Sexual reproduction, clonal diversity and genetic differentiation in patchily distributed populations of the temperate forest herb Paris quadrifolia (Trilliaceae)

Clonal plant species have been shown to adopt different strategies to persist in heterogeneous environments by changing relative investments in sexual reproduction and clonal propagation. As a result, clonal diversity and genetic variation may be different along environmental gradients. We examined the regional and local population structure of the clonal rhizomatous forest herb Paris quadrifolia in a complex of forest fragments in Voeren (Belgium). Relationships between population size (the number of shoots), shoot density (the number of shoots per m²) and local growth conditions were investigated for 47 populations. Clonal diversity and genetic variation within and among 19 populations were investigated using amplified fragment length polymorphism markers. To assess the importance of sexual reproduction, seed set, seed weight and germination success were determined in 18 populations. As predicted, local growth conditions largely affected population distribution, size and density of P. quadrifolia. Populations occurring in moist and relatively productive sites contained significantly more shoots. Here, shoots were also much more sparsely distributed compared to populations occurring in dry and relatively unproductive sites, where shoots showed a strongly aggregated distribution pattern. Clonal diversity was relatively high, compared with other clonal species (G/N ratio = 0.43 and Simpson’s D=0.81). Clonal diversity significantly (P<0.01) decreased with increasing shoot density while molecular genetic variation was significantly (P<0.01) affected by population size and local environmental conditions. Lack of recruitment and out-competition of less-adapted genotypes may explain the decreased genetic variation in dry sites. Analysis of molecular variance revealed significant genetic variation among populations (Φ _ST=0.42, P<0.001), whereas pairwise genetic distances were not correlated to geographic distances, suggesting that gene flow among populations is limited. Finally, the number of generative shoots, the number of seeds per fruit and seed weight were significantly and positively related to population size and local growth conditions. We conclude that under stressful conditions populations of clonal forest plant species can slowly evolve into remnant populations characterized by low levels of genetic variation and limited sexual reproduction. Conservation of suitable habitat conditions is therefore a prerequisite for effective long-term conservation of clonal forest plant species.     

EMBRYONIC GENETIC LOAD IN THE HIGHBUSH BLUEBERRY,VACCINIUM CORYMBOSUM (ERICACEAE)

Hand-pollinations of 28 autotetraploid V. corymbosum accessions from a single population resulted in lower self- than outcross seed set. Fertility varied widely, ranging from clones that were effectively female sterile to individuals with high seed yields in both matings. Self- and outcross fertility were highly correlated. A genetic load model was invoked to explain these phenomena. Reduced self-fertility was attributed to homozygosity for sublethal mutations at loci controlling embryo development, or to loss of heterotic interactions at these loci. Near zero cross-fertility in some clones may be evidence of partially dominant mutational load. Estimates of the number of lethal equivalents per zygote carried by individuals in this population ranged from 2.2 to 20.4, with a mean of 9.6. Embryonic genetic load at the individual level was significantly correlated with heterozygosity at nine enzyme loci. Low pollen viability and reduced receptivity to pollen from any source were also noted in the low fertility genotypes. It is suggested that gametic, gametophytic, and embryonic development are symptomatic of the amount of genetic load carried by individuals.     

Inbreeding depression influences genet size distribution in a marine angiosperm

Although inbreeding depression is a major genetic phenomena influencing individual fitness, it is difficult to measure in wild populations. An alternative approach is to correlate heterozygosity, measured using highly polymorphic markers, with a fitness-correlated trait. In clonal plants, genet size is predicted to be fitness correlated. Here we test the prediction that the genet size distribution of the marine clonal plant Zostera marina (eelgrass) is influenced by inbreeding depression. We used nine polymorphic microsatellite markers to access the fine scale clonal structure and to measure individual heterozygosity within 4 plots (each corresponds to 256 m2, sampled at 1-m intervals) in two populations along the German Baltic Coast. The same plots were also sampled for flowering and vegetative shoots to obtain estimates for sexual reproductive output at the level of the genetic individual. We found substantial differences in the genet size distribution between the two populations that may be explained by different disturbance frequency. In both populations, clone size was significantly positively correlated with the total number of flowering shoots, indicating that larger clones have a higher reproductive output. Individual heterozygosity was significantly positively associated with clone size. The effect was much stronger in Falkenstein (low disturbance) than in Maasholm (high disturbance). The results indicate that in a low disturbance population the relatively outbred clones occupy a higher proportion of the available space, possibly because they outcompete relatively inbred neighbours.     

The impact of forest disturbance on the genetic diversity and population structure of a late-successional moss

Abstract

Human-induced disturbances threaten the genetic variation of wild plant populations. The genetic diversity and spatial population structure of the moss Isothecium myosuroides, a late-successional forest species, was investigated in subtropical cloud forests (La Gomera, Canary Islands) using inter-simple sequence repeat (ISSR) markers. Inter- and intrapopulation genetic variability was assessed in two ancient and four disturbed forest stands, which were classified according to their vegetation, forest age and type of disturbance. ISSR analysis of 144 epiphyte colonies with eight primers resulted in 211 reliably amplified bands. Our findings show that in disturbed forest stands, the population structure is increased, and the genetic diversity decreased compared with the levels observed in ancient forests. Although ancient and disturbed stands were located relatively close to each other, the (re-) established epiphyte populations did not reach their original genetic condition, 40 years following disturbance. Strong differentiation among populations of I. myosuroides at several spatial scales and differences in genetic diversity are mainly related to the local environmental conditions and the availability of suitable microhabitats in anthropogenically disturbed forest stands.     

The extent of clonality in large stands of Lycopodium annotinum L.

In the Rothaargebirge (Northrhine-Westphalia) the interrupted club moss (Lycopodium annotinum L.) often grows in large (maximum size of patches observed: 18,000 m²) and dense (club moss cover 60–90%) clusters. By DNA amplification fingerprinting (DAF) analysis it was shown in three populations comprising a total of 69 samples that the clusters are of great genetical uniformity. Based on data from 47 polymorphic loci amplified with 13 primers 11 multilocus genotypes were identified, nine in one population and one per population in the other two. The data were subjected to similarity analysis, generating Jaccard′s similarity coefficients, on the basis of which cluster analysis was performed. Calculation of Nei's genetic diversity (1987) resulted in a mean value of 0.77 over all samples and a mean within populations diversity of 0.3. Corrected G′_ST value for the fraction of diversity among the populations was 0.7. Two out of three sites are most probably formed by one clone only. As the annual growth rate of the shoots is known, it has to be stated that the stands under investigation are at least 80–90 years old. Taking into consideration that annual accretion is virtually non-existent following forest thinning measures, it becomes very likely that the club moss plants are approximately as old as the trees of their forests (150–180 years). This hypothesis is supported by the observation that within the forests only large (i.e. old) stands, but no single shoots (i.e. young individuals) of the club moss exist. Thus one can conclude that in undisturbed forests no sexual reproduction of L. annotinum takes place.     

Reproductive phenology in the leafy hepatic Lophozia silvicola Buch in southern Finland

Abstract

Reproductive phenology was described in the leafy dioecious hepatic Lophozia silvicola Buch during three successive growing seasons in an old-growth forest population in southern Finland. The sequence of phenological events was quantified by a maturity index M _i, which was calculated on the basis of the rankings of the developmental stages and the numbers of individual shoots in each stage. The developmental cycle of antheridia was correlated with the temperature during the growing season, with maturation from July to August. Gametangia maturation from initials to gametangia dehiscence takes about 10 months including a probable pause during winter. Antheridia in early developmental stages were present in the population under study throughout the growing season. The timing of the developmental cycle of archegonia varied among years. Fertilization was estimated to occur in early to mid-summer on the basis of the presence of dehisced antheridia and the subsequent emergence of 'swollen venter' archegonia. Maturation of archegonia and the proportion of sporophyte-bearing shoots were correlated with mean rainfall and relative humidity during the week preceding each sampling. Total shoot number per sample, an indication of population density, was correlated with numbers and proportions of females and sporophyte-bearing shoots in the samples. The proportion of sex-expressing shoots in the population was on average 26%. The proportion of females was on average 8%, while the proportion of males was 17%, the difference between them being significant. The female to male sex ratio varied between the samples, with a mean of 0.61 indicating male-biased overall sex ratio in the population studied.     

Local forest environment largely affects below-ground growth, clonal diversity and fine-scale spatial genetic structure in the temperate deciduous forest herb Paris quadrifolia

Paris quadrifolia (herb Paris) is a long-lived, clonal woodland herb that shows strong differences in local population size and shoot density along an environmental gradient of soil and light conditions. This environmentally based structuring may be mediated by differences in clonal growth and seedling recruitment through sexual reproduction. To study the interrelationship between environmental conditions and spatial patterns of clonal growth, the spatial genetic structure of four P. quadrifolia populations growing in strongly contrasting sites was determined. In the first place, plant excavations were performed in order to (i) determine differences in below-ground growth of genets, (ii) investigate connectedness of ramets and (iii) determine total genet size. Although no differences in internode length were found among sites, clones in moist sites were much smaller (genets usually consisted of 1-3 interconnected shoots, most of them flowering) than genets in dry sites, which consisted of up to 15 interconnected shoots, the majority of which were vegetative. Further, amplified fragment length polymorphism (AFLP) markers were used. Clonal diversity was higher in populations located in moist and productive ash-poplar forests compared to those found in drier and less productive mixed forest sites (G/N: 0.27 and 0.14 and Simpson's D: 0.84 and 0.75, respectively). Patterns of spatial population genetic structure under dry conditions revealed several large clones dominating the entire population, whereas in moist sites many small genets were observed. Nevertheless, strong spatial genetic structure of the genet population was observed. Our results clearly demonstrate that patterns of clonal diversity and growth form of P. quadrifolia differ among environments. Limited seedling recruitment and large clone sizes due to higher connectedness of ramets explain the low clonal diversity in dry sites. In moist sites, higher levels of clonal diversity and small clone sizes indicate repeated seedling recruitment, whereas strong spatial genetic structure suggests limited seed dispersal within populations.     

Comparison of quantitative genetic parameters between two natural populations of a selfing plant species, Medicago truncatula Gaertn.

 In this paper we compare mean values, heritability estimates, coefficient of genetic variation, and genetic correlations among several fitness components of two natural populations of a selfing plant species, Medicago truncatula L. It is shown that the population that had been found most polymorphic for molecular markers in a previous study was also the most variable for quantitative characters. Depending on the traits, the larger heritabilities in this population were due to either larger coefficients of genetic variances or smaller coefficients of environmental variances. Whereas genetic and phenotypic correlation matrices were very similar within each population, they were quite different between populations. In particular, although a positive correlation between age and size at maturity was found in both populations, the correlation between age at maturity and reproductive success was negative in the more variable population (late flowering plant, with a larger size at flowering, produced fewer pods), whereas no correlation was observed in the less variable population. We suggest that while in the less variable population all individuals have a high reproductive effort, several strategies coexist in the more variable population, with some early-flowering genotypes showing a high reproductive effort and other late-flowering genotypes showing a larger competitive ability through increased vegetative growth. Received: 25 June 1996 / Accepted: 11 October 1996     

Genetic differentiation of Albizia lebbeck (L.) Benth. populations estimated by RAPD and ISSR markers

Abstract

Albizia lebbeck (L.) Benth., a popular multi‐purpose legume tree species, has a wide distribution throughout the Indian subcontinent. The species is highly valued for its quality timber, gum yield and therapeutical uses. However, the increasing social and economical pressures are devastating the natural stands of A. lebbeck forests. So, there is a need to estimate the genetic variation present in A. lebbeck populations. Both RAPD and ISSR molecular markers were used to analyse 172 individuals representing eight populations of the species in different geographical range. The within‐population genetic diversity ranged from 1.23 to 1.38. The total gene variability was 0.34 of which 0.17 (50%) accounted for within‐population gene variability. The genetic differentiation between populations (Gst = 0.49) was significantly correlated to geographical distance (r = 0.61, p < 0.001). An UPGMA clustering suggests a high level of genetic isolation due to distance. This study revealed the genetic differentiation which will provide a template for adaptation and evolution of the populations and species.     

Sexual reproduction in the phyllodioicous bryophyte Homalothecium lutescens (Hedw.) H.Rob. in relation to habitat age,growth conditions and genetic variation

Sporophyte production and female fertility were investigated in seventeen calcareous grassland demes of the moss Homalothecium lutescens (Hedw.) H.Rob. on the Baltic island of Öland, with the aim of understanding the relationships between sexual reproduction, habitat age, genetic variation and factors related to growth conditions. The overall proportion of fertile female shoots (with perichaetia) was 35%. Fertility status at the level of individual shoots was positively associated with shoot length and density, while within deme fertility was positively associated with bush cover. There was no association between female fertility and habitat age, genetic diversity (H_S) or allelic richness. Out of 1344 investigated shoots, only two were normal-sized fertile males. Dwarf males were also extremely rare, and found almost exclusively on shoots with sporophytes. Few sporophytes were observed (in the two demes with highest fertility and bush cover). No relationship between genetic variation and the frequency of sporophytes and males was found. The lack of a relationship between sexual reproduction and genetic variation suggests that sexual reproduction may not occur in the same grassland fragments as the recruitment of new clones (from spores or vegetative fragments). The majority of the dry, open grassland habitats, where H. lutescens is typically found in the study area, appear to be suboptimal for both dwarf males and fertilization. Sexual reproduction is more likely to occur in shaded (although grazed) grassland patches, where moisture levels are likely to be higher and the moss colonies are generally more vigorous.     

Homogeneous genetic structure and variation in tree architecture of <Emphasis Type="Italic">Larix kaempferi</Emphasis> along altitudinal gradients on Mt. Fuji

Variations in tree architecture and in the genetic structure of Larix kaempferi on Mt. Fuji were surveyed along altitudinal gradients using 11 nSSR loci. In total, 249 individuals from six populations along three trails at altitudes ranging from approximately 1,300 to 2,700 m were investigated. Gradual changes in tree architecture with increasing elevation, from erect trees to flag trees and krummholz mats, were observed in the high-altitude populations (>2,000 m) on all trails. These findings suggest that tree architecture is correlated with the severe environmental conditions associated with increasing elevation, such as strong winds. In contrast to obvious variations in tree architecture, the genetic diversity of populations along the trails was almost uniform (H _E = 0.717–0.762) across the altitudinal range. The results of the AMOVA and STRUCTURE analyses, and the analysis for isolation by distance pattern, suggest homogeneous genetic structuring across all populations on Mt. Fuji, while the pairwise F _ST showed barriers to gene flow between altitudinal populations that were demarcated as high- or low-altitude populations by Abies-Tsuga forest. Although the evergreen coniferous forests on the mountainside may hinder gene flow, this may be explained by the long-distance seed dispersal of the Japanese larch and/or a short population history resulting from eruptions or slush avalanches, although evergreen coniferous forests on the mountainside may hinder gene flow.     

Life history characteristics of tule perch (Hysterocarpus traski) populations in contrasting environments

Synopsis The life history characteristics of tule perch were compared within and among populations in three drainages with substantially different environmental conditions. Within populations there were, in general, substantial increases in brood size, size of young, brood weight, and gonadal-somatic index (GSI) with age and with size of female. In at least one population there was a trade-off between the number and size of young produced. However, in a lake where individual growth was very slow, brood weight, GSI, and other life history characters showed decreasing trends with age. Among populations in isolated drainages, female length at first reproduction and longevity varied directly and mean brood size varied inversely with environmental predictability. Morphological and geological evidence and some comparative litter characteristics suggest that life history differences among populations in isolated drainages are in part genetic.     

Notes on African Mosses. I. Andreaea camerunensis sp.nov. and other Mosses mostly from Nigeria and the British Cameroons

Abstract

Reproductive ecological traits such as success of fertilization, partitioning of sexes, the relative success of sexual versus asexual reproduction and dispersal distances are likely to considerably influence genetic structure within and among plant populations. In the liverwort Mannia fragrans both sexual and asexual reproduction can be frequently observed: sporophytes are produced abundantly every year and asexual propagation by fragmentation of thalli is also common. The aim of this study was to use ecological and molecular methods (ISSR markers) to separate the role of sexual and asexual components in shaping the partitioning of genetic variability within and among populations. In addition to genetic analyses conducted seasonally, sex expression and fertilization rates, sex ratios, regeneration from vegetative fragments and outcrossing was estimated in 3 populations of the species. Sex expression rates were high and, in spite of strongly female biased sex ratios, high fertilization rates were detected. However, capacity for regeneration from fragments was also high. Despite frequent spore production genetic diversity was low within populations. This is probably the result of the predominance of asexual reproduction s. 1. including crossing between genetically identical plants. Although recombination and mutation occasionally generates new haplotypes, these have little chance to spread because of the large spores mainly falling into their own patch, where chances for germination are low. Due to small size and isolation of the populations, genetic drift is likely to eliminate these haplotypes. Remote populations differed significantly, each being dominated by a few clones, reflecting negligible gene flow among them. Differences among individual populations can partly be related to differences in their reproductive behaviour and degree of isolation.     

Genetic population structure of the ectomycorrhizal fungus Pisolithus microcarpus suggests high gene flow in south-eastern Australia

Pisolithus are ectomycorrhizal fungi that associate with roots of numerous plant species in natural and plantation forests worldwide. Despite the fact that Pisolithus spp. are present in plantation forests in many countries, knowledge of the genetic population structure of Pisolithus spp. remains limited. In this study, we have tested the hypothesis that a propensity for long-distance spore dispersal in Pisolithus microcarpus, along with the widespread distribution of potential eucalypt and acacia plant hosts in south-eastern Australia facilitates gene flow that limits population differentiation. Five polymorphic simple sequence repeat markers were used to investigate the population structure of P. microcarpus. Isolates were grouped according to geographical origin and isolate genotypes were analysed among the geographical populations. Pairwise F _ST estimates indicated limited genetic differentiation among the geographical populations. Analysis of molecular variance revealed that most of the genetic variation present was within geographical populations, with only 1.3% of the genetic variation among P. microcarpus geographical populations. This was particularly pronounced for four geographical populations within a ca 7,000 km² area New South Wales, which were each separated by <100 km and appeared to be genetically homogeneous. The lack of population structure is suggested to be due to a high degree of gene flow, via basidiospores, between the New South Wales geographical populations.     

Genetic structure of <Emphasis Type="Italic">Leucojum aestivum</Emphasis> L. in the Po Valley (N-Italy) drives conservation management actions

The aim of this study was to assess the genetic variation and population structure of the geophyte Leucojum aestivum L. across the Po river valley (N-Italy), to inform conservation management actions with the selection of most suitable source populations for translocation purposes. L. aestivum is self-incompatible and occurs in S-Europe in fragmented wetlands and lowland forests along rivers. The species is particularly interesting for habitat restoration practices for its simplicity of ex situ conservation and cultivation. AFLP analyses were carried out on 16 fragmented populations, using four primer combinations. Correlations between genetic variation and demographic and ecological traits were tested. AFLP produced a total of 202 bands, 95.5% of which were polymorphic. Our results suggest that L. aestivum holds low to moderate levels of genetic diversity (mean Nei’s genetic diversity: H?=?0.125), mostly within-population. We found a gradient of two main biogeographic groups along western and eastern populations, while the STRUCTURE analysis found that the most likely number of clusters was K?=?3, shaping a partially consistent pattern. We explain the unusual negative correlation between genetic variation and population size with the high rate of vegetative reproduction. The levels of population differentiation suggest that fragmentation in L. aestivum populations has occurred, but that an active gene flow between fragmented populations still exists, maintained by flooding events or pollinators. Conservation management actions should improve habitat connectivity, especially for pollinators that vehicle upstream gene flow. Moreover, the west–east structure due to the lithological composition of the gravel and sand forming the alluvial plain of the Po river, should be considered when selecting source populations for translocation purposes.     

Genetic diversity of four populations of Qualea grandiflora Mart. in fragments of the Brazilian Cerrado

We analyzed the genetic structure and diversity of Qualea grandiflora Mart., the most abundant woody species in the Brazilian Cerrado. Eight microsatellite loci were used to analyze samples from four populations subjected to different types of anthropic pressure, distributed throughout the state of São Paulo in the regions of Assis, Brotas, Itirapina and Pedregulho. Results indicated a mean number of 12 alleles per locus, but only six effective alleles. Alleles private to particular populations and rare alleles were also detected. An excess of homozygotes and moderate levels of inbreeding were observed. No clones were identified. All populations departed from Hardy–Weinberg equilibrium (p < 0.05). Spatial structure was observed in the distribution of specimens in distance classes ranging from 30 to 40 km and three genetic clusters were identified, with genotypes in the Pedregulho population differing from the others by up to 90 %. The influence of the Wahlund effect on the studied populations lies between 8.5 and 53.3 %. Estimates of effective population size were low (<10), and the minimum viable area for conservation in the short-, medium- and long-term was estimated to be between 4 and 184 ha. Gene flow was high enough to counter the effects of genetic drift. The genetic diversity and divergence between the studied populations indicated that the Pedregulho population should be considered an Evolutionary Significant Unit and a Management Unit.     

Structure and Dynamics of Populations of Japanese Barberry (Berberis Thunbergii DC.) in Deciduous Forests of New Jersey

Japanese barberry, Berberis thunbergii DC., has become a prominent exotic species in deciduous forests throughout the eastern and midwestern US. Populations range from small plants occurring at low densities to dense, impenetrable thickets of plants with up to 40 stems/individual. A study was undertaken at Morristown National Historical Park in New Jersey to document plant densities, plant size, recruitment through vegetative processes of new shoot initiation and clonal spread and recruitment from seedling establishment, and mortality of stems and plants. Nearly 2000 shoots on 370 plants were individually marked and followed for two growing seasons, and over 1000 seedlings were also individually marked and followed. Populations vary much more in total shoots/area than they do in plant individuals/area, or in mean plant size (shoots/plant), as even the sparse populations have a few large individuals. Shoot mortality is less than new shoot initiation, but most plants do not change in size or change by small numbers of stems. However, the number of new shoots per plant increases as plant size increases. Once plants have three stems, they suffer little or no mortality. Seedling establishment is proportional to the density of shoots, so that as plants grow in size, local recruitment from seed increases. Large numbers of seedlings, and a survival rate of 10%, combine to make seedling recruitment a major component of population increase. The combination of multiple forms of vegetative and seed-based population growth, and the very low rates of plant mortality due to the multi-stemmed growth form explains the ability of this invasive species to rapidly produce dense, persistent populations.     

Understanding the population genetic structure of Gleditsia triacanthos L.: seed dispersal and variation in female reproductive success

Fine-scale genetic structuring is influenced by a variety of ecological factors and can directly affect the evolutionary dynamics of plant populations by influencing effective population size and patterns of viability selection. In many plant species, genetic structuring within populations may result from highly localized patterns of seed dispersal around maternal plants or by the correlated dispersal and recruitment of siblings from the same fruit. This fine-scale genetic structuring may be enhanced if female parents vary significantly in their reproductive success. To test these hypotheses, we used genetic data from 17 allozyme loci and a maximum-likelihood, ‘maternity-analysis’ model to estimate individual female fertilities for maternal trees across a large number of naturally established seedlings and saplings in two populations of Gleditsia triacanthos L. (Leguminosae). Maximum-likelihood fertility estimates showed that the three highest fertility females accounted for 58% of the 313 progeny at the first site and 46% of the 651 progeny at the second site, whereas 18 of 35 and 16 of 34 females, respectively, had fertility estimates that did not exceed 1%. Additional analyses of the second site found individual female fertility to vary significantly both within and among juvenile age classes. Female fertility at the first site was weakly correlated with maternal tree size and spatial location relative to the open, old-field portions of the population, where the great majority of seedlings and saplings were growing, but no such correlations were found at the second site. Estimates of realized seed dispersal distances indicated that dispersal was highly localized at the first site, but was nearly random at the second site, possibly reflecting differences between the two sites in the behaviour of animal dispersers. The combined estimates of seed dispersal patterns and fertility variation are sufficient to explain previously described patterns of significant fine-scale spatial genetic structure in these two populations. In general, our results demonstrate that effective seed dispersal distributions may vary significantly from population to population of a species due to the unpredictable behaviour of secondary dispersers. Consequently, the effects of seed dispersal on realized fine-scale genetic structure may also be relatively unpredictable.     

Correlated responses to clonal selection in populations of Daphnia pulicaria: mechanisms of genetic correlation and the creative power of sex

Genetic correlations among traits alter evolutionary trajectories due to indirect selection. Pleiotropy, chance linkage, and selection can all lead to genetic correlations, but have different consequences for phenotypic evolution. We sought to assess the mechanisms contributing to correlations with size at maturity in the cyclic parthenogen Daphnia pulicaria. We selected on size in each of four populations that differ in the frequency of sex, and evaluated correlated responses in a life table. Size at advanced adulthood, reproductive output, and adult growth rate clearly showed greater responses in high‐sex populations, with a similar pattern in neonate size and r. This pattern is expected only when trait correlations are favored by selection and the frequency of sex favors the creation and demographic expansion of highly fit clones. Juvenile growth and age at maturity did not diverge consistently. The inter‐clutch interval appeared to respond more strongly in low‐sex populations, but this was not statistically significant. Our data support the hypothesis that correlated selection is the strongest driver of genetic correlations, and suggest that in organisms with both sexual and asexual reproduction, adaptation can be enhanced by recombination.