Studies Of Mating Systems Research Articles

Low queen mating frequency in the seed-harvester ant Pogonomyrmex (Ephebomyrmex) pima: implications for the evolution of polyandry

The evolution of polyandry is a central problem in the study of insect mating systems, and both material and genetic benefits have been proposed to offset the presumed costs of multiple mating. Although most eusocial Hymenoptera queens mate with just one or occasionally two males, high levels of polyandry are exhibited by several taxa, including seed-harvester ants of the genus Pogonomyrmex. Previous studies of queen mating frequency in Pogonomyrmex have focused on monogynous (one queen per colony) species in the subgenus Pogonomyrmex. We performed a genetic mother–offspring analysis of mating frequency in Pogonomyrmex (Ephebomyrmex) pima, a queen-dimorphic species with dealate and intermorph queens that differ in colony structure (intermorph colonies contain multiple queens). Our results demonstrate that both dealate and intermorph queens of P. (E.) pima are typically single maters, unlike their congeners analyzed thus far. Polyandry appears to be a derived trait in Pogonomyrmex, but comparative tests between P. (E.) pima queen morphs and across the genus provide no evidence that it evolved as an adaptation to increase genetic diversity within colonies or to obtain more sperm, respectively.

Low Inbreeding and High Pollen Dispersal Distances in Populations of Two Amazonian Forest Tree Species

ABSTRACTRecent studies suggest that tropical tree species exhibit low inbreeding and high gene dispersal levels despite the typically low density of conspecifics in tropical forests. To examine this, we undertook a study of pollen gene dispersal and mating system of two Amazonian tree species. We analyzed 341 seeds from 33 trees at four microsatellite loci in a Carapa guianensis population from Brazil, and 212 seeds from 22 trees at four microsatellite loci in a Sextonia rubra population from French Guiana. Differentiation of allele frequencies among the pollen pool of individual trees was ΦFT= 0.053 (95% CI: 0.027–0.074) for C. guianensis and ΦFT= 0.064 (95% CI: 0.017–0.088) for S. rubra. The mean pollen dispersal distances were estimated at 69–355 m for C. guianensis, and 86–303 m for S. rubra, depending on the pollen dispersal model and the estimate of reproductive tree density used. The multi‐locus outcrossing rate was estimated at 0.918 and 0.945, and the correlation of paternity at 0.089 and 0.096, for C. guianensis and S. rubra, respectively, while no significant levels of biparental inbreeding were detected. Comparing trees with high and low local density of conspecifics, we found no evidence for differences in inbreeding levels. The results are discussed within the framework of the emerging picture of the reproductive biology of tropical forest trees.

Combining population genetics and demographical approaches in evolutionary studies of plant mating systems

Combining population genetics and demographical approaches in evolutionary studies of plant mating systems

Combining population genetics and demographical approaches in evolutionary studies of plant mating systems

The striking amount of variation in the mating systems of higher plants has stimulated fruitful research by both ecologists and population geneticists. Historically, these two schools of thought have developed independent theoretical treatments and empirical approaches to account for the evolution of such diversity. We highlight the approach adopted by each field. Population geneticists have developed an approach centred on gene properties of individuals and their role on the evolution of self‐fertilisation (transmission rules and the deleterious role of mutations), while ecologists have mostly focused on demographic properties of self‐fertilisation (seed production, colonisation ability of selfers). As a result, the two approaches sometimes use conflicting notions of fitness. The recent empirical advances on inbreeding depression, a topic typically motivated by population genetic questions, have emphasized the need to adopt a demographical perspective for fitness. In this paper, we suggest generalizing this approach in mating system evolution and we expect further improvements by integrating demographic and genetics perspectives.

Composition of the pollinator community, pollination and the mating system for a shrub in fragments of species rich kwongan in south-west Western Australia

In this study we investigate the composition of the potential honeyeater pollinator community, patterns of honeyeater visitation, pollination and the mating system in a range of population fragments for the bird-pollinated mixed mating system shrub Calothamnus quadrifidus R.Br. Specifically, we aimed to answer the following questions. For smaller and more isolated population fragments are honeyeater species lost from the pollinator community, patterns of visitation different, levels of pollination lower and rates of selfing, biparental inbreeding and correlated paternity higher. The composition of the honeyeater community was similar across population fragments and there was no relationship between the abundance of birds and population fragment size. Honeyeaters were most commonly observed visiting numerous inflorescences within single plants in all populations, but as population fragments became larger movements between plants were more commonly observed. Our observations of honeyeater visitation were generally consistent with our measurements of pollination and patterns in the mating system across population fragments. We found no significant relationship between population fragment size and levels of pollination. Mating system studies showed outcrossing rates (t m) comparable to those found in other bird-pollinated Myrtaceae, and ranged from 0.54 to 0.90 across populations. Outcrossing rates were not significantly correlated with log population size, but correlations of outcrossed paternity indicate a clear trend from low correlated paternity in larger populations to significantly higher correlated paternities in smaller populations. As a consequence mating in small populations will occur between much smaller groups of plants, and this may affect population fitness in subsequent generations.

Identification of microsatellite loci in Collinsia verna (Veronicaceae)

AbstractWe developed eight polymorphic microsatellite loci for Collinsia verna (Veronicaceae). In a sample of 18–35 individuals from a single population, we found two to 15 alleles per locus (mean 8.3). We also tested these loci for cross‐amplification in all 22 species in the tribe Collinseae. Overall, more than half the species in the tribe amplified one microsatellite while three species most closely related to C. verna (Collinsia violacea, Collinsia parviflora and Collinsia grandiflora) amplified multiple microsatellite loci. These microsatellite loci will be used in future studies of mating system in this tribe and other quantitative genetic and population genetic studies.

Isolation of microsatellite loci and cross‐species amplifications in three gobiid fish of the genus Pomatoschistus

AbstractGobiids of the genus Pomatoschistus are increasingly being investigated as models for adaptation to coastal environments and for mating system studies. Among the dozen currently analysed species, microsatellite primers have been characterized only for Pomatoschistus minutus. This paper describes seven new polymorphic loci isolated from Pomatoschistus marmoratus and Pomatoschistus microps, two species that hybridize. Cross‐species amplification was tested for these new loci, together with seven already published P. minutus loci. Systematic amplification of samples of each of the three species provided a first indication of their polymorphism.

Isolation of highly polymorphic autosomal microsatellite loci and a sex‐linked locus from sugarbirds

AbstractWe describe the isolation of six tetranucleotide microsatellites from the Cape sugarbird (Promerops cafer) using an enrichment protocol. All loci were highly variable with number of alleles ranging from nine to 26 and values of observed heterozygosity ranging from 0.534 to 0.931. All loci were in Hardy–Weinberg equilibrium with the exception of Pro66 and Pro86. Further analysis of Pro86 indicated it was Z‐linked. All loci amplified and were variable in the congeneric Gurneys sugarbird (Promerops gurneyi). These loci will be used in mating system and phylogeographic studies of Cape sugarbirds in South Africa.

DO WING MARKINGS IN FRUIT FLIES (DIPTERA: TEPHRITIDAE) HAVE SEXUAL SIGNIFICANCE?

The patterned wings of tephritid fruit flies often are moved in complex manners during sexual encounters. However, there are few cases of sexual dimorphism, and wing movements also may occur in non-sexual contexts. There was no evidence that enhancing or obliterating the patterns on the wings of male Caribbean fruit flies, Anastrepha suspensa (Loew), had any effect on their sexual success. There is convergence in wing patterns with another Dipteran family, the distantly related Bombyliidae. Additional studies of mating systems with this family might illuminate the significance of similar wing patterns in tephritids.

Mating patterns, pollen dispersal, and the ecological maternal neighbourhood in a Prunus mahaleb L. population

Gender polymorphism, plant-animal interactions, and environmental heterogeneity are the three important sources of variation in mating system and pollen dispersal patterns. We used progeny arrays and paternity analysis to assess the effects of gender type and density level on variation in mating patterns within a highly isolated population of Prunus mahaleb, a gynodioecious species. All the adult trees in the population were sampled and located. The direct estimate of long-distance insect-mediated pollination events was low (< 10%). Gender expression deeply influenced the mating system, decreasing the outcrossing rates (t(m)) and the pollen pool diversity in hermaphrodite trees. Long intermate distances (> 250 m) were significantly more frequent among female mother trees. Variation in local tree density also affected pollen pool diversity and intermate distance, with a higher effective number of fathers (k(e)) and longer intermate distances for female trees in low-density patches. A canonical correlation analysis showed significant correlations between mating variables and the maternal ecological neighbourhood. Only the first canonical variable was significant and explained 78% of variation. Outcrossing rates tended to decrease, and the relatedness among the fathers tended to increase, when mother trees grew in dense patches with high cover of other woody species and taller vegetation away from the pine forest edge. We highlight the relevance of considering maternal ecological neighbourhood effects on mating system and gene flow studies as maternal trees act simultaneously as receptors of pollen and as sources of the seeds to be dispersed.

Extra-pair paternity in Seaside Sparrows

Abstract Seaside Sparrows (Ammodramus maritimus) nest at varying population densities, and breeding pairs may occupy either large, all-purpose activity spaces or small nesting territories, foraging in undefended areas separate from the nest site. We determined the prevalence of extra-pair paternity in a large, socially monogamous population of Seaside Sparrows nesting in small, overlapping territories. We used six microsatellite DNA markers and a likelihood-based approach to paternity assignment. Five of 47 chicks (11%) in three of 18 broods (17%) in this population were sired by extra-pair males. Although this is the first study of the genetic mating system in the genus Ammodramus, the rate of extra-pair paternity we observed is lower than in most other New World emberizines. As the first measurment of extra-pair paternity in Seaside Sparrows, this study provides a baseline for comparative studies of how extra-pair paternity is influenced by the wide variation in nesting density and territoriality found ...

Identifying spiders through DNA barcodes

With almost 40 000 species, the spiders provide important model systems for studies of sociality, mating systems, and sexual dimorphism. However, work on this group is regularly constrained by difficulties in species identification. DNA-based identification systems represent a promising approach to resolve this taxonomic impediment, but their efficacy has only been tested in a few groups. In this study, we demonstrate that sequence diversity in a standard segment of the mitochondrial gene coding for cytochrome c oxidase I (COI) is highly effective in discriminating spider species. A COI profile containing 168 spider species and 35 other arachnid species correctly assigned 100% of subsequently analyzed specimens to the appropriate species. In addition, we found no overlap between mean nucleotide divergences at the intra- and inter-specific levels. Our results establish the potential of COI as a rapid and accurate identification tool for biodiversity surveys of spiders.

Inbreeding coefficients in six species of Ainsliaea and two species of Pertya (Asteraceae)

As a basis for comparative studies of mating systems, we estimated genetic diversities and inbreeding coefficients for six perennial species of Ainsliaea and two shrubby species of Pertya (Asteraceae). These related species are known to vary from frequent cleistogamy to xenogamy by bumblebee pollination, and we examined allozyme variation in these species to describe mating system variation in further detail. Significant heterozygote deficit was found in five species, while no heterozygote deficit was found in three species. A cleistogamous species showed no genetic polymorphism. Multilocus average of inbreeding coefficients among seven species ranged from −0.12 to 0.78. These findings indicated that related species can vary from predominant selfers to predominant outcrossers under perennial life cycles.

Characterization of tetranucleotide microsatellite markers in guppy (Poecilia reticulata)

AbstractTen tetranucleotide microsatellite loci are characterized for guppy, Poecilia reticulata, an important model species in the study of adaptation and mating systems. Loci were isolated following a microsatellite enrichment procedure using probe‐labelled magnetic beads. These microsatellites were designed for use in examining gene flow, reproductive isolation, and parentage within natural guppy populations.

Mating System and Genetic Variations of Tricholoma crassum (Berk.) Sacc. in Some Area of Thailand by Isozyme Electrophoresis and PCR-RFLP Method

Tricholoma crassum (Tricholomataceae, Agaricales) is a large, good edible species. It has nutritional quality, having 10.02 gm carbohydrate, 0.287 gm fats, 18.58 gm protein, 2.71 mg calcium, and 3.35 mg iron in every 100 gm of fresh weight. It is found growing abundantly throughout Thailand.The mating system of T. crassum was studied. The monokaryon isolates were selected from ten sporocarp collections in five provinces in Thailand—Ubonratchathani, Sakonnakorn, Mahasarakham, Srisaket, and Nakornratcha-sima. Suitable growth conditions for the mycelial cultivation were PDYA medium pH 7 and 25 °C incubation. Twelve fast-growing monokaryotic strains were selected for mating system studies. The mating system was determined by pairing the monokaryotic mycelia of each collection in all pairwise combinations. The presence of clamp connections after mating indicated sexual compatibility. The ratio of compatible crosses to all combination crosses were 1:4, which indicated tetrapolar heterothallism. In addition, multiple alleles among the monokaryons for each sporocarp of the five provinces were examined on the basis of their mating interactions, and the results were two factors (A and B), and each possessed 16 different alleles.One hundred and thirty-eight monokarytic isolates of T. crassum from the above five provinces were cultured on growth media. The suitable conditions for the mycelial growth were PDYB medium at 25 °C for 21 days. All samples were analyzed for isozyme variability on polyacrylamide gel electrophoresis with 11 enzyme systems: isocitrate dehydrogenase, leucine aminopeptidase, acid phosphatase, phosphogluconate dehydrogenase, alkaline phosphatase, alcohol dehydrogenase, glucose− 6−phosphate dehydrogenase, lactate dehydrogenase, malate dehydrogenase, laccase, and esterase. Eight of the systems showed polymorphism. Cluster analysis based on isozyme variability using the NTSYSpc 2.00 and UPGMA methods revealed two clusters at a similarity coefficient of 0.67. The first cluster consisted of monokaryotic isolates from Nakornratchasima, Mahasalakham, and eight samples of Ubonratchathani. The second cluster consisted of the isolates from Sakonnakhorn, Srisaket, and 30 samples of Ubonratchathani.The genetic variations of nine additional samples of T. crassum from four additional provinces—Roiyed, Burerum, Patumthani, and Nakhon Pathom—were studied by the technique of PCR-RFLP. Two pairs of primers, ITS1- ITS4 and O1-LR12R, were used respectively for PCR amplification on ITS (internal transcribed spacer) and IGS (intergenic spacer) regions of the nuclear ribosomal gene, followed by digestion with HindIII, DdeI, HaeIII, EcoRI, and HinfI. Data analyses of the PCR-RFLP products based on the similarity index and the UPGMA method in the WinBoot program revealed three clusters that were related to their geographic origins, except the samples from Burirum, which showed genetic variation from the same areas at a similarity coefficient of 0.8 and were grouped into the third cluster.

Novel microsatellite loci identified from the Australian eastern small‐eyed snake (Elapidae: Rhinocephalus nigrescens) and cross species amplification in the related genus Suta

AbstractA total of 15 microsatellite primers pairs were developed for the Australian small‐eyed snake Rhinoplocephalus nigrescens. Five primers were used to screen 93 individuals of R. nigrescens and were also tested against eight species of the closely related genus Suta. Allelic diversity in R. nigrescens was high in three loci (12–27) and there was high heterozygosity (0.58–0.82). Observed heterozygosity did not deviate from Hardy–Weinberg expectations for the five loci tested. These primers will be useful in studies of population genetics and mating systems of small‐eyed snakes and related species.

Genetic quality and sexual selection: an integrated framework for good genes and compatible genes

Why are females so choosy when it comes to mating? This question has puzzled and marveled evolutionary and behavioral ecologists for decades. In mating systems in which males provide direct benefits to the female or her offspring, such as food or shelter, the answer seems straightforward--females should prefer to mate with males that are able to provide more resources. The answer is less clear in other mating systems in which males provide no resources (other than sperm) to females. Theoretical models that account for the evolution of mate choice in such nonresource-based mating systems require that females obtain a genetic benefit through increased offspring fitness from their choice. Empirical studies of nonresource-based mating systems that are characterized by strong female choice for males with elaborate sexual traits (like the large tail of peacocks) suggest that additive genetic benefits can explain only a small percentage of the variation in fitness. Other research on genetic benefits has examined nonadditive effects as another source of genetic variation in fitness and a potential benefit to female mate choice. In this paper, we review the sexual selection literature on genetic quality to address five objectives. First, we attempt to provide an integrated framework for discussing genetic quality. We propose that the term 'good gene' be used exclusively to refer to additive genetic variation in fitness, 'compatible gene' be used to refer to nonadditive genetic variation in fitness, and 'genetic quality' be defined as the sum of the two effects. Second, we review empirical approaches used to calculate the effect size of genetic quality and discuss these approaches in the context of measuring benefits from good genes, compatible genes and both types of genes. Third, we discuss biological mechanisms for acquiring and promoting offspring genetic quality and categorize these into three stages during breeding: (i) precopulatory (mate choice); (ii) postcopulatory, prefertilization (sperm utilization); and (iii) postcopulatory, postfertilization (differential investment). Fourth, we present a verbal model of the effect of good genes sexual selection and compatible genes sexual selection on population genetic variation in fitness, and discuss the potential trade-offs that might exist between mate choice for good genes and mate choice for compatible genes. Fifth, we discuss some future directions for research on genetic quality and sexual selection.

Molecular parentage analysis in experimental newt populations: the response of mating system measures to variation in the operational sex ratio.

Molecular studies of parentage have been extremely influential in the study of sexual selection in the last decade, but a consensus statistical method for the characterization of genetic mating systems has not yet emerged. Here we study the utility of alternative mating system measures by experimentally altering the intensity of sexual selection in laboratory-based breeding populations of the rough-skinned newt. Our experiment involved skewed sex ratio (high sexual selection) and even sex ratio (low sexual selection) treatments, and we assessed the mating system by assigning parentage with microsatellite markers. Our results show that mating system measures based on Bateman's principles accurately reflect the intensity of sexual selection. One key component of this way of quantifying mating systems is the Bateman gradient, which is currently underutilized in the study of genetic mating systems. We also compare inferences based on Bateman's principles with those obtained using two other mating system measures that have been advocated recently (Morisita's index and the index of resource monopolization), and our results produce no justification for the use of these alternative measures. Overall, our results show that Bateman's principles provide the best available method for the statistical characterization of mating systems in nature.

Cohabitation of juvenile females with mature males promotes sexual cannibalism in fishing spiders

Precopulatory sexual cannibalism, or female predation of a potential mate before mating, illustrates an extreme intersexual conflict. Unlike sexual cannibalism occurring after mating, precopulatory sexual cannibalism cannot be construed as a male strategy. Thus, research on the adaptive significance of this phenomenon has focused on female benefits. In the present study, I test the idea that precopulatory sexual cannibalism represents an adaptive female trade-off between the material costs and benefits of mating with a male (forgoing food, securing sperm) and preying on a male (forgoing sperm, securing food). I pay particular attention to the rarely tested prediction that precopulatory sexual cannibalism by virgin females should increase as each female’s expectation of future mating opportunities increases. I use the phenomenon of cohabitation between adult males and juvenile females nearing sexual maturity as a means to manipulate female expectation of future mate availability. Results indicate that feeding on a male has significant positive effects on several measures of female fecundity. However, the likelihood of precopulatory attacks was not explained by a female’s recent feeding history. Finally, as predicted, juvenile female cohabitation with mature males (expectation of future mating opportunities) heightens the prevalence of precopulatory attacks by virgin females, suggesting that juvenile experience can alter a female’s propensity for sexual cannibalism. This is the first study to suggest that juvenile experience can alter a female’s propensity for sexual cannibalism. This finding emphasizes the point that studies of sexual selection and mating systems need to consider the effects of juvenile experience on adult behavior. Key words: adaptive foraging, fishing spiders, juvenile experience, male-female cohabitation, precopulatory sexual cannibalism. [Behav Ecol]

Mating system and pollination biology of the spring‐flowering shrub, Dirca palustris

Abstract Dirca palustris L., eastern leatherwood or wicopy (Thymelaeaceae), a widely distributed shrub of eastern North America, flowers in early spring and so may face some of the same constraints faced by ephemeral vernal herbs of the eastern deciduous forest, most notably the influence of low temperature on pollinator activity. I studied the mating system of D. palustris and the influence of temperature on pollinator visitation of flowers, during three field seasons in a small stream valley in north‐western Pennsylvania, USA. Specifically, I was interested in how a species with apparently specialized floral morphology, like D. palustris, may ensure reproductive success in a thermally unpredictable vernal environment. Pollinator visitation of flowers of D. palustris was strongly regulated by temperature, with no visits occurring below 14.9°C. Lack of treatment effects in mating system studies, especially the lack of significant differences in fruit set between the bagged, self‐pollination treatment and various cross‐pollination treatments accessible to pollinators, suggests that D. palustris is self‐compatible or perhaps apomictic. Thus, like other spring‐flowering species faced with pollinator unpredictability, D. palustris may rely on a mixed mating system to ensure reproductive success during cool temperate springs.