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Journal articles on the topic 'Sex determination of birds'
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Trukhina, Antonina V., and Aleksandr F. Smirnov. "Problems of Birds Sex Determination." Natural Science 06, no. 15 (2014): 1232–40. http://dx.doi.org/10.4236/ns.2014.615111.
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Eaton, T. "Sex determination of monomorphic birds." Veterinary Record 116, no. 2 (January 12, 1985): 58. http://dx.doi.org/10.1136/vr.116.2.58.
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Vucicevic, Milos, Jevrosima Stevanovic, Milanko Sekler, Radmila Resanovic, and Zoran Stanimirovic. "Historical overview of methods for sex determination in birds." Veterinarski glasnik 70, no. 3-4 (2016): 145–57. http://dx.doi.org/10.2298/vetgl1604145v.
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Determining the sex in birds is very difficult, primarily because over 50% of species is monomorphic (no morphological differences between the sexes). Before the application of molecular genetic methods, there were used numerous methods all of which were un?reliable. Because of the importance of the analyses, they have to be reliable, economical, safe and prompt. Highly conserved CHD gene is defined in 1995. on W chromosome in birds, while on Z chromosome it was defined two years later. The difference in the length of the intronic sequences of CHD gene of Z and W chromosomes enables the distinguishing of the sexes after amplification of specific fragments by the application of specific primers. Molecular genetic methods have the supremacy over all the other methods because, ex?cept for being safe (both for birds and people), they provide reliable results, and also can be applied in all bird species.
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Alipanah, M., A. Torkamanzehi, and H. Taghavi. "Sex determination in ostrich (Struthio camelus) using DNA markers." Canadian Journal of Animal Science 90, no. 3 (September 1, 2010): 357–60. http://dx.doi.org/10.4141/cjas09125.
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Production of bird species such as ostrich (Struthio camelus) has been gaining increasing importance in Iran as well as many other countries. Ostrich, similar to many other species of birds, lacks sexual dimorphism, making it difficult to differentiate between males and females, especially at an early age, which can be problematic in breeding programs. Recently developed molecular genetic methods that utilize polymerase chain reaction (PCR) based techniques can facilitate rapid identification of the bird’s sex in these species using a DNA sample, which can be easily extracted from blood or feather pulps. We successfully applied a PCR-based RFLP technique and sex chromosome primers for sex determination in a sample of 30 Ostrich chicks using DNA extracted from blood and feather pulps. Both DNA samples (blood and feather pulps) provided useful results. However, using feather pulps from 1-day-old chicks can provide an easy and inexpensive method for sex determination in ostrich. Key words: Ostrich (struthio camelus), sex determination, sexual dimorphism, polymerase chain reaction, RFLP
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Guioli, Silvana, Sunil Nandi, Debiao Zhao, Jessica Burgess-Shannon, Robin Lovell-Badge, and Michael Clinton. "Gonadal Asymmetry and Sex Determination in Birds." Sexual Development 8, no. 5 (2014): 227–42. http://dx.doi.org/10.1159/000358406.
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Tagirov, M. T. "SEX DETERMINATION AND CONTROL MECHANISMS IN BIRDS." Biotechnologia Acta 6, no. 1 (2013): 62–72. http://dx.doi.org/10.15407/biotech6.01.062.
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Akter, S., SC Das, AS Apu, T. Ahmed, A. Lahiry, A. Afrin, and NJ Nishat. "Early sex determination of Turkey by observation of differences in body weight between male and female." Progressive Agriculture 31, no. 3 (March 1, 2021): 218–26. http://dx.doi.org/10.3329/pa.v31i3.52126.
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The present study was conducted to determine the early sex in turkeys by observation of the differences in body weight between male and female birds. A total of 30-day old black color unsexed poults having almost similar body weight at hatching were considered for the experimentation and housed at the Poultry Farm of Bangladesh Agricultural University, Mymensingh-2202, Bangladesh. All birds were reared up to 12 weeks of age under intensive management with supplementation of commercial broiler starter and grower feeds. Birds were reared under similar management conditions. Significantly higher (p<0.01) body weight was attained in male poults (104g/bird) than the female (90g/bird) at the end of 1st week of age. Similarly, at the end of 2nd week of age higher (p<0.01) body weight attained by male poults (198.31g/bird) than the female (162.13g/bird). At the end of 3rd weeks of age male poults attained higher (p<0.01) body weight (307.23g/bird) than the female (251.33g/bird). After 4 weeks of rearing, male turkeys attained significantly higher (p<0.01) live body weight (424.46g/bird) than the female turkeys (347.87g/bird). The weekly average body weight gains of male and female birds were 94.18g/bird and 76.5g/bird, respectively. Thus, the male and female birds were successfully identified on the basis of differences in their body weight. Weekly feed intake for both the male and female birds was also increased with their age. Up to 4 weeks of age, both the male and female poults consumed same amount of feed (753.46g/bird). The FCR of male and female poults differed non-significantly in 1st, 3rd and 4th week. On the contrary, in 2nd week of age the FCR of male poults (1.60) was significantly lower (p<0.01) than female (2.11). Survivability was 100% up to 4th week of age irrespective of sex of the poults. The birds were reared up to 12 weeks of age until to confirm their sex by observation of the phenotypic appearance. Results of the phenotypic observation of male and female birds correspondence hundred percent accuracy with the results obtained in body weight based differences between male and female birds. It is therefore concluded that farmers can identify male or female poults as early as first week of age on the basis of body weight differences.
Progressive Agriculture 31 (3): 218-226, 2020
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Ioannidis, Jason, Gunes Taylor, Debiao Zhao, Long Liu, Alewo Idoko-Akoh, Daoqing Gong, Robin Lovell-Badge, Silvana Guioli, Mike J. McGrew, and Michael Clinton. "Primary sex determination in birds depends on DMRT1 dosage, but gonadal sex does not determine adult secondary sex characteristics." Proceedings of the National Academy of Sciences 118, no. 10 (March 3, 2021): e2020909118. http://dx.doi.org/10.1073/pnas.2020909118.
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In birds, males are the homogametic sex (ZZ) and females the heterogametic sex (ZW). Primary sex determination is thought to depend on a sex chromosome gene dosage mechanism, and the most likely sex determinant is the Z chromosome gene Doublesex and Mab-3–Related Transcription factor 1 (DMRT1). To clarify this issue, we used a CRISPR-Cas9–based monoallelic targeting approach and sterile surrogate hosts to generate birds with targeted mutations in the DMRT1 gene. The resulting chromosomally male (ZZ) chicken with a single functional copy of DMRT1 developed ovaries in place of testes, demonstrating the avian sex-determining mechanism is based on DMRT1 dosage. These ZZ ovaries expressed typical female markers and showed clear evidence of follicular development. However, these ZZ adult birds with an ovary in place of testes were indistinguishable in appearance to wild-type adult males, supporting the concept of cell-autonomous sex identity (CASI) in birds. In experiments where estrogen synthesis was blocked in control ZW embryos, the resulting gonads developed as testes. In contrast, if estrogen synthesis was blocked in ZW embryos that lacked DMRT1, the gonads invariably adopted an ovarian fate. Our analysis shows that DMRT1 is the key sex determination switch in birds and that it is essential for testis development, but that production of estrogen is also a key factor in primary sex determination in chickens, and that this production is linked to DMRT1 expression.
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Widya Pintaka Bayu Putra. "PREDICTING THE GROWTH CURVE OF BODY WEIGHT IN MALEO BIRDS (MACROCEPHALON MALEO)." OISAA Journal of Indonesia Emas 4, no. 2 (June 15, 2021): 59–63. http://dx.doi.org/10.52162/jie.2021.004.02.4.
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Maleo bird (Macrocephalon maleo) is the one of protected bird’s species and originated from Sulawesi island of Indonesia. This study was carried out to obtain the growth curve of body weight (BW) in mixed-sex Maleo birds from hatching to yearling ages. The growth curve in this study was calculated with non-linear regression of Logistic (L) and Gompertz (G) models using CurveExprt 1.4. computer program. The primary data in this study was cited from previous study through a literature study. Research showed that the asymptotic weight (A) in birds was 1825.34 g (L) and 3429.23 g (G). The weight of inflection (Wi) in studied birds were 912.67 g (L) and 1260.75 g (G). The time of inflection (ti) in birds was 8.51 months (L) and 11.00 months (G). The maximum growth rate in birds was 159.72 g/month (L) and 151.29 g/month (G). The coefficient of determination (R2) in both models included of very high category (0.80<R2<1.00) but the lower of standard error (SE) value showed in L model. It can be concluded that the non-linear regression of Logistic model can be used as BW predictors in mixed-sex Maleo birds.
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Kerry, KR, DJ Agnew, JR Clarke, and GD Else. "USe of morphometric parameters for the determination of sex of Adelie penguins." Wildlife Research 19, no. 6 (1992): 657. http://dx.doi.org/10.1071/wr9920657.
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The sex of Addie penguins, Pygoscelis adeliae, may be determined by cloacal examination during the early part of the breeding season. Later in the season it becomes increasingly difficult to determine the sex of penguins by this method as the structures used for identification regress. Discriminant analysis of morphometric characters has been suggested as an alternative. This technique was examined for breeding birds of known sex near Mawson Station, Antarctica. The sex of 89% of breeding birds could be correctly determined by comparing the discriminant score D = 0.582 Bl + 1.118 Bd + 0.219Fw, where Bl is bill length, Bd is bill depth and Fw is flipper width, with a mean discriminant score (MDS) of 55.39. In all, the sexes of 87% were correctly determined by means of length and depth only (D=0.601Bl+ 1.154Bd, MDS=44.96). The sex of juvenile birds could not be determined. Determination of sex by discriminant analysis is shown to give acceptable estimates of morphometric characters divided by sex where only the mean and variance of these variables but not the sexual identity of individual birds is required. Where absolute accuracy in sex determination is required, 80% of the birds in our samples would have to be discarded to be 90% confident of the sex of the remainder.
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Janes, Daniel E., Christopher L. Organ, Rami Stiglec, Denis O'Meally, Stephen D. Sarre, Arthur Georges, Jennifer A. M. Graves, et al. "Molecular evolution of Dmrt1 accompanies change of sex-determining mechanisms in reptilia." Biology Letters 10, no. 12 (December 2014): 20140809. http://dx.doi.org/10.1098/rsbl.2014.0809.
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In reptiles, sex-determining mechanisms have evolved repeatedly and reversibly between genotypic and temperature-dependent sex determination. The gene Dmrt1 directs male determination in chicken (and presumably other birds), and regulates sex differentiation in animals as distantly related as fruit flies, nematodes and humans. Here, we show a consistent molecular difference in Dmrt1 between reptiles with genotypic and temperature-dependent sex determination. Among 34 non-avian reptiles, a convergently evolved pair of amino acids encoded by sequence within exon 2 near the DM-binding domain of Dmrt1 distinguishes species with either type of sex determination. We suggest that this amino acid shift accompanied the evolution of genotypic sex determination from an ancestral condition of temperature-dependent sex determination at least three times among reptiles, as evident in turtles, birds and squamates. This novel hypothesis describes the evolution of sex-determining mechanisms as turnover events accompanied by one or two small mutations.
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Kuroiwa, Asato. "No final answers yet on sex determination in birds." Nature 462, no. 7269 (November 2009): 34. http://dx.doi.org/10.1038/462034b.
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Davitkov, Dajana, Milos Vucicevic, Uros Glavinic, Ivan Skadric, Vladimir Nesic, Jevrosima Stevanovic, and Zoran Stanimirovic. "Potential of Inter- and Intra-Species Variability of CHD1 Gene in Birds as a Forensic Tool." Acta Veterinaria 71, no. 2 (June 1, 2021): 147–57. http://dx.doi.org/10.2478/acve-2021-0013.
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Abstract Nowadays, illegal trafficking and smuggling of animals are among the greatest threats to many avian species. Most commonly smuggled birds belong to parrots, song birds, raptor species and owls. All of these species are protected by national and international legislations. In order to prevent and reduce wildlife trafficking, DNA methods have become an important forensic tool in species and sex identification. In this study, CHD1R/CHD1F primer pair was used to amplify a part of the CHD1 gene from 65 birds that belong to 43 species. For 36 species this is the first time that the length of CHD1 amplicons was measured for the purpose of species determination. The results were visualized using capillary electrophoresis and enabled simultaneous determination of sex and species. Based on the number of amplicons (two in females, one in males) sex was successfully determined in all species, even in cases where gel electrophoresis failed to give results. Moreover, the species was successfully determined in most bird species based on the species-specific sizes of CHD1 amplicon. The method used in this study is of great importance for veterinary forensic medicine and the prevention of wildlife smuggling. Still, further work is necessary to confirm the effectiveness of the method in all bird species.
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Smith, C. A. "Sex Determination in Birds: HINTs from the W Sex Chromosome?" Sexual Development 1, no. 5 (2007): 279–85. http://dx.doi.org/10.1159/000108934.
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Andersson, Stina, Daniel Bengtsson, Magnus Hellström, and Jonas Waldenström. "Age and sex determination of Mallards Anas platyrhynchos in autumn." Ornis Svecica 26, no. 2 (April 1, 2016): 61–81. http://dx.doi.org/10.34080/os.v26.22530.
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Male and female mallards Anas platyrhynchos are easily told apart, whereas ageing is problematic, due to individual timing of moult and lack of easily defined age criteria. From examination and photographic documentation of mallards caught at Ottenby Bird Observatory (56°12′N, 16°24′E), we describe nine characters of plumage and bare parts to be used for ageing in autumn. The reliability of these characters was tested by letting experienced bird ringers determine putative age of birds from photos. Age determination from any single character proved to be uncertain, as correctly assigned mallard photos of each character was in the range of 51–85% for males and 48–89% for females. For both sexes, the lowest figure represented post-humerals and the highest represented tertials. Rectrices, tertial coverts, and greater coverts had high scores (71–85%). Using all characters, 91% of the males and 95% of the females were correctly aged. As young mallards, with the progress of pre-breeding moult (completed from October onwards), acquire tail and tertials identical to adults, untypical individuals are better not assigned to an age category.
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Annisa, Mariana Fikriyanti, and Susanti Withaningsih. "DNA sexing for gender determination of Changeable Hawk-Eagle (Nisaetus cirrhatus, Gmelin, 1788)." E3S Web of Conferences 249 (2021): 03012. http://dx.doi.org/10.1051/e3sconf/202124903012.
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The Changeable hawk-eagle (Brontok eagle) is a protected bird species. It is one of the most frequently hunted and traded birds in Indonesia. The processes of being traded changes this bird natural behaviour. Therefore, a rehabilitation effort to return the eagle’s behaviour to conform to its natural habits is needed. The ultimate goal of rehabilitation is to release the changeable hawk-eagle back into its natural habitat. In conservation and breeding programs, efforts to determine the sex of eagles to be released are very important to help increase the population of changeable hawk-eagles in their habitat by looking at the sex ratio. At the present, sex determination at the Kamojang Conservation Eagle Center (Pusat Konservasi Elang Kamojang or PKEK) uses the morphometric method. This research used the DNA sexing method with primers 2550F and 2718R to determine the sex of Changeable hawk-eagles in PKEK by extracting DNA from blood samples of 30 eagles. Comparison of DNA sexing results and morphometric data showed differences. This proves that DNA sexing, is suitable in determining changeable hawk-eagles’ sex.
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Rutkowska, Joanna, and Alexander V. Badyaev. "Meiotic drive and sex determination: molecular and cytological mechanisms of sex ratio adjustment in birds." Philosophical Transactions of the Royal Society B: Biological Sciences 363, no. 1497 (November 28, 2007): 1675–86. http://dx.doi.org/10.1098/rstb.2007.0006.
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Differences in relative fitness of male and female offspring across ecological and social environments should favour the evolution of sex-determining mechanisms that enable adjustment of brood sex ratio to the context of breeding. Despite the expectation that genetic sex determination should not produce consistent bias in primary sex ratios, extensive and adaptive modifications of offspring sex ratio in relation to social and physiological conditions during reproduction are often documented. Such discordance emphasizes the need for empirical investigation of the proximate mechanisms for modifying primary sex ratios, and suggests epigenetic effects on sex-determining mechanisms as the most likely candidates. Birds, in particular, are thought to have an unusually direct opportunity to modify offspring sex ratio because avian females are heterogametic and because the sex-determining division in avian meiosis occurs prior to ovulation and fertilization. However, despite evidence of strong epigenetic effects on sex determination in pre-ovulatory avian oocytes, the mechanisms behind such effects remain elusive. Our review of molecular and cytological mechanisms of avian meiosis uncovers a multitude of potential targets for selection on biased segregation of sex chromosomes, which may reflect the diversity of mechanisms and levels on which such selection operates in birds. Our findings indicate that pronounced differences between sex chromosomes in size, shape, size of protein bodies, alignment at the meiotic plate, microtubule attachment and epigenetic markings should commonly produce biased segregation of sex chromosomes as the default state, with secondary evolution of compensatory mechanisms necessary to maintain unbiased meiosis. We suggest that it is the epigenetic effects that modify such compensatory mechanisms that enable context-dependent and precise adjustment of primary sex ratio in birds. Furthermore, we highlight the features of avian meiosis that can be influenced by maternal hormones in response to environmental stimuli and may account for the precise and adaptive patterns of offspring sex ratio adjustment observed in some species.
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Waldenström, Jonas, and Ulf Ottosson. "The accuracy of field sex determination in the Common Whitethroat Sylvia c. communis." Ornis Svecica 10, no. 2 (January 25, 2020): 67–70. http://dx.doi.org/10.34080/os.v10.20574.
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The accuracy of field sex determination of Common Whitethroats captured during spring migration in Nigeria was tested with a genetic sex determination technique. Among both age classes males were more often correctly sexed than females. In total, one out of four birds were incorrectly sexed, and the ability to sex correctly varied considerably between ringers. Hence, a cautious attitude must be held at all times towards the use of field sex assessment in Common Whitethroats.
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Çiçek Rathert, Tülin, İnan Güven, and Fatih Üçkardeş. "Sex Determination of Japanese Quails (Coturnix Coturnix Japonica) using with Zoometric Measurements." Turkish Journal of Agriculture - Food Science and Technology 5, no. 9 (September 12, 2017): 1002. http://dx.doi.org/10.24925/turjaf.v5i9.1002-1005.1278.
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The difficulty of sex determination in most poultry species causes significant financial losses for poultry production as birds cannot be separated at early stages of growth for meat or egg production. Therefore it is important to determine bird’s sex with zoometric parameters. This study was carried out to determine the sex of Japanese quails with zoometric measurements, such as live weight, body length, chest depth and chest width. Eighty-eight male and female Japanese quail chicks were used individually for live weight, chest depth (mm), chest width (mm) and body length (mm) with using digital scaled balance and caliper for every week over a period of six weeks. The weekly collected data were applied to t test for estimating the sex discrimination. The Pearson’s correlation was applied for examining the interrelationship between sex and biometric traits. The results indicated that there was a significant positive correlation between live weight and body length beginning with the 2nd week. Therefore, zoometric measurement of these body traits is suitable for discriminating the sex of Japanese quails in early phase of life.
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Alekseevich, L. A., N. A. Lukina, N. S. Nikitin, A. A. Nekrasova, and A. F. Smirnov. "Problems of sex determination in birds exemplified by Gallus gallus domesticus." Russian Journal of Genetics 45, no. 3 (March 2009): 255–65. http://dx.doi.org/10.1134/s1022795409030016.
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Correa, Stephanie M., Elizabeth Adkins-Regan, and Patricia A. Johnson. "High progesterone during avian meiosis biases sex ratios toward females." Biology Letters 1, no. 2 (May 13, 2005): 215–18. http://dx.doi.org/10.1098/rsbl.2004.0283.
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Evidence of altered primary sex ratios in birds shows that mothers can manipulate the sex of their offspring before oviposition. In birds, females are the heterogametic sex (ZW) and males are homogametic (ZZ). Sex is determined in the first meiotic division, when one sex chromosome is retained in the oocyte and the other segregates to the polar body. Altered primary sex ratios suggest that birds may be capable of biasing the segregation of sex chromosomes during meiosis I. During the time of meiosis I, follicular steroid production is limited primarily to progesterone (P4). We experimentally manipulated the levels of P4 in female domestic chickens during the approximate time of meiosis I. We advanced the ovulation of the first egg of a sequence (or clutch) with a subcutaneous injection of P4. We found a significant effect of P4 dose on the sex of the resulting egg. The high progesterone group produced 25% males whereas the low progesterone group produced 61% males and the control group produced 63% males in the first ovulation of the sequence. We propose that variation in maternal progesterone during the critical time for genetic sex determination is the mechanism for primary sex ratio manipulation in birds.
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Yudkin, V. A., and M. A. Grabovski. "QUANTITATIVE METHOD OF ESTIMATE OF AERODROME BIRDS HAZARD RISK." Civil Aviation High TECHNOLOGIES 21, no. 4 (August 28, 2018): 48–59. http://dx.doi.org/10.26467/2079-0619-2018-21-4-48-59.
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The formalized parameters of bird hazard assessment at the aerodrome are presented. The size of total biomass of all birds that are in a zone of aircraft movement reflects the aggregate characteristic of ornithological hazard. This is a dynamic parameter, its dimensionality is kg/hour‧km2. The size of biomass is differentiated on high-altitude layers and the directions of its movement. In addition, it is necessary to estimate activity of each bird species at the aerodrome as component parts of bird hazard. Its dimensionality is individuals/hour‧km2. One more parameter of aerodrome bird hazard in the assessment process of activity of each bird species is the behavior pattern of birds in aerodrome airspace. This parameter will allow to reveal the sources of bird arrivals at the airfield and to detect the causes of it. Assessment of this share is necessary to choose the effective measures to decrease bird strike risk. The birds recording technique at airfield has been designed to obtain quantitative values of main parameters of bird hazard. The birds recording is carried out from the observation points located on the opposite sides of the runway. The birds recording technique is based on visual detection of birds, identification of species, sex and age determination, expert estimate of altitude and direction of their movement. Except the flying birds, the foraging and resting birds on the ground are also considered. The contribution of these birds to the aggregate value of ornithological hazard is bigger than overflying birds. The birds recording technique is described in detail. The norms and frequency of birds recording to obtain data on daily and seasonal dynamics of aerodrome bird hazard are substantiated. The algorithm of processing the results of birds recording and calculation of the main parameters value of bird hazard is stated. Gradations of bird hazard and relevant measures to decrease quantity of birds at airfield are proposed.
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Baehaqi, Ibnu, Tyas Rini Saraswati, and Enny Yusuf Wachidah Yuniwarti. "Sex Determination in Male and Female Melopsittacus undulates using a Morphometric Method." Biosaintifika: Journal of Biology & Biology Education 10, no. 3 (December 19, 2018): 533–38. http://dx.doi.org/10.15294/biosaintifika.v10i3.14067.
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Parakeets (Melopsittacus undulates) are classified parrot order Psittaciformes. Parakeets are monomorphic birds whose sex is difficult to be distinguished. Sex identification is very important for breeding efforts in order to increase the parakeet population. External morphology was determined to identify the sex of the birds. This research was conducted to determine the sex of parakeets (male and female). This study used five male and five female parakeets aged 4 months as the study objects. This study used the quantitative and qualitative method. Results of this study was verified by performing surgery to determine the sex of parakeet based on their reproductive organs. The t-test results of morphometric characteristics showed no significant different in the length of body, upper bill, lower bill, wing, tail, femur, tibial-tarsus, tarsometatarsus and digits as well as the body weight between male and female parakeets. The color of the cere was useful to accurately determine sex in parakeets (blue in males and white in females). This research provided information to the public about the differences between male and female parakeets for the selection of good broodstock in order to increase their population in captivity.
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Rovatsos, Michail, Martina Pokorná, Marie Altmanová, and Lukáš Kratochvíl. "Cretaceous park of sex determination: sex chromosomes are conserved across iguanas." Biology Letters 10, no. 3 (March 2014): 20131093. http://dx.doi.org/10.1098/rsbl.2013.1093.
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Many poikilothermic vertebrate lineages, especially among amphibians and fishes, possess a rapid turnover of sex chromosomes, while in endotherms there is a notable stability of sex chromosomes. Reptiles in general exhibit variability in sex-determining systems; as typical poikilotherms, they might be expected to have a rapid turnover of sex chromosomes. However, molecular data which would enable the testing of the stability of sex chromosomes are lacking in most lineages. Here, we provide molecular evidence that sex chromosomes are highly conserved across iguanas, one of the most species-rich clade of reptiles. We demonstrate that members of the New World families Iguanidae, Tropiduridae, Leiocephalidae, Phrynosomatidae, Dactyloidae and Crotaphytidae, as well as of the family Opluridae which is restricted to Madagascar, all share homologous sex chromosomes. As our sampling represents the majority of the phylogenetic diversity of iguanas, the origin of iguana sex chromosomes can be traced back in history to the basal splitting of this group which occurred during the Cretaceous period. Iguanas thus show a stability of sex chromosomes comparable to mammals and birds and represent the group with the oldest sex chromosomes currently known among amniotic poikilothermic vertebrates.
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Küpper, Clemens, Jakob Augustin, Scott Edwards, Tamás Székely, András Kosztolányi, Terry Burke, and Daniel E. Janes. "Triploid plover female provides support for a role of the W chromosome in avian sex determination." Biology Letters 8, no. 5 (May 30, 2012): 787–89. http://dx.doi.org/10.1098/rsbl.2012.0329.
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Two models, Z Dosage and Dominant W , have been proposed to explain sex determination in birds, in which males are characterized by the presence of two Z chromosomes, and females are hemizygous with a Z and a W chromosome. According to the Z Dosage model, high dosage of a Z-linked gene triggers male development, whereas the Dominant W model postulates that a still unknown W-linked gene triggers female development. Using 33 polymorphic microsatellite markers, we describe a female triploid Kentish plover Charadrius alexandrinus identified by characteristic triallelic genotypes at 14 autosomal markers that produced viable diploid offspring. Chromatogram analysis showed that the sex chromosome composition of this female was ZZW. Together with two previously described ZZW female birds, our results suggest a prominent role for a female determining gene on the W chromosome. These results imply that avian sex determination is more dynamic and complex than currently envisioned.
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Hasselquist, D., and B. Kempenaers. "Parental care and adaptive brood sex ratio manipulation in birds." Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 357, no. 1419 (March 29, 2002): 363–72. http://dx.doi.org/10.1098/rstb.2001.0924.
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Under many circumstances, it might be adaptive for parents to bias the investment in offspring in relation to sex. Recently developed molecular techniques that allow sex determination of newly hatched offspring have caused a surge in studies of avian sex allocation. Whether females bias the primary brood sex ratio in relation to factors such as environmental and parental quality is debated. Progress is hampered because the mechanisms for primary sex ratio manipulation are unknown. Moreover, publication bias against non–significant results may distort our view of adaptive sex ratio manipulation. Despite this, there is recent experimental evidence for adaptive brood sex ratio manipulation in birds. Parental care is a particularly likely candidate to affect the brood sex ratio because it can have strong direct effects on the fitness of both parents and their offspring. We investigate and make predictions of factors that can be important for adaptive brood sex ratio manipulation under different patterns of parental care. We encourage correlational studies based on sufficiently large datasets to ensure high statistical power, studies identifying and experimentally altering factors with sex–differential fitness effects that may cause brood sex ratio skew, and studies that experimentally manipulate brood sex ratio and investigate fitness effects.
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Abu-Almaaty, A. H. "Determination of somatic and sex chromosomes of three Egyptian birds species using cytogenetic analysis." Genetika 49, no. 1 (2017): 285–95. http://dx.doi.org/10.2298/gensr1701285a.
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Study of karyotypes has been revealing important information on the taxonomic relationships and evolutionary patterns in various groups of birds. Karyotypes analysis and morphometric measurement of the chromosomes of three birds species of Geopelia cuneata (Columbiformes), Oriolus oriolus and Corvus ruficollis (Passeriformes) and their karyological have been studied. The diploid chromosome numbers of three species were, 2n=72, 2n=80 and 2n =80 respectively. The karyotypes of three species were different. The somatic and sex chromosomes and karyotypes of three species discussed and compared with other related species in the present study.
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Clinton, M., and L. C. Haines. "An overview of factors influencing sex determination and gonadal development in birds." Cellular and Molecular Life Sciences 55, no. 7 (1999): 876. http://dx.doi.org/10.1007/s000180050341.
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Radder, Rajkumar S., Alexander E. Quinn, Arthur Georges, Stephen D. Sarre, and Richard Shine. "Genetic evidence for co-occurrence of chromosomal and thermal sex-determining systems in a lizard." Biology Letters 4, no. 2 (December 18, 2007): 176–78. http://dx.doi.org/10.1098/rsbl.2007.0583.
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An individual's sex depends upon its genes (genotypic sex determination or GSD) in birds and mammals, but reptiles are more complex: some species have GSD whereas in others, nest temperatures determine offspring sex (temperature-dependent sex determination). Previous studies suggested that montane scincid lizards ( Bassiana duperreyi , Scincidae) possess both of these systems simultaneously: offspring sex is determined by heteromorphic sex chromosomes (XX–XY system) in most natural nests, but sex ratio shifts suggest that temperatures override chromosomal sex in cool nests to generate phenotypically male offspring even from XX eggs. We now provide direct evidence that incubation temperatures can sex-reverse genotypically female offspring, using a DNA sex marker. Application of exogenous hormone to eggs also can sex-reverse offspring (oestradiol application produces XY as well as XX females). In conjunction with recent work on a distantly related lizard taxon, our study challenges the notion of a fundamental dichotomy between genetic and thermally determined sex determination, and hence the validity of current classification schemes for sex-determining systems in reptiles.
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HALVERSON, J. L., and J. DVORAK. "Genetic Control of Sex Determination in Birds and the Potential for Its Manipulation." Poultry Science 72, no. 5 (May 1993): 890–96. http://dx.doi.org/10.3382/ps.0720890.
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Kroczak, Aleksandra, Magdalena Wołoszyńska, Heliodor Wierzbicki, Marcin Kurkowski, Krzysztof Aleksander Grabowski, Tomasz Piasecki, Livio Galosi, and Adam Dawid Urantówka. "New Bird Sexing Strategy Developed in the Order Psittaciformes Involves Multiple Markers to Avoid Sex Misidentification: Debunked Myth of the Universal DNA Marker." Genes 12, no. 6 (June 7, 2021): 878. http://dx.doi.org/10.3390/genes12060878.
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Sexing of birds is indispensable for scientific, breeding and conservation programs but is difficult in many species and is particularly problematic in the case of nestlings showing no sexual dimorphism. Most useful and efficient methods of sex determination are based on unique features of the Z and W sex chromosomes detected via PCR to distinguish males (ZZ) and females (ZW). During the last twenty-five years researchers searched for the universal marker capable of sexing a maximally wide spectrum of species in a single PCR assay. We screened the phylogenetically representative set of 135 Psittaciformes species including 59 species sexed for the first time. Two known (P2P8, CHD1iA) PCR markers and four additional W/Z polymorphisms (CHD1iE, CHD1i16, CHD1i9 and NIPBLi16) located within the Chromo Helicase DNA binding CHD1 or the Nipped-B homolog NIPBL genes were applied. We present the electrophoretic patterns obtained for the PCR products of the analyzed markers including most typical and atypical patterns allowing sex determination, as well as those obtained when the given marker failed in sexing. Technical aspects of molecular sex determination are discussed: the optimization of amplification conditions, direct PCR and potential misinterpretations. A truly universal marker has not been found, and therefore, we propose a sexing strategy based on multiple CHD1i16, NIPBLi16, CHD1i9 and CHD1iE markers. This new strategy confirms the sex of a given bird with at least two markers detecting independent Z/W polymorphisms, reduces the number of necessary PCR reactions and minimizes the risk of sex misidentification.
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BADYAEV, A. V., R. L. YOUNG, G. E. HILL, and R. A. DUCKWORTH. "Evolution of sex-biased maternal effects in birds. IV. Intra-ovarian growth dynamics can link sex determination and sex-specific acquisition of resources." Journal of Evolutionary Biology 21, no. 2 (March 2008): 449–60. http://dx.doi.org/10.1111/j.1420-9101.2007.01498.x.
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Gunski, Ricardo J., Rafael Kretschmer, Marcelo Santos de Souza, Ivanete de Oliveira Furo, Suziane A. Barcellos, Alice L. Costa, Marcelo B. Cioffi, Edivaldo H. C. de Oliveira, and Analía del Valle Garnero. "Evolution of Bird Sex Chromosomes Narrated by Repetitive Sequences: Unusual W Chromosome Enlargement in Gallinula melanops (Aves: Gruiformes: Rallidae)." Cytogenetic and Genome Research 158, no. 3 (2019): 152–59. http://dx.doi.org/10.1159/000501381.
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Among birds, species with the ZZ/ZW sex determination system generally show significant differences in morphology and size between the Z and W chromosomes (with the W usually being smaller than the Z). In the present study, we report for the first time the karyotype of the spot-flanked gallinule (Gallinula melanops) by means of classical and molecular cytogenetics. The spot-flanked gallinule has 2n = 80 (11 pairs of macrochromosomes and 29 pairs of microchromosomes) with an unusual W chromosome that is larger than the Z. Besides being totally heterochromatic, it has a secondary constriction in its long arm corresponding to the nucleolar organizer region, as confirmed by both silver staining and mapping of 18S rDNA probes. This is an unprecedented fact among birds. Additionally, 18S rDNA sites were also observed in 6 microchromosomes, while 5S rDNA was found in just 1 microchromosomal pair. Seven out of the 11 used microsatellite sequences were found to be accumulated in microchromosomes, and 6 microsatellite sequences were found in the W chromosome. In addition to the involvement of heterochromatin and repetitive DNAs in the differentiation of the large W chromosome, the results also show an alternative scenario that highlights the plasticity that shapes the evolutionary history of bird sex chromosomes.
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Gam, A. E., and K. J. Navara. "Endogenous Corticosterone Elevations Five Hours Prior to Ovulation do not Influence Offspring Sex Ratios in Zebra Finches." Avian Biology Research 9, no. 3 (September 2016): 131–38. http://dx.doi.org/10.3184/175815516x14495923605779.
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Previous research suggests that environmental and social factors can drive female birds to bias offspring sex ratios. The underlying mechanisms controlling these adjustments remain unclear. Results from experimental and correlative research suggest that maternal corticosterone plays an important role in this process. Since females are the heterogametic sex in birds, corticosterone may potentially bias offspring sex ratios during meiotic segregation, through non-random segregation of sex chromosomes. In a previous study, we showed that pharmacological elevations of corticosterone near the time of meiotic segregation exerted an effect on offspring sex ratio, causing female Zebra Finches ( Taeniopygia guttata) to produce significantly more males. Here, we aimed to determine whether endogenous elevations in the physiological range have similar effects on offspring sex. First we examined offspring sex ratio in relation to baseline corticosterone levels to determine if natural variation in circulating corticosterone near the time of meiotic segregation is related to offspring sex ratio. Next, we used a 5-minute bag handling protocol to induce corticosterone elevations 5 hours prior to ovulation. Maternal baseline corticosterone levels did not correlate with average clutch sex ratios. In addition, the sex ratios produced by females exposed to handling stress did not differ from sex ratios produced by unmanipulated females. Together these results suggest that physiological levels of endogenous corticosterone, both baseline and acutely elevated near the time of sex determination may not be involved in the adjustment of primary sex ratios in Zebra Finches.
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Bagi, Zoltán, and Szilvia Kusza. "Application of molecular genetic methods for birds (literature review)." Acta Agraria Debreceniensis, no. 69 (March 23, 2016): 37–41. http://dx.doi.org/10.34101/actaagrar/69/1785.
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Ornithology studies have been extended by molecular genetic techniques. In this paper we are dealing with the most common use of areas. Our basic aim is to give a comprehensive view of the most commonly used methods in ornithological studies, including the available results by their use. We also deal with the following areas: an essential step during examination namely the applicability of sample collecting methods, and the unique identification, also the sex determination, methodology of DNA barcoding, as well as the role of molecular methods to protect endangered species. We discussed the advantages and disadvantages of the methods, such as the current trend for each method.
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Freedberg, Steven, Rachel M. Bowden, Michael A. Ewert, Dale R. Sengelaub, and Craig E. Nelson. "Long-term sex reversal by oestradiol in amniotes with heteromorphic sex chromosomes." Biology Letters 2, no. 3 (April 11, 2006): 378–81. http://dx.doi.org/10.1098/rsbl.2006.0454.
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Oestradiol application during embryonic development reverses the sex of male embryos and results in normal female differentiation in reptiles lacking heteromorphic sex chromosomes, but fails to do so in birds and mammals with heteromorphic sex chromosomes. It is not clear whether the evolution of heteromorphic sex chromosomes in amniotes is accompanied by insensitivity to oestradiol, or if the association between oestradiol insensitivity and heteromorphic sex chromosomes can be attributable to phylogenetic constraints in these taxa. Turtles provide an ideal system to examine the potential relationship between oestradiol insensitivity and sex chromosome heteromorphy, since there are species with heteromorphic sex chromosomes that are closely related to species lacking heteromorphic sex chromosomes. We investigated this relationship by examining the long-term effects of oestradiol-17β application on sex determination in Staurotypus triporcatus and Staurotypus salvinii , two turtle species with male heterogamety. After raising the turtles in the lab for 3 years, we found follicular and Müllerian duct morphology in oestradiol-treated turtles that was identical to that of untreated females. The lasting sex reversal suggests that the evolutionary transition between systems lacking heteromorphic sex chromosomes and those with heteromorphic sex chromosomes is not constrained by a fundamental mechanistic difference.
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Rudaуа, S. V., О. О. Katerynych, M. V. Drahulian, A. B. Chaplygina, and O. Y. Pakhomov. "Sex identification of different species of wild birds using a single universal protocol to the bird sexing method based on gene polymorphism." Regulatory Mechanisms in Biosystems 11, no. 3 (July 13, 2020): 399–404. http://dx.doi.org/10.15421/022061.
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This article presents an elaboration of the protocol for the method of sexing wild birds based on the polymorphism of the CHD gene using P2/P8 primer for Common Pheasant – Phasianus colchicus (Linnaeus, 1758; Galliformes, Phasianidae); Silver Lofur or Silver Pheasant – Lophura nycthemera (Linnaeus, 1758; Galliformes, Phasianidae), Budgerigar – Melopsittacus undulatus (Shaw, 1805; Psittaciformes, Psittacidae), Herring Gull – Larus argentatus (Pontoppidan, 1763; Charadriiformes, Laridae), and White Stork – Ciconia ciconia (Linnaeus, 1758; Ciconiiformes, Ciconiidae). Blood samples were taken from Common Pheasant, Silver Pheasant and White Stork using the “drop of blood on paper” method. For the Budgerigar and the Herring Gull, DNA was isolated from the feather follicle. To isolate DNA, a commercial NeoPrep 100 DNA reagent kit (Neogen, Ukraine) was used. Primers P2/P8 were used for PCR; PCR was performed using GenPac PCR Core reagents (Neogen, Ukraine). We selected the optimal amount of Tag polymerase, the amount of DNA and primers and, according to the amount of reagents, set acceptable amplification modes and electrophoresis agarose gel percentage. Prior to PCR, additional DNA gel electrophoresis purification is proposed, which increases the percentage of positive sex determination results. It was found that the ideal mixture for the 5 bird species was an amplification mixture (total volume 20 µL, containing 1 U Tag polymerase, 100 ng DNA and 0.6 µM of each primer). The amplified CHD-Z fragment of Common and Silver pheasants is of ~340 n. p., CHD-W ~360 n. p. Herring Gull and Budgerigar have ~350 n. p. of CHD-Z length, and ~400 n. p. of CHD-W length, White Stork has its CHD-Z of ~ 370 n. p. long. It is advisable to investigate the genome of the experimental bird species using horizontal electrophoresis in agar’s gel with the concentration of 5%, which makes it possible to clearly visualize the female genotype. The universal protocol of the method of sex determination based on polymorphism of the CHD gene for the 5 studied bird species is described. These results of the study led to the conclusion that for the simultaneous sexing of several species of birds, it is advisable to develop a unified protocol for determining the status of the CHD gene, with the aim of clarifying the gender, as well as new approaches in ornithology and ecology aimed at determining interspecific differences associated with gene polymorphism. Identification of differences in fragment sizes may be useful for identifying the species in cases when birds form mixed pairings for taxonomic and phylogenetic comparisons.
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Tsend-Ayush, Enkhjargal, Shu Ly Lim, Andrew J. Pask, Diana Demiyah Mohd Hamdan, Marilyn B. Renfree, and Frank Grützner. "Characterisation of ATRX, DMRT1, DMRT7 and WT1 in the platypus (Ornithorhynchus anatinus)." Reproduction, Fertility and Development 21, no. 8 (2009): 985. http://dx.doi.org/10.1071/rd09090.
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One of the most puzzling aspects of monotreme reproductive biology is how they determine sex in the absence of the SRY gene that triggers testis development in most other mammals. Although monotremes share a XX female/XY male sex chromosome system with other mammals, their sex chromosomes show homology to the chicken Z chromosome, including the DMRT1 gene, which is a dosage-dependent sex determination gene in birds. In addition, monotremes feature an extraordinary multiple sex chromosome system. However, no sex determination gene has been identified as yet on any of the five X or five Y chromosomes and there is very little knowledge about the conservation and function of other known genes in the monotreme sex determination and differentiation pathway. We have analysed the expression pattern of four evolutionarily conserved genes that are important at different stages of sexual development in therian mammals. DMRT1 is a conserved sex-determination gene that is upregulated in the male developing gonad in vertebrates, while DMRT7 is a mammal-specific spermatogenesis gene. ATRX, a chromatin remodelling protein, lies on the therian X but there is a testis-expressed Y-copy in marsupials. However, in monotremes, the ATRX orthologue is autosomal. WT1 is an evolutionarily conserved gene essential for early gonadal formation in both sexes and later in testis development. We show that these four genes in the adult platypus have the same expression pattern as in other mammals, suggesting that they have a conserved role in sexual development independent of genomic location.
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Wada, Haruka, Buddhamas P. Kriengwatana, Todd D. Steury, and Scott A. MacDougall-Shackleton. "Incubation temperature influences sex ratio and offspring’s body composition in Zebra Finches (Taeniopygia guttata)." Canadian Journal of Zoology 96, no. 9 (September 2018): 1010–15. http://dx.doi.org/10.1139/cjz-2017-0099.
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Incubation temperature has the potential to influence offspring sex, phenotype, and survival, particularly in species with temperature-dependent sex determination. However, relatively little is known about how incubation temperature affects sex ratio and offspring condition in other animals. Incubating birds allocate varying time for egg incubation depending on the parents’ condition and ambient temperature, likely altering nest microclimate. To understand how incubation temperature impacts offspring phenotype in birds, we artificially incubated Zebra Finch (Taeniopygia guttata (Vieillot, 1817)) eggs at 36.2, 37.4, or 38.4 °C during the entire incubation period and examined sex ratio and offspring quality. We found that incubation temperature of 36.2 °C resulted in a greater likelihood of a young being male compared with 37.4 °C, indicating that it is more likely for males to survive until the juvenile stage compared with females in the 36.2 °C group. We also found sex-specific effects of incubation temperature on body composition. Although incubation temperature did not affect fat or lean mass of female young, male offspring from the 38.4 °C group had significantly less lean mass throughout their lives compared with males from 37.4 or 36.2 °C. This study shows that there are sex differences in the effects of incubation temperature, and variable incubation temperature has a capacity to influence offspring secondary sex ratio and body condition in songbirds.
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Bista, Basanta, and Nicole Valenzuela. "Turtle Insights into the Evolution of the Reptilian Karyotype and the Genomic Architecture of Sex Determination." Genes 11, no. 4 (April 11, 2020): 416. http://dx.doi.org/10.3390/genes11040416.
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Sex chromosome evolution remains an evolutionary puzzle despite its importance in understanding sexual development and genome evolution. The seemingly random distribution of sex-determining systems in reptiles offers a unique opportunity to study sex chromosome evolution not afforded by mammals or birds. These reptilian systems derive from multiple transitions in sex determination, some independent, some convergent, that lead to the birth and death of sex chromosomes in various lineages. Here we focus on turtles, an emerging model group with growing genomic resources. We review karyotypic changes that accompanied the evolution of chromosomal systems of genotypic sex determination (GSD) in chelonians from systems under the control of environmental temperature (TSD). These transitions gave rise to 31 GSD species identified thus far (out of 101 turtles with known sex determination), 27 with a characterized sex chromosome system (13 of those karyotypically). These sex chromosomes are varied in terms of the ancestral autosome they co-opted and thus in their homology, as well as in their size (some are macro-, some are micro-chromosomes), heterogamety (some are XX/XY, some ZZ/ZW), dimorphism (some are virtually homomorphic, some heteromorphic with larger-X, larger W, or smaller-Y), age (the oldest system could be ~195 My old and the youngest < 25 My old). Combined, all data indicate that turtles follow some tenets of classic theoretical models of sex chromosome evolution while countering others. Finally, although the study of dosage compensation and molecular divergence of turtle sex chromosomes has lagged behind research on other aspects of their evolution, this gap is rapidly decreasing with the acceleration of ongoing research and growing genomic resources in this group.
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Pilz, Kevin M., Elizabeth Adkins-Regan, and Hubert Schwabl. "No sex difference in yolk steroid concentrations of avian eggs at laying." Biology Letters 1, no. 3 (June 28, 2005): 318–21. http://dx.doi.org/10.1098/rsbl.2005.0321.
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Yolk steroids of maternal origin have been proposed to influence genetic sex determination in birds, based on sex differences in yolk steroid concentrations of peafowl eggs incubated for 10 days. More recent reports dispute this proposal, as yolk steroids in eggs incubated for 3 days do not show such sex differences. To date, research examining this phenomenon has only analysed incubated eggs, although sex in avian species is determined before incubation begins. This may be a serious methodological flaw because incubation probably affects yolk steroid concentrations. Therefore, we investigated sex differences in yolk steroid concentrations of unincubated avian eggs. We withdrew yolk for steroid analysis from fresh, unincubated Japanese quail ( Coturnix japonica ) eggs by biopsy, and then incubated those eggs for 10 days, after which we harvested the embryonic material for genetic sexing and the incubated yolk for further steroid analysis. We found no sex differences in fresh Japanese quail eggs; however, sex differences were apparent in yolk steroids by day 10 of incubation, when female eggs had significantly more oestrogen in relation to androgen than male eggs. Concentrations of all yolk androgens decreased dramatically between laying and day 10 of incubation, whereas oestradiol (E2) concentrations increased marginally. Thus, yolk concentrations of androgens and E2 do not appear critical for avian sex determination.
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Polani, P. E. "A Bird's Eye View of Human Sex Determination." Acta geneticae medicae et gemellologiae: twin research 45, no. 1-2 (April 1996): 137–41. http://dx.doi.org/10.1017/s0001566000001215.
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In the beginning the dogma was that sex determination in man followed the Drosophila pattern in which XO is male, XXY female, and the Y chromosome has no direct influence on the determination of sex. On the grounds of specific anomalies with which they presented, females with Turner Syndrome were sex chromatin tested and found to be chromatin negative [1]. This result, confirmed in 1956 by the male frequency of red-green colour blindness in these subjects which indicated that they carried only one X chromosome in spite of their female phenotype, suggested that therefore they might be XO, and, so, hinted that sex determination in man might not follow the then accepted pattern [2]. In 1959 chromosome studies confirmed that XOs were female [3] and showed that subjects with the symmetrical XXY sex-chromosome anomaly were with Klinefelter syndrome [4]. In the same year, by showing that XOs were females also in mice [5] it became accepted that the Y chromosome was the determiner of the formation of the testis in the mammalian embryo, and so was the key element in primary sexual differentation. It would seem appropriate to call this formal model of chromosomal sex determination the Malandrium pattern [6].In 1966 Jacobs and Ross [7], from work on males with Y chromosome deletions narrowed down the testis determining function of the Y chromosome to its short arm. Then, in 1975, Wachtel and collaborators [8] were the first to formulate a hypothesis on the sex determining gene, or, more precisely on the nature of its product. They suggested that this developmental role might be played by the H-Y antigen, a weak histocompatibility antigen which had been known to be involved in the rejection of male skin grafted onto otherwise histocompatible female mice. The idea had run into technical difficulties and a major problem was related to the significance that should be attached to the results of two different ways for demonstrating the antigen, namely the cell-mediated cytotoxicity test or the serological test. Efforts were made to keep the H-Y hypothesis alive, largely because there was a certain elegance about it [9, 10]. However eventually XX male mice, lacking H-Y by either test, spelt the end of the candidature of H-Y as the testis determining mechanism [11, 12].
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Rovatsos, Michail, Jasna Vukić, Petros Lymberakis, and Lukáš Kratochvíl. "Evolutionary stability of sex chromosomes in snakes." Proceedings of the Royal Society B: Biological Sciences 282, no. 1821 (December 22, 2015): 20151992. http://dx.doi.org/10.1098/rspb.2015.1992.
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Amniote vertebrates possess various mechanisms of sex determination, but their variability is not equally distributed. The large evolutionary stability of sex chromosomes in viviparous mammals and birds was believed to be connected with their endothermy. However, some ectotherm lineages seem to be comparably conserved in sex determination, but previously there was a lack of molecular evidence to confirm this. Here, we document a stability of sex chromosomes in advanced snakes based on the testing of Z-specificity of genes using quantitative PCR (qPCR) across 37 snake species (our qPCR technique is suitable for molecular sexing in potentially all advanced snakes). We discovered that at least part of sex chromosomes is homologous across all families of caenophidian snakes (Acrochordidae, Xenodermatidae, Pareatidae, Viperidae, Homalopsidae, Colubridae, Elapidae and Lamprophiidae). The emergence of differentiated sex chromosomes can be dated back to about 60 Ma and preceded the extensive diversification of advanced snakes, the group with more than 3000 species. The Z-specific genes of caenophidian snakes are (pseudo)autosomal in the members of the snake families Pythonidae, Xenopeltidae, Boidae, Erycidae and Sanziniidae, as well as in outgroups with differentiated sex chromosomes such as monitor lizards, iguanas and chameleons. Along with iguanas, advanced snakes are therefore another example of ectothermic amniotes with a long-term stability of sex chromosomes comparable with endotherms.
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Lisachov, Artem P., Svetlana A. Galkina, Alsu F. Saifitdinova, Svetlana A. Romanenko, Daria A. Andreyushkova, Vladimir A. Trifonov, and Pavel M. Borodin. "Identification of sex chromosomes in Eremias velox (Lacertidae, Reptilia) using lampbrush chromosome analysis." Comparative Cytogenetics 13, no. 2 (May 14, 2019): 17–28. http://dx.doi.org/10.3897/compcytogen.v13i2.34116.
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Reptiles are good objects for studying the evolution of sex determination, since they have different sex determination systems in different lineages. Lacertid lizards have been long-known for possessing ZZ/ZW type sex chromosomes. However, due to morphological uniformity of lacertid chromosomes, the Z chromosome has been only putatively cytologically identified. We used lampbrush chromosome (LBC) analysis and FISH with a W-specific probe in Eremiasvelox (Pallas, 1771) to unequivocally identify the ZW bivalent and investigate its meiotic behavior. The heterochromatic W chromosome is decondensed at the lampbrush stage, indicating active transcription, contrast with the highly condensed condition of the lampbrush W chromosomes in birds. We identified the Z chromosome by its chiasmatic association with the W chromosome as chromosome XIII of the 19 chromosomes in the LBC karyotype. Our findings agree with previous genetic and genomic studies, which suggested that the lacertid Z chromosome should be one of the smaller macrochromosomes.
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McGrath, Casey. "Highlight: The Birds and the Bees and the Bearded Dragons—Evolution of a Sex-Determination System." Genome Biology and Evolution 11, no. 12 (December 1, 2019): 3496–97. http://dx.doi.org/10.1093/gbe/evz268.
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Kostmann, Alexander, Lukáš Kratochvíl, and Michail Rovatsos. "Poorly differentiated XX/XY sex chromosomes are widely shared across skink radiation." Proceedings of the Royal Society B: Biological Sciences 288, no. 1943 (January 20, 2021): 20202139. http://dx.doi.org/10.1098/rspb.2020.2139.
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Differentiated sex chromosomes are believed to be evolutionarily stable, while poorly differentiated sex chromosomes are considered to be prone to turnovers. With around 1700 currently known species forming ca 15% of reptile species diversity, skinks (family Scincidae) are a very diverse group of squamates known for their large ecological and morphological variability. Skinks generally have poorly differentiated and cytogenetically indistinguishable sex chromosomes, and their sex determination was suggested to be highly variable. Here, we determined X-linked genes in the common sandfish ( Scincus scincus ) and demonstrate that skinks have shared the same homologous XX/XY sex chromosomes across their wide phylogenetic spectrum for at least 85 million years, approaching the age of the highly differentiated ZZ/ZW sex chromosomes of birds and advanced snakes. Skinks thus demonstrate that even poorly differentiated sex chromosomes can be evolutionarily stable. The conservation of sex chromosomes across skinks allows us to introduce the first molecular sexing method widely applicable in this group.
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Kalina, J., J. Mucksová, H. Yan, and P. Trefil. " Rapid sexing of selected Galliformes by polymerase chain reaction." Czech Journal of Animal Science 57, No. 4 (April 27, 2012): 187–92. http://dx.doi.org/10.17221/5894-cjas.
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Vent sexing of one-day-old chicks in commercial hatcheries has long been common practice and can be highly accurate. However, there are circumstances when this technique is not applicable such as smaller breeds, non-domestic birds, or where is the necessity of precise sexing. In this study we present a simple and reliable method for fast gender determination in selected Galliformes for which phenotypic determination of sex is difficult until maturity. Four species were tested: two commercial species – chicken (Gallus gallus) and turkey (Meleagris gallopavo), and two game birds – common pheasant (Phasianus colchicus) and wood grouse (Tetraro urogallus). DNA was tested with universal single-pair primers polymerase chain reaction (PCR) detecting W chromosome specific sequence yielding a single band of length specific for each species. The method was developed with regards to time consumption and cost-effectiveness giving results in less than two hours. The method may also be used for early sexing in commercial chicken and turkey flocks as well as sexing of smaller game birds flocks or for research laboratories when rapid sexing of selected Galliformes cells is required.
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Kratochvíl, Lukáš, Lukáš Kubička, and Eva Landová. "Yolk hormone levels in the synchronously developing eggs of Paroedura picta, a gecko with genetic sex determination." Canadian Journal of Zoology 84, no. 11 (November 2006): 1683–87. http://dx.doi.org/10.1139/z06-152.
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Sex steroid hormones of presumably maternal origin have been found in yolk of many oviparous vertebrates. Their effects on behavioural or physiological traits are well documented in birds, but until now are largely unknown in reptiles. The investigations of yolk steroids in reptiles have been focused mainly on species with temperature-dependent sex determination, where steroid levels are suggested to determine the sex of progeny. Here we report initial oestradiol (E2) and testosterone (T) levels in the yolk of the Madagascar ground gecko, Paroedura picta (Peters, 1854), a species with genetic sex determination. The yolk concentration was 0.39 ± 0.02 ng/g (mean ± SE) in E2, whereas the concentration of T was much higher (1.48 ± 0.06 ng/g, mean ± SE). Geckos usually lay two exceptionally large eggs per clutch; vitellogenesis and ovulation of both eggs proceed in phase. Individual two-egg clutches differed considerably in E2 and T levels. A clutch mean of E2 levels varied from 0.22 to 0.53 ng/g, whereas T levels varied from a clutch mean of 1.02 to 1.99 ng/g. Both eggs in a clutch possessed very similar levels of E2 and T. Initial yolk steroid levels thus presumably reflect maternal conditions during egg formation rather than differential allocation of hormones according to offspring sex.
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Piferrer, Francesc, and Dafni Anastasiadi. "Do the Offspring of Sex Reversals Have Higher Sensitivity to Environmental Perturbations?" Sexual Development 15, no. 1-3 (2021): 134–47. http://dx.doi.org/10.1159/000515192.
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Sex determination systems in vertebrates vary along a continuum from genetic (GSD) to environmental sex determination (ESD). Individuals that show a sexual phenotype opposite to their genotypic sex are called sex reversals. Aside from genetic elements, temperature, sex steroids, and exogenous chemicals are common factors triggering sex reversal, a phenomenon that may occur even in strict GSD species. In this paper, we review the literature on instances of sex reversal in fish, amphibians, reptiles, birds, and mammals. We focus on the offspring of sex-reversed parents in the instances that they can be produced, and show that in all cases studied the offspring of these sex-reversed parents exhibit a higher sensitivity to environmental perturbations than the offspring of non-sex-reversed parents. We suggest that the inheritance of this sensitivity, aside from possible genetic factors, is likely to be mediated by epigenetic mechanisms such as DNA methylation, since these mechanisms are responsive to environmental cues, and epigenetic modifications can be transmitted to the subsequent generations. Species with a chromosomal GSD system with environmental sensitivity and availability of genetic sex markers should be employed to further test whether offspring of sex-reversed parents have greater sensitivity to environmental perturbations. Future studies could also benefit from detailed whole-genome data in order to elucidate the underlying molecular mechanisms. Finally, we discuss the consequences of such higher sensitivity in the context of global climate change.
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Singh, M., T. Durali, and A. J. Cowieson. "Use of n-alkanes for determination of Kikuyu grass (Pennisetum clandestinum) intake in free-range broilers." Animal Production Science 56, no. 7 (2016): 1152. http://dx.doi.org/10.1071/an14778.
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N-alkanes, long-chained saturated hydrocarbons occurring in plant cuticles, were used for estimating grass intake in fast-growing, free-range broilers. A total of 1440 as hatched mixed sex Cobb 500 broilers were equally divided between one of four experimental treatments in a 2 by 2 factorial arrangement involving conventional (barn) or free-range (barn and range access) production systems and diets (crude protein: 21%, metabolisable energy: 13 MJ/K) with or without in-feed antibiotic (Zinc Bacitracin: Albac® G 150 antibiotic feed premix, Pfizer Australia Pty Ltd, Sydney, NSW, Australia). Day-old chicks were randomly allocated to 48 pens (12 replicates/treatment) with 30 birds in each pen. Chicks were assigned to treatment diets on Day 1 while free-range access was available to birds from Day 21 onwards. Alkane concentrations in litter were measured and compared with alkane profiles of the intake components (grass, diet pellets and woodchip). Correction for incomplete recovery followed by estimation using a non-negative least square procedure resulted in calculation of total grass intake from the range area. Kikuyu grass consumption was estimated to be 13.5–14.7% of total ‘as-fed’ intake, equating to 6.34–6.78 g of grass per bird per hour of range access in this study. Taking into account grass consumption, this resulted in a significant increase in feed intake by 8.7–8.9% (P < 0.01) and feed conversion ratio from 2.30 to 2.54 points (P < 0.01). It can be concluded that broilers reared under free-range conditions eat a substantial quantity of grass. However, the nutrient profile of grass is not complementary to the formulated ration and its consumption is likely to lead to an array of nutritional changes for the bird, thus affecting performance.