Molecular Ecology
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High frequency of multiple paternity in the largest rookery of Mediterranean loggerhead sea turtles Abstract Mating systems are a central component in the evolution of animal life histories and in conservation genetics. The patterns of male reproductive skew and of paternal shares in batches of offspring, for example, affect genetic effective population size. A prominent characteristic of mating systems of sea turtles seem to be a considerable intra‐ and interspecific variability in the degree of polyandry. Because of the difficulty of observing the mating behaviour of sea turtles directly in the open sea, genetic paternity analysis is particularly useful for gaining insights into this aspect of their reproductive behaviour. We investigated patterns of multiple paternity in clutches of loggerhead sea turtles in the largest Mediterranean rookery using four highly variable microsatellite loci. Furthermore, we tested for a relationship between the number of fathers detected in clutches and body size of females. More than one father was detected in the clutches of 14 out of 15 females, with two clutches revealing the contribution of at least five males. In more than half the cases, the contributions of different fathers to a clutch did not depart from equality. The number of detected fathers significantly increased with increasing female body size. This relationship indicates that males may prefer to mate with large, and therefore productive, females. Our results suggest that polyandry is likely to increase effective population size compared to a population in which females would mate with only one male; male reproductive contributions being equal.
Molecular Ecology - Tập 16 Số 17 - Trang 3703-3711 - 2007
Single paternity of clutches and sperm storage in the promiscuous green turtle (<i>Chelonia mydas</i>) Paternity of 22 green turtle (Chelonia mydas ) clutches from 13 females of the southern Great Barrier Reef breeding population was determined through microsatellite analyses at five loci, including the analysis of successive clutches for nine of the females. A large number of alleles per locus (10–40) provided probabilities of detecting multiple paternity that were quite high, particularly at all loci combined (99.9%). Although green turtles are promiscuous breeders and there was an expectation of finding extensive multiple paternity, only two clutches were multiply sired and, in these, very few eggs had been fertilized by a secondary male. The rarity of multiple paternity may reflect either a low proportion of multiple matings by females in this population, or sperm competition, possibly resulting from a first‐male sperm preference. Additionally, the analysis of > 900 offspring provided data on mutations, which included 20 mutation events that were observed in 27 offspring and involved both maternal and paternal lineages. Most mutations (n = 16) occurred at a single highly variable locus and their presence emphasizes the need to use multiple loci in paternity studies.
Molecular Ecology - Tập 7 Số 5 - Trang 575-584 - 1998
Multiple paternity in a natural population of a salamander with long‐term sperm storage Abstract Sperm competition appears to be an important aspect of any mating system in which individual female organisms mate with multiple males and store sperm. Postcopulatory sexual selection may be particularly important in species that store sperm throughout long breeding seasons, because the lengthy storage period may permit extensive interactions among rival sperm. Few studies have addressed the potential for sperm competition in species exhibiting prolonged sperm storage. We used microsatellite markers to examine offspring paternity in field‐collected clutches of the Ocoee salamander (Desmognathus ocoee ), a species in which female organisms store sperm for up to 9 months prior to fertilization. We found that 96% of clutches were sired by multiple males, but that the majority of females used sperm from only two or three males to fertilize their eggs. The high rate of multiple mating by females suggests that sperm competition is an important aspect of this mating system. Comparison of our data with those of other parentage studies in salamanders and newts reveals that multiple mating may be common in urodele amphibians. Nevertheless, the number of males siring offspring per clutch in D. ocoee did not differ appreciably from that in other species of urodeles with shorter storage periods.
Molecular Ecology - Tập 14 Số 6 - Trang 1803-1810 - 2005
Multiple paternity increases effective population size
Molecular Ecology - Tập 18 Số 15 - Trang 3124-3127 - 2009
Detection of multiple paternity in the Kemp's ridley sea turtle with limited sampling An important question in sea turtle biology is the number of males that contribute to the fertilization of a clutch of eggs. Previous studies on other sea turtle species have indicated little to no multiple paternity. We conclude here that female Kemp's ridleys, Lepidochelys kempi , are polyandrous. DNA from 26 mother and offspring groups was analysed at three microsatellite loci to identify paternal alleles. Three paternal alleles were observed among 14 of the clutches; four paternal alleles were observed among the offspring of an additional female. A maximum likelihood analysis not only rejects the model of single paternity, but also rejects the model of equal paternal contribution to the clutch. By explicitly addressing the high mutation rate of microsatellite markers, our analysis rejected mutation as the sole cause of multiple paternal alleles.
Molecular Ecology - Tập 8 Số 5 - Trang 819-830 - 1999
Reconstructing paternal genotypes to infer patterns of sperm storage and sexual selection in the hawksbill turtle Abstract Postcopulatory sperm storage can serve a range of functions, including ensuring fertility, allowing delayed fertilization and facilitating sexual selection. Sperm storage is likely to be particularly important in wide‐ranging animals with low population densities, but its prevalence and importance in such taxa, and its role in promoting sexual selection, are poorly known. Here, we use a powerful microsatellite array and paternal genotype reconstruction to assess the prevalence of sperm storage and test sexual selection hypotheses of genetic biases to paternity in one such species, the critically endangered hawksbill turtle, Eretmochelys imbricata . In the majority of females (90.7%, N = 43), all offspring were sired by a single male. In the few cases of multiple paternity (9.3%), two males fertilized each female. Importantly, the identity and proportional fertilization success of males were consistent across all sequential nests laid by individual females over the breeding season (up to five nests over 75 days). No males were identified as having fertilized more than one female, suggesting that a large number of males are available to females. No evidence for biases to paternity based on heterozygosity or relatedness was found. These results indicate that female hawksbill turtles are predominantly monogamous within a season, store sperm for the duration of the nesting season and do not re‐mate between nests. Furthermore, females do not appear to be using sperm storage to facilitate sexual selection. Consequently, the primary value of storing sperm in marine turtles may be to uncouple mating and fertilization in time and avoid costly re‐mating.
Molecular Ecology - Tập 22 Số 8 - Trang 2301-2312 - 2013
Multiple paternity in reptiles: patterns and processes Abstract The evolution of female promiscuity poses an intriguing problem as benefits of mating with multiple males often have to arise via indirect, genetic, effects. Studies on birds have documented that multiple paternity is common in natural populations but strong evidence for selection via female benefits is lacking. In an attempt to evaluate the evidence more broadly, we review studies of multiple paternity in natural populations of all major groups of nonavian reptiles. Multiple paternity has been documented in all species investigated so far and commonly exists in over 50% of clutches, with particularly high levels in snakes and lizards. Marine turtles and lizards with prolonged pair‐bonding have relatively low levels of multiple paternity but levels are nevertheless higher than in many vertebrates with parental care. There is no evidence that high levels of polyandry are driven by direct benefits to females and the evidence that multiple paternity arises from indirect genetic benefits is weak. Instead, we argue that the most parsimonious explanation for patterns of multiple paternity is that it represents the combined effect of mate‐encounter frequency and conflict over mating rates between males and females driven by large male benefits and relatively small female costs, with only weak selection via indirect benefits. A crucial step for researchers is to move from correlative approaches to experimental tests of assumptions and predictions of theory under natural settings, using a combination of molecular techniques and behavioural observations.
Molecular Ecology - Tập 17 Số 11 - Trang 2566-2580 - 2008
Microsatellites provide insight into contrasting mating patterns in arribada vs. non‐arribada olive ridley sea turtle rookeries Abstract Molecular studies of sea turtles have shown that the frequency of multiple paternity (MP) varies between species, and between rookeries of the same species. This study uses nuclear microsatellite markers to compare the incidence of MP in two neighbouring olive ridley rookeries on the Pacific coast of Costa Rica, with contrasting nesting behaviours — the ‘arribada’ population nesting at Ostional and the solitary nesters of Playa Hermosa. Using two highly polymorphic microsatellite markers, we tested 13 nests from each location and found a significant difference (P < 0.001) between the level of MP of the arribada rookery (92%— the highest found for marine turtles) and that of the solitary nesting rookery (30%). Additional analyses based on six microsatellite loci revealed no genetic differentiation between nesting females from the two locations, or between nesting females and attendant males from the Ostional breeding area. Sixty‐nine per cent of the nests with MP were fathered by a minimum of three different males, and three nests showed evidence of at least four fathers. The results suggest that the differences observed in levels of MP between arribada and solitary rookeries are due to an effect of abundance of individuals on the mating system. This is supported by a regression analysis combining other paternity studies on sea turtles which shows that levels of MP increase with increasing abundance of nesting females.
Molecular Ecology - Tập 15 Số 9 - Trang 2567-2575 - 2006
The leatherback turtle, <i>Dermochelys coriacea</i>, exhibits both polyandry and polygyny Abstract The leatherback turtle (Dermochelys coriacea ) is an endangered species, and world‐wide populations are declining. To understand better the mating structure of this pelagic and fragile species, we investigated paternity in nearly 1000 hatchlings from Playa Grande in Parque Marino Nacional Las Baulas, Costa Rica. We collected DNA samples from 36 adult female leatherbacks and assessed allele frequency distributions for three microsatellite loci. For 20 of these 36 females, we examined DNA from hatchlings representing multiple clutches, and in some cases assessed up to four successive clutches from the same female. We inferred paternal alleles by comparing maternal and hatchling genotypes. We could not reject the null hypothesis of single paternity in 12 of 20 families (31 of 50 clutches), but we did reject the null hypothesis in two families (eight of 50 clutches). In the remaining six families, the null hypothesis could not be accepted or rejected with certainty because the number of hatchlings exhibiting extra nonmaternal alleles was small, and could thus be a result of mutation or sample error. Successive clutches laid by the same female had the same paternal allelic contribution, indicating sperm storage or possibly monogamy. None of 20 females shared the same three‐locus genotype whereas there were two instances of shared genotypes among 17 inferred paternal three‐locus genotypes. We conclude that both polyandry and polygyny are part of the mating structure of this leatherback sea turtle population.
Molecular Ecology - Tập 11 Số 10 - Trang 2097-2106 - 2002
Ultrasequencing of the meiofaunal biosphere: practice, pitfalls and promises Abstract Biodiversity assessment is the key to understanding the relationship between biodiversity and ecosystem functioning, but there is a well‐acknowledged biodiversity identification gap related to eukaryotic meiofaunal organisms. Meiofaunal identification is confounded by the small size of taxa, morphological convergence and intraspecific variation. However, the most important restricting factor in meiofaunal ecological research is the mismatch between diversity and the number of taxonomists that are able to simultaneously identify and catalogue meiofaunal diversity. Accordingly, a molecular operational taxonomic unit (MOTU)‐based approach has been advocated for en mass meiofaunal biodiversity assessment, but it has been restricted by the lack of throughput afforded by chain termination sequencing. Contemporary pyrosequencing offers a solution to this problem in the form of environmental metagenetic analyses, but this represents a novel field of biodiversity assessment. Here, we provide an overview of meiofaunal metagenetic analyses, ranging from sample preservation and DNA extraction to PCR, sequencing and the bioinformatic interrogation of multiple, independent samples using 454 Roche sequencing platforms. We report two examples of environmental metagenetic nuclear small subunit 18S (nSSU) analyses of marine and tropical rainforest habitats and provide critical appraisals of the level of putative recombinant DNA molecules (chimeras) in metagenetic data sets. Following stringent quality control measures, environmental metagenetic analyses achieve MOTU formation across the eukaryote domain of life at a fraction of the time and cost of traditional approaches. The effectiveness of Roche 454 sequencing brings substantial advantages to studies aiming to elucidate the molecular genetic richness of not only meiofaunal, but also all complex eukaryotic communities.
Molecular Ecology - Tập 19 Số s1 - Trang 4-20 - 2010
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