Female preference exerts selection on male traits. How such preferences affect male traits, how female preferences change and the genetic correlation between male traits and female preference were examined by an experiment in which females were either mated to males they preferred (S lines) or to males chosen at random from the population (R lines). Female preference was predicted to increase the time spent calling by males. Thirteen other song components were measured. Preference for individual traits was greatest for time spent calling(CALL), volume(VOL) and chirp rate(CHIRP) but the major contributors in the multivariate function were CALL and CHIRP, the univariate influence of VOL arising from correlations to these traits. Estimation of β, the standardized selection differential, for CALL resulting from female preference showed that it was under strong direct selection. However, contrary to prediction, CALL did not change over the course of the experiment whereas VOL, CHIRP and other song components did. Simulation of the experiment using the estimated G matrix showed that lack of change in CALL resulted from indirect genetic effects negating direct effects. Changes in song components were largely due to indirect effects. This experiment showed that female preference may exert strong selection on traits but how they respond to such selection will depend greatly upon the G matrix. As predicted, female preference declined in the R lines. The genetic correlations between preference and preferred traits did not decline significantly more in the R lines, suggesting correlations resulted from both linkage disequilibrium and pleiotropy.

Female preference exerts selection pressure on male traits. This results in a complex interplay of phenotype and genotype. This complexity was examined by an experiment in which females were either mated to males they preferred (S lines) or to males chosen at random from the population (R lines). If genetic correlations between preference and preferred traits (14 song components) resulted from linkage disequilibrium, the correlation would diminish more in the S than the R line. This was not observed, suggesting that the correlation was generated by linkage disequilibrium and pleiotropy. Univariate preference was greatest for time spent calling (CALL), volume (VOL) and chirp rate (CHIRP) but the major contributors in the multivariate function were CALL and CHIRP, the univariate influence of VOL arising from correlations to these traits. Estimation of β for CALL and VOL resulting from female preference showed that both were under strong direct selection. However, CALL did not change over the course of the experiment whereas VOL, CHIRP and other song components did. Simulation of the experiment using the G matrix estimated from generation 11 showed that the lack of change in CALL resulted from indirect genetic effects negating direct effects. CHIRP and VOL were predicted to change as observed. Changes in song components were largely due to indirect effects. This experiment showed that female preference may exert strong selection on traits but how they respond to such selection will depend greatly upon the details of the G matrix.

The evolution of sexual dimorphisms requires divergence between sexes in the evolutionary trajectories of the traits involved. Discerning how genetic architecture could facilitate such divergence has proven challenging because of the difficulty in estimating non-additive and sex-linked genetic variances using traditional quantitative genetic designs. Here we use a three-generation, double-first-cousin pedigree design to estimate additive, sex-linked and dominance (co)variances for 12 traits in the water strider, Aquarius remigis . Comparisons among these traits, which have size ratios ranging from 1 to 5 (larger/smaller), allow us to ask if sexual dimorphisms are associated with characteristic patterns of quantitative genetic variation. We frame our analysis around three main questions, derived from existing theory and empirical evidence: Are sexual dimorphisms associated with (1) lower additive inter-sex genetic correlations, (2) higher proportions of sex-linked variance, or (3) differences between sexes in autosomal additive and dominance genetic variances? For questions (1) and (2), we find weak and non-significant trends in the expected directions, which preclude definitive conclusions. However, in answer to question (3), we find strong evidence for a positive relationship between sexual dimorphism and differences between sexes in proportions of autosomal dominance variance. We also find strong interactions among the three genetic components indicating that their relative influence differs among traits and between sexes. These results highlight the need to include all three components of genetic (co)variance in both theoretical evolutionary models and empirical estimations of the genetic architecture of dimorphic traits.

An organism’s phenotype has been shaped by evolution but the specific processes have to be indirectly inferred for most species. For example, correlations among traits imply the historical action of correlated selection and, more generally, the expression and distribution of traits is expected to be reflective of the adaptive landscapes that have shaped a population. However, our expectations about how quantitative traits—like most behaviors, physiological processes, and life-history traits—should be distributed under different evolutionary processes are not clear. Here, we show that genetic variation in quantitative traits is not distributed as would be expected under dominant evolutionary models. Instead, we found that genetic variation in quantitative traits across six phyla and 60 species (including both Plantae and Animalia) is consistent with evolution across high-dimensional “holey landscapes.” This suggests that the leading conceptualizations and modeling of the evolution of trait integration fail to capture how phenotypes are shaped and that traits are integrated in a manner contrary to predictions of dominant evolutionary theory. Our results demonstrate that our understanding of how evolution has shaped phenotypes remains incomplete and these results provide a starting point for reassessing the relevance of existing evolutionary models.

Evolutionary change of thermal traits (i.e., heat tolerance and behavioural thermoregulation) is one of the most important mechanisms exhibited by organisms to respond to global warming. However, the evolutionary potential of heat tolerance, estimated as narrow-sense heritability, depends on the methodology employed. An alternative adaptive mechanism to buffer extreme temperatures is behavioural thermoregulation, although the association between heat tolerance and thermal preference is not clearly understood. We suspect that methodological effects associated with the duration of heat stress during thermal tolerance assays are responsible for missing this genetic association. To test this hypothesis, we estimated the heritabilities and genetic correlations for thermal traits in Drosophila subobscura, using high-temperature static and slow ramping assays. We found that heritability for heat tolerance was higher in static assays (h2  = 0.134) than in slow ramping assays (h2  = 0.084), suggesting that fast assays may provide a more precise estimation of the genetic variation of heat tolerance. In addition, thermal preference exhibited a low heritability (h2  = 0.066), suggesting a reduced evolutionary response for this trait. We also found that the different estimates of heat tolerance and thermal preference were not genetically correlated, regardless of how heat tolerance was estimated. In conclusion, our data suggest that these thermal traits can evolve independently in this species. In agreement with previous evidence, these results indicate that methodology may have an important impact on genetic estimates of heat tolerance and that fast assays are more likely to detect the genetic component of heat tolerance.

Vibrational communication is known in some subterranean insects. Except for their use in sexual signaling, vibration behavior has rarely been reported. We report here four distinct types of substrate-based vibration behaviors in the mole cricket, Gryllotalpa orientalis, which are not associated with sexual signaling because of the occurrence of these behaviors in nymphs: (1) scraping with the forelegs; (2) foreleg taps (tapping with the forelegs); (3) palpal taps (tapping with the maxillary palpi); and (4) tremulation (back-and-forth movement of the whole body). Scraping is hypothesized to be used for the inspection of borrows. Foreleg taps are possibly informing nearby individuals of their presence, because it is never observed in solitary conditions. Palpal taps are rarely observed and its function is unknown. Tremulation is possibly related to avoidance of conspecific individual approaching and touching. The combination of the four vibration behaviors in the mole cricket may be unique among insects.

Phenotypically plastic responses have been increasingly documented in response to intraspecific, behavioral (often sexual) signals such as mating calls. We explored the effect of short-term exposure to male calling song on a reproductive life-history trade-off in adult females of the wing dimorphic cricket species, Gryllus firmus. In G. firmus, long-winged females possess flight muscles and small ovaries immediately after the adult molt, whereas short-winged females possess small, nonfunctional flight muscles and large ovaries at the same age. In long-winged females, flight muscles are histolyzed during ovary growth that occurs after the adult molt. Because of these differences in reproductive physiology, we predicted different responses to calling song exposure between the 2 morphs. We hypothesized that such exposure would boost ovary growth in both wing morphs, but also increase flight muscle histolysis in long-winged females, producing a greater relative response to exposure in this morph. As expected, we saw a significant increase in ovary mass in exposed females of both morphs, and a greater relative response in long-winged females. Calling song exposure did not have a strong effect on flight muscle histolysis, suggesting that the relatively larger ovary response in long-winged females was perhaps fueled instead by reallocation of flight fuels. Our study documents the rapid adult response of a fitness-linked trait to the adult social environment, a result with far-reaching implications, as the experience of mating signals during adulthood should be nearly universal across species.

Previous articleNext article No AccessGeneticsStatistical Approaches to Gene x Environment Interactions for Complex Phenotypes. Edited by Michael Windle. Cambridge (Massachusetts): MIT Press. $50.00. viii + 296 p.; ill.; index. ISBN: 978-0-262-03468-5. 2016.Derek A. RoffDerek A. RoffEvolution, Ecology & Organismal Biology, University of California, Riverside, California Search for more articles by this author Evolution, Ecology & Organismal Biology, University of California, Riverside, CaliforniaPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 93, Number 1March 2018 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/696767 Views: 27Total views on this site For permission to reuse, please contact [email protected]PDF download Crossref reports no articles citing this article.

Previous articleNext article No AccessEvolutionEvolutionary Biology: Biodiversification from Genotype to Phenotype. Edited by Pierre Pontarotti. Cham (Switzerland) and New York: Springer. $179.00. ix + 409 p.; ill.; index. ISBN: 978-3-319-19931-3 (hc); 978-3-319-19932-0 (eb). 2015.Derek RoffDerek RoffBiology, University of California, Riverside, California Search for more articles by this author Biology, University of California, Riverside, CaliforniaPDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Quarterly Review of Biology Volume 92, Number 3September 2017 Published in association with Stony Brook University Article DOIhttps://doi.org/10.1086/693597 Views: 35Total views on this site For permission to reuse, please contact [email protected]PDF download Crossref reports no articles citing this article.

In some mammals, female characteristics have been shown to depend, in part, on the intrauterine position during development of female fetuses relative to male fetuses. Females developing in close proximity to males show behavioral, physiological and life history characteristics that are masculinized. With the exception of one inconclusive study, nothing is known of the genetic basis of this phenomenon. In this paper, we reported an analysis of the quantitative genetic basis of masculinization, as indicated by the anogenital distance (AGD) at birth and weaning, in the rodent Octodon degus. Because AGD is related to weight, we included a genetic analysis of pup weight at birth and weaning. Pairwise correlations showed that AGD at birth varied negatively with litter size and parturition number but positively with weaning AGD, birth weight, dam AGD and percentage of males in the litter. AGD at weaning varied similarly except that it tended to vary positively with litter size. Genetic (co)variances of AGD at birth and weight at birth differed in females and males. In females, the best genetic model included substantial effects of direct additive, additive maternal and a negative additive genetic covariance between these two. In males, variances were small and there was difficulty in discriminating between additive maternal and common environmental variances. By weaning, genetic (co)variances had somewhat declined in weight and were not statistically significant in AGD in either sex. This paper showed the occurrence of both phenotypic and genetic components in masculinization with effects being greater in females.

Estimation of mating preferences is a prerequisite for understanding how sexual selection through mate choice shapes both mating systems and sexual dimorphisms. Most studies of mating preferences assay mate choice using either a no choice or a binary choice design. Binary choice trials typically employ either an artificial signal or some fixed difference (e.g. colour or size) between the signalling individuals. Although statistically more powerful than no choice designs, such experiments cannot be used to detect stabilizing preference. Further, the use of artificial signals is problematic because signal components tend to be varied in isolation, and hence do not reflect natural variation. Here, we present a new method that uses natural variation among individuals in choice trials to determine if mating preference is absent, directional, and/or stabilizing. The protocol is tested using simulation and shown to be robust to the preference function, to have the required statistical power, to be unbiased in almost all cases, and to give confidence regions that modestly overestimate the desired 95% criterion. We demonstrate the use of the method with data from mate choice trials of the sand cricket, Gryllus firmus. Software to apply this new approach is provided in Dryad.

exciting new territory, but it is also challenging, and requires both careful construction of appropriate models and extremely powerful data sets. Arguments that behavior is “special” are not entirely convincing to us—though perhaps because we are not true behavioral ecologists—but such studies will certainly be valuable, regardless of whether they support the idea that IGEs increase evolvabilities of behavioral traits or not. We also think there is great potential in studies that: first, explore the consequences of IGEs on multivariate phenotypes (including, for instance, morphology and life history as well as behavior); and, second, recognize that social plasticity may involve both IGEs and GxE simultaneously, and hence the possibility of (direct) G × (indirect) G interactions. Finally, we hope that growing interest in IGEs will help correct the current imbalance in the literature, where theoretical and methodological treatments abound but empirical estimates, especially from natural systems, are still scarce.

Many cryptic species have been discovered in various taxonomic groups based on molecular phylogenetic analyses and mating experiments. Some sympatric cryptic species share equivalent resources, which contradicts the competitive exclusion principle. Two major theories have been proposed to explain the apparent lack of competitive exclusion, i.e. niche-based coexistence and neutral model, but a conclusive explanation is lacking. Here, we report the co-occurrence of cryptic spider wasp species appearing to be ecologically equivalent. Molecular phylogenetic analyses and mating experiments revealed that three phylogenetically closely related species are found sympatrically in Japan. These species share the same resources for larval food, and two of the species have the same niche for nesting sites, indicating a lack of competitive exclusion. This evidence may suggest that ecologically equivalent species can co-occur stably if their shared resources are sufficiently abundant that they cannot be over-exploited.

Natural selection acts on multiple traits simultaneously. How mechanisms underlying such traits enable or constrain their response to simultaneous selection is poorly understood. We show how antagonism and synergism among three traits at the developmental level enable or constrain evolutionary change in response to simultaneous selection on two focal traits at the phenotypic level. After 10 generations of 25% simultaneous directional selection on all four combinations of body size and development time in Manduca sexta (Sphingidae), the changes in the three developmental traits predict 93% of the response of development time and 100% of the response of body size. When the two focal traits were under synergistic selection, the response to simultaneous selection was enabled by juvenile hormone and ecdysteroids and constrained by growth rate. When the two focal traits were under antagonistic selection, the response to selection was due primarily to change in growth rate and constrained by the two hormonal traits. The approach used here reduces the complexity of the developmental and endocrine mechanisms to three proxy traits. This generates explicit predictions for the evolutionary response to selection that are based on biologically informed mechanisms. This approach has broad applicability to a diverse range of taxa, including algae, plants, amphibians, mammals, and insects.

In addition to nutritional conditions experienced by individuals themselves, those experienced by their parents can affect their immune function. Here, we studied the intra- and trans-generational effects of larval diet on susceptibility to an entomopathogenic fungus, Beauveria bassiana, in the greater wax moth, Galleria mellonella. In the first part of the study, a split-brood design was used to compare the susceptibility of full sibs raised either on low- or on high-nutrition larval diet. In the second part of the study, a similar experimental design was employed to investigate the effects of maternal and paternal diet as well as their interaction on offspring's susceptibility. In the first part of the study, we found that individuals fed with high-nutrition diet had higher mortality from infection than individuals fed with low-nutrition diet. However, diet did not affect post-infection survival time. Conversely, in the second part of the study, maternal diet was found to have no significant effect on final mortality rate of offspring, but it affected survival time: larvae with high-nutrition maternal diet survived fewer days after infection than larvae with low-nutrition maternal diet. Paternal diet had no significant effect on offspring's susceptibility to the fungus, indicating that paternal effects are not as important as maternal effects in influencing immune function in this species. Our findings provide further indication that maternal nutrition affects immune function in insects, and suggest that the direct effects of nutrition on immunity may be different, yet parallel, to those caused by parental nutrition.