Rozprawy doktorskie na temat „Mating tactics”

Bitterling are a group of freshwater fishes that lay their eggs on the gills of living freshwater mussels, using the mussel as a protective environment for embryo development and utilising the mussels own respiration to ensure fertilisation. This unusual spawning mechanism, using a spawning site that can be easily manipulated, makes bitterling ideal of reinvestigating sperm competition and making system evolution. Here, using a range of bitterling species, a series of aquarium experiments were conducted, as well as morphological and histological studies of the sperm and testes. It was shown that males were highly sensitive to sperm competition, ejaculating at a higher frequency and subsequently becoming more sperm depleted where sperm competition was high. There were few differences between mating tactics except in relative testis size, where larger males had proportionally larger reproductive apparatus, but ejaculates were of a similar size. The timing of ejaculates was found to be crucial, with a peak in sperm concentration within the mussel mantle cavity 30 seconds after ejaculation. The spatial clustering of fertilisation opportunities and OSR were found to affect ejaculate frequency, ejaculate distribution among mussels, the dominance of gender males and subsequently the opportunity of subordinate males to sneak fertilisations. Significant differences in the spermatogenic strategy and the structure of the reproductive apparatus among species were identified, as well as significant differences between species in the morphology of spermatozoa.

The aim of this study was to investigate the basis to male mating decisions in two related species of bitterling: Rhodeus ocellatus and R. amarus. Bitterling have a resource-based mating system; females lay eggs in the gills of live freshwater mussels and males fertilize the eggs by releasing sperm into the inhalant syphon of the mussel. Male bitterling perform courtship behaviour and aggressively defend mussels in a territory from which they exclude other males. Using laboratory and field experiments it was shown that male aggressive behaviour is inherited through additive maternal genes. Male aggression is also influenced by the number of conspecific males encountered in competition for a mussel, and by the degree of clustering of mussels. Limited availability of mussels results in stronger selection on traits males use in mating context: hence they are more aggressive, larger and more colourful. The differences in mating behaviours in different environments may indicate a conflict between male dominance and female choice, but have not led to reproductive isolation. Resource availability during ontogenesis and male density during embryogenesis, however, do not exert an effect on male aggressive behaviour. Red carotenoid-based nuptial coloration functions as an inter- and intra-sexual signal and undergoes rapid variation in response to changes in mating context. Male bitterling do not modulate their courtship and aggressive behaviour in response to variation in female size, and their choice of mussel species is influenced by, and consistent with, female oviposition choice.

Polygyny is the most common mating system in mammalian species (95%), yet our understanding of polygynous systems and microevolutionary processes is still limited. Pinniped mating systems range from extreme polygyny (e.g. elephant seals) to sequential female defence by males and hence have often been used as models for mating system studies. Parentage analysis has enabled the examination of mating success, the identification of pedigrees, and the elucidation of social organisation, greatly enhancing our understanding of mating systems (Chapter 1). However, such analyses are not without pitfalls, with erroneous assignments common in open systems (i.e. when parental and offspring samplings are incomplete). We investigated the effects of the user-defined parameters on the accuracy of parental assignment using two commonly used parental allocation programme, CERVUS and PASOS (Chapter 2). We showed that inaccurate user-defined parameters in CERVUS and PASOS can lead to highly biased output e.g. the assignment rate at 95% CL of offspring with a sampled known mother to sampled males decreased from 58% to 32% when the proportion of candidate males sampled in the parameter options decreasing 4-fold. We found that the use of both CERVUS and PASOS for parentage assignment can increase the likelihood of correctly allocating offspring to sampled parents to 97% in our study system. Incorrect parental assignment can bias estimates of various biological parameters, such as lifetime reproductive success and mate choice preference, and hence bias ecological and evolutionary interpretations. Here, we propose solutions to increase the power of parentage assignment and hence decrease the bias in biological parameter estimates. In addition, we analysed the effects of the intrinsic bias in likelihood assignment approaches towards assigning higher probability of parentage on individuals with rare alleles and those with heightened offspring-parent matches, which increase with the number of homozygous loci (Chapter 3). We showed that, as a consequence of the algorithms employed in the programmes CERVUS and PASOS, heterozygote males with rare genotypes are assigned higher rates of parentage than males with common alleles. Consequently, where two males could both be biological fathers of a given offspring, parentage assignment will more often go to the male with the rarer alleles (most often in heterozygous loci). Thus, the commonly used parentage assignment methods may systematically bias the results of parentage analyses towards supporting the notion that females prefer more genetically unusual, most often heterozygous, males. Such a bias may sway investigators towards incorrectly supporting the concept that females choose genetically more unusual males for heterozygosity fitness benefits that underpin the good genes hypothesis, when in fact no such relationship may exist. In polygynous mammals, successful males mate with multiple females by competing with and limiting the access of other males to females. When the status of many males (age, size, health, genetic etc.) prevents them from achieving the primary mating tactic, theory predicts selection for a diversification of male mating tactics. Recent studies in pinnipeds have shown that observed male mating success was correlated to male paternity success in some species (elephant-seals), but not in others (grey seals). The existence of alternative mating strategies can explain those discrepancies. Chapter 4 implemented the guidelines provided in Chapter 2 and 3 and focused on the polygynous New Zealand fur seal Arctocephalus forsteri, predicting that 1) competition for females is likely to cause a diversification of male mating tactics; and 2) that alternative tactics can yield reproductive success. Our results indicated three male behavioural profiles; one corresponded to large territorial males and two illustrated a continuum of alternative tactics employed by non-territorial subordinate males. Our study highlights that holding a territory is not a necessary condition for reproductive success in a population of otariids. The degree of sexual size dimorphism in polygynous species is expected to increase with the degree of intra-sexual competition and in turn with the degree of polygyny. The life history of an individual is the pattern of resource allocations to growth, maintenance, and reproduction throughout its lifetime. Both females and males incur viability costs of mating and reproduction. However, male viability costs due to increase growth and male-male competition can be greater than female viability costs of mate choice and reproduction. Although an abundant literature on sexual dimorphism in morphology, physiology, and parasite infections is available, little is known on the intra-sexual differences in physiology and parasite infections associated to the reproductive success of different mating strategies in mammalian species. Chapter 5 examined the reproductive costs between territorial and subordinate males New Zealand fur seal related to their relative reproductive success using a multidisciplinary approach (behaviour, genetics, endocrinology, parasitology). We found that dominant New Zealand fur seal males endure higher reproductive costs due to the direct and indirect effects of high testosterone levels and parasite burdens. Our study highlights that holding a territory confers a higher reproductive success, but induces higher costs of reproduction that may impair survival. Understanding microevolutionary processes associated to polygynous systems is fundamental in light of the ongoing anthropogenic alteration of the environment through climatic variations and habitat reduction which ultimately affect opportunity for sexual selection and shape the life history trade-offs.

The processes and mechanisms that govern brain size evolution remain a widely discussed topic in evolutionary biology. How relative brain size relates to animal behaviour and cognition is even more controversial. Recent comparative and experimental studies have shown a positive relationship between relative brain size and complexity of behaviour. Some of the most important behaviours that have direct consequences for an individual’s fitness are reproductive behaviours, and they sometimes require quite complex behavioural repertoires. Selection for complex behaviour might therefore induce an expansion of brain size to allow for cognitively demanding tasks during courtship and mating. In the present study we investigated the effect of relative brain size on reproductive behaviour in male guppies (Poecilia reticulata), using fish from a recently established brain size artificial selection experiment. Females were paired with either a large- or a small-brained male, and we collected data on a suite of male courtship behaviours including sneak copulation attempts, courtship display, gonopodial swings and time spent following the female. Although the extent of orange colouration, a trait that varies across large- and small-brained males, affected male behaviour, we were not able to detect any difference in reproductive behaviour between the brain size selection lines. These results suggest that there is no strong association between male mating behaviour and relative brain size, and future studies will examine this question further. But currently, our results indicate that relative brain size might not be linked to reproductive behaviour to any significant extent, at least not in the guppy.

In meiner Dissertation untersuche ich das Paarungs- und Fortpflanzungsverhalten des Europäischen Grasfrosches (Rana temporaria) in einem evolutionären Kontext. Mein Ziel ist es zu verstehen, welche Mechanismen zur Bildung von Paaren führen, ob die Partnerwahl die Paarungsmuster erklärt, die wir beobachten können, und ob es evolutive Vorteile gibt, die sich aus der Paarung mit einem bestimmten Partner ergeben. Die Suche nach und die Konkurrenz um Paarungspartner führt zur Entwicklung verschiedener Paarungssysteme, Strategien und Taktiken, um den Reproduktionserfolg während der gesamten Lebensdauer zu erhöhen. Das Paarungsverhalten wird durch natürliche und sexuelle Selektion beeinflusst, wobei beide in unterschiedliche Richtungen wirken können. Für die meisten Individuen ist das Überleben unerlässlich, um sich so oft wie möglich zu reproduzieren, und dadurch die reproduktive Gesamtfitness zu erhöhen. Andererseits könnte ein auffälliges Verhalten bei der Fortpflanzung das Prädationsrisiko erhöhen. Der Akt der Paarung selbst kann bereits mit Risiken verbunden sein, welche sich auf die Überlebensraten auswirken können. Durch sexuelle Selektion könnten bestimmte sekundäre Geschlechtsmerkmale begünstigt werden, entweder aufgrund von Vorteilen im Wettbewerb innerhalb eines Geschlechts (intrasexuell), oder aufgrund spezifischer Präferenzen zwischen den Geschlechtern (intersexuelle Selektion). Damit sich die Partnerwahl entwickeln kann, muss der gewählte Paarungspartner Vorteile aufweisen, von denen der wählende Partner profitiert, denn die Wahl ist mit energetischen Kosten und zeitlichem Aufwand verbunden. Als Frühlaicher muss der Europäische Grasfrosch mit einem eingeschränktem Paarungszeitraum umgehen. Die Männchen konkurrieren um den Zugang zu Weibchen und es wird angenommen, dass sich Weibchen während der Paarung und Reproduktion passiv verhalten, da der hohe "Männchen-Überschuss" keine Wahl zulassen würde. Aus evolutionärer Sicht sollten Weibchen jedoch das wählerische Geschlecht sein und entscheiden mit wem sie sich paaren, da sie mehr Energie in die Eierproduktion investieren.
In my thesis, I examine the mating and reproductive behaviour of the European Common Frog (Rana temporaria) in an evolutionary context. I aim to understand which mechanisms lead to the formation of pairs, if mate choice shapes the patterns of mating that we can observe and if there are benefits derived from pairing with a specific mate. The search and competition for mating partners lead to the evolution of various mating systems, strategies and tactics to increase lifetime reproductive success. The mating behaviour is influenced by natural and sexual selection, whereby both could act in different directions. For most individuals, survival is essential in order to reproduce as often as possible to increase lifetime reproductive fitness. On the other hand, reproduction could increase predation risk due to conspicuous behaviour and risks associated with mating itself. Sexual selection could favour specific secondary sexual traits, either due to advantages in intrasexual competition, or by specific preferences of the choosy sex (intersexual selection). For mate choice to evolve, there need to be benefits associated with the chosen mating partner, because choosiness involves costs in terms of energy and time constraints during mating. As an explosive breeder, the European Common Frog has to deal with time constraints during the short breeding season. The males are competing for the access to females and it is assumed that females are passive during breeding due to a high male-biased operational sex ratio. However, from an evolutionary perspective females should be the choosy sex and should decide with whom to mate, as they invest more energy into the production of eggs.

The availability of reproductive sites is a major factor shaping the behavior of males and females in species with resource-based mating systems. Using a meta-analytic approach, we tested five predictions directly or indirectly derived from the mating system theory. We expected that reproductive site limitation would lead to: (1) intense male-male competition for resource possession; (2) high variance in male reproductive success, generating high values of opportunity for sexual selection; (3) high intensity of selection on male traits related to resource possession; (4) high sperm competition risk; and (5) low quality of paternal care. We compiled information from observational and experimental studies that compared the reproductive behavior of individuals of the same species under low and high reproductive site limitation. We found that, when reproductive sites are limited, there is a slight increase in male-male competition, with higher rates of nest takeover and agonistic interactions, and a slight increase in the selection gradient on male traits, with successful males tending to be larger than unsuccessful males. Reproductive site limitation has no consistent effect on the opportunity for sexual selection and on the sperm competition risk. However, territorial males invest more in gonads and lose less paternity when reproductive sites are limited. There is also no clear effect of reproductive site limitation on the quality of paternal care, but few studies have addressed this subject. Taken together, our findings indicate that predictions on how reproductive site limitation affects several aspects of resource-based mating systems have weak empirical support. These predictions do not consider the plasticity in the mating tactics of males and females, which make them too simplistic. Moreover, since the original proposition of the mating system theory, our understanding of sperm competition increased a lot. We now know that accurate predictions on the intensity and direction of sexual selection should take into account both pre- and post-copulatory processes. Finally, the interplay between sexual selection and parental care is complex, and the original framework of mating system theory does not provide sufficient elements to derive clear and taxonomically broad predictions
A disponibilidade de sítios reprodutivos influencia tanto o comportamento de machos quanto de fêmeas em espécies cujo sistema de acasalamento depende da defesa de recursos. Usando uma abordagem meta-analítica, testamos cinco previsões direta ou indiretamente relacionadas à teoria de sistemas de acasalamento. Esperávamos que a limitação de sítios reprodutivos promoveria: (1) aumento na competição masculina pela posse de recursos; (2) aumento na variância do sucesso reprodutivo dos machos, gerando valores alto de oportunidade para a seleção sexual; (3) aumento da intensidade da seleção sobre características masculinas relacionadas à posse de recursos; (4) aumento no risco de competição espermática e (5) diminuição da qualidade do cuidado paternal. Compilamos informações de estudos observacionais e experimentais que compararam o comportamento reprodutivo de indivíduos da mesma espécie em situação de alta e baixa disponibilidade de sítios reprodutivos. Encontramos que, quando os sítios reprodutivos são escassos, há um ligeiro aumento na competição masculina, com maiores taxas de roubo de ninhos e interações agonísticas, e um ligeiro aumento no gradiente de seleção sobre características masculinas, com machos bem sucedidos tendendo a ser maiores do que machos mal sucedidos em monopolizar recursos. A disponibilidade de sítios reprodutivos não teve nenhum efeito consistente sobre a oportunidade para a seleção sexual e o risco de competição espermática. Entretanto, machos territoriais investiram mais em gônadas e perderam menos paternidade quando os sítios reprodutivos eram escassos. Não encontramos nenhum efeito da disponibilidade de sítios reprodutivos sobre a qualidade do cuidado paternal. Em conjunto, nossos resultados indicam que as previsões sobre como a disponibilidade de sítios reprodutivos influencia diversos aspectos de sistemas de acasalamento baseados na defesa de recursos têm fraco respaldo empírico. Tais previsões não consideram a plasticidade nas táticas de acasalamento de machos e fêmeas, tornando-as demasiadamente simplistas. Adicionalmente, desde a formulação original da teoria de sistemas de acasalamento, nossa compreensão sobre competição espermática aumentou. Sabemos atualmente que previsões acuradas sobre a intensidade e direção da seleção sexual devem levar em consideração processos pré- e pós-copulatórios. Finalmente, a interconexão entre seleção sexual e cuidado parental é complexa e a teoria original de sistemas de acasalamento não provê elementos suficientes para a construção de previsões claras e de amplo escopo taxonômico

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Bachelors
Sciences
Psychology

In a territorial population of pronghorn from Antelope Island, UT, interaction between male dominance and territory defense was examined. High-ranking males were more likely to defend territories. Closely ranked animals engaged in more dominance interactions than distantly ranked individuals, and middle-ranked animals were involved in disproportionately more interactions than either high- or low-ranking animals. Large males possessed large horns and prongs as well as small cheek patches. Results from a factor analysis suggested that large males defended territories with a high density of sage. However, in this study, we did not observe pronghorn feed on sage during the territorial season. Though male pronghorn practiced resource defense polygyny, large, dominant males did not defend territories with a high density of green vegetation or green forbs. Large males appeared to defend territories with low visibility. In 1996, intruders entered areas that contained females throughout the territorial season. During the next year, highly visible, small territories received the most intrusions. Together, these observations suggest defense of tactical locations. Defending a tactical location may help females avoid harassment and males hide the presence of females. Different populations of pronghorn practice different mating systems. To understand this variation, we examined the behavior patterns/rates of individual territorial and bachelor males. The highest rates of activity and behavior patterns occurred in March/April and in September. Territorial males cheek rubbed at a higher rate than bachelors. Territorial males were more active and SPUD (sniff, paw, urinate, and defecate) marked at a higher rate than bachelor males in 1996. After the formation of a bachelor herd in 1997, bachelor males showed higher rates of male-male interactions than territorial males. Territorial males maintained the same activity and behavioral rates in the presence and absence of females. Dispersion pattern of scent marks was more clumped in the presence of females. These findings suggest cheek rubs function more as a space-claiming behavior while SPUD marking is more strongly associated with male-male interactions. Comparison to male behavior in nonterritorial populations indicates that the behavioral mechanisms are present in all populations to accommodate shifts in social systems.

This thesis contains introduction to the principles of dynamic plantography and it´s clinical application. Afterwards it is described feet anatomy, types of feet arch and human walking process. Next part describes principles of various types of tactile sensors and electrical platform Arduino. Most important part of this thesis is focused on teoretical design of device and it’s practical realization. The last part of diploma thesis is devoted to discussion of parameters of the device and to results of measuring of group of volunteers.

Arctic ground squirrels are the northernmost hibernating mammal and they live in an extremely harsh and unpredictable environment with a short growing season. This environment has the potential to exert strong selection pressure on life-history traits and behaviour. I studied arctic ground squirrels living at high elevation in alpine tundra in Southwest Yukon in order to answer 5 main questions: (1) How do changes in elevation and associated habitat affect demography of arctic ground squirrels? (2) What is the fate of adult males that disappear at very high rates from local populations? (3) What factors are correlated with an individual's probability of death and dispersal?, (4) What factors are correlated with a male's reproductive tactic and success?, and (5) Why do adult males disperse? Female arctic ground squirrels living at high elevation in the alpine had higher reproductive output and survival during the active season, but lower survival over winter, than their counterparts living at lower elevation in the boreal forest. A demographic model indicated that the forest was sink habitat (λ < 1) but that the alpine habitat maintained a ground squirrel population in the absence of immigration (λ ≥ 1). Adult males had two peak periods of disappearance during the active season - late in the mating season, caused by mortality, and around the time of juvenile emergence, caused by dispersal. Age was an important predictor of both mating season and winter survival, with older (≥ 2 years old) males having a lower survival rate than yearlings. Age may also have played a key role in the mating and dispersal tactics of adult males. Older males invested more energy into reproduction than yearlings, and the reasons why yearlings and older males disperse differed. Older males may have dispersed to avoid mating with their daughters, to increase their access to mates, or to increase their access to unrelated mates, but yearlings appeared to disperse for other reasons. I combined the results of my study and previous studies in a conceptual model relating mating tactics, natal and breeding dispersal, and survival in male arctic ground squirrels. This model provides testable hypotheses about casual relationships among variables.

Darwin identified sexual selection as an important evolutionary process resulting from differences among males in their ability to secure mates. In the latter half of the 20th century, it became apparent that females often mate with multiple partners within the same reproductive cycle, leading to the overlap of ejaculates from multiple males and sperm competition for the fertilization of the eggs. Here, I examine how sperm competition has influenced the evolution of Xiphophorus nigrensis, an internally fertilized, livebearing fish with alternative male mating tactics that are dependent upon male size. I find that variation in male tactic is correlated with variation in traits relevant to sperm competition: small males that sneak copulations produce ejaculates with a greater proportion of fertilization-capable sperm (sperm viability) and sperm that is longer-lived following activation compared to large males that court females. Sperm morphology is also divergent between tactics and correlated with sperm performance: smaller males have larger midpieces and midpiece size is positively correlated with sperm velocity and longevity. Social environment also affects ejaculate quality, with sperm velocity rapidly increasing when a small male is exposed to another small male compared to when he is exposed to a large male. Large male ejaculates were invariant across social environments. Next, I demonstrate experimentally that the observed variation in sperm quality has important consequences for the outcome of sperm competition. Males with superior sperm viability sire more offspring, while sperm velocity is negatively associated with sperm competitive ability when sperm are stored within the female prior to fertilization. Finally, I show that sperm competition is likely to have important effects on male reproductive success in the wild by characterizing the genetic mating system of X. nigrensis. I find that 61% of females collected from the Nacimiento Río Choy produce offspring sired by 2-4 males. Paternity is strongly skewed among sires, with an average of 70% of offspring sired by one of the males represented in the brood. These studies illustrate sperm competition can have potent effects on the evolution of animals.
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碩士
東海大學
生命科學系
100
To achieve mating success, animals may use more than one tactic to gain mating opportunities. The chosen tactic may depend on the resources abundance, body size, and population density. There are at least two reproductive tactics in fiddler crabs including underground mating and surface mating. In several previous studies, predation risk, food availability population density, plant coverage and body size were proposed to be important to the mating tactics of fiddler crabs. Among these factors, predation risk and population density were shown to affect the mating tactics. Uca lactea lives at the higher intertidal zone where food supplement is unstable. This species is suitable for testing the food effect. Second, although it was reported that the degree of ovary maturity influence the mating behavior of fiddler crabs, it is not known whether they also affect the mating tactics of crabs. The aim of the present study is to test the effects of these two factors on the mating tactics in U. lactea. In the first part, I changed the food level in the habitat of U. lactea and analyzed the behavior of crab by the digital video. To test the effects of ovary maturity on mating tactics, I measured the ovary index of crabs of different behavior. My results assured that the mating tactics of both sexes were affected by food availability. When food is more abundant, a reproductive male tends to build semidome, waves claw to females, and constructs larger burrow, while a reproductive female tends to leave her burrow to search for mates. In conclusion, both food availability and ovary maturity affect the decision of mating tactics in U. lactea.

The aim of this investigation was to determine whether there is a significant difference in the academic achievement of sixth grade Science students when teaching styles are matched to their learning styles. The research problem is encompassed in the following question: "Is there a relationship between matching teaching and learning styles and the academic success in Science?" A quantitative approach was undertaken, specifically, the pretest-posttest control group experimental design. The population comprised of sixth grade students selected according to a non-probability sampling method of convenience. The sample comprised of two class units randomly selected. The dependent sample t-test inferential statistic was used to analyze the data collected. The results indicated a statistically significant difference between the pretest and posttest scores of the experimental group. The conclusion reached is that matching teaching styles to learning styles improves the academic success of sixth grade learners in Science.
Educational Studies
M.Ed. (Educational Psychology)