Influence of incubation temperature, maternal effects, and paternity on quality of olive ridley hatchlings (Lepidochelys olivacea) from a mass-nesting beach in the Mexican Pacific.

Future climate change scenarios project that the increase in surface temperatures will affect ocean temperatures, inducing shifts in marine biodiversity. Sea turtles are species that are particularly vulnerable to the effects of climate change because temperature is a factor that influences embryonic development. We collected clutches of olive ridley turtles from a mass-nesting beach in the Mexican Pacific, which were incubated in ex situ conditions. When the hatchlings emerged, we measured the body condition index-which evaluates the weight-length relationship-and swim thrust, both were considered traits associated with fitness, termed "fitness proxies," and evaluated the effects of incubation temperature, maternal effects, and paternity on these fitness proxies. The body condition index was correlated positively and significantly with the arribada month and temperature during the last third of the incubation period but showed an inverse relationship with the maternal effect. While swim thrust was positively correlated with the maternal effect and the arribada month, there was an inverse relationship with incubation temperature during the first third of the period. Paternity, whether single or multiple, did not have a significant effect on either fitness proxies; however, it may have effects on the average fitness of a population of hatchlings. These results underscore the need to expand research on the sublethal effects of high incubation temperatures on the adaptation and survival of sea turtles, particularly in scenarios of rapid climate change.

How much multiple paternity should we expect? A study of birds and contrast with mammals.

Parentage analyses via molecular markers have revealed multiple paternity within the broods of polytocous species, reshaping our understanding of animal behavior, ecology, and evolution. In a meta-analysis of multiple paternity in bird and mammal species, we conducted a literature search and found 138 bird and 64 mammal populations with microsatellite DNA paternity results. Bird populations averaged 19.5% multiple paternity and mammals more than twice that level (46.1%). We used a Bayesian approach to construct a null model for how multiple paternity should behave at random among species, under the assumption that all mated males have equal likelihood of siring success, given mean brood size and mean number of sires. We compared the differences between the null model and the actual probabilities of multiple paternity. While a few bird populations fell close to the null model, most did not, averaging 34.0-percentage points below null model predictions; mammals had an average probability of multiple paternity 13.6-percentage points below the null model. Differences between bird and mammal species were also subjected to comparative phylogenetic analyses that generally confirmed our analyses that did not adjust for estimated historical relationships. Birds exhibited extremely low probabilities of multiple paternity, not only compared to mammals but also relative to other major animal taxa. The generally low probability of multiple paternity in birds might be produced by a variety of factors, including behaviors that reflect sexual selection (extreme mate guarding or unifocal female choice) and sperm competition (e.g., precedence effects favoring fertilization by early or late matings).

Pollinator foraging tactics have divergent consequences for the mating system of a tropical plant.

Resolving the consequences of pollinator foraging behaviour for plant mating systems is a fundamental challenge in evolutionary ecology. Pollinators may adopt particular foraging tactics: complete trapline foraging (repeated movements along a fixed route), sample-and-shift trapline foraging (a variable route that incorporates information from previous experiences) and territorial foraging (stochastic movements within a restricted area). Studies that integrate these pollinator foraging tactics with plant mating systems are generally lacking. We investigate the consequences of particular pollinator foraging tactics for Heliconia tortuosa. We combine parentage and sibship inference analysis with simulation modelling to: estimate mating system parameters; infer the foraging tactic adopted by the pollinators; and quantify the impact of pollinator foraging tactics on mating system parameters. We found high outcrossing rates, ubiquitous multiple paternity and a pronounced departure from near-neighbour mating. We also found that plants repeatedly receive pollen from a series of particular donors. We infer that the pollinators primarily adopt complete trapline foraging and occasionally engage in sample-and-shift trapline foraging. This enhances multiple paternity without a substantial increase in near-neighbour mating. The particular pollinator foraging tactics have divergent consequences for multiple paternity and near-neighbour mating. Thus, pollinator foraging behaviour is an important driver of the ecology and evolution of plant mating systems.

Conservation Genetics of the Loggerhead Sea Turtle, Caretta caretta, from the Central Mediterranean: An Insight into the Species' Reproductive Behaviour in Maltese Waters.

Loggerhead sea turtle, Caretta caretta (Linnaeus, 1758), nestlings were investigated through specimens found dead either after hatching or unhatched (n = 120) from eight nests around the Maltese islands (Central Mediterranean). Molecular genetics was used to conduct maternity and paternity tests of the collected specimens utilizing expanded mitochondrial DNA sequences from the control region (858 bp) and 25 microsatellite loci (12 dinucleotide loci and 13 tetranucleotide loci). Mitochondrial data produced two haplotypes, CC-A2.1 and CC-A3.1, with the most common haplotype being present in seven nests. Microsatellite data revealed the identity of six different females that were involved in the deposition of the eggs in the eight turtle nests analysed. This confirms that two females laid multiple nests. Additionally, microsatellite data allowed for the determination of multiple paternity, with one clutch being sired by two fathers. These results are useful for monitoring the genetic diversity of loggerhead sea turtle nestlings and of the turtle mothers and fathers contributing to future turtle offspring, which rely on Maltese sandy beaches for their successful start to life. Effective conservation management benefits from merging scientific knowledge with effective measures at potential nesting sites to avoid losses of nestlings caused by human negligence.

How many fathers? Study design implications when inferring multiple paternity in crocodilians.

Up to 10 males were reported to sire clutches of crocodilian eggs but review of the underlying study designs raised questions of potential upward bias of inferred sire numbers. To test this premise, different scenarios were explored using a published dataset of 16 known single-sire saltwater crocodile pairs and their offspring which were originally confirmed using a 11 loci microsatellite panel in CERVUS. Varying the number of microsatellites, omitting one or both parental genotypes and using different parentage analysis techniques revealed that total allele number, rather than number of loci, determined inferred sire accuracy in two opposing ways. Using the single-locus minimum method and GERUD, which both require prior knowledge of family groupings (i.e., nests), fewer alleles (and loci) accurately inferred only one father. In contrast, CERVUS and COLONY required all 11 loci (65 alleles) and both parental genotypes to (a) assign correct family groups and (b) infer the correct sire number, except in one family where two sires were equally assigned based on their number of homozygous loci. When less genotype information was provided, CERVUS and COLONY inferred up to six and seven sires, respectively. Given this data is from confirmed single-sire matings, and yet up to seven sires could be inferred, the significance of inappropriate study design is clearly demonstrated. Consideration should be carefully given to genotype data, particularly those collected specifically for population diversity studies, which are also used to infer multiple paternity because the underlying data collection assumptions are not equivalent between the two outcomes.

Regional variation in multiple paternity in the brown smooth-hound shark Mustelus henlei from the northeastern Pacific.

Multiple paternity (MP) in the brown smooth-hound shark (Mustelus henlei) was assessed in 15 litters (15 mothers and 97 embryos) collected in the northern Gulf of California of which 86.7% were sired by more than one male (i.e., from 2 to 4 sires). When taken together with results from previous studies, this record indicates that there is regional variation in MP in M. henlei in the northeastern Pacific. This pattern is associated with variations in the reproductive traits of each population (e.g., female size and litter size). In the Gulf of California, the results of a generalized linear model (GLZ) indicated that the litters of larger females had a higher probability of MP compared to those of smaller females.

NONPIGMENTED VERSUS PIGMENTED: HEALTH VARIABLES AND GENETICS OF ALBINO FLORIDA GREEN TURTLE (CHELONIA MYDAS) HATCHLINGS COMPARED WITH NORMALLY PIGMENTED HATCHLINGS FROM THE SAME CLUTCH.

At the time of hatchling emergence from a nest laid on Juno Beach, Florida, US, by a normally pigmented green turtle (Chelonia mydas), 23 albino hatchlings and 75 normally pigmented hatchlings were observed. This condition is rarely seen in sea turtles, and little is known about blood analytes and genetics of albino wildlife to date. Therefore, the objective of our study was to assess and compare morphometric measurements (mass, minimum straight carapace length, body condition index), carapacial scute anomalies, a suite of hematologic and plasma biochemical analytes, and two glucose analysis methodologies (glucometer and dry chemistry analysis) in albino (n=20) versus normally pigmented (n=24) hatchlings from this nest. Genetic analyses were completed to identify paternal contributions of hatchlings and to test Mendelian inheritance assumptions. Although morphometric measurements, scute anomalies, and leukocyte morphology were similar between albino and normally pigmented hatchlings, several differences were observed in blood analyte data: immature erythrocytes, packed cell volume, heterophil:lymphocyte ratio, and glucose concentrations (by both methodologies) were significantly higher, whereas absolute immature heterophils, absolute lymphocytes, number of erythrocyte micronuclei, sodium, and chloride were significantly lower in albino hatchlings compared with normally pigmented hatchlings. Considerations for these differences include a stress response from sampling (e.g., timing of procedures or possibly from photosensitivity or reduced visual acuity in albinos) and different osmoregulation, which may reflect physiologic variations or stress. There was a small positive bias (0.10 mmol/L) with glucose by glucometer, similar to reports in other sea turtle species and confirming its suitability for use in hatchlings. All albino hatchlings analyzed (n=10) were from the same father, but the normally pigmented hatchlings (n=24) were from two other fathers. These findings provide insight into the physiology and genetics of albinism in sea turtles.

The macroecology of extra-pair paternity in birds.

Extra-pair paternity (EPP) is a key aspect of the mating behaviour of birds and its frequency varies widely among populations and species. Several hypotheses predict patterns of geographical variation in the occurrence and frequency of EPP, but a global-scale study on variation in this trait is still lacking. We collected data on EPP from 663 populations of 401 avian species and explored the geographical variation in the frequency of EPP among populations, species and species assemblages. We modelled the variation in the frequency of EPP within the species' breeding range accounting for the specific ecological context of each population, and used the model predictions to compute frequencies of EPP at the level of species assemblages. A global map of assemblage-level EPP rates shows clear differences between zoogeographical realms, with the highest EPP values in the Nearctic realm. Our results show that the frequency of EPP (1) decreases with latitude and increases with the distance from the breeding range boundary within the species' breeding range, (2) is negatively associated with generation length and pair-bond duration among species, and (3) decreases with latitude at assemblage level. The latitudinal decline of EPP is consistent across zoogeographical realms.

Leukocytes count and profile during early postnatal ontogenesis in domestic cat: Effect of litter size and multiple paternity.

Since blood cells count is the most important indicator of animals' physiological status, we investigated the effects of age, litter size, and multiple paternity on the total number of white blood cells, the number of their individual types (lymphocytes, neutrophils, eosinophils, monocytes), and the ratio of neutrophils to lymphocytes in domestic cat during early postnatal ontogenesis. The study was conducted on kittens living in outdoor conditions, aged from birth to 6 months. The number of white blood cells was evaluated using a hemoanalyzer, the leukocyte formula and the proportion of cell types were determined manually from blood smears. Age significantly affected the number of leukocytes in the first 3 months of kittens' age. The number and proportion of neutrophils were the highest after birth and gradually decreased during the first month. Lymphocytes number, on the contrary, increased during this period. Monocytes and eosinophils increased in number in the first 2 months. The litter size affected the number of leukocytes and neutrophils in the first 2 months of life, their number being significantly higher in kittens from the small litters than from the large ones. In kittens from the litters with multiple paternity, the number of leukocytes and the proportion of neutrophils was higher than in litters from a single male. Thus, age, litter size and type of paternity may affect the hematological indices in domestic cats, which must be taken into account during the estimation of the health status of kittens in domestic and wild cats.

Patterns of Genetic Diversity and Mating Systems in a Mass-Reared Black Soldier Fly Colony.

The black soldier fly (BSF), Hermetia illucens, is a promising candidate for the emerging insect farming industry with favourable characteristics for both bioremediation and production of animal delivered nutritive and industrial compounds. The genetic management of commercial colonies will become increasingly important for the sustainability of the industry. However, r-selected life history traits of insects pose challenges to conventional animal husbandry and breeding approaches. In this study, the long-term genetic effects of mass-rearing were evaluated as well as mating systems in the species to establish factors that might influence genetic diversity, and by implication fitness and productivity in commercial colonies. Population genetic parameters, based on microsatellite markers, were estimated and compared amongst two temporal wild sampling populations and four generations (F28, F48, F52, and F62) of a mass-reared colony. Furthermore, genetic relationships amongst mate pairs were evaluated and parentage analysis was performed to determine the oc-currence of preferential mate choice and multiple paternity. The mass-reared colony showed a reduction in genetic diversity and evidence for inbreeding with significant successive generational genetic differentiation from the wild progenitor population. Population-level analysis also gave the first tentative evidence of positive assortative mating and genetic polyandry in BSF. The homoge-neity of the mass-reared colony seems to result from a dual action caused by small effective popu-lation size and increased homozygosity due to positive assortative mating. However, the high ge-netic diversity in the wild and a polyandrous mating system might suggest the possible restoration of diversity in mass-reared colonies through augmentation with the wild population.

Multiple paternity and the number of offspring: A model reveals two major groups of species.

Parentage analyses via microsatellite markers have revealed multiple paternity within the broods of polytocous species of mammals, reptiles, amphibians, fishes and invertebrates. The widespread phenomenon of multiple paternity may have attending relationships with such evolutionary processes as sexual selection and kin selection. However, just how much multiple paternity should a species exhibit? We developed Bayesian null models of how multiple paternity relates to brood sizes. For each of 114 species with published data on brood sizes and numbers of sires, we compared our null model estimates to published frequencies of multiple paternity. The majority of species fell close to our null model, especially among fish and invertebrate species. Some species, however, had low probabilities of multiple paternity, far from the predictions of the null model, likely due to sexual selection and environmental constraints. We suggest a major division among species' mating systems between those with close to random mating and high levels of multiple paternity, and those with constraints that produce low levels of multiple paternity.

Accessing Multiple Paternity in the Shortfin Mako Shark (Isurus oxyrinchus).

Multiple paternity has been demonstrated in a variety of sharks with different reproductive modes (i.e., viviparous, ovoviviparous, adelphophagy, oviparous), although the number of sires per litter varies considerably among species. To date, such analyses have focused mainly on coastal and nearshore shark species due to the difficulty in sampling oceanic sharks. In the present study, we observed multiple paternity in the oceanic shark Isurus oxyrinchus from seven polymorphic microsatellite loci and three litters collected from Nanfangao Fishing Port. Paternity tests showed that an average of 4.6 sires were assigned to each litter of I. oxyrinchus using COLONY software, and that the average number of sires dropped to 2.5 when using GERUD. These findings suggest that multiple paternity could be a common reproductive strategy used by the shortfin mako shark, and that this mating system should be integrated into a demographic model to make more accurate population projections and risk analyses in the future.

Breeding patterns of female prairie voles (Microtus ochrogaster) displaying alternative reproductive tactics.

Individuals of either sex may display alternative behaviors to obtain copulations, but few studies have examined the breeding patterns of females and males in populations where individuals of both sexes exhibit alternative reproductive tactics (ARTs). In prairie voles (Microtus ochrogaster), most adults are territorial, residing at a single nest site either as male-female pairs or as solitary individuals. However, some adults adopt nonterritorial, wandering tactics. During two field seasons monitoring prairie vole populations maintained in seminatural enclosures, we found evidence that females exhibiting different ARTs bred differentially with resident and wandering males. Females residing at a nest with a male bred significantly more often with a paired resident male, primarily their social partner, and significantly less often with male wanderers compared to single resident females or wandering females. These patterns were not due to chance, because paired resident females produced offspring with paired resident males significantly more than expected based on the relative abundance of these males in the population, whereas single resident females produced offspring with male wanderers significantly more than expected based on the proportion of male wanderers in the population. We did not find any evidence that multiple paternity was greater in the litters of single resident females and wanderer females even though these females lacked a male social partner to limit mating access by multiple males. This suggests that mate guarding by a female's male social partner was not the primary determinant of multiple paternity in the litters of females exhibiting different reproductive tactics. However, male ART did affect the likelihood of multiple paternity. Females that produced offspring with single resident or wanderer males had an increased likelihood of multiple paternity relative to females producing offspring with paired resident males. The results of this study show that female and male ARTs can affect breeding patterns.

Of mice and women: advances in mammalian sperm competition with a focus on the female perspective.

Although initially lagging behind discoveries being made in other taxa, mammalian sperm competition is now a productive and advancing field of research. Sperm competition in mammals is not merely a 'sprint-race' between the gametes of rival males, but rather a race over hurdles; those hurdles being the anatomical and physiological barriers provided by the female reproductive tract, as well as the egg and its vestments. With this in mind, in this review, I discuss progress in the field while focusing on the female perspective. I highlight ways by which sperm competition can have positive effects on female reproductive success and discuss how competitive outcomes are not only owing to dynamics between the ejaculates of rival males, but also attributable to mechanisms by which female mammals bias paternity toward favourable sires. Drawing on examples across different species-from mice to humans-I provide an overview of the accumulated evidence which firmly establishes that sperm competition is a key selective force in the evolution of male traits and detail how females can respond to increased sperm competitiveness with increased egg resistance to fertilization. I also discuss evidence for facultative responses to the sperm competition environment observed within mammal species. Overall, this review identifies shortcomings in our understanding of the specific mechanisms by which female mammals 'select' sperm. More generally, this review demonstrates how, moving forward, mammals will continue to be effective animal models for studying both evolutionary and facultative responses to sperm competition. This article is part of the theme issue 'Fifty years of sperm competition'.

How sperm competition shapes the evolution of testes and sperm: a meta-analysis.

Females of many species mate with multiple males, thereby inciting competition among ejaculates from rival males for fertilization. In response to increasing sperm competition, males are predicted to enhance their investment in sperm production. This prediction is so widespread that testes size (correcting for body size) is commonly used as a proxy of sperm competition, even in the absence of any other information about a species' reproductive behaviour. By contrast, a debate about whether sperm competition selects for smaller or larger sperm has persisted for nearly three decades, with empirical studies demonstrating every possible response. Here, we synthesize nearly 40 years of sperm competition research in a meta-analytical framework to determine how the evolution of sperm number (i.e. testes size) and sperm size (i.e. sperm head, midpiece, flagellum and total length) is influenced by varying levels of sperm competition across species. Our findings support the long-held assumption that higher levels of sperm competition are associated with relatively larger testes. We also find clear evidence that sperm competition is associated with increases in all components of sperm length. We discuss these results in the context of different theoretical predictions and general patterns in the breeding biology and selective environment of sperm. 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'.

Chromosome-Level Assembly of the Common Lizard (Zootoca vivipara) Genome.

Squamate reptiles exhibit high variation in their phenotypic traits and geographical distributions and are therefore fascinating taxa for evolutionary and ecological research. However, genomic resources are very limited for this group of species, consequently inhibiting research efforts. To address this gap, we assembled a high-quality genome of the common lizard, Zootoca vivipara (Lacertidae), using a combination of high coverage Illumina (shotgun and mate-pair) and PacBio sequencing data, coupled with RNAseq data and genetic linkage map generation. The 1.46-Gb genome assembly has a scaffold N50 of 11.52 Mb with N50 contig size of 220.4 kb and only 2.96% gaps. A BUSCO analysis indicates that 97.7% of the single-copy Tetrapoda orthologs were recovered in the assembly. In total, 19,829 gene models were annotated to the genome using a combination of ab initio and homology-based methods. To improve the chromosome-level assembly, we generated a high-density linkage map from wild-caught families and developed a novel analytical pipeline to accommodate multiple paternity and unknown father genotypes. We successfully anchored and oriented almost 90% of the genome on 19 linkage groups. This annotated and oriented chromosome-level reference genome represents a valuable resource to facilitate evolutionary studies in squamate reptiles.

Why do females of a lekking species mate with multiple males?

In Focus: Rivers, P. R., & DuVal, E. H. (2020). Multiple paternity in a lek mating system: Females mate multiply when they choose inexperienced sires. Journal of Animal Ecology, 89, 1142-1152. In many socially monogamous species with biparental care, some females engage in extra-pair copulations, despite the apparent risk of losing male help in raising their brood. Why females mate with multiple males remains the focus of intense debate, but may be linked to constraints in social mate choice. If so, multiple mating is not expected in a lekking mating system, where females receive no resources from the male other than sperm and are free to choose the 'best' mate to sire their offspring. Rivers and DuVal (2020) report on the occurrence of multiple paternity in lekking lance-tailed manakins and test several hypotheses to explain it. Their study shows that lower-ranked males and males with less experience were more likely to share paternity. However, the process underlying this pattern remains puzzling. The authors suggest female choice related to male characteristics that change with experience as an explanation, but alternative scenarios cannot be excluded.

Examining multiple paternity in the raccoon dog (Nyctereutes procyonoides) in Japan using microsatellite analysis.

We analyzed the genotypes of three pregnant females and their litters to investigate the phenomenon of multiple paternity in wild raccoon dogs (Nyctereutes procyonoides) using 17 microsatellite markers. If a female has mated with only one male during estrus, then the maximum number of paternal alleles will not exceed two among littermates with the same father. The results revealed two out of three litters had three or four paternal alleles at one or five microsatellite loci. Therefore, the female had mated with more than one male during estrus. To the best of our knowledge, the present study is the first to report the possibility of multiple paternity in wild raccoon dogs.

In the surf zone: Reproductive strategy of the calico surfperch (Amphistichus koelzi) in a comparative context.

We examined the reproductive life history of calico surfperch (Amphistichus koelzi), including mating season, pregnancy, gestation and multiple paternity utilizing restriction site-associated DNA sequencing. Furthermore, we compared the mating season of calico with barred (Amphistichus argenteus), walleye (Hyperprosopon argenteum) and silver (Hyperprosopon ellipticum) surfperches to determine if the timing of reproduction is divergent within and between the genera. In calico surfperch, the mating season occurs from October to November, and females gestate from December to May. All broods exhibit multiple paternity with a range of four to seven sires per brood. The mating season of calico overlaps completely with barred surfperch; however, barred surfperches have a protracted mating season which extends until the beginning of December, which may be due to differences in reproductive strategy such as size at first reproduction. In the genus, the Hyperprosopon mating season begins earlier than Amphistichus, with divergence in the onset of mating between Hyperprosopon congeners of approximately 1 month.