Patterns Of Paternity Research Articles

Removal of older males increases extra-pair siring success of yearling males.

In animals, reproductive performance typically improves over time early in life. Several ultimate and proximate mechanisms may contribute to such an age-related improvement and these mechanisms can act in a relative or in an absolute sense. Low performance of young individuals may be the consequence of a comparison or competition with older individuals (relative), or it may be due to specific traits of young individuals and be unrelated to the presence of older competitors (absolute). Here, we perform a test to disentangle whether the effect of age class (yearling or older) on male extra-pair siring success is relative or absolute. Male age is the most consistent predictor of male extra-pair siring success across bird species, yet the mechanisms underlying this pattern are not well understood. Low extra-pair siring success of yearling males may be a consequence of the presence of older ("adult") males (hypothesis 1), because adult males are more successful in intra- and intersexual interactions or because females prefer to copulate with adult males when available (relative preference). Alternatively, low extra-pair siring success of yearlings may be independent of the presence of adult males (hypothesis 2), for example, if yearling males on average invest less in extra-pair behavior or if females avoid them as extra-pair mates, independent of the availability of older males (absolute preference). To distinguish between these 2 hypotheses, we experimentally manipulated the age structure of a nest-box-breeding population of blue tits (Cyanistes caeruleus) by removing almost all adult males, and compared patterns of extra-pair paternity in the experimental year with those from the preceding 15 "control" years. Removal of adult males resulted in a substantial increase in the extra-pair siring success of yearling males compared to the "control" years, but did not affect the population-level frequency of extra-pair paternity or its spatial patterns. Our results provide clear evidence that extra-pair siring success of yearlings can increase and that it depends on the presence of older males in the population, indicating a relative effect of age on reproductive performance. These results suggest that older males outcompete yearling males in direct or indirect interactions, in sperm competition or as a result of differences in attractiveness to females.

Novel insights into paternity skew in a polyandrous social wasp.

Females of many species are polyandrous. However, polyandry can give rise to conflict among individuals within families. We examined the level of polyandry and paternity skew in the common eastern yellowjacket wasp, Vespula maculifrons, in order to gain a greater understanding of conflict in social insects. We collected 10 colonies of V. maculifrons and genotyped workers and prereproductive queens at highly variable microsatellite markers to assign each to a patriline. Genotypic data revealed evidence of significant paternity skew among patrilines. In addition, we found that patrilines contributed differentially to caste production (worker vs. queen), suggesting an important role for reproductive conflict not previously discovered. We also investigated if patterns of paternity skew and mate number varied over time. However, we found no evidence of changes in levels of polyandry when compared to historical data dating back almost 40years. Finally, we measured a suite of morphological traits in individuals from the most common and least common patrilines in each colony to test if males that showed highly skewed reproductive success also produced offspring that differed in phenotype. Our data revealed weak correlation between paternity skew and morphological phenotype of offspring sired by different males, suggesting no evidence of evolutionary tradeoffs at the level investigated. Overall, this study is the first to report significant paternity and caste-associated skew in V. maculifrons, and to investigate the phenotypic consequences of skew in a social wasp. Our results suggest that polyandry can have important consequences on the genetic and social structure of insect societies.

Paternity patterns in a long-term resident bottlenose dolphin community

Genetic analyses, initiated in 1984, have played a major role in our understanding of the structure and social relationships of the long-term resident community of common bottlenose dolphins (Tursiops truncatus) in Sarasota Bay, Florida (SBDC). One component of our ongoing study of the community’s social system involves using blood samples from periodic catch-and-release sampling for life history and health assessment studies, as well as skin from biopsy dart sampling studies and strandings, to investigate paternity and mating strategies in this community. These analyses, covering a span of four generations of calves, were originally based on chromosomes and protein electrophoresis, but with the advent of microsatellite DNA technology, the latter has become our analysis of choice. We have performed paternity analyses on 204 known mother-calf pairs. For 151 of the calves (74%), sires were identified within the SBDC, but for the remaining 26% of the calves all sampled males associated with the community were excluded and it is likely that a substantial contribution of paternity to the SBDC comes from outside the community. Of the SBDC males, only 52 males of the more than 200 potential sires were sires. The age of sires at time of conception of a calf ranged from 10 to 43 years, averaging 24 years old. These males have sired 1-7 calves during a documented period of reproductive tenure of as much as 24 years (average = 21.4 years). Four males have sired 6-7 calves each, these males siring calves in the community for more than 20 years. Another 19 males have each sired 3-5 calves and the remaining 30 males were identified as sires of 1-2 calves. Paired males sired 75% of the calves while 25% of the calves were sired by unpaired males. Females with multiple offspring generally had multiple sires for these offspring. These paternity analyses support the hypothesis that a major avenue of gene flow in the SBDC is through the males given their greater ranges, with occasional exchangeviavisits from males from other areas, as well as the occasional brief movements of females from outside the community range into the community.

Paternity sharing in insects with female competition for nuptial gifts.

Male parental investment is expected to be associated with high confidence of paternity. Studies of species with exclusive male parental care have provided support for this hypothesis because mating typically co-occurs with each oviposition, allowing control over paternity and the allocation of care. However, in systems where males invest by feeding mates (typically arthropods), mating (and thus the investment) is separated from egg-laying, resulting in less control over insemination, as male ejaculates compete with rival sperm stored by females, and a greater risk of investing in unrelated offspring (cuckoldry). As strong selection on males to increase paternity would compromise the fitness of all a female's other mates that make costly nutrient contributions, paternity sharing (males not excluded from siring offspring) is an expected outcome of sperm competition. Using wild-caught females in an orthopteran and a dipteran species, in which sexually selected, ornamented females compete for male nuptial food gifts needed for successful reproduction, we examined paternity patterns and compared them with findings in other insects. We used microsatellite analysis of offspring (lifetime reproduction in the orthopteran) and stored sperm from wild-caught females in both study species. As predicted, there was evidence of shared paternity as few males failed to sire offspring. Further support for paternity sharing is the lack of last-male sperm precedence in our study species. Although paternity was not equal among sires, our estimates of paternity bias were similar to other insects with valuable nuptial gifts and contrasted with the finding that males are frequently excluded from siring offspring in species where males supply little more than sperm. This suggests paternity bias may be reduced in nuptial-gift systems and may help facilitate the evolution of these paternal investments.

Effects of spawning group sex ratio and stocking density on the outcome of captive reproduction in golden cuttlefish Sepia esculenta

The supplemental release of hatchery-reared animals is important for maintaining or enhancing fishery resources. The golden cuttlefish, Sepia esculenta, is a commercially important cephalopod utilized in stock enhancement activities throughout East Asia. The long-term success of such activities requires proper breeding regimes to ensure the efficient use of resources and the preservation of genetic diversity in the offspring. For captive-bred cephalopods, information concerning the effects of different mating regimes on the paternity of offspring is scarce. However, it could be of particular importance for polyandric species such as golden cuttlefish. As previous studies have suggested that both the number and mating order of males are related to female fecundity, we investigated the effects of stocking density and sex ratio on female fecundity and determined the paternity of the offspring in golden cuttlefish. We used two experimental approaches. First, four different female (F): male (M) sex ratios (1F:1M, 1F:2.5 M, 1F:3M, 1F:6M) were set up to investigate the effects of operational sex ratio on mating behavior, female fecundity, and hatchling paternity. Next, we investigated female fecundity and hatchling paternity patterns under low and high stocking densities (5 or 10 individuals ∙ m−3), following a standard sex ratio setting that is widely employed in cuttlefish hatcheries (1F:2M). With an increasing proportion of males, the average fecundity of females and the participation rate of males in paternity decreased. With increasing stocking density, the females had lower average daily egg production, and the males had a high variance in reproductive success and decreased participation rate in spawning. The estimated effective number of breeders (Ne) was 19.29 (Ne/N ratio = 0.54) at high-density and 10.17 (Ne/N ratio = 0.57) at low density. To achieve high reproductive performance and assure genetic diversity of golden cuttlefish offspring, our study suggests that equal (1F:1M) or slightly male-biased (1F:2.5 M) sex ratios and a low stocking density may be useful when breeding golden cuttlefish in captivity.

Patterns of sperm use by twice-mated female Queensland fruit flies.

Multiple mating by females, polyandry, is common in insects, including in tephritid fruit flies. Female insects that remate commonly store sperm of multiple males. How the sperm of different males contribute to paternity is an important element of sexual selection. Sexual behavior and reproduction of the Queensland fruit fly (Qfly), Bactrocera tryoni, has been extensively investigated both in relation to understanding this economically important species' reproductive biology and in relation to implications for Sterile Insect Technique (SIT), whereby sterile flies are released to constrain reproduction of pest populations. Despite numerous studies of pre- and postcopulatory sexual selection in Qfly, there have been no direct studies of paternity patterns in polyandrous female Qflies. We used two morphologically distinguishable lines to investigate patterns of sperm use in Qfly. The two lines showed comparable mating performance evidenced by similar mating and remating frequency, copula duration, and proportion of second mate paternity (P2) between reciprocal crosses. The mechanism of sperm usage, with P2 close to 0.5 immediately after the second mating followed by gradual decrease of P2 as females aged, is most consistent with stratification or repositioning of sperm. Patterns observed in the present study are compared with the available information from other tephritid fruit flies, and are discussed in relation to this species' reproductive biology, known patterns of sperm storage, and SIT.

Extra-pair paternity in a species with frequent extra-pair courtship feedings, few extra-pair copulations, and male-biased parental care

Patterns of extra pair paternity (EPP) and intraspecific brood parasitism (IBP) were studied in a Whiskered Tern Chlidonias hybrida population characterized by female brood desertion, a high level of extra pair courtship feedings (10%) and a low level of extra pair copulation (EPC; 0.6%). In this study, we used a set of microsatellite loci to analyse parentage in 56 Whiskered Tern families from southern Poland. Depending on the method, we detected that 1.4%–3.6% of chicks were sired by an extra-pair male, and extra-pair chicks were present in 3.6%–8.9% of broods. IBP was observed in 8.9%–14.3% of broods, corresponding to 3.6%–6.4% of the chicks. The low rate of EPP is in agreement with the hypothesis that in species with high male parental investment, females should avoid EPC. The low level of IBP indicates that intraspecific egg dumping is not a common female strategy in Whiskered Tern, similar to many other colonial waterbird species.

Extra‐pair paternity in Blue Tits (Cyanistes caeruleus) depends on the combination of social partners' age

There is growing evidence that engaging in extra‐pair copulations may be a strategy by which females can modify their initial mate choice if they are constrained by primary choice of the social mate. Several factors such as genetic similarity and adult phenotypic traits can affect extra‐pair paternity (EPP) patterns, but the relative importance of these factors may vary among species. Moreover, interactive effects of male and female characteristics have rarely been considered. Here, we aimed to study how multiple parameters characterizing a breeding pair (i.e. genetic similarity between mates, partners’ age and laying date) predict the occurrence of EPP at the brood level. The study uses 4 years of data from a wild population of Blue Tits Cyanistes caeruleus. Contrary to predictions of the inbreeding avoidance hypothesis, we did not find a positive relationship between the occurrence of EPP and the relatedness of social mates. We also found that the probability of EPP was unrelated to laying date. However, EPP was predicted by an interaction of social partners' ages. Specifically, EPP was less likely when old females were paired with old males in comparison to old females paired to young males. Our study suggests that the occurrence of EPP may be the result of behavioural interactions in which both male and female age are important for determining the outcome. Our results confirm the importance of considering the interactions of male and female characteristics in studies investigating EPP patterns.

Within-season shifts in multiple paternity patterns in mass-nesting olive ridley sea turtles

Multiple paternity is common to all sea turtle species, but its causes and consequences are hard to ascertain and the behaviors and success of males difficult to observe. This study aims to describe patterns of multiple paternity for olive ridley turtles Lepidochelys olivacea at Playa de Escobilla, an ‘arribada’ (mass-nesting) site on the Mexican Pacific coast with over a million clutches laid each reproductive season. A total of 15 females and their hatchlings were sampled during 3 arribada events which occurred over the 2016-2017 nesting season. Females and hatchlings (N = 329) were genotyped at 5 microsatellite loci, from which we inferred the alleles of 46 contributing males. Multiple paternity was detected in 60% of the analyzed clutches, which were sired by a range of 2 to 7 males. Multiple paternity rates differed significantly across arribada events, suggesting more males achieved fertilizations earlier in the breeding season. Paternal contribution in 6 of the clutches with multiple paternity was skewed towards a single male; the remaining clutches had a homogeneous male contribution. However, our results are based on relatively small within-arribada sample sizes. The frequency of multiple paternity among turtle clutches laid on this arribada beach could be related to the density of breeding individuals in the reproductive patch off Playa de Escobilla, rather than to the nesting population size or female size.

Sperm competition when transfer is dangerous.

Aggressive and cannibalistic female spiders can impose strong selection on male mating and fertilization strategies. Furthermore, the distinctive reproductive morphology of spiders is predicted to influence the outcome of sperm competition. Polyandry is common in spiders, leading to defensive male strategies that include guarding, plugging and self-sacrifice. Paternity patterns are highly variable and unlikely to be determined solely by mating order, but rather by relative copulation duration, deployment of plugs and cryptic female choice. The ability to strategically allocate sperm is limited, either by the need to refill pedipalps periodically or owing to permanent sperm depletion after mating. Further insights now rely on unravelling several proximate mechanisms such as the process of sperm activation and the role of seminal fluids. This article is part of the theme issue 'Fifty years of sperm competition'.

Sperm competition in squamate reptiles

Multiple paternity is ubiquitous within the polyphyletic group called 'reptiles', especially within the lizards and snakes. Therefore, the probability of sperm competition occurring, and being intense, is high. Squamates exhibit a diversity of tactics to ensure fertilization success in the face of sperm competition. The duration of female sperm storage, which can be many months and even years in some species, remains an enigma. Here, we emphasize some mechanisms that might affect patterns of paternity, the source and function of ejaculates and features of the female reproductive tract that may aid in long-term sperm storage. In doing so, we present a new analysis of the relationship between sperm size, the strength of sperm competition and the duration of female sperm storage. Lizards and snakes are a diverse group that has provided many excellent models for the study of an array of life-history strategies. However, when it comes to postcopulatory sexual selection, there is much left to discover. This article is part of the theme issue 'Fifty years of sperm competition'.

High Degree of Multiple Paternity and Reproductive Skew in the Highly Fecund Live-Bearing Fish Poecilia gillii (Family Poeciliidae)

Multiple paternity is a common phenomenon within the live-bearing fish family Poeciliidae. There is a great variety in brood sizes of at least two orders-of-magnitude across the family. However, little is known about the ramifications of this remarkable variation for the incidence and degree of multiple paternity and reproductive skew. Mollies (subgenus Mollienesia, genus Poecilia) produce some of the largest broods in the family Poeciliidae, making them an excellent model to study the effects of intra-specific variation in brood size on patterns of multiple paternity. We collected samples of the live-bearing fish Poecilia gillii from 9 locations in Costa Rica. We measured body size of 159 adult females, of which 72 were pregnant. These samples had a mean brood size of 47.2 ± 3.0 embryos, ranging from 4 to 130 embryos. We genotyped 196 field-collected specimens with 5 microsatellite markers to obtain location-specific allele frequencies. In addition, we randomly selected 31 pregnant females, genotyped all their embryos (N = 1346) and calculated two different parameters of multiple paternity: i.e., the minimum number of sires per litter using an exclusion-based method (GERUD) and the estimated number of sires per litter using a maximum likelihood approach (COLONY). Based on these two approaches, multiple paternity was detected in 22 and 27 (out of the 31) females, respectively, with the minimum number of sires ranging from 1 to 4 (mean ± SE: 2.1 ± 0.16 sires per female) and the estimated number of fathers ranging from 1 to 9 (mean ± SE: 4.2 ± 0.35 sires per female). The number of fathers per brood was positively correlated with brood size, but not with female size. Next, we calculated the reproductive skew per brood using the estimated number of sires, and found that in 21 out of the 27 multiply sired broods sires did not contribute equally to the offspring. Skew was not correlated with either female size, brood size or the number of sires per brood. Finally, we discuss several biological mechanisms that may influence multiple paternity and reproductive skew in P. gillii as well as in the Poeciliidae in general.

The evolution of pueriparity maintains multiple paternity in a polymorphic viviparous salamander

The reduction in fecundity associated with the evolution of viviparity may have far-reaching implications for the ecology, demography, and evolution of populations. The evolution of a polygamous behaviour (e.g. polyandry) may counteract some of the effects underlying a lower fecundity, such as the reduction in genetic diversity. Comparing patterns of multiple paternity between reproductive modes allows us to understand how viviparity accounts for the trade-off between offspring quality and quantity. We analysed genetic patterns of paternity and offspring genetic diversity across 42 families from two modes of viviparity in a reproductive polymorphic species, Salamandra salamandra. This species shows an ancestral (larviparity: large clutches of free aquatic larvae), and a derived reproductive mode (pueriparity: smaller clutches of larger terrestrial juveniles). Our results confirm the existence of multiple paternity in pueriparous salamanders. Furthermore, we show the evolution of pueriparity maintains, and even increases, the occurrence of multiple paternity and the number of sires compared to larviparity, though we did not find a clear effect on genetic diversity. High incidence of multiple paternity in pueriparous populations might arise as a mechanism to avoid fertilization failures and to ensure reproductive success, and thus has important implications in highly isolated populations with small broods.

High variation in last male sperm precedence and genital morphology in the emerald damselfly, Lestes sponsa

Abstract In organisms in which individuals mate multiply, knowledge of the proportion of offspring sired by the last male to mate (P2) under field conditions is important for a thorough understanding of how sexual selection works in nature. In many insect groups, pronounced intraspecific variation in P2 is commonplace. Interestingly, however, in stark contrast to these observations, compilation of P2 data in dragonflies and damselflies (Odonata) indicates that a high P2, seldom below 0.95, is a feature of this taxon. Here we used double digest restriction-site associated DNA sequencing to generate a panel of single nucleotide polymorphisms (SNPs) with which we could determine paternity and estimate values of P2 in the offspring of 19 field-collected pairs of the emerald damselfly Lestes sponsa. We also estimated the relationship between P2 and male genital shape of 16 males using geometric morphometric analysis. P2 was variable (range = 0.0–1.0; mean = 0.5), and there was a marginally non-significant (P = 0.069) relationship between genital shape and P2, suggesting that males with a high P2 had an aedeagus with a broader tip. We suggest that the high P2-values reported in past studies in Odonata are partly due to the methods used to infer paternity. Use of SNPs to determine patterns of paternity and P2 in odonates is needed for a better appraisal of fitness in odonates, and would open many future avenues for use of odonates as models of sexual selection.

Winter associations predict social and extra-pair mating patterns in a wild songbird.

Despite decades of research, our understanding of the underlying causes of within-population variation in patterns of extra-pair paternity (EPP) remains limited. Previous studies have shown that extra-pair mating decisions are linked to both individual traits and ecological factors. Here, we examine whether social associations among individuals prior to breeding also shape mating patterns, specifically the occurrence of EPP, in a small songbird, the blue tit. We test whether associations during the non-breeding period predict (1) future social pairs, (2) breeding proximity (i.e. the distance between breeding individuals) and (3) the likelihood that individuals have extra-pair young together. Individuals that were more strongly associated (those that foraged more often together) during winter tended to nest closer together. This, by itself, predicts EPP patterns, because most extra-pair sires are close neighbours. However, even after controlling for spatial effects, female–male dyads with stronger social associations prior to breeding were more likely to have extra-pair young. Our findings reveal a carry-over from social associations into future mating decisions. Quantifying the long-term social environment of individuals and studying its dynamics is a promising approach to enhance our understanding of the process of (extra-)pair formation.

Mating failure shapes the patterns of sperm precedence in an insect

Estimates of last male sperm precedence (P2) are often used to infer mechanisms of sperm competition, a form of post-copulatory sexual selection. However, high levels of mating failure (i.e. copulations resulting in no offspring) in a population can lead to misinterpretations of sperm competition mechanisms. Through simulations, García-González (2004) illustrated how mating failure could cause bimodal distributions of paternity with peaks at P2 = 0 and 1, under a random sperm mixing mechanism. Here, we demonstrate this effect empirically with the seed bug Lygaeus simulans, a species known to exhibit high levels of mating failure (40–60%), using a morphological marker to estimate paternity. Contrary to previous findings in a sister species, we did not find strong evidence for last male sperm precedence. There was a tendency towards last male precedence (P2 = 0.58) but within the expected range for random sperm mixing. Instead, P2 was highly variable, with a bimodal distribution, as predicted by García-González (2004). After taking mating failure into account, the strongest driver of paternity outcome was copulation duration. Furthermore, we found evidence that mating failure could partly be a female-associated trait. Some doubly-mated females were more likely to produce no offspring or produce offspring from two different sires than expected by chance. Therefore, some females are more prone to experience mating failure than others, a result that mirrors an earlier result in male L. simulans. Our results confirm that mating failure needs to be considered when interrogating mechanisms of post-copulatory sexual selection.Significance statementMating failure arises when animals fail to produce offspring across their lifetime. This may be due to a failure to find a mate or a failure to produce offspring after one or more apparently successful matings. Sperm competition is when ejaculates of rival males compete to fertilize a female’s eggs. Estimates of second male paternity (P2) are often used to infer mechanisms of sperm competition (i.e. which male “wins” and how). However, García-González (2004) suggested that high levels of mating failure can skew paternity (i.e. give spuriously high/low levels of P2) and lead to misinterpretations of these mechanisms. We carried out sperm competition experiments on Lygaeus simulans seed bugs using a morphological marker to estimate paternity. We show empirically that mating failure does skew patterns of paternity, causing a bimodal distribution of P2. Therefore, by disrupting patterns of sperm competition, mating failure influences both the action of post-copulatory sexual selection and also our understanding of the mechanisms of sperm competition.

The role of genetic constraints and social environment in explaining female extra-pair mating.

Why do females of socially monogamous species engage in extra-pair copulations? This long-standing question remains a puzzle, because the benefits of female promiscuous behavior often do not seem to outweigh the costs. Genetic constraint models offer an answer by proposing that female promiscuity emerges through selection favoring alleles that are either beneficial for male reproductive success (intersexual pleiotropy hypothesis) or beneficial for female fecundity (intrasexual pleiotropy hypothesis). A previous quantitative genetic study on captive zebra finches, Taeniopygia guttata, reported support for the first, but not for the second hypothesis. Here, we re-examine both hypotheses based on data from lines selected for high and low male courtship rate. In contrast to previous conclusions, our new analyses clearly reject the hypothesis that male and female promiscuity are genetically homologous traits. We find some support for a positive genetic correlation between female promiscuity and fecundity. This study also shows that the behavioral outcome of extra-pair courtships primarily depends on individual-specific female preferences and not on the "attractiveness" of the social mate. In contrast, patterns of paternity are strongly influenced by the social partner and the pair bond, presumably reflecting variation in copulation behavior, fertility, or sperm competitiveness.

Extra-pair paternity patterns in European barn swallows Hirundo rustica are best explained by male and female age rather than male ornamentation

Adaptive explanations for the evolution of extra-pair paternity (EPP) in birds often assume cuckolding males to be better-ornamented than cuckolded males. Several studies have confirmed that either male sexual ornamentation is associated with EPP or that phenotypes of cuckolded and cuckolding males differ. Expression of male ornamentation may change with age; however, a recent meta-analysis has identified age itself as an important factor that differed in cuckolding and cuckolded males. The age of social female partner may also affect EPP, though this has received little attention. Here, by using detailed data on age of individual barn swallows (Hirundo rustica rustica), we identified age as the major predictor of male and female promiscuity. Our results revealed that, whereas a male’s ability to obtain an extra-pair mate increased linearly with age, the only predictor of the probability of a male being cuckolded was the age of his social partner, with older females engaging more frequently in EPP. In contrast, male ornamentation was not significantly related to EPP pattern. Tarsus length was the sole significant phenotypic trait in comparison between cuckolding and cuckolded males. Our data provide little support for the hypothesis that extra-pair mate choice in our barn swallow population was ornament driven. This may indicate either a non-adaptive scenario for EPP, for example with older males better able to coerce females into copulation, or EPP mating based on other than absolute mate-choice criteria associated with the expression of male ornamentation. SIGNIFICANCE STATEMENT: We analysed patterns of extra-pair paternity (EPP) in barn swallows. Derived from observation of 160 nests, our results appear to differ from the findings of some previous studies that identified ornamental traits as being associated with extra-pair and within-pair paternity (WPP) in this iconic model taxon of sexual selection. In particular, tail streamer length had no detectable association with WPP or a male’s ability to obtain an extra-pair partner. Pairwise comparisons of cuckolded and cuckolding males, involving 76 mixed paternity nests, also supported the hypothesis that male ornamentation does not play a role in determining EPP patterns in the focal barn swallow population. When statistically controlled for clutch initiation date, the probability of obtaining an extra-pair partner only increased with increasing age of males, while WPP was only associated with the age of their female social partners. Our data provide little support for the hypothesis that extra-pair mate choice in our barn swallow population is ornament driven and indicated that age, rather than ornaments, would be a better predictor of paternity.

Multiple paternity at the largest green turtle (Chelonia mydas) rookery in the Mediterranean

Sea turtle abundance estimates are often based on nest numbers or female-tagging projects. However, because male sea turtles do not emerge on the beach and are difficult to observe at sea, the number of males contributing to the breeding population is difficult to characterize. Using a molecular approach like genotyping hatchings to infer paternal genotypes can provide an indirect estimate of breeding male population size. This would help to estimate operational sex ratios, which is of vital significance for the conservation of sea turtle populations. We investigated the pattern of multiple paternity and reconstructed paternal genotypes in the largest green turtle nesting site of the Mediterranean, Akyatan beach, Turkey, using nine dinucleotide microsatellite loci. We genotyped 22 randomly selected unique female green turtles (approx.33.3% of all nesting females during 2009 nesting season) and tissue biopsies from 15 hatchlings from each of their nests n = 330). We identified multiple paternity in 59–63.6 % of the nests analysed and identified 68 individual males that had sired offspring within these nests. The operational sex ratio within our sample of the population was 1 female for every 3 males. We found 3 repeating males (males that sired offspring with more than one female) in 6 clutches resulting in 11 paternal sibships.

Genetic evidence for alloparental care and frequent multiple paternity in the brooding sea star (Leptasterias sp.)

Echinoderms form an abundant and ecologically important group of marine animals, and they are found in nearly every marine environment, from shallow tropical waters to deep polar benthos and even in the pelagic zone. They exhibit a wide diversity of reproductive strategies that range from broadcasting millions of gametes, with no parental care, to internal brooding of a few embryos for several weeks. While many echinoderm species have become model systems for studies of community ecology, evolutionary genetics, and development biology, very little is known about the distribution of mating and reproductive success in natural populations. In this study, we examined patterns of genetic maternity and paternity in the six-rayed sea star Leptasterias sp., an important predator of many intertidal communities and a species that exhibits maternal care of embryos. We used next-generation sequencing to rapidly develop informative microsatellite markers for this species, and used these markers to genotype 439 juveniles across 15 broods collected from the intertidal in Fogarty Creek, Oregon, USA. Our data show an unambiguous pattern of multiple paternity in all but one clutch examined, with some broods showing some of the highest levels of polyandry reported for a marine invertebrate. Moreover, we detected two cases of mixed maternity in which a female sea star carried another mother’s offspring mixed with her own. Alloparental care by females is rare, and since female Leptasterias do not eat during the 40–60 days brooding period, this expensive behavior may provide a useful system for examining the evolutionary costs and benefits of parental care in dynamic intertidal environments.