Relative Reproductive Success Research Articles

Diversifying selection by Desmodiinae legume species on Bradyrhizobium symbionts.

Desmodium and Hylodesmum (Papilionoideae Subtribe Desmodiinae) are among the most common herbaceous perennial legumes native to eastern North America. To analyze the population structure of their Bradyrhizobium sp. root-nodule bacteria, 159 isolates were sampled from ten host species across a 1000 km region. Phylogenetic analysis of four housekeeping loci (2164 bp) and two loci in the symbiosis island (SI) chromosomal region (1374 bp) indicated extensive overlap in symbiont utilization, with each common bacterial clade found on 2-7 species of these legume genera. However, host species differed considerably in the relative proportion of symbionts belonging to different Bradyrhizobium clades. High phylogenetic incongruence between trees for housekeeping loci and SI loci suggested that diversification of these Bradyrhizobium lineages involved substantial horizontal gene transfer. Plant inoculation with strains from six Bradyrhizobium clades revealed marked disparity in relative bacterial reproductive success across four Desmodium species. Estimated yield of Bradyrhizobium progeny cells per plant ranged from zero to >10(9), and strains with high fitness on one host sometimes reproduced poorly on other host species. Diversifying selection on bacteria, arising from differential success in habitats with different Desmodium and Hylodesmum taxa, is therefore likely to affect Bradyrhizobium diversity patterns at the landscape level.

Low rates of pollen contamination in a Scots pine seed orchard in Sweden: the exception or the norm?

We investigated mating structure and gene flow in a clonal seed orchard of Scots pine (Pinus sylvestris L.) over three consecutive pollination seasons (2010–2012) with nine nuclear microsatellite markers. The paternity of 1991 offspring from four maternal parents was assigned to 28 candidate fathers using an exclusion procedure and a likelihood-based method implemented in the program CERVUS. Relative reproductive success was highly variable among pollen parents but consistent across years and ranged from 0.1% to 18.3%. Consequently, the seed crops’ effective number of fathers was reduced to 52.9%, 48.8%, and 45.7% of the census in the three seasons, respectively. Self-fertilization fluctuated around the orchard's expected value of 5.1%, reaching 4.05%, 7.71%, and 6.61%, respectively. Pollen contamination was estimated to be 5.64%, 7.29%, and 4.89%, respectively, after correction for cryptic gene flow. CERVUS provided similar results as the exclusion method, but estimates greatly varied depending on the input parameters, mainly the proportion of fathers sampled. These results indicate the studied seed orchard is a well-functioning production population with only minor negative effects of self-fertilization and pollen contamination on the quality of seed crops. Genotyping issues associated with microsatellites as a potential source of false paternity assignment and exclusion are discussed.

BATEMANATER: a computer program to estimate and bootstrap mating system variables based on Bateman's principles.

Bateman's principles continue to play a major role in the characterization of genetic mating systems in natural populations. The modern manifestations of Bateman's ideas include the opportunity for sexual selection (i.e. I(s) - the variance in relative mating success), the opportunity for selection (i.e. I - the variance in relative reproductive success) and the Bateman gradient (i.e. β(ss) - the slope of the least-squares regression of reproductive success on mating success). These variables serve as the foundation for one convenient approach for the quantification of mating systems. However, their estimation presents at least two challenges, which I address here with a new Windows-based computer software package called BATEMANATER. The first challenge is that confidence intervals for these variables are not easy to calculate. BATEMANATER solves this problem using a bootstrapping approach. The second, more serious, problem is that direct estimates of mating system variables from open populations will typically be biased if some potential progeny or adults are missing from the analysed sample. BATEMANATER addresses this problem using a maximum-likelihood approach to estimate mating system variables from incompletely sampled breeding populations. The current version of BATEMANATER addresses the problem for systems in which progeny can be collected in groups of half- or full-siblings, as would occur when eggs are laid in discrete masses or offspring occur in pregnant females. BATEMANATER has a user-friendly graphical interface and thus represents a new, convenient tool for the characterization and comparison of genetic mating systems.

GPS-loggers influence behaviour and physiology in the black-legged kittiwake Rissa tridactyla

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 521:237-248 (2015) - DOI: https://doi.org/10.3354/meps11140 GPS-loggers influence behaviour and physiology in the black-legged kittiwake Rissa tridactyla Oddvar Heggøy1,2,*, Signe Christensen-Dalsgaard1,3, Peter S. Ranke4, Olivier Chastel5, Claus Bech1 1Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway 2Norwegian Ornithological Society, Sandgata 30B, 7012 Trondheim, Norway 3Norwegian Institute for Nature Research (NINA), Terrestrial Ecology Department, PO Box 5685 Sluppen, 7485 Trondheim, Norway 4Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology, 7491 Trondheim, Norway 5Centre d’Etudes Biologiques de Chizé, UMR 7372 - CNRS et Université de La Rochelle, 79360 Villiers-en-bois, France *Corresponding author: oddvah@gmail.com ABSTRACT: In recent decades, data loggers and radio- and satellite transmitters have become an important technological part of research on free living animals. Loggers to track movements and behaviour are especially useful in seabird studies, as seabirds often travel considerable distances at sea where visual observations are challenging. The potential negative effects of these devices on mortality, behaviour and reproduction of birds have received some attention, but few studies have investigated the physiological effects of instrument attachment. In the present study, effects of global positioning system (GPS) loggers on black-legged kittiwakes Rissa tridactyla were investigated by obtaining behavioural and physiological parameters of stress (nest attendance, plasma levels of the avian stress hormone corticosterone [CORT], relative leucocyte counts, body mass and reproductive success) during 2 d of GPS-deployment. GPS-equipped kittiwakes had significantly elevated levels of CORT at recapture and also significantly extended the duration of feeding trips compared to controls. Kittiwakes with low body condition index (BCI) attended nests less than controls, and this pattern was more pronounced among GPS-equipped birds. The study underlines the need to take device effects into consideration when instrumenting seabirds. Potentially, effects may become more evident in birds with low body condition or in years where food is limited, and results from GPS-equipped birds should be viewed with this in mind. KEY WORDS: GPS-loggers · Effects · Physiology · Behaviour · Black-legged kittiwake · Rissa tridactyla Full text in pdf format PreviousNextCite this article as: Heggøy O, Christensen-Dalsgaard S, Ranke PS, Chastel O, Bech C (2015) GPS-loggers influence behaviour and physiology in the black-legged kittiwake Rissa tridactyla. Mar Ecol Prog Ser 521:237-248. https://doi.org/10.3354/meps11140 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 521. Online publication date: February 17, 2015 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2015 Inter-Research.

Conservation biology of Chionodoxa lochiae and Scilla morrisii (Asparagaceae): Two priority bulbous plant species of the European Union in Cyprus

This paper presents data regarding conservation biology of Chionodoxa lochiae and Scilla morrisii; two threatened endemic plants of Cyprus, which are included as priority species in Annex II of the Habitats Directive. The population size and geographical distribution of the species were monitored for three years. C. lochiae was recorded in ten locations and S. morrisii was recorded in five locations. C. lochiae occurs in Pinus forests with/without Quercus alnifolia understory or in forest margins and riparian vegetation with Platanus orientalis. Favorable habitat of S. morrisii is the understory of Quercus infectoria stands and the Pistacia terebinthus-Quercus coccifera-Styrax officinalis shrubs. The distribution pattern of the species seems to follow habitat availability. Fecundity and Relative Reproductive Success of C. lochiae were stable and low, while in S. morrisii were constantly high. The lack of pollinators seems to be the main cause of the low sexual reproduction of C. lochiae. The germination strategy for both species is dependent on temperature. Some of the seeds are dormant and dormancy is broken by nitrates. The investigation of certain aspects of the biology of the two species yielded the information needed to identify the critical aspects affecting their survival and to propose sound conservation measures.

Environment-dependent microevolution in a Mediterranean pine (Pinus pinaster Aiton).

BackgroundA central question for understanding the evolutionary responses of plant species to rapidly changing environments is the assessment of their potential for short-term (in one or a few generations) genetic change. In our study, we consider the case of Pinus pinaster Aiton (maritime pine), a widespread Mediterranean tree, and (i) test, under different experimental conditions (growth chamber and semi-natural), whether higher recruitment in the wild from the most successful mothers is due to better performance of their offspring; and (ii) evaluate genetic change in quantitative traits across generations at two different life stages (mature trees and seedlings) that are known to be under strong selection pressure in forest trees.ResultsGenetic control was high for most traits (h2 = 0.137-0.876) under the milder conditions of the growth chamber, but only for ontogenetic change (0.276), total height (0.415) and survival (0.719) under the more stressful semi-natural conditions. Significant phenotypic selection gradients were found in mature trees for traits related to seed quality (germination rate and number of empty seeds). Moreover, female relative reproductive success was significantly correlated with offspring performance for specific leaf area (SLA) in the growth chamber experiment, and stem mass fraction (SMF) in the experiment under semi-natural conditions, two adaptive traits related to abiotic stress-response in pines. Selection gradients based on genetic covariance of seedling traits and responses to selection at this stage involved traits related to biomass allocation (SMF) and growth (as decomposed by a Gompertz model) or delayed ontogenetic change, depending also on the testing environment.ConclusionsDespite the evidence of microevolutionary change in adaptive traits in maritime pine, directional or disruptive changes are difficult to predict due to variable selection at different life stages and environments. At mature-tree stages, higher female effective reproductive success can be explained by differences in their production of offspring (due to seed quality) and, to a lesser extent, by seemingly better adapted seedlings. Selection gradients and responses to selection for seedlings also differed across experimental conditions. The distinct processes involved at the two life stages (mature trees or seedlings) together with environment-specific responses advice caution when predicting likely evolutionary responses to environmental change in Mediterranean forest trees.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-014-0200-5) contains supplementary material, which is available to authorized users.

Pairing patterns in relation to body size, genetic similarity and multilocus heterozygosity in a tropical monogamous bird species

The relative influence of genetic and phenotypic quality on pairing status and mating patterns in socially monogamous species remains poorly documented. We studied social status and pairing patterns in relation to genetic similarity and multilocus heterozygosity (MLH) estimates from 11 microsatellite markers, and both tarsus length and wing chord (as a measure of competitive ability in territorial defence) in a socially monogamous tropical bird species where individuals defend territories year-round, alone or in pairs, the Zenaida dove, Zenaida aurita. Tarsus length and wing chord did not differ between unpaired territorial birds and paired ones in either sex, whereas paired females, but not paired males, tended to be more heterozygous than unpaired ones. Among 84 pairs, we found no evidence for assortative mating for tarsus length, wing chord, MLH or genetic similarity. However, within pairs, male wing chord was positively related to female MLH and female tarsus length was positively related to male MLH, with no evidence for local effects, suggesting assortative mating by individual quality. Although the observed pattern of mating in Zenaida doves may be the product of mutual mate choice, further assessment of this hypothesis requires direct investigation of both mating preference in each sex and lifetime reproductive success in relation to body size and MLH.

Size-dependent gender modification in Lilium apertum (Liliaceae): does this species exhibit gender diphasy?

Variation in the relative female and male reproductive success of flowering plants is widespread, despite the fundamental hermaphroditic condition of the majority of species. In many hermaphroditic populations, environmental conditions and their influence on development and size can influence the gender expression of individuals through the formation of hermaphroditic and unisexual flowers. This study investigates the hypothesis that the bulbous, animal-pollinated, perennial Lilium apertum (Liliaceae) exhibits a form of size-dependent gender modification known as gender diphasy, in which the sexual expression of individuals depends on their size, with plants often changing sex between seasons. Variation in floral traits was examined in relation to their size using marked individuals in natural populations, and also under glasshouse conditions. Measurements were taken of the height, flower number, floral sex expression, flower size, flower biomass and pollen production of individuals over consecutive years between 2009 and 2012 in seven populations in south-west China. Flowers of L. apertum are either perfect (hermaphroditic) or staminate (male) and, in any given season, plants exhibit one of three sex phenotypes: only hermaphrodite flowers, a mixture of hermaphroditic and male flowers, or only male flowers. Transitions between each of these sex phenotypes were observed over consecutive years and were commonly size-dependent, particularly transitions from small plants bearing only male flowers to those that were taller with hermaphroditic flowers. Hermaphroditic flowers were significantly larger, heavier and produced more pollen than male flowers. The results for L. apertum are consistent with the 'size advantage hypothesis' developed for animal species with sex change. The theory predicts that when individuals are small they should exhibit the sex for which the costs of reproduction are less, and this usually involves the male phase. L. apertum provides an example of gender diphasy, a rare sexual system in flowering plants.

Sex ratio does not influence sex change despite its effect on reproductive success

The sex ratio of adults in a population affects the reproductive value of being either a male or female and thus may be a cue for sex change in sequentially hermaphroditic species. We examined the effect of the sex ratio on reproduction and sex change of the reef fish, Lythrypnus dalli, and predicted that the sex ratio would influence the reproductive success for a given body size and thus the probability of sex change. We varied adult sex ratios on artificial patch reefs, monitored egg production over 20 days, and examined rates of sex change. We found no evidence that sex ratio influenced the size at which individuals change sex despite its influence on relative reproductive success. The sex ratio influenced the average reproductive success of males but not females, with males having both a higher probability of mating and higher per capita reproductive success on strongly female-biased reefs. However, females did not capitalize by changing sex to male more frequently. Female per capita reproductive success did not vary with changes in the sex ratio or female density, suggesting that females were not limited by male or resource availability. Male to female sex change was rare, suggesting that, although physiologically possible, this behavior may be uncommon in natural populations. Overall, our results indicate that the sex ratio may not be a good predictor of the reproductive value of sex change for a given individual and that body size alone may provide sufficient information regarding reproductive potential for a given sex.

Influence of early-life nutrition on mortality and reproductive success during a subsequent famine in a preindustrial population

Individuals with insufficient nutrition during development often experience poorer later-life health and evolutionary fitness. The Predictive Adaptive Response (PAR) hypothesis proposes that poor early-life nutrition induces physiological changes that maximize fitness in similar environments in adulthood and that metabolic diseases result when individuals experiencing poor nutrition during development subsequently encounter good nutrition in adulthood. However, although cohort studies have shown that famine exposure in utero reduces health in favorable later-life conditions, no study on humans has demonstrated the predicted fitness benefit under low later-life nutrition, leaving the evolutionary origins of such plasticity unexplored. Taking advantage of a well-documented famine and unique datasets of individual life histories and crop yields from two preindustrial Finnish populations, we provide a test of key predictions of the PAR hypothesis. Known individuals from fifty cohorts were followed from birth until the famine, where we analyzed their survival and reproductive success in relation to the crop yields around birth. We were also able to test whether the long-term effects of early-life nutrition differed between individuals of varying socioeconomic status. We found that, contrary to predictions of the PAR hypothesis, individuals experiencing low early-life crop yields showed lower survival and fertility during the famine than individuals experiencing high early-life crop yields. These effects were more pronounced among young individuals and those of low socioeconomic status. Our results do not support the hypothesis that PARs should have been favored by natural selection and suggest that alternative models may need to be invoked to explain the epidemiology of metabolic diseases.

Comment on “Bateman in Nature: Predation on Offspring Reduces the Potential for Sexual Selection”

Byers and Dunn (Reports, 9 November 2012, p. 802) claimed that predation on offspring reduced the potential for sexual selection in pronghorn. We argue that the potential for sexual selection is not affected by random offspring mortality when relative reproductive success is considered and increases when measured with the opportunity for selection, a metric that describes the potential for selection.

Dwarf males, large hermaphrodites and females in marine species: A dynamic optimization model of sex allocation and growth

In this study, we investigate the evolutionarily stable schedule of growth and sex allocation for marine benthic species that contain dwarf males. We consider a population in an ephemeral microhabitat that receives a constant supply of larvae. Small individuals can immediately reproduce as a dwarf male or remain immature and grow. Large individuals allocate reproductive resources between male and female functions. The fraction c of newly settled individuals who remain immature and the sex allocation of large individuals m are quantities to evolve. In the stationary ESS, if the relative reproductive success of dwarf males is greater than the survivorship of immature individuals until they reach a mature size, then the population is a mixture of females and dwarf males. If the opposite inequality holds, the population is dominated by hermaphrodites and lacks dwarf males. There is no case in which a mixture of hermaphrodites and dwarf males to be the ESS in the stationary solution. The ESS can be solved by dynamic programming when the strategies depend on the age of the microhabitat (c(t) and m(t)). Typically, the ESS schedule begins with a population composed only of hermaphrodites, which is replaced by a mixture of dwarf males and hermaphrodites and then by a mixture of dwarf males and pure females. The relative importance of these three phases depends on multiple parameters.

High degree of paternity loss in a species with alternative reproductive tactics

In many mating systems, males adopt alternative reproductive tactics (ARTs) to maximize reproductive success. In fishes, guarding males often invest more energy into courtship, defense, and paternal care, whereas cuckolding males forego such costs and steal fertilizations by releasing their sperm in the nest of a guarding male. These two tactics have been documented in the plainfin midshipman fish (Porichthys notatus), yet the relative reproductive success of the guarding and cuckolding male tactics remains unknown. In this study, we used microsatellite markers to determine the level of paternity of the guarding type I males. We explored how paternity varied with male phenotype and across the breeding season. Our results revealed the lowest documented levels of paternity in a species with obligate paternal care. Although paternity remained consistently low, it did increase as the breeding season progressed. Male body size did not significantly predict paternity. The low paternity in this species may be explained, in part, by aspects of their reproductive ecology including the duration of parental care period, limited nest availability and competition for nests, as well as the occurrence of nest takeovers. Overall, our findings contribute to the understanding of the ultimate factors underlying ARTs in this species and highlight the importance of investigating reproductive success across the entire breeding season.

Reduced fitness of Atlantic salmon released in the wild after one generation of captive breeding

Salmonids rank among the most socioeconomically valuable fishes and the most targeted species by stocking with hatchery-reared individuals. Here, we used molecular parentage analysis to assess the reproductive success of wild- and hatchery-born Atlantic salmon over three consecutive years in a small river in Québec. Yearly restocking in this river follows a single generation of captive breeding. Among the adults returning to the river to spawn, between 11% and 41% each year were born in hatchery. Their relative reproductive success (RRS) was nearly half that of wild-born fish (0.55). RRS varied with life stage, being 0.71 for fish released at the fry stage and 0.42 for fish released as smolt. The lower reproductive success of salmon released as smolt was partly mediated by the modification of the proportion of single-sea-winter/multi-sea-winter fish. Overall, our results suggest that modifications in survival and growth rates alter the life-history strategies of these fish at the cost of their reproductive success. Our results underline the potential fitness decrease, warn on long-term evolutionary consequences for the population of repeated stocking and support the adoption of more natural rearing conditions for captive juveniles and their release at a younger stage, such as unfed fry.

Natural genetic variation in male reproductive genes contributes to nontransitivity of sperm competitive ability in Drosophila melanogaster

Female Drosophila melanogaster frequently mate with multiple males, and the success of a given male depends not only on his genotype but also on the genotype of his competitor. Here, we assess how natural genetic variation affects male-male interactions for traits influencing pre- and postcopulatory sexual selection. Males from a set of 66 chromosome substitution lines were competed against each other in a 'round-robin' design, and paternity was scored using bulk genotyping. We observed significant effects of the genotype of the first male to mate, the second male to mate and an interaction between the males for measures of male mating rate and sperm utilization. We also identified specific combinations of males who show nontransitive patterns of reproductive success and engage in 'rock-paper-scissors' games. We then tested for associations between 245 polymorphisms in 32 candidate male reproductive genes and male reproductive success. We identified eight polymorphisms in six reproductive genes that associate with male reproductive success independent of the competitor (experimentwise P < 0.05). We also identified four SNPs in four different genes where the relative reproductive success of the alternative alleles changes depending on the competing males' genetic background (experimentwise P < 0.05); two of these associations include premature stop codons. This may be the first study that identifies the genes contributing to nontransitivity among males and further highlights that 'rock-paper-scissors' games could be an important evolutionary force maintaining genetic variation in natural populations.

Supportive breeding boosts natural population abundance with minimal negative impacts on fitness of a wild population of Chinook salmon

While supportive breeding programmes strive to minimize negative genetic impacts to populations, case studies have found evidence for reduced fitness of artificially produced individuals when they reproduce in the wild. Pedigrees of two complete generations were tracked with molecular markers to investigate differences in reproductive success (RS) of wild and hatchery-reared Chinook salmon spawning in the natural environment to address questions regarding the demographic and genetic impacts of supplementation to a natural population. Results show a demographic boost to the population from supplementation. On average, fish taken into the hatchery produced 4.7 times more adult offspring, and 1.3 times more adult grand-offspring than naturally reproducing fish. Of the wild and hatchery fish that successfully reproduced, we found no significant differences in RS between any comparisons, but hatchery-reared males typically had lower RS values than wild males. Mean relative reproductive success (RRS) for hatchery F1 females and males was 1.11 (P = 0.84) and 0.89 (P = 0.56), respectively. RRS of hatchery-reared fish (H) that mated in the wild with either hatchery or wild-origin (W) fish was generally equivalent to W × W matings. Mean RRS of H × W and H × H matings was 1.07 (P = 0.92) and 0.94 (P = 0.95), respectively. We conclude that fish chosen for hatchery rearing did not have a detectable negative impact on the fitness of wild fish by mating with them for a single generation. Results suggest that supplementation following similar management practices (e.g. 100% local, wild-origin brood stock) can successfully boost population size with minimal impacts on the fitness of salmon in the wild.

Predicting evolutionary responses to selection on polyandry in the wild: additive genetic covariances with female extra-pair reproduction

The evolutionary forces that underlie polyandry, including extra-pair reproduction (EPR) by socially monogamous females, remain unclear. Selection on EPR and resulting evolution have rarely been explicitly estimated or predicted in wild populations, and evolutionary predictions are vulnerable to bias due to environmental covariances and correlated selection through unmeasured traits. However, evolutionary responses to (correlated) selection on any trait can be directly predicted as additive genetic covariances (covA) with appropriate components of relative fitness. I used comprehensive life-history, paternity and pedigree data from song sparrows (Melospiza melodia) to estimate covA between a female's liability to produce extra-pair offspring and two specific fitness components: relative annual reproductive success (ARS) and survival to recruitment. All three traits showed non-zero additive genetic variance. Estimates of covA were positive, predicting evolution towards increased EPR, but 95% credible intervals overlapped zero. There was therefore no conclusive prediction of evolutionary change in EPR due to (correlated) selection through female ARS or recruitment. Negative environmental covariance between EPR and ARS would have impeded evolutionary prediction from phenotypic selection differentials. These analyses demonstrate an explicit quantitative genetic approach to predicting evolutionary responses to components of (correlated) selection on EPR that should be unbiased by environmental covariances and unmeasured traits.

Age at pollination modifies relative male and female reproductive success in a monoecious fig tree

Plants that depend on a single species of insect pollinator must often contend with infrequent and unpredictable visitation. Prolongation of floral receptivity comes at the cost of reduced male and/or female reproductive success among older flowers. Fig trees (Ficus spp.) have a highly specific pollination symbiosis and individual inflorescences (syconia) that remain receptive for days or weeks. Reproductive success in monoecious fig trees involves production of both seeds and fig wasp offspring. We assessed whether the reproductive output of individual syconia changes with the length of time they waited for pollination, and whether the relative female and male reproductive success also changes. A pollination experiment was conducted in an SE Asian monoecious fig tree Ficus curtipes, in which receptive syconia were covered with mesh bags to exclude wasps and pollinated by single pollinators of this fig tree at their different receptive ages. When the syconia matured their size and contents were recorded. Seed quality was also assessed. The results showed that pollinators entered syconia that had been waiting for up to 36 days. The frequencies of abortions among syconia pollinated at different ages were low throughout. The number of un-utilised flowers increased progressively in older syconia. Seed production was highest in syconia entered on the first day of receptivity, whereas pollinator production peaked in syconia pollinated on day 12, then declined in older syconia. Consequently, overall reproductive efficiency declined with syconium age and floral sex allocation became more male-biased in older syconia. Older syconia also produced lighter seeds. These results suggest that un-pollinated syconia of F. curtipes can remain receptive for several weeks. This makes pollination of each syconium more likely, but at the cost of reduced productivity and with more ovules allocated to male function. However, the prolongation of floral receptivity has significance for the co-adaptation between syconia and fig wasps and for the evolution of the fig tree-fig wasp symbiosis.

Maternal height and the sex ratio

Abstract This paper tests the generalized Trivers Willard hypothesis in the spirit of Kanazawa (2005), which predicts that parents with heritable traits that increase the relative reproductive success of males compared to females will have relatively more male than female offspring. We test whether taller mothers are more likely to have a male first-born using data on 400,302 mothers in a sample of Demographic Health and Surveys (DHS) from 46 developing countries. Despite using a plethora of statistical models that take into account the multi-level structure of the data, we find no strong evidence in favor of the hypothesis between and within communities, as well as on a country-by-country basis. Conversely, Andrews (1989)'s inverse power calculations suggest that the absence of a statistically small effect cannot be rejected.

The ecological–evolutionary interplay: density‐dependent sexual selection in a migratory songbird

Little is understood about how environmental heterogeneity influences the spatial dynamics of sexual selection. Within human-dominated systems, habitat modification creates environmental heterogeneity that could influence the adaptive value of individual phenotypes. Here, we used the gray catbird to examine if the ecological conditions experienced in the suburban matrix (SM) and embedded suburban parks (SP) influence reproductive strategies and the strength of sexual selection. Our results show that these habitats varied in a key ecological factor, breeding density. Moreover, this ecological factor was closely tied to reproductive strategies such that local breeding density predicted the probability that a nest would contain extra-pair offspring. Partitioning reproductive variance showed that while within-pair success was more important in both habitats, extra-pair success increased the opportunity for sexual selection by 39% at higher breeding densities. Body size was a strong predictor of relative reproductive success and was under directional selection in both habitats. Importantly, our results show that the strength of sexual selection did not differ among habitats at the landscape scale but rather that fine-scale variation in an ecological factor, breeding density, influenced sexual selection on male phenotypes. Here, we document density-dependent sexual selection in a migratory bird and hypothesize that coarse-scale environmental heterogeneity, in this case generated by anthropogenic habitat modification, changed the fine-scale ecological conditions that drove the spatial dynamics of sexual selection.