The endangered White's seahorse Hippocampus whitei chooses artificial over natural habitats

To explore whether the endangered White's seahorse Hippocampus whitei would choose to inhabit artificial over natural habitats, 10 adult H. whitei individuals were put through a series of binary choice trials in aquaria, during which they were offered different paired combinations of natural (different types of macroalga and seagrass) and artificial habitat (panels of swimming-net material). It was found that H. whitei displayed a significant choice for swimming-net material over all other available natural habitats and chose habitats according to the following rankings: (a) Net; (b) Sargassum sp.; (c) Posidonia australis; (d) Zostera muelleri. Hippocampus whitei’s choice of swimming net material over natural habitat suggests that these artificial structures could be a useful conservation measure for seahorses in areas where natural habitat is becoming less favourable due to declines in abundance or quality.     

Correlates of reproductive success in a Caribbean village

Genealogical, demographic, and economic data collected in a rural Trinidadian village indicate that: (1) individuals with more land have more offspring, (2) males with more land have higher mating success, (3) young adults with parents resident in the village have higher reproductive success, and (4) the residence of father has a strong effect on young adult male reproductive success, but apparently has no effect on young adult female reproductive success, suggesting a gender bias in nepotism. The results indicate that there are important gender differences in the effect of resources on reproduction and in patterns of parent-offspring interaction.     

Correlates of lifetime reproductive success in three species of European ducks

Number of breeding attempts is a strong correlate of lifetime reproductive success (LRS) in birds, but the relative importance of potentially interacting factors affecting LRS has rarely been fully evaluated. We considered simultaneously five main factors hypothesized to influence LRS (age at first breeding, nesting date, number of breeding attempts, female traits, brood parasitism) by analyzing with path analysis 22-year data sets for 1,279 individually marked females and their offspring in tufted duck (Aythya fuligula), common pochard (A. ferina) and northern shoveler (Anas clypeata). We recaptured marked offspring as breeding adults (n=496 females) and obtained more complete estimates of LRS by incorporating information about banded ducklings of both sexes shot by hunters 12 months after banding (n=138). In tufted ducks and especially pochard (both diving duck species), late-hatched females tended to delay nesting until 2-years old. Most females (tufted duck, 74%; pochard, 71%; shoveler, 59%) apparently produced no breeding-age offspring. Number of breeding attempts (i.e., longevity) was the strongest correlate of LRS in all species, after controlling effects of age at first breeding, relative nest initiation date, wing length and body mass. Percentage of females producing recruits increased gradually with number of breeding attempts for all three species. Also, as expected, females nesting early in the breeding season had higher LRS than late-nesting individuals. In shoveler, female-specific characteristics of relatively longer wings and heavier late incubation body mass had positive effects on LRS, the latter feature being more common in 2-year-old nesters. In diving ducks, no relationships were detected between LRS and female-specific traits like wing length or body mass, and nor did acceptance of parasitic eggs have any deleterious impact on fitness estimates. Overall, number of fledged ducklings and LRS were related in tufted duck, weakly associated in pochard and unrelated in shoveler, implying that fledging success is not always a reliable measure of LRS.     

Mate choice, operational sex ratio, and social promiscuity in a wild population of the long-snouted seahorse Hippocampus guttulatus

Mate competition and mate choice are not mutually exclusivebehaviors. Both behaviors may drive sexual selection in oneor both sexes of a population. One of several factors affectingwhich behavior is exhibited by which sex is the operationalsex ratio (OSR) in the study population. The present study combinesbehavioral observations in the field with controlled experimentsin aquaria to investigate social interactions and mate choicein both male and female long-snouted seahorses Hippocampus guttulatusin the context of the population OSR. Compared with the morereadily studied pipefishes, data on OSR and mate choice in seahorsesare scarce in the published literature. Our field data providenovel evidence of social promiscuity, size-assortative mating,and an OSR that varies from being unbiased early and midseasonto male biased at the end of the breeding season. Our mate choiceexperiments revealed intersexual differences in mate preferencewith males significantly preferring larger females to familiarones. Taken together, our field and experimental results suggestthat mate choice rather than intrasexual competition could drivesexual selection in seahorses.     

Correlates of reproductive success in male lizards of the alpine species Iberolacerta cyreni

We followed a field population of the alpine lizard Iberolacertacyreni over 2 consecutive breeding seasons and assigned paternityto the offpring using 8 microsatellite markers. Paternity data,combined with observations of the behavior, morphology, andspacing patterns of lizards, allowed us to document the extentof polygamy, the phenotypic correlates of the number of offspringsired, and the correlation between male reproductive success(RS) and probability of recapture the second year of our study.Multiple paternity was observed in nearly 50% of clutches, andthe mating system was highly polygynandrous. In the first yearof our study, male RS increased with body size, activity, taillength, and color saturation of the dorsum. In the second year,male RS increased with activity and body condition. Overall,increased male activity, a trait that is expected to decreasesurvivorship, was the explanatory variable that had the greatesteffect on RS. However, the residents of our first study yearthat were recaptured in the second year had longer tails, weremore active, and sired more offspring than their conspecificsthat were not recaptured. Thus, contrary to expectations, nonegative correlation between present reproduction and futuresurvival was found, which suggests that male investment in reproductionis condition dependent and positively correlated with the abilityto pay the underlying costs of increased activity.     

Male mating success, reproductive success and multiple paternity in a natural population of sand lizards: behavioural and molecular genetics data

Sand lizard Lacerta agilis females characteristically mate with several males which, in staged mating experiments, results in multiple paternity of the offspring. In order to investigate multiple paternity in a natural population and interpret male reproductive behaviours in terms of sired young, we sampled the blood of females, potential fathers and hatchlings, and determined paternity using multilocus DNA fingerprinting as well as the variation at a single locus detected by the probe (TC) _n . The paternity analyses were preceded by a laboratory experiment in which we established that the parental alleles identified by the single locus probe were inherited in a Mendelian way. Our molecular data demonstrated that 12 out of 13 males (92%) that sired offspring were correctly identified from the 56 sexually mature males in the population. Also smaller males were accepted as sexual partners by the females, but sired fewer young in competition with larger males and were less able to maintain prolonged post-copulatory mate guarding. This may result in that some sexually successful males are only observed inside a female's home range, but never in pair-association with the female.     

Grape variety affects female but also male reproductive success in wild European grapevine moths

Abstract.  1. For insect herbivores the quality of the larval host plant is a key determinant of their fitness. Only little attention, however, has been given to the effects of plants on mating success of males and its consequence for the reproductive output of their mates. In addition, almost all the studies that have investigated the influence of host plants on herbivore fitness components have been done in the laboratory, and less is known of these effects in natural conditions.
2. Using the phytophagous European grapevine moth ( Lobesia botrana Den. & Schiff., Lepidoptera: Tortricidae), we tested the influence of grape cultivars as larval food on the probability of acquiring a mate for both sexes, and on the reproductive output of females and males.
3. Results from this study stress the importance of larval host plants on the reproductive success of both sexes. Larval diet differentially affected mating success and reproductive output of male and female moths. Fecundity, egg size, and egg hatchability were significantly different when larvae were fed on particular grape cultivars.
4. A given cultivar that is of poor quality for females is generally also of poor quality for males. A cultivar, however, could be suitable for females but not for males and vice-versa. Apparently, the nutrients required for adult reproduction are not necessarily the same for males and females.
5. The important conclusion from this study is that evaluating the differential effect of host-plant species on traits associated with reproductive success of herbivores requires that the effects on both sexes be taken into account.     

Mhc‐linked survival and lifetime reproductive success in a wild population of great tits

Major histocompatibility complex (Mhc) genes are frequently used as a model for adaptive genetic diversity. Although associations between Mhc and disease resistance are frequently documented, little is known about the fitness consequences of Mhc variation in wild populations. Further, most work to date has involved testing associations between Mhc genotypes and fitness components. However, the functional diversity of the Mhc, and hence the mechanism by which selection on Mhc acts, depends on how genotypes map to the functional properties of Mhc molecules. Here, we test three hypotheses that relate Mhc diversity to fitness: (i) the maximal diversity hypothesis, (ii) the optimal diversity hypothesis and (iii) effect of specific Mhc types. We combine mark–recapture methods with analysis of long‐term breeding data to investigate the effects of Mhc class I functional diversity (Mhc supertypes) on individual fitness in a wild great tit (Parus major) population. We found that the presence of three different Mhc supertypes was associated with three different components of individual fitness: survival, annual recruitment and lifetime reproductive success (LRS). Great tits possessing Mhc supertype 3 experienced higher survival rates than those that did not, whereas individuals with Mhc supertype 6 experienced higher LRS and were more likely to recruit offspring each year. Conversely, great tits that possessed Mhc supertype 5 had reduced LRS. We found no evidence for a selective advantage of Mhc diversity, in terms of either maximal or optimal supertype diversity. Our results support the suggestion that specific Mhc types are an important determinant of individual fitness.     

Culled males,infant mortality and reproductive success in a pre-industrial Finnish population

Theoretical and empirical literature asserts that the sex ratio (i.e. M/F) at birth gauges the strength of selection in utero and cohort quality of males that survive to birth. We report the first individual-level test in humans, using detailed life-history data, of the ‘culled cohort’ hypothesis that males born to low annual sex ratio cohorts show lower than expected infant mortality and greater than expected lifetime reproductive success. We applied time-series and structural equation methods to a unique multigenerational dataset of a natural fertility population in nineteenth century Finland. We find that, consistent with culled cohorts, a 1 s.d. decline in the annual cohort sex ratio precedes an 8% decrease in the risk of male infant mortality. Males born to lower cohort sex ratios also successfully raised 4% more offspring to reproductive age than did males born to higher cohort sex ratios. The offspring result, however, falls just outside conventional levels of statistical significance. In historical Finland, the cohort sex ratio gauges selection against males in utero and predicts male infant mortality. The reproductive success findings, however, provide weak support for an evolutionarily adaptive explanation of male culling in utero.     

Criteria of reproductive success

To determine reproductive success, it is necessary for the researcher to specify a criterion of success, such as the number of a parent's offspring living to the age of reproduction. A measurement model, which includes the researcher's choice of criterion, has been proposed to estimate the lifetime reproductive success (R) of long-lived animals from complete or incomplete knowledge of the reproductive life histories of mothers and the survival fates of offspring. This research uses R and data from female baboons of Mikumi National Park, Tanzania, as vehicles to investigate the relationship between reproductive success and several criteria. Secondarily, it also investigates the relationship between R and the number and rate of offspring production. Seven criteria of reproductive success, ranging in 12-month increments from 0 (birth) to 72 months of offspring life, were applied to 10.5 years of reproductive data from 61 Mikumi females. Theoretically, the best scenario for comparative purposes is an invariant R across different criteria; however, the mean R systematically increased as the criteria increased. This is more an inconvenience than a serious problem because high correlations indicate high predictability between Rs from pairs of criteria. R was modestly correlated with the rate of offspring production, indicating that rate can be employed as a rough index of reproductive success. The choice of a criterion is a trade off between theory, practicality, the strength of the criterion, and the effect of the choice upon sample representativeness and size. Am. J. Primatol. 41:87–101, 1997. © 1997 Wiley-Liss, Inc.     

Population dynamics and life history of a geographically restricted seahorse, Hippocampus whitei

The aim of this study was to collect data on population dynamics and life history for White's seahorse Hippocampus whitei, a geographically restricted species that is listed as data deficient under the IUCN Red List. Data from H. whitei populations were collected from two regions, Port Stephens (north) and Sydney Harbour (south) in New South Wales, Australia, covering most of the known range of H. whitei, from 2005 to 2010. Over 1000 individuals were tagged using fluorescent elastomer and on subsequent recaptures were re-measured for growth data that were used in a forced Gulland-Holt plot to develop growth parameters for use in a specialized von Bertalanffy growth-function model. Growth parameters for Port Stephens were: females L(∞) = 149·2 mm and K = 2·034 per year and males L(∞) = 147·9 mm and K = 2·520 per year compared with estimates from Sydney Harbour: females L(∞) = 139·8 mm and K = 1·285 per year and males L(∞) = 141·6 mm and K = 1·223 per year. Whilst there was no significant difference in growth between sexes for each region, H. whitei in Port Stephens grew significantly quicker and larger and matured and reproduced at a younger age than those from Sydney Harbour. The life span of H. whitei is at least 5 years in the wild with six individuals recorded reaching this age. Data collected on breeding pairs found that H. whitei displays life-long monogamy with three pairs observed remaining pair bonded over three consecutive breeding years. Baseline population densities were derived for two Port Stephens' sites (0·035 and 0·110 m(-2) ) and for Manly in Sydney Harbour (1·050 m(-2) ). Even though the life-history parameters of H. whitei suggest it may be reasonably resilient, precaution should be taken in its future management as a result of its limited geographical distribution and increasing pressures from anthropogenic sources on its habitats.     

Voice pitch predicts reproductive success in male hunter-gatherers

The validity of evolutionary explanations of vocal sexual dimorphism hinges upon whether or not individuals with more sexually dimorphic voices have higher reproductive success than individuals with less dimorphic voices. However, due to modern birth control methods, these data are rarely described, and mating success is often used as a second-rate proxy. Here, we test whether voice pitch predicts reproductive success, number of children born and child mortality in an evolutionarily relevant population of hunter-gatherers. While we find that voice pitch is not related to reproductive outcomes in women, we find that men with low voice pitch have higher reproductive success and more children born to them. However, voice pitch in men does not predict child mortality. These findings suggest that the association between voice pitch and reproductive success in men is mediated by differential access to fecund women. Furthermore, they show that there is currently selection pressure for low-pitch voices in men.     

Microsatellite determination of male reproductive success in a natural population of the territorial ornate dragon lizard, Ctenophorus ornatus

It is now evident that the genetic mating system can be very different to the observed mating system. However, it is less well known what makes particular individuals more (or less) successful than expected from the observed system. In this study the observed territorial structure of a field population of the agamid lizard, Ctenophorus ornatus, was compared with the mating system as evidenced by microsatellite parentage assignment. This study also investigated whether any male traits predicted reproductive success. Sixty-five per cent of clutches were sired at least partially by a male other than the main territory-holding male and 35% of clutches were sired by a male with no overlap of the female's territory. Multiple paternity was moderately frequent at 25% of clutches. Male chest patch size predicted territory size and the number of females in the territory, but did not predict reproductive success. Instead, male head depth and body size were independently related to the number of offspring sired. As male head depth also predicted the number of females in a territory, these males are likely to be gaining increased reproductive success as a consequence of the higher number of females in their territories. Larger body size males, however, did not have a greater number of females in their territory and instead had more extra-territorial copulations. Whether these extra-territorial copulations are due to female choice or success in male competition is unknown.     

Indices of reproductive skew depend on average reproductive success

Several indices of reproductive skew, which quantify the degree of unequal partitioning of reproductive output among members in an animal society, have been proposed. Here we point out the drawbacks of these indices. The most serious problem is the dependence of the indices on mean reproductive success: skew values tend to be larger, as average numbers of offspring decrease, due to random sampling error in numbers of offspring. Thus it is difficult to compare societies with different average lifetime reproductive success using these indices, even though we have presented methods to calculate the expected reproductive skew caused by random sampling error, especially when average numbers of offspring are small, as is often the case with cooperatively breeding vertebrates. As an alternative, we propose using the spatial dispersion indices of population ecology (Morisita's index or its standardized version) for the measurement of reproductive skew. These indices are almost independent of average fecundity and have their own method of testing for random variation in offspring numbers. This revised version was published online in July 2006 with corrections to the Cover Date.     

Monogamous pair bonds and mate switching in the Western Australian seahorse Hippocampus subelongatus

Apparently monogamous animals often prove, upon genetic inspection, to mate polygamously. Seahorse males provide care in a brood pouch. An earlier genetic study of the Western Australian seahorse demonstrated that males mate with only one female for each particular brood. Here we investigate whether males remain monogamous in sequential pregnancies during a breeding season. In a natural population we tagged males and sampled young from two successive broods of 14 males. Microsatellite analyses of parentage revealed that eight males re‐mated with the same female, and six with a new female. Thus, in this first study to document long‐term genetic monogamy in a seahorse, we show that switches of mates still occur. Polygynous males moved greater distances between broods, and tended to have longer interbrood intervals, than monogamous males, suggesting substantial costs associated with the breaking of pair bonds which may explain the high degree of social monogamy in this fish genus.     

Reduced reproductive success of hatchery coho salmon in the wild: insights into most likely mechanisms

Supplementation of wild salmonids with captive-bred fish is a common practice for both commercial and conservation purposes. However, evidence for lower fitness of captive-reared fish relative to wild fish has accumulated in recent years, diminishing the apparent effectiveness of supplementation as a management tool. To date, the mechanism(s) responsible for these fitness declines remain unknown. In this study, we showed with molecular parentage analysis that hatchery coho salmon (Oncorhynchus kisutch) had lower reproductive success than wild fish once they reproduced in the wild. This effect was more pronounced in males than in same-aged females. Hatchery spawned fish that were released as unfed fry (age 0), as well as hatchery fish raised for one year in the hatchery (released as smolts, age 1), both experienced lower lifetime reproductive success (RS) than wild fish. However, the subset of hatchery males that returned as 2-year olds (jacks) did not exhibit the same fitness decrease as males that returned as 3-year olds. Thus, we report three lines of evidence pointing to the absence of sexual selection in the hatchery as a contributing mechanism for fitness declines of hatchery fish in the wild: (i) hatchery fish released as unfed fry that survived to adulthood still had low RS relative to wild fish, (ii) age-3 male hatchery fish consistently showed a lower relative RS than female hatchery fish (suggesting a role for sexual selection), and (iii) age-2 jacks, which use a sneaker mating strategy, did not show the same declines as 3-year olds, which compete differently for females (again, implicating sexual selection).     

Diet composition of the seahorses, Hippocampus guttulatus Cuvier, 1829 and Hippocampus hippocampus (L., 1758) (Teleostei, Syngnathidae) in the Aegean Sea

The diet composition of the European seahorses, Hippocampus guttulatus and Hippocampus hippocampus was determined based on the analysis of 279 and 19 specimens, respectively, collected in the Aegean Sea. The diet of both species was mainly based on Crustacea, with Amphipoda, Anomura Decapoda and Mysidacea being the dominant prey categories. ANOSIM analyses, however, indicated statistically significant differences in the diet of the two species as well as differences in the diet composition of non-brooding males, brooding males and females within each species. In H. guttulatus , stomach fullness percentages and vacuity coefficient values indicated that female individuals seem to have a higher feeding activity in relation to males.     

Male reproductive success in harem troops of hanuman langurs (Presbytis entellus)

Based on cross-sectional and longitudinal data collected in 1967–1988 by various observers, male reproductive success was studied in the Hanuman langurs of Jodhpur, India. The harem-structured social organization ensures a high degree of paternity certainty. Births occur throughout the year, with significant peaks and minima in March and November, respectively (n =398).The interbirth interval averages 16.7 months (n = 114).The duration of harem residencies varies between 3 days and ≥ 74.0 months, with a mean of 26.5 (n = 64). Harem holder replacements occur during all months of the year. No male achieves residency in more than one troop, suggesting that residency is associated with a distinct peak in the resource holding potential of a given male. Reproductive success among males varies considerably. Male mortality is high due to migration and intrasexual competition, leading to an adult sex ratio of 1:4.9. It is estimated that one-quarter of all adult males will never gain harem residency. Conceptions achieved outside harem residencies are so rare (4.7%) that a viable low-risk strategy, opting for longevity instead of harem residency, is unlikely. Tenure length has a stronger influence on male reproductive success than harem size because interbirth intervals are significantly shorter in small harems than in larger ones. It is assumed that females in one-male breeding structures compete for sperm and that such competition is more intense in larger harems.     

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.