No evidence for a genetic association between female mating preference and male secondary sexual trait in a Lake Victoria cichlid fish

Sexual selection by female mating preference for male nuptial coloration has been suggested as a driving force in the rapid speciation of Lake Victoria cichlid fish. This process could have been facilitated or accelerated by genetic associations between female preference loci and male coloration loci. Preferences, as well as coloration, are heritable traits and are probably determined by more than one gene. However, little is known about potential genetic associations between these traits. In turbid water, we found a population that is variable in male nuptial coloration from blue to yellow to red. Males at the extreme ends of the phenotype distribution resemble a reproductively isolated species pair in clear water that has diverged into one species with blue-grey males and one species with bright red males. Females of the turbid water population vary in mating preference coinciding with the male phenotype distribution. For the current study, these females were mated to blue males. We measured the coloration of the sires and male offspring. Parents-offspring regression showed that the sires did not affect male offspring coloration, which confirms earlier findings that the blue species breeds true. In contrast, male offspring coloration was determined by the identity of the dams, which suggests that there is heritable variation in male color genes between females. However, we found that mating preferences of the dams were not correlated with male offspring coloration. Thus, there is no evidence for strong genetic linkage between mating preference and the preferred trait in this population [Current Zoology 56 (1): 57-64 2010].     

Male dominance rank and offspring-initiated affiliative behaviors were not predictors of paternity in a captive group of pigtail macaques (Macaca nemestrina)

Paternity of 16 pigtail macaque offspring was determined using a DNA profile analysis and was based on two independent assays of the genome of each individual using multilocus DNA probes. The offspring were members of a group of 59 pigtail macaques, including 5 adult males, 1 subadult male, and 37 adult and subadult females. Rank was unrelated to paternity as the first ranking male sired 0, the second ranking male sired 3; the third ranking male sired 0, the fourth ranking male sired 8, and the fifth ranking male sired 2 offspring. The subadult male sired 0 offspring. The DNA analysis was effective in excluding possible sires of 3 offspring whose mothers had become pregnant by another male before being introduced to the study males. Subsequent semen evaluation revealed an absence of sperm in the semen of the alpha male, but revealed a sperm count within normal limits in the third ranking male, who also sired no offspring. Behavioral data focusing on male-offspring interactions found that offspring did not preferentially affiliate with their sire and that males did not affiliate with their offspring frequently enough for analysis. Thus, this study of one captive pigtail macaque group demonstrates that: (1) rank was not a predictor of reproductive success; and (2) there was no preferential attraction for one's own offspring by males or one's own sire by offspring.     

Microsatellite analysis of kinkajou social organization

Kinkajou social groups generally consist of one adult female, two males, one subadult and one juvenile. Based on analysis of variation in 11 microsatellite loci, we assess the degree of kinship within and between four social groups totaling 25 kinkajous. We use exclusion and likelihood analyses to assign parents for seven of the eight offspring sampled, five with >/= 95% certainty, and two with >/= 80% certainty. Five of six identified sires of group offspring came from the same social group as the mother and pup. Adult males and females within a group were unrelated and subadults and juveniles were offspring of the group adults, suggesting a family structure. All five identified paternities within a social group were by the dominant male of the group. However, this copulation asymmetry does not necessarily reflect cooperation due to kinship ties between the two adult males within a group as one of two adult male pairs sampled was unrelated. Neighbouring male kinkajous were more closely related to each other than neighbouring female kinkajous, suggesting that females disperse more often or farther than males.     

Do sires and juvenile male mice (C57BL/6) contribute to the rearing of the offspring?

Copulation and/or cohabitation with a pregnant female facilitate paternal behavior in male mice. However, their contribution to the rearing of the offspring is still not well understood. Our aims were to investigate the behavior of sires toward own or alien pups; the immediate consequences of the presence of fathers on the offspring and the behavior of the mother; and whether the exposure of juvenile males to newborn siblings, in an overlapping litters context, facilitates paternal behavior in C57BL/6 mice. We found that sires behaved paternally toward alien pups at both postpartum days 3 and 7; did not affect the behavior of the mother (e.g., licking and grooming, retrieval behavior, time in the nest, and crouching postures); and reduced the time offspring stayed alone in the nest. The exposure to newborn siblings did not promote paternal behavior in juvenile males. Therefore, sires are more paternal than usually described in the literature for laboratory mice, suggesting a facultative role in the rearing of the offspring. However, juvenile male mice, in contrast to juvenile females, could be adapted to leave the nest earlier without major contribution to the offspring.     

Paternity in Sooty Mangabeys

We determined paternity for 78 sooty mangabeys [(Cercocebus torquatus atys (Groves, 1978) equivalent to C. atys (Napier and Napier, 1967)], born between 1986 and 1993, using DNA profile analysis. The analysis is based on two independent assays of the genome of each individual via multilocus DNA probes. The mangabeys were members of either a large (n = 98) or a small (n = 18) group. Overall, during two periods of analysis in the large group, higher-ranking males sired more offspring than their lower-ranking counterparts did, though during one period the correlation between dominance rank and reproductive success is not significant. Of the two males in the small group, the alpha male sired all of the offspring during one period. There is a significant correlation between mounts and the number of surviving offspring each male sired in one birth year. Moreover, the same male did not always sire the offspring of a given female from year to year. Behavioral data focusing on male–offspring interactions show that offspring (n = 15) did not preferentially affiliate with their sire and that males affiliated with infants too infrequently for analysis. Thus, in a large sooty mangabey colony: (1) dominance rank generally predicts reproductive success; (2) adult males are not preferentially attracted to their offspring, or infants to their sires; and (3) the same male generally does not sire the offspring of a given female from year to year.     

The more the better – polyandry and genetic similarity are positively linked to reproductive success in a natural population of terrestrial salamanders (Salamandra salamandra)

Although classically thought to be rare, female polyandry is widespread and may entail significant fitness benefits. If females store sperm over extended periods of time, the consequences of polyandry will depend on the pattern of sperm storage, and some of the potential benefits of polyandry can only be realized if sperm from different males is mixed. Our study aimed to determine patterns and consequences of polyandry in an amphibian species, the fire salamander, under fully natural conditions. Fire salamanders are ideal study objects, because mating, fertilization and larval deposition are temporally decoupled, females store sperm for several months, and larvae are deposited in the order of fertilization. Based on 18 microsatellite loci, we conducted paternity analysis of 24 female‐offspring arrays with, in total, over 600 larvae fertilized under complete natural conditions. More than one‐third of females were polyandrous and up to four males were found as sires. Our data clearly show that sperm from multiple males is mixed in the female's spermatheca. Nevertheless, paternity is biased, and the most successful male sires on average 70% of the larvae, suggesting a ‘topping off’ mechanism with first‐male precedence. Female reproductive success increased with the number of sires, most probably because multiple mating ensured high fertilization success. In contrast, offspring number was unaffected by female condition and genetic characteristics, but surprisingly, it increased with the degree of genetic relatedness between females and their sires. Sires of polyandrous females tended to be genetically similar to each other, indicating a role for active female choice.     

Role-Reversed Nepotism Among Cubs and Sires in the Spotted Hyena (Crocuta crocuta)

Nepotism is widespread among parents and offspring, and is typically associated with fundamental asymmetries; parents can usually do more to help their offspring than vice versa, and the cost of a given nepotistic behavior is usually less for parents than for offspring. This may not be so among spotted hyenas (Crocuta crocuta); sires never achieve social rank equal to that of their cubs, to whom they provide no obvious paternal care. Nepotism by sires towards their cubs is thus socially constrained. However, the higher social status of cubs might offset cubs’ developmental disadvantages and permit nepotistic treatment of sires by offspring. We therefore sought to determine whether the interactions among spotted hyena cubs and adult males were influenced by kinship, using long‐term observations from one clan of spotted hyenas. Sires exhibited no overt nepotism towards their cubs in most behaviors, but they did associate more closely with their daughters than with unrelated control females. Sires also associated more closely with their daughters than with their sons, with whom they associated no more closely than they did with unrelated control males. Cubs favored their sires by directing less intense aggression towards them than towards unrelated control males. Cubs of both sexes also associated more closely with their sires than with control males after the cubs were independent of the clan's communal den. Although sires evidently recognize their offspring, paternal nepotism by sires towards their cubs is weaker than filial nepotism by cubs towards their sires. The small size and immaturity of cubs thus appear to be weaker constraints on nepotism than is the low social status of their sires.     

The effects of deletions of the mouse Y chromosome long arm on sperm function--intracytoplasmic sperm injection (ICSI)-based analysis

In mouse and man, Y chromosome deletions are frequently associated with spermatogenic defects. XY(Tdy)(m1)qdelSry males have an extensive Yq deletion that almost completely abolishes the expression of two gene families, Ssty and Sly, located within the male-specific region of the mouse Y long arm. These males exhibit severe sperm defects and sterility. XY(RIII)qdel males have a smaller interstitial Yq deletion, removing approximately two thirds of Ssty/Sly gene copies, and display an increased incidence of mild sperm head anomalies with impairment of fertility and an intriguing distortion in the sex ratio of offspring in favor of females. Here we used intracytoplasmic sperm injection (ICSI) to investigate the functional capacity of sperm from these Yq deletion males. Any selection related to the ability of sperm to fertilize in vitro is removed by ICSI, and we obtained two generations of live offspring from the infertile males. Genotyping of ICSI-derived offspring revealed that the Y(Tdym1)qdel deletion does not interfere with production of Y chromosome-bearing gametes, as judged from the frequency of Y chromosome transmission to the offspring. ICSI results for XY(RIII)qdel males also indicate that there is no deficiency of Y sperm production in this genotype, although the data show an excess of females following in vitro fertilization and natural mating. Our findings suggest that 1) Yq deletions in mice do not bias the primary sex ratio and 2) Y(RIII)qdel spermatozoa have poorer fertilizing ability than their X-bearing counterparts. Thus, a normal complement of the Ssty and/or Sly gene families on mouse Yq appears necessary for normal sperm function. Summary: ICSI was successfully used to reproduce infertile mice with Yq deletions, and the analysis of sperm function in obtained offspring demonstrated that gene families located within the deletion interval are necessary for normal sperm function.     

Subandrodioecy and male fitness in Sagittaria lancifolia subsp. lancifolia (Alismataceae)

Sagittaria lancifolia subsp. lancifolia is described as cosexual (monoecious), but the study population consisted of 84% cosexuals that typically had 35% pistillate buds and 16% predominant males that typically had 0-2% pistillate buds. Hand-pollinations showed that pistillate flowers required pollination to set seed, and pollen from both male and cosexual plants was potent. No gender switching was seen in the field or greenhouse. From 24 experimental crosses, 890 offspring were grown to maturity. Among these, all offspring of cosexual sires were cosexual, but approximately half the offspring of male sires were male, implying that maleness was inherited as a single, dominant allele. These results indicate that S. lancifolia is subandrodioecious, a very rare breeding system. It is rare, in part because its maintenance requires a large male-fitness differential between male and cosexual plants. In the study population, this condition was met by the differential survival of staminate buds on male racemes. Larvae of the weevil Listronotus appendiculatus killed many staminate buds. They did so in a vertical gradient, with buds lower on racemes safer. Male plants have replaced pistillate with staminate buds at these safer positions and thereby enjoy disproportionally higher male fitness.     

SEXUAL SELECTION IN AMERICAN TOADS: A TEST OF A GOOD-GENES HYPOTHESIS

Adaptive mate choice in species lacking male resource control and/or paternal care might be maintained by selection because preferred males sire genetically superior offspring. For such a process to occur, some male phenotypic trait(s) must both reliably indicate male genetic quality and influence the pattern of mate choice by females. In American toads, Bufo americanus, male body length has been documented to influence female mating patterns: females usually mate with males that are larger than average. However, the relationship between male size and male genetic quality is unknown. We conducted a controlled breeding experiment using 48 sires and 19 dams to determine if larger males sire offspring with superior larval performance characteristics (greater survival to metamorphosis, larger mass at metamorphosis, and earlier metamorphosis). We also aged each sire to test the hypothesis that older males are, on average, genetically superior to younger males. We crossed each female with three sires representing three body size categories (mean and 1 SD ± mean snout-ischium length). Hatchlings (500 from each cross) were reared to metamorphosis in seminatural ponds in the field. Metamorph weight (log transformed) and age at metamorphosis showed significant heritability and were genetically correlated with each other. Hence, sires differed in genetic quality. However, none of the three measures of offspring performance was correlated with sire body size or age. Thus, we obtained no support for the prediction that sire body size or age is related to genetic quality.     

Artificial selection of rams for sexual performance and its effect on the sexual behavior and fecundity of male and female progeny

The objective of this study was to determine the effect of a single generation of artificial selection for sexual performance in rams on the sexual behavior and fecundity of their male and female progeny. Ninety-two ram lambs born to sires selected for either high or low sexual performance were evaluated for their sexual behaviors at approximately 8 months of age when individually exposed to four estrous ewes for 30min in four weekly serving capacity tests. Number of mounts and successful matings (ejaculations) were recorded. Fourteen of the 17 high-performing ram lambs identified were sired by high-performing sires, whereas 22 of 37 low-performing ram lambs were sired by low-performing sires (P<0.01). Sons of high-performing sires exhibited more ejaculations (P<0.04) and more mounts without ejaculation (P<0.02) than sons of low-performing sires. The two groups of ram lambs did not differ in mating efficiency (ratio of ejaculations to total mounts). Daughters of high-performing rams (N=79) exhibited their first behavioral estrus approximately 8 days earlier than daughters (N=61) of low-performing sires (P<0.005). Ovulation rates for the two groups of ewe lambs did not differ (P=0.55). It was concluded that there was sufficient genetic variation in the population of sheep studied to obtain a significant response to selection for ram sexual performance in both male and female offspring in a single generation.     

Study of fertilising capacity of spermatozoa after heterospermic insemination in rabbit using DNA markers

The aim of this study was to evaluate the fertilising capacity of males belonging to a rabbit line selected for growth rate using heterospermic insemination and genetic markers. Semen from five males was used to make pools of three of them, and to perform homospermic insemination. Insemination was carried out in receptive multiparous lactating does with 6 million spermatozoa per insemination dose. DNA from 360 young rabbits born from heterospermic insemination, 5 sires and 42 does were amplified to nine microsatellite loci for determination of the offspring rate per male. Although each female was inseminated with the same number of spermatozoa from each male (2 million from a total dose of 6 million), sperm from one male was always dominant, notable differences being observed in the offspring among the males with similar semen quality (83-68% from dominant male versus 31-0% from non-dominant, P<0.05 ).     

Reconstruction of Parentage in a Band of Captive Hamadryas Baboons

The male leaders of free-ranging harem groups of hamadryas baboons are believed to mate exclusively with the female members of their harems, which typically contain no more than 2–3 females. Using no-parent parentage exclusion analysis (PEA) we identified the paternity of 25 offspring born in a captive band of hamadryas baboons (Papio hamadryas hamadryas) containing five adult males, each with a stable harem of about five females. Nine of 13 microsatellite (SSR) loci known to be highly polymorphic in rhesus macaques (Macaca mulatta) were successful in identifying the sires of all but two offspring without knowledge of the dams' genotypes, and we were able to determine the sires of all offspring when the dams' genotypes were considered. Mating success of the males ranged between 2 and 7 offspring and bore no clear relationship to the males' ages, ranks or the number of females in their harems. The males sired 7 of the 25 offspring with females outside their own harems, with higher-ranking males exhibiting greater success monopolizing access to females in their harem than lower-ranking males did. More surprisingly, the females assigned as the dams of 14 of the 25 offspring could be unequivocally excluded from parentage. The identity of the true dam could be determined for each of these 14 offspring using single-parent PEA and was uncorrelated with the ranks of these offsprings' sires and whether the offspring were born to dams outside the sires' harem groups. The combined effect of this extraharem mating and kidnapping was that only 12 of the 25 offspring were raised within their sires' harem groups. A second group of hamadryas baboons of identical structure exhibited the same high incidences of infant kidnapping and mating outside the harem group. It is unclear whether these behaviors provide an adaptive advantage or represent aberrant behavior resulting from captivity or other circumstances.     

DNA fingerprinting reveals polygyny in the subterranean rodent Ctenomys talarum

DNA fingerprinting was used to characterize patterns of paternity in two populations of Ctenomys talarum from Buenos Aires Province, Argentina. The multilocus probe PV47-2 was used to detect variation in genomic DNA extracted from 12 females, their 32 offspring, and 14 putative sires. For 11 out of 12 litters examined, a single male capable of providing all nonmaternal bands was identified. Within each study population, individual males sired more than one litter, suggesting that C. talarum is polygynous. No evidence of multiple paternity of litters was found. High band-sharing values among females suggest that further research is needed to assess the population genetic structure of this species.     

Mapping quantitative trait loci affecting fatness and breast muscle weight in meat-type chicken lines divergently selected on abdominal fatness

Quantitative trait loci (QTL) for abdominal fatness and breast muscle weight were investigated in a three-generation design performed by inter-crossing two experimental meat-type chicken lines that were divergently selected on abdominal fatness. A total of 585 F₂ male offspring from 5 F₁ sires and 38 F₁ dams were recorded at 8 weeks of age for live body, abdominal fat and breast muscle weights. One hundred-twenty nine microsatellite markers, evenly located throughout the genome and heterozygous for most of the F₁ sires, were used for genotyping the F₂ birds. In each sire family, those offspring exhibiting the most extreme values for each trait were genotyped. Multipoint QTL analyses using maximum likelihood methods were performed for abdominal fat and breast muscle weights, which were corrected for the effects of 8-week body weight, dam and hatching group. Isolated markers were assessed by analyses of variance. Two significant QTL were identified on chromosomes 1 and 5 with effects of about one within-family residual standard deviation. One breast muscle QTL was identified on GGA1 with an effect of 2.0 within-family residual standard deviation.     

Social status and reproductive success of male Macaca fascicularis

Dominant males of nonseasonally breeding species should have more opportunity than seasonal breeders to monopolize access to estrous females and thus enhance their reproductive success. They may also use other strategies for maximizing reproductive success such as producing offspring by relatively high ranking females. To test these hypotheses, the paternity of 35 (80%) of 44 Macaca fascicularis offspring, born over a 28-month period, was established using electrophoretically and serologically defined genetic markers. The social ranks of each of the seven potential fathers and 26 potential mothers were determined by recording outcomes of dyadio agonistic interactions. No evidence could be found to support either hypothesis. Further, in view of previously reported significant, positive correlations between male social rank and sexual activity rates in this study group, sexual activity rates do not appear to predict the number of offspring a male sires in this species.     

Survival of extrapair and within-pair young in tree swallows

In monogamous species, it is generally accepted that males seekextrapair matings to increase their reproductive success withoutadditional parental investment; however, the benefits of extrapairmatings to females are much less clear. One possibility isthat females obtain genes for enhanced offspring viabilityfrom the extrapair sires. If this is the case, then the increasedviability of extrapair young may be evident throughout the periodof embryonic development as well as later in life. Tree swallows(Tachycineta bicolor) have one of the highest known levelsof extrapair mating in birds, and females have substantialcontrol over the paternity of their offspring. We used moleculartechniques to determine the parentage of nestlings and unhatchedembryos to examine the possibility that female tree swallowsgain viability benefits for their extrapair offspring. Althoughboth extrapair paternity and mortality of embryos and nestlingswere high (89% and 54% of broods respectively), we found nodifference in the viability of within-pair and extrapair youngprior to fledging. In addition, extrapair young were not morelikely to be male. There was no bias in the sex of young atfledging, but unhatched embryos were more likely to be male.Our results do not support the idea that female tree swallowsengage in extrapair mating to increase offspring viability,at least early in life.     

Arctic charr strain crosses: effects on growth and sexual maturity

Three Arctic charr strains and their crosses were evaluated with respect to growth and sexual maturation frequency. No significant heterosis was observed for growth. One out of five crosses was heavier, but not significantly so, than the best performing parental strain at ages 1 + and 2. The five other crosses did not perform better than the best performing parental strain at any age. Cross-breeding was not recommended as an effective method to improve growth performance in Arctic charr. Growth performance of reciprocal crosses differed significantly in all strain combinations: crosses resembled more the male parent strain than the female parent strain. ANOVA for male maturation frequency showed a highly significant effect of the male parent strain and a weakly significant effect of female parent strain. In the Ottsjö strain mature males were significantly larger than immature fish and females. Such size difference was also observed in the offspring when sires of the Ottsjö strain were crossed with dams of the faster growing Honavan strain or with dams of the Rensjö strain. When Ottsjö dams were crossed to sires of the other strains no significant size difference between mature males and other fish was found.     

Evidence of multiple paternity in the bluntnose klipfish, <Emphasis Type="Italic">Clinus cottoides</Emphasis> (Blennioidei: Clinidae: Clinini)

Clinids of the tribe Clinini are viviparous fishes occurring in the temperate waters of southern Africa. Females of the genus Clinus exhibit reproductive traits suggesting multiple paternity. These traits include prolonged gestation periods, matrotrophy and superfetation. We tested the hypothesis that broods of the species C. cottoides are sired by multiple males with the use of microsatellites. We genotyped three broods from known mothers and analysed the relationships within each brood using the software program COLONY, we also used allele counting to find evidence of multiple paternity. Our results revealed that multiple paternity occurred in all three broods analysed; two broods likely had two sires and one brood three sires. One male appear to have fathered offspring with separate females. Our study represents the first molecular analysis of parentage in C. cottoides.     

Fitness benefits of polyandry for experienced females

Females often mate with several different males, which may promote sperm competition and increase offspring viability. However, the potential benefits of polyandry remain controversial, particularly in birds where recent reviews have suggested that females gain few genetic benefits from extra‐pair mating. In tree swallows (Tachycineta bicolor), we found that females with prior breeding experience had more sires per brood when paired to genetically similar social mates, and, among experienced females, broods with more sires had higher hatching success. Individual females breeding in two consecutive years also produced broods with more sires when they were more genetically similar to their mate. Thus, experienced females were able to avoid the costs of mating with a genetically similar social mate and realize fitness benefits from mating with a relatively large number of males. This is one of the first studies to show that female breeding experience influences polyandry and female fitness in a natural population of vertebrates. Our results suggest that the benefits of polyandry may only be clear when considering both the number of mates females acquire and their ability to modify the outcome of sexual conflict.