rates from small study areas or spatial or temporal comparisons of return rates because of spatial and temporal variation in extent of emigration. In addition, our results suggest that additional assessments of the reliability of transient-type models under some sampling schemes may be warranted.
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GITHIRU, MWANGI, LEON BENNUN, and LUC LENS. "Regeneration patterns among bird-dispersed plants in a fragmented Afrotropical forest, south-east Kenya." Journal of Tropical Ecology 18, no. 1 (January 2002): 143–49. http://dx.doi.org/10.1017/s0266467402002092.
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Fruit-eating birds play an important role in the seed dispersal of many tropical plants (e.g. Herrera 1984), and the foraging behaviour of avian frugivores may affect their seed-dispersal capabilities (Loiselle & Blake 1999,Schupp 1993, Traveset 1994). For instance,shorter visits tend to produce less clumped seed distributions (Graham et al. 1995). Also,avian frugivores often feed on the fruits of several plant species over short periods of time (Herrera 1984, 1988a; Levey et al. 1994) in some non-random pattern (Herrera 1998). This potentially produces a predictable spatial pattern of the dispersed seeds (White & Stiles 1990). Forest destruction leads to fragmentation and degradation of the remaining habitats, which may influence patterns of adult tree distribution if the production, predation, dispersal, and/or regeneration of tree seeds is affected (Harrington et al. 1997). If dispersal of avian frugivores is disrupted by habitat fragmentation, plant species might face reduced regeneration, or even local extinction if they depend on a single, locally extinct disperser (Kellman et al. 1996). Increased predation of seeds and regenerating plants in the edges and gaps may also directly reduce regeneration rates (Corlett & Turner 1997, Harrington et al. 1997, Schupp 1988).
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Lang, Jason D., Larkin A. Powell, David G. Krementz, and Michael J. Conroy. "Wood Thrush Movements and Habitat Use: Effects of Forest Management for Red-Cockaded Woodpeckers." Auk 119, no. 1 (January 1, 2002): 109–24. http://dx.doi.org/10.1093/auk/119.1.109.
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Abstract We monitored adult and juvenile breeding-season movements and habitat use of radio-tagged Wood Thrushes (Hylocichla mustelina) at the Piedmont National Wildlife Refuge, central Georgia, USA. We investigated the effects that management for Red-cockaded Woodpeckers (Picoides borealis), thinning and burning >30 year old loblolly pine (Pinus taeda) habitat, had on Wood Thrushes, a ground-foraging and midstory-nesting species. Adult Wood Thrush pairs regularly moved long distances between nesting attempts (range 1 to 17,388 m). The only experimental effect we found on adult movements was a decrease in weekly emigration rates (Ψ) from thinned and burned compartments after silvicultural management. Adult males preferred riparian hardwoods with sparse to moderate cover and those preferences increased following management. Juveniles remained near their nest site (x̄ = 177 m, SE = 113) for an average 24 days (SE = 6.3), and then dispersed a mean 2,189 m (SE = 342). Before dispersal, juveniles preferred upland hardwood–pine mixed habitat (P < 0.05) with moderate overstory cover (P < 0.05). We found no management effects on dispersal distances or predispersal habitat use. However, juveniles from thinned and burned compartments dispersed to hardwood habitats with dense cover, whereas birds from control compartments dispersed to pine-dominated habitats with sparse cover. All juveniles dispersed to areas with habitat similar to what they used before dispersal. Small-scale thinning and burning for Red-cockaded Woodpeckers may have had little effect on Wood Thrush habitat use and movements because typical movements were often larger than the scale (stand or compartment) targeted for management.
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Drilling, Nancy E., and Charles F. Thompson. "Natal and Breeding Dispersal in House Wrens (Troglodytes aedon)." Auk 105, no. 3 (July 1, 1988): 480–91. http://dx.doi.org/10.1093/auk/105.3.480.
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Abstract We studied the natal and breeding dispersal of yearling and adult House Wrens (Troglodytes aedon) for 7 yr in central Illinois. The forested study areas contained 910 identical nest boxes placed in a grid pattern. On average 38.1% (n = 643) of the adult males and 23.3% (n = 1,468) of the adult females present in one year returned the next; 2.8% (n = 6,299) of the nestlings that survived to leave the nest returned each year. Adult male (median distance = 67 m) and adult female (median = 134 m) breeding dispersal was less than yearling male (median = 607.5 m) and yearling female (median = 674 m) natal dispersal. Females that returned had produced more offspring the previous season than had nonreturning females, and females that successfully produced at least one chick in their last nesting attempt of the previous season moved shorter distances than did unsuccessful females. There were, however, no consistent differences between returning and nonreturning females in two other measures of reproductive success. Females that were unsuccessful in their last breeding attempt of the previous year were more likely to be successful in their next attempt if they moved two or more territories than if they did not move. Reproductive success did not affect the likelihood that a male would return nor the distance that he moved. The success of subsequent nesting attempts by males was also not related to the distance moved. Inbreeding avoidance may explain differences between breeding and natal dispersal, but it does not explain the lack of difference in dispersal of yearling females and males. Differences between adult and yearling dispersal are best explained by advantages accruing to adults that remain near former breeding sites and by the necessity for yearlings to move farther because of their late return from the wintering grounds. The advantages for adults to reoccupy previous breeding sites are counterbalanced, especially in females, by advantages associated with moving after breeding failure.
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Spendelow, Jeffrey A., Carolyn S. Mostello, Ian C. T. Nisbet, C. Scott Hall, and Linda Welch. "Interregional Breeding Dispersal of Adult Roseate Terns." Waterbirds 33, no. 2 (June 2010): 242–45. http://dx.doi.org/10.1675/063.033.0213.
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Allen, Michael R. "Measuring and modeling dispersal of adult zooplankton." Oecologia 153, no. 1 (March 21, 2007): 135–43. http://dx.doi.org/10.1007/s00442-007-0704-4.
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Cowan, PE, and DS Rhodes. "Electric Fences and Poison Buffers as Barriers to Movements and Dispersal of Brushtail Possums (Trichosurus Vulpecula) on Farmland." Wildlife Research 20, no. 5 (1993): 671. http://dx.doi.org/10.1071/wr9930671.
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Limitation of the spread of bovine tuberculosis by brushtail possums (Trichosurus vulpecula) in New Zealand involves creating buffer zones 3-5km wide around areas where the disease is endemic in possum populations; low possum density is established by aerial and ground poisoning and maintained by repeated control. The effectiveness of a buffer zone was examined using live-trapping and radiotracking to study movements and dispersal of juvenile and adult possums in comparison with a nearby, undisturbed (control) site. At a third site, the effect of a 3-km long, 9-strand electric fence, erected from ridge to ridge across a valley catchment, for reducing possum dispersal was measured, as an alternative to a buffer zone. Adult possums were highly sedentary; only one permanent shift of more than 0.5km was detected during repeated live-trapping and radio-tracking, and most consecutive live captures were in traps less than 200m apart. None of the radio-tagged adults adjacent to the poison buffer zones moved permanently into the low-density areas. By contrast, about 20% of radio-tagged juveniles dispersed more than 0.5km, moving up to 11.6km from their natal areas, most in a generally west-north-west to east-north-east direction. About equal numbers dispersed upstream, downstream, or in other directions. Significantly more males dispersed than females, but their dispersal distances were similar. Some dispersing possums moved more than 2km overnight, and females, particularly, often made several moves before settling. Most juveniles dispersed before they were one year old, mainly in the three months immediately preceding the peak of births in autumn. Neither the poison buffer zone nor the electric fence appeared to influence the proportion of juveniles that dispersed more than 0.5km, or the average distance dispersed. The implications of these findings in preventing the spread of bovine tuberculosis are discussed.
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Rosenberry, Christopher S., Mark C. Conner, and Richard A. Lancia. "Behavior and dispersal of white-tailed deer during the breeding season." Canadian Journal of Zoology 79, no. 1 (January 1, 2001): 171–74. http://dx.doi.org/10.1139/z00-186.
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Sexual competition and aggression by adult females have been hypothesized to prompt dispersal by male white-tailed deer (Odocoileus virginianus). We observed behavioral interactions of 21 yearling males (14 dispersers and 7 nondispersers) at Chesapeake Farms during the early part of the breeding season prior to actual breeding. Interactions with adult males and females constituted a small portion of all interactions and yearling males were similarly subordinate to adults. Dispersers participated in breeding-season behaviors with yearling males more often than nondispersers did (P = 0.005), and tended to be more subordinate than nondispersers (P = 0.095). Behavioral differences related to sexual competition with other yearlings appeared to be correlated with dispersal by yearling males at Chesapeake Farms. We recommend that both sexual competition and aggression by adult females be considered in future attempts to understand the dispersal behavior of white-tailed deer.
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Briers, Robert A., Helen M. Cariss, and John H. R. Gee. "Dispersal of adult stoneflies (Plecoptera) from upland streams draining catchments with contrasting land-use." Fundamental and Applied Limnology 155, no. 4 (December 9, 2002): 627–44. http://dx.doi.org/10.1127/archiv-hydrobiol/155/2002/627.
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BYHOLM, PATRIK, PERTTI SAUROLA, HARTO LINDÉN, and MARCUS WIKMAN. "Causes of Dispersal in Northern Goshawks (Accipiter Gentilis) in Finland." Auk 120, no. 3 (July 1, 2003): 706–16. http://dx.doi.org/10.1093/auk/120.3.706.
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Abstract Environmental quality has the potential to influence dispersal if cost of dispersing is outweighed by cost of staying. In that scenario, individuals experiencing different conditions in their natal area are expected to differ in their dispersal. Even if there is wide agreement that reasons behind the dispersal decision are multiple, it is often less clear what conditions actually add to the observed dispersal behavior. The scale at which the dispersal behavior is analyzed can also be of crucial importance for a correct understanding of the dispersal process. Furthermore, in long-lived species factors influencing dispersal behavior of juveniles may differ from those adding to dispersal of adults. Using 12 years of banding data (1989–2000), we studied dispersal behavior of Northern Goshawks (Accipiter gentilis) hatched over a wide area in Finland in relation to local demographic and ecological conditions. Hatching rank and hatching date added to the probability of leaving in the first place; whereas hatching date, local prey availability, and sex of the disperser were related to dispersal distance. Among adult birds (+3 years), none of the analyzed variables were related to distance; whereas the probability of remaining locally was related to local grouse density in the hatching year (for males only). Results show that the combined effects of factors working at several levels act together on dispersal behavior in Northern Goshawks and highlight the importance of studying different age classes separately in long-lived species. In summary, our results suggest that goshawk individuals distribute themselves spatially in parallel with factors determining the costs and advantages of dispersing where philopatry seems to be connected to factors positively associated with survival; but to test the validity of that idea, more data on fitness consequences of dispersal are needed.
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Chaves, C. L., A. M. Sebbenn, A. Baranoski, B. D. Goez, A. P. S. C. Gaino, C. F. Ruas, E. Ruas, and P. M. Ruas. "Gene dispersal via seeds and pollen and their effects on genetic structure in the facultative-apomictic Neotropical tree Aspidosperma polyneuron." Silvae Genetica 65, no. 2 (December 1, 2016): 46–57. http://dx.doi.org/10.1515/sg-2016-0016.
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Abstract Facultative apomictic trees can produce offspring with a genotype identical to the mother due to asexual propagation through the embryo derived from cells in the maternal ovule tissues. These trees can also produce offspring with a genotype different from the mother due to genetic recombination. For many trees, these reproductive processes remain largely unexplored. Herein, we use microsatellite markers to identify apomictic and sexual reproduction in samples of adult and juvenile trees of the tropical, insect pollinated and wind seed dispersed Aspidosperma polyneuron, within a conservation area in Brazil. We also investigate seed and pollen flow and dispersal patterns and compare the genetic diversity, inbreeding, and intrapopulation spatial genetic structure (SGS) between adults and juveniles in two plots. Our results show that the species present both apomictic and sexual reproduction. Sexual reproduction occurred mainly by outcrossing, but we did detect instances of self-fertilization and mating among relatives, which explains the inbreeding observed in juveniles. Seed dispersal distance was shorter than pollen dispersal distance in one of the plots, suggesting that insect vectors are more efficient in gene dispersal than wind for seed dispersal in a high density tropical forest. The patterns of pollen and seed dispersal showed isolation by distance, explaining the SGS detected for adults and juveniles. Our results show that both seed and pollen flow increase the allelic diversity in the population. The regeneration of apomictic individuals may guarantee the continuation of genotypes adapted specifically to the study site, while sexual reproduction results in new genotypes.
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Inanaga, Michiko, Atsushi Nakanishi, Takeshi Torimaru, Naoyuki Nishimura, and Nobuhiro Tomaru. "Distance-dependent but genetically random mating in a Japanese beech (Fagus crenata) population." Botany 92, no. 11 (November 2014): 795–803. http://dx.doi.org/10.1139/cjb-2014-0024.
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In plant populations, limited seed dispersal may generate the aggregation of related individuals, which is referred to as spatial genetic structure (SGS). If short-distance pollination frequently occurs in populations with SGS, it may lead to frequent mating between related individuals (biparental inbreeding). In this study, we examined patterns of pollen dispersal and inbreeding under such conditions in a population of the wind-pollinated tree species Fagus crenata Blume using microsatellite analyses of adult trees and dispersed seeds. The population showed weak but significant SGS and the pollen dispersal in the population involved a combination of distance-dependent (largely short-range) dispersion at the local scale and long-distance transport. Although SGS and distance-dependent pollination co-occurred, individual inbreeding coefficients for both adults and seeds were almost zero, suggesting that mating generating sound seeds was genetically random with little or no inbreeding, probably because of the weak SGS, long-distance pollen dispersal, and postpollination mechanisms including self-incompatibility and inbreeding depression. The production of sound seeds through genetically random mating may be important for maintaining F. crenata populations because the resulting seedlings may be less affected by inbreeding depression than those resulting from the mating of related individuals.
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Dique, David S., Jim Thompson, Harriet J. Preece, Deidré L. de Villiers, and Frank N. Carrick. "Dispersal patterns in a regional koala population in south-east Queensland." Wildlife Research 30, no. 3 (2003): 281. http://dx.doi.org/10.1071/wr02043.
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Koala dispersal was investigated as part of a detailed ecological study of a nationally significant koala population located 20 km south-east of Brisbane, Queensland. From 1996 to 2000, 195 koalas from three sites were captured and fitted with radio-collars. A total of 40 koalas (23 males and 17 females) dispersed from these sites. Most (93%) dispersing individuals were 20–36 months of age. Three adult females (more than 36 months old) dispersed and no adult males dispersed during the study. A significantly higher proportion of young males dispersed than females. Dispersal occurred between June and December, with most dispersal of males commencing in July and August and that of females commencing between September and November prior to, and early in, the annual breeding season. The mean straight-line distance between the natal and breeding home ranges for males and females was similar and was measured at 3.5 km (range 1.1–9.7 km) and 3.4 km (range 0.3–10.6 km) respectively. Dispersing males and females tended to successfully disperse south and west of their natal home ranges and were generally unable to successfully disperse to urban areas within the study area, as a high proportion of the mortality of dispersing koalas was associated with attacks by domestic dogs and with collisions with vehicles on roads. Information from other studies indicates that most young koalas disperse from their natal areas. It is likely that the social behaviour and mating systems of koala populations provide mechanisms for young koalas to disperse. The potential role of dispersal in the dynamics of regional koala populations is discussed.
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Young, Shawn P., and J. Jeffery Isely. "Posttournament Survival and Dispersal of Adult Striped Bass." North American Journal of Fisheries Management 26, no. 4 (November 2006): 1030–33. http://dx.doi.org/10.1577/m05-105.1.
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Eisenberg, R. M., L. E. Hurd, W. F. Fagan, K. J. Tilmon, W. E. Snyder, K. S. Vandersall, S. G. Datz, and J. D. Welch. "Adult Dispersal of Tenodera aridifolia sinensis (Mantodea: Mantidae)." Environmental Entomology 21, no. 2 (April 1, 1992): 350–53. http://dx.doi.org/10.1093/ee/21.2.350.
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Wickler, W., and U. Seibt. "Aerial dispersal by ballooning in adult Stegodyphus mimosarum." Naturwissenschaften 73, no. 10 (October 1986): 628–29. http://dx.doi.org/10.1007/bf00368783.
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van Hooff, Jan A. R. A. M., Erik P. Willems, Serge A. Wich, and Elizabeth H. M. Sterck. "Female dispersal, inbreeding avoidance and mate choice in Thomas langurs (Presbytis thomasi)." Behaviour 142, no. 7 (2005): 845–68. http://dx.doi.org/10.1163/1568539055010093.
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AbstractFemale social dispersal in primates differs from the general mammalian pattern of locational dispersal. Both nulliparous and parous females may disperse to another group. Several hypotheses can explain female social dispersal: reduction of predation risk, inbreeding avoidance, and offspring protection through mate choice. We tested these hypotheses with an extended data set of Thomas langurs (Presbytis thomasi) and investigated parameters of male behaviour that females may use in their dispersal decisions. Data were collected over a 12.5-year period from a wild population in Sumatra, Indonesia, allowing for some critical tests of the hypotheses. Females dispersed to a group smaller than their original one, thereby refuting the predation risk hypothesis. Maturing nulliparous females only dispersed when their father was resident. Therefore, dispersal by nulliparous females was best explained through inbreeding avoidance. Parous females transferred to young, adult males. These males provided better protection to offspring against predation and infanticide than the old, late tenure males. Therefore, females transfer to better protector males. The male behavioural cues that females use to assess male quality were unclear. Females, however, may use proxies of male age, such as group composition and acoustical characteristics of loud calls, as indicators of male quality. The results suggest that female mate choice is an important function of social dispersal by parous females. Its importance in locational dispersal remains to be investigated.
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Monzón-Argüello, C., F. Dell'Amico, P. Morinière, A. Marco, L. F. López-Jurado, Graeme C. Hays, Rebecca Scott, Robert Marsh, and Patricia L. M. Lee. "Lost at sea: genetic, oceanographic and meteorological evidence for storm-forced dispersal." Journal of The Royal Society Interface 9, no. 73 (February 8, 2012): 1725–32. http://dx.doi.org/10.1098/rsif.2011.0788.
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For many species, there is broad-scale dispersal of juvenile stages and/or long-distance migration of individuals and hence the processes that drive these various wide-ranging movements have important life-history consequences. Sea turtles are one of these paradigmatic long-distance travellers, with hatchlings thought to be dispersed by ocean currents and adults often shuttling between distant breeding and foraging grounds. Here, we use multi-disciplinary oceanographic, atmospheric and genetic mixed stock analyses to show that juvenile turtles are encountered ‘downstream’ at sites predicted by currents. However, in some cases, unusual occurrences of juveniles are more readily explained by storm events and we show that juvenile turtles may be displaced thousands of kilometres from their expected dispersal based on prevailing ocean currents. As such, storms may be a route by which unexpected areas are encountered by juveniles which may in turn shape adult migrations. Increased stormy weather predicted under climate change scenarios suggests an increasing role of storms in dispersal of sea turtles and other marine groups with life-stages near the ocean surface.
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Boudreau, S., and M. J. Lawes. "Density- and distance-dependent seedling survival in a ballistically dispersed subtropical tree species Philenoptera sutherlandii." Journal of Tropical Ecology 24, no. 1 (January 2008): 1–8. http://dx.doi.org/10.1017/s026646740700466x.
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Abstract:We examine the density- and distance-dependent seedling survival of Philenoptera sutherlandii, a common pod-bearing and dehiscent legume (Fabaceae) in Ongoye Forest, South Africa. Short-range ballistic dispersal causes seed to fall beneath the parent tree, where density- or distance-dependent mortality effects are expected to be concentrated. One hundred and eighty marked seedlings were monitored in a 0.5-ha plot containing 30 adults. Our survival data do not support the escape hypothesis. Predation levels declined with increasing seedling density (positive density-dependent survival), but seedling survival after 15 mo was not distance-dependent. Nevertheless, a unimodal (hump-shaped) recruitment curve, typically associated with decreasing seedling density and increasing seedling survival with distance, was observed. In the context of ballistic dispersal, this recruitment curve may indicate a hump-shaped dispersal kernel with predator satiation at high seedling densities near a parent tree. This recruitment curve likely arises because generalized insect seedling predators while attracted to the adult trees also tend to forage farther away. Short dispersal distances, in turn generate the high densities needed to satiate seed and seedling predators. Predator satiation results in long-term survival rates in P. sutherlandii similar to more widely dispersed and less common tree species.
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Bassetti, Stefano, Werner E. Bischoff, Mark Walter, Barbara A. Bassetti-Wyss, Lori Mason, Beth A. Reboussin, Ralph B. D'Agostino, Jack M. Gwaltney, Michael A. Pfaller, and Robert J. Sherertz. "Dispersal ofStaphylococcus aureusInto the Air Associated With a Rhinovirus Infection." Infection Control & Hospital Epidemiology 26, no. 2 (February 2005): 196–203. http://dx.doi.org/10.1086/502526.
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AbstractObjective:To determine whether healthy adult nasal carriers ofStaphylococcus aureuscan disperseS. aureusinto the air after rhinovirus infection.Design:We investigated the “cloud” phenomenon among adult nasal carriers ofS. aureusexperimentally infected with a rhinovirus. Eleven volunteers were studied for 16 days in an airtight chamber wearing street clothes, sterile garb, or sterile garb plus surgical mask; rhinovirus inoculation occurred on day 2. Daily quantitative air, nasal, and skin cultures forS. aureus; cold symptom assessment; and nasal rhinovirus cultures were performed.Setting:Wake Forest University School of Medicine, Winston-Salem, North Carolina.Participants:Wake Forest University undergraduate or graduate students who had persistent nasal carriage ofS. aureusfor 4 or 8 weeks.Results:After rhinovirus inoculation, dispersal ofS. aureusinto the air increased 2-fold with peak increases up to 34-fold. Independent predictors ofS. aureusdispersal included the time period after rhinovirus infection and wearing street clothes (P< .05). Wearing barrier garb but not a mask decreased dispersal ofS. aureusinto the air (P< .05).Conclusion:Virus-induced dispersal ofS. aureusinto the air may have an important role in the transmission ofS. aureusand other bacteria.
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Nyasani, Johnson O., Sevgan Subramanian, Benedict Orindi, Hans-Michael Poehling, and Rainer Meyhöfer. "Short range dispersal of western flower thrips in field-grown French beans in Kenya." International Journal of Tropical Insect Science 37, no. 02 (April 18, 2017): 79–88. http://dx.doi.org/10.1017/s1742758417000054.
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Abstract The short-range diurnal dispersal pattern of adult western flower thrips Frankliniella occidentalis (Pergande), in relation to spatial distribution of French beans, was determined in the field. A total of 1200 adult female F. occidentalis were released on 60 French bean plants with 20 adult thrips per plant at the central release point of 3.14 m2. Dispersal was determined in terms of the number of thrips recorded on French beans planted on concentric circles at 0.9, 1.8, 3.6, 7.2 and 14.4 m radii from a circular central release point for five days. Results indicated that there was a steady increase in the proportion of dispersing adult F. occidentalis from the first to the fourth day in the first planting season, and from the first to the third day in the second planting season. The peak hour for dispersal was 10.15 h in the first season while it was 13.15 h in the second season. Temperature and wind speed were positively associated with the dispersal activity of adult F. occidentalis. Minimal flight activity was at temperatures below 15 °C and peak flight activity was at 19 °C. The prevailing wind direction did not influence the dispersal pattern of adult F. occidentalis in both seasons. Adult F. occidentalis moved up to 7.2 m on French beans on the first day. In both seasons, the mean direction of thrips dispersal was mostly uniformly distributed (not oriented to a particular compass direction) around the central release point. The results provide an insight into developing integrated management strategies against the pest based on isolation of farm fields, management of alterative hosts around French bean fields and insecticide application.
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Proctor, Michael F., Bruce N. McLellan, Curtis Strobeck, and Robert M. R. Barclay. "Gender-specific dispersal distances of grizzly bears estimated by genetic analysis." Canadian Journal of Zoology 82, no. 7 (July 1, 2004): 1108–18. http://dx.doi.org/10.1139/z04-077.
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Natal dispersal is difficult to quantify, and long-distance events are often undetected, leading to biased estimates. Following offspring from their natal home range to their postdispersal adult breeding home range is challenging, and gathering sufficient data for large mammals with long generation times is particularly difficult. Here we measure average sex-specific dispersal distances in grizzly bears (Ursus arctos L., 1758) using individual-based genetic analysis. We genetically sampled and generated 15-locus microsatellite genotypes for 711 grizzly bears over a range of 100 000 km2 in southwestern Canada. Microsatellite markers are inherited in a Mendelian fashion, allowing us to use likelihood-based parentage analyses to estimate parent–offspring dyads. We used the distance between individually captured females of parent–offspring pairs (i.e., mother–daughter) to estimate female natal dispersal distances and found that, on average, females dispersed 14.3 km from the center of their natal home range. We used the distance between males of parent–offspring pairs (i.e., father–son) to estimate average male dispersal distances and found that males dispersed, on average, 41.9 km from their natal, or maternal, home range (mother–son dispersal distance). We used a simulation model to estimate the bias associated with measuring the father–son (male–male) distance as an estimate of the mother–son distance.
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Binns, Loren A., W. J. Loughry, Colleen M. McDonough, and Corey Devin Anderson. "Spatial genetic structure within a population of nine-banded armadillos in western Mississippi." Journal of Mammalogy 101, no. 1 (December 4, 2019): 143–50. http://dx.doi.org/10.1093/jmammal/gyz174.
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Abstract The nine-banded armadillo (Dasypus novemcinctus) is unique among mammals because females produce litters of genetically identical quadruplets via monozygotic polyembryony. This unusual form of reproduction could have profound impacts on the spatial genetic structure of populations of armadillos, but at present it is unclear whether littermates remain together as adults, or if sex-biased dispersal occurs. The goal of our study was to determine whether fine-scale spatial genetic structure (FSGS) within a population of armadillos diminishes with age (i.e., from juvenile to adult due to the dispersal of littermates away from one another), and if the degree of FSGS for a given age class differs between the sexes. We obtained genotype data at seven microsatellite DNA loci for 421 individuals in a wild population of armadillos inhabiting the Yazoo National Wildlife Refuge in western Mississippi. Correlogram analyses based on measures of spatial genetic autocorrelation showed weak but significant FSGS that was driven by positive spatial genetic autocorrelation among both male and female juveniles and adult males, but not adult females. Positive spatial genetic autocorrelation among adult males could be due to either female-biased dispersal or high variance in male reproductive success. Further work is required to discriminate between these two possibilities.
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Parsons, BC, JC Short, and MC Calver. "Evidence for male-biased dispersal in a reintroduced population of burrowing bettongs Bettongia lesueur at Heirisson Prong, Western Australia." Australian Mammalogy 24, no. 2 (2002): 219. http://dx.doi.org/10.1071/am02219.
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The pattern of dispersal of burrowing bettongs (Bettongia lesueur) was studied in a population reintroduced to a peninsula protected from exotic predators at Heirisson Prong in Shark Bay, Western Australia. The reintroduced population was growing strongly in numbers and expanding in area during the study. Young were first marked in the pouch and subsequently monitored by trapping and radio-telemetry after independence to establish their movements relative to those of their mothers. B. lesueur on Heirisson Prong dispersed between the ages of 170 and 250 days, coinciding with the period from weaning to sexual maturity. Dispersal was male-biased. Young males dispersed significantly further than young females with mean dispersal distances of 4600 m and 1100 m respectively. Male B. lesueur also frequented significantly more warrens than females, being located at a mean of 0.37 warrens per daily radio-tracking fix compared with a mean of 0.24 per fix for females. Scarring from intraspecific aggression occurred in male bettongs only. Males may disperse to the periphery of the population to escape aggressive interactions with established adult males and visit more warrens to increase mating opportunities. Dispersal in females may be related to resource quality or inbreeding avoidance.
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Ferron, J., and J. P. Ouellet. "Temporal and intersexual variations in the use of space with regard to social organization in the woodchuck (Marmota monax)." Canadian Journal of Zoology 67, no. 7 (July 1, 1989): 1642–49. http://dx.doi.org/10.1139/z89-235.
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The use of space by adult woodchucks (Marmota monax) in a field habitat has been studied by radiotracking. Results are analysed according to two periods, each lasting 50 days, preceding and following the onset of natal dispersal; within each period a finer analysis is performed on a 10-day basis. Variations in the use of space within a daily period are also analysed. The number of burrows used, the average distance between burrows successively occupied by the same animal, and home-range size are considered. During the period preceding natal dispersal, adult males are more mobile and have a larger home range than do females accompanied by young. During the period of natal dispersal, the pattern of space use is similar for adults of both sexes, females becoming less sedentary and males reducing their movements. The onset of natal dispersal is a major event affecting the pattern of space use by females accompanied by young. As hibernation approaches, there is a decrease in the amplitude of movements between burrows. Results also suggest that woodchucks are territorial. Comparison with other woodchuck populations reveals differences in social organization that may be related to population densities.
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O'Callaghan, M., and T. A. Jackson. "Adult grass grub dispersal of Serratia entomophila." Proceedings of the New Zealand Plant Protection Conference 46 (January 8, 1993): 235–36. http://dx.doi.org/10.30843/nzpp.1993.46.11138.
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SODE, ANNETTE, and PETER WIBERG-LARSEN. "Dispersal of adult Trichoptera at a Danish forest brook." Freshwater Biology 30, no. 3 (December 1993): 439–46. http://dx.doi.org/10.1111/j.1365-2427.1993.tb00827.x.
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Delettre, Yannick R., and Natahalie Morvan. "Dispersal of adult aquatic Chironomidae (Diptera) in agricultural landscapes." Freshwater Biology 44, no. 3 (July 2000): 399–411. http://dx.doi.org/10.1046/j.1365-2427.2000.00578.x.
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Knighton, James, Tanya Dapkey, and Jason Cruz. "Random walk modeling of adult Leuctra ferruginea (stonefly) dispersal." Ecological Informatics 19 (January 2014): 1–9. http://dx.doi.org/10.1016/j.ecoinf.2013.11.001.
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Pollock, Henry S., Evan C. Fricke, Evan M. Rehm, Martin Kastner, Nicole Suckow, Julie A. Savidge, and Haldre S. Rogers. "Såli (Micronesian starling – Aplonis opaca) as a key seed dispersal agent across a tropical archipelago." Journal of Tropical Ecology 36, no. 2 (January 17, 2020): 56–64. http://dx.doi.org/10.1017/s0266467419000361.
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AbstractSeed dispersal is an important ecological process that structures plant communities and influences ecosystem functioning. Loss of animal dispersers therefore poses a serious threat to forest ecosystems, particularly in the tropics where zoochory predominates. A prominent example is the near-total extinction of seed dispersers on the tropical island of Guam following the accidental introduction of the invasive brown tree snake (Boiga irregularis), negatively impacting seedling recruitment and forest regeneration. We investigated frugivory by a remnant population of Såli (Micronesian starling – Aplonis opaca) on Guam and two other island populations (Rota, Saipan) to evaluate their ecological role as a seed disperser in the Mariana archipelago. Using a combination of behavioural observations, nest contents and fecal samples, we documented frugivory of 37 plant species. Native plants comprised the majority (66%) of all species and 90% of all seeds identified in fecal and nest contents. Diet was highly similar across age classes and sampling years. In addition, plant species consumed by Såli comprised 88% of bird-dispersed adult trees and 54% of all adult trees in long-term forest monitoring plots, demonstrating the Såli’s broad diet and potential for restoring native forests. Overall, we provide the most comprehensive assessment to date of frugivory by the Såli and confirm its importance as a seed disperser on Guam and throughout the Marianas.
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Wilson, Michael, Laura Kruitbos, and Stuart Heritage. "Phoretic dispersal of entomopathogenic nematodes by Hylobius abietis." Nematology 11, no. 3 (2009): 419–27. http://dx.doi.org/10.1163/156854109x446999.
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AbstractPhoresis is a strategy in which one organism (the phoretic) attaches to another (the host) for the implied purpose of dispersal and is valuable for small flightless invertebrates with limited mobility. Previous work has shown that the relatively immobile larvae of Hylobius abietis (the large pine weevil) are highly susceptible to entomopathogenic nematodes (EPN) and support nematode reproduction whereas adults do not. Here, we demonstrate that the infective juveniles (IJ) of two species of EPN, Heterorhabditis megidis and Steinernema carpocapsae, can use the resistant but highly mobile adults of H. abietis for phoretic dispersal. The ability to use adult H. abietis for phoresis depended on nematode species and habitat (sand vs peat) and there was no evidence of sex-biased dispersal in S. carpocapsae for which the IJ are dioecious. We hypothesise that phoretic dispersal may be a significant mechanism to avoid sibling competition and inbreeding in EPN, which produce tens of thousands of offspring at point sources in a relatively impenetrable habitat.
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Cagáň, Ľ., and I. Rosca. "Seasonal dispersal of the Western corn rootworm (Diabrotica virgifera virgifera) adults in Bt and non-Bt maize fields." Plant Protection Science 48, Special Issue (December 12, 2012): S36—S42. http://dx.doi.org/10.17221/79/2012-pps.
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32 experimental plots were sown at Borovce (district Trnava) in Slovakia during 2008 with 8 maize hybrids, including coleopteran-protected MON 88017, the lepidopteran-protected MON 89034, the stacked product, MON 89034 × MON 88017, that same hybrids isoline that did not have the Bt trait or traits, and 4 commercial hybrids. Part of the fourth repetition was unexpectedly infested and damaged with the Western corn rootworm (WCR). High numbers of the WCR adults were found in the damaged plots on July 8. Adult WCR abundance remained concentrated in this area until August 12–19. The beetles apparently began to disperse during August 19–September 2, and after September 2. The trap captures increased in the uninfested areas up to September 16, no significant difference having been found in the adult WCR captures between the infested and uninfested plots, including the plots with MON 88017. Bt-maize hybrids containing MON 88017 strongly influenced the level of the WCR damage as assessed by lodging of the maize plants, and they also influenced the numbers of the WCR adults before maize flowering. We found that intensive movement of the WCR adults from the place of their origin started later in the vegetation season.
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Stow, A. J., N. Minarovic, J. Eymann, D. W. Cooper, and L. S. Webley. "Genetic structure infers generally high philopatry and male-biased dispersal of brushtail possums (Trichosurus vulpecula) in urban Australia." Wildlife Research 33, no. 5 (2006): 409. http://dx.doi.org/10.1071/wr06019.
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The brushtail possum (Trichosurus vulpecula) is in decline throughout much of its natural range with the notable exception of urban areas and a few islands. In some urban areas, its density can be high enough to cause conflict with householders. We provide the first genetic-based study of dispersal for T. vulpecula in the urban environment. Seven microsatellite markers were used to investigate genetic structure of adult male (n = 53) and female (n = 39) possums sampled from mainland suburbs of Sydney, and on nearby Scotland Island. Samples from Scotland Island also provide an opportunity to assess the effect of isolation on genetic variability, which, as theory would predict, was significantly lower than observed in mainland samples. Male-biased dispersal was inferred from patterns of relatedness between individuals of each sex. Average relatedness was significantly higher between adult female possums than between adult male possums sampled within the same garden area. In addition, males were genotypically more similar to one another at substantially greater geographic distances than females. Along with male-biased dispersal, strong localised genetic structure for both sexes infers generally high philopatry. Dispersal distances were greatest for adult male possums sampled from mainland locations. However, even for these males, genotypic similarity between possums separated by distances further than ~900 m was lower than the sample average, suggesting infrequent dispersal beyond this distance. Knowledge of dispersal patterns is important to managing the density levels of overabundant T. vulpecula in urban areas.
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Rhainds, Marc, and Les Shipp. "Dispersal of adult western flower thrips (Thysanoptera: Thripidae) in greenhouse crops." Canadian Entomologist 136, no. 2 (April 2004): 241–54. http://dx.doi.org/10.4039/n03-028.
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AbstractThis study characterized the spatial distribution of adult western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), released at the centres of greenhouses stocked with either cucumber (Cucumis sativus L. (Cucurbitaceae)) or chrysanthemum (Dendranthema grandiflora (Tzelev) (Asteraceae)) plants. Experiments conducted using either adults marked with fluorescent powder or unmarked adults revealed that the density of females per plant decreased as an inverse function of the distance from the release point. Inverse regression models with steep decreases in density over small distances may commonly describe the dispersal behaviour of insects that have limited flight capacity and settle on the first plants that they encounter. Females were found on plants farther from the release point as time elapsed, dispersing throughout the greenhouse at an average rate of 0.18 to 0.29 m per day. Distinct sex ratios for adults captured on sticky cards or sampled on host plants suggested that males and females exhibit different dispersal behaviours. The spatial distribution of F. occidentalis varied across generations, with females exhibiting a lower level of aggregation around the release site than their nymphal progeny. The average rate of spread between consecutive generations fluctuated between 0.05 and 0.17 m per day. Considering the limited dispersal of F. occidentalis, outbreaks may be effectively suppressed by applying insecticides or releasing natural enemies in relatively small concentric areas surrounding heavily infested plants, as well as near the edges of greenhouses.
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Naranjo, Steven E., and Alan J. Sawyer. "A SIMULATION MODEL OF NORTHERN CORN ROOTWORM, DIABROTICA BARBERI SMITH AND LAWRENCE (COLEOPTERA: CHRYSOMELIDAE), POPULATION DYNAMICS AND OVIPOSITION: SIGNIFICANCE OF HOST PLANT PHENOLOGY." Canadian Entomologist 121, no. 2 (February 1989): 169–91. http://dx.doi.org/10.4039/ent121169-2.
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AbstractBased on field and laboratory research, a simulation model was developed that describes the within-season population dynamics and oviposition of adult northern corn rootworm beetles, Diabrotica barberi Smith and Lawrence, in field corn, Zea mays L. Particular emphasis was placed on the role of host plant phenology. Overall goals were to examine the contribution of insect dispersal to the dynamics of single fields, and provide a means of examining the factors influencing insect/plant synchrony and the relationship between adult abundance, oviposition, and crop phenology. The model is process-oriented and integrates component models for corn phenology, and adult emergence, mortality, dispersal, reproductive development, and oviposition.Comparison of field data with simulations excluding dispersal generally indicated a net emigration of beetles from corn fields on a season-long basis; however, the timing and magnitude of dispersal from fields were strongly influenced by the relative timing of corn flowering, beetle sex, and the reproductive maturity of females. Simulation and field data were used to describe and estimate the parameters of a component model for dispersal incorporating these features. Various component models and the overall system model were validated against independent field data. The model provided adequate prediction of adult emergence and crop phenology for three varieties on which it was based, but consistently underpredicted total oviposition and poorly predicted the phenology of two different corn varieties. Overall, the model accurately predicted seasonal population trends, the relative abundance of mature females, and the relationship between adult abundance and oviposition.
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Coates-Estrada, Rosamond, and Alejandro Estrada. "Frugivory and seed dispersal in Cymbopetalum baillonii (Annonaceae) at Los Tuxtlas, Mexico." Journal of Tropical Ecology 4, no. 2 (May 1988): 157–72. http://dx.doi.org/10.1017/s0266467400002650.
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ABSTRACTFruit production, frugivore foraging activity and seed dispersal was studied at 10 Cymbopetalum baillonii (Annonaceae) trees during an entire fruiting season. Fruits dehisced during the first six months of the year offer to potential dispersal agents a package of 8–24 arillate seeds. Insects and fungi, however, killed up to 14% of the seeds potentially available for dispersal before fruit dehiscence. Visitation by 24 species of birds and one mammal to the trees closely followed the availability of arillate seeds. The foraging activity of Peromyscus and Heteromys rodents accounted for ≥ 80% mortality of the seeds deposited under the crown of the parent tree. Among those seedlings that became established under the crown mortality was ≥ 90% after 12 months. Seeds dispersed under conspecific fruiting trees experienced intense predation by vertebrates. Field experiments showed that seeds and seedlings planted ≥ 30 m away from adult trees survived significantly longer than those planted under the crown and at distances ≤ 30 m. An unequivocal advantage to dispersal away from the tree and under allospecific trees was evident from the data. A very narrow range of frugivores (N = 8 species) accounted for the quality component of dispersal services to the trees. The tree with the lowest animal visitation and fruit crop was the most efficient in the dispersal of its seeds.
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Jung, Chuleui, and Brian A. Croft. "Aerial dispersal of phytoseiid mites (Acari: Phytoseiidae): estimating falling speed and dispersal distance of adult females." Oikos 94, no. 1 (July 2001): 182–90. http://dx.doi.org/10.1034/j.1600-0706.2001.11044.x.
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Eriksson, Ove. "Ontogenetic niche shifts and their implications for recruitment in three clonal Vaccinium shrubs: Vaccinium myrtillus, Vaccinium vitis-idaea, and Vaccinium oxycoccos." Canadian Journal of Botany 80, no. 6 (June 1, 2002): 635–41. http://dx.doi.org/10.1139/b02-044.
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Ontogenetic niche shifts, i.e., changes in niche breadth and (or) position during the life of individuals, have received rather limited attention in plant ecology. An experiment was designed to assess ontogenetic niche shifts in three clonal Vaccinium shrubs in order to examine their recruitment behavior. Seeds were sown, and juveniles transplanted, at sites along a gradient of changing occurrence of the three species. Recruitment was seed limited, varied among sites, and was correlated with juvenile survivorship. No niche shift occurred during seed to seedling stages for any of the plants. For Vaccinium myrtillus L., recruitment was not related to adult occurrence, whereas for Vaccinium oxycoccos L., recruitment was highest at the site where adults dominated. However, for both of these species, recruitment also occurred outside the range of adult occurrence. Vaccinium vitis-idaea L. exhibited a negative relationship between adult occurrence and recruitment and between adult occurrence and juvenile survivorship, indicating an ontogenetic niche shift. For V. myrtillus the results suggested an uncoupling of niche requirements of juvenile and adult stages, whereas for V. oxycoccos the results suggested a niche contraction towards the requirements for adults. Thus, the form of ontogenetic niche shifts differs among the species. These differences in niche shifts contribute to understanding dispersal and recruitment behavior of the species.Key words: clonal plants, dispersal, niche shifts, recruitment.
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Melo, Felipe P. L., Esteban Martínez-Salas, Julieta Benítez-Malvido, and Gerardo Ceballos. "Forest fragmentation reduces recruitment of large-seeded tree species in a semi-deciduous tropical forest of southern Mexico." Journal of Tropical Ecology 26, no. 1 (December 8, 2009): 35–43. http://dx.doi.org/10.1017/s0266467409990435.
Full textAbstract:
Abstract:This study tested whether the reduction in the number of large-bodied seed dispersers is correlated with shifts in the taxonomic and functional (e.g. dispersal mode and seed size) traits of the seeding communities within small fragments of semi-deciduous forest, southern Mexico. In five fragments (2.3–640 ha) and one continuous forest site we sampled tree and seedling species in 40 (20 × 20 m) and 120 (3 × 3 m) plots respectively, and recorded the incidence (presence/absence) of the disperser fauna (three common large-birds and >500-g mammals). Tree and seedling species were categorized according to dispersal mode, seed size and whether they originated from local (i.e. from dropped) or immigrant (i.e. from actively dispersed) seeds. Fragment size negatively correlated with number of species of medium to large vertebrate seed-dispersers and number of seedlings of large-seeded species, but had no influence on functional traits of the adult-tree community. Between 41% and 61% of all seedlings were considered as immigrants and the proportion of immigrant seedlings of large-seeded tree species was negatively correlated with forest size. The results suggest that biased defaunation in small forest fragments may seriously reduce recruitment of large-seeded tree species (>1.4 cm length) dispersed by vertebrates, negatively affecting successional trajectories of small forest fragments.