Can dominance genetic variance be ignored in evolutionary quantitative genetic analyses of wild populations?

Accurately estimating genetic variance components is important for studying evolution in the wild. Empirical work on domesticated and wild outbred populations suggests that dominance genetic variance represents a substantial part of genetic variance, and theoretical work predicts that ignoring dominance can inflate estimates of additive genetic variance. Whether this issue is pervasive in natural systems is unknown, because we lack estimates of dominance variance in wild populations obtained in situ. Here, we estimate dominance and additive genetic variance, maternal variance, and other sources of nongenetic variance in eight traits measured in over 9000 wild nestlings linked through a genetically resolved pedigree. We find that dominance variance, when estimable, does not statistically differ from zero and represents a modest amount (2-36%) of genetic variance. Simulations show that (1) inferences of all variance components for an average trait are unbiased; (2) the power to detect dominance variance is low; (3) ignoring dominance can mildly inflate additive genetic variance and heritability estimates but such inflation becomes substantial when maternal effects are also ignored. These findings hence suggest that dominance is a small source of phenotypic variance in the wild and highlight the importance of proper model construction for accurately estimating evolutionary potential.     

Mating Resets Male Cricket Aggression

An animal’s motivational state can significantly impact its behavior. We examined the effects of mating on the aggression of male Acheta domesticus crickets. Pairs of males were allowed to establish dominance and subordinance and were then physically separated. Subordinate males were then allowed to either copulate with a female or to have chemo-tactile contact with, but to not copulate with, a female. Less than 15 min after separation, all male pairs engaged in a second agonistic encounter. Subordinate males that copulated with females were significantly more aggressive toward their dominant partners than un-mated subordinate males. Many mated subordinates became dominant. Allowing a subordinate male to contact, but not copulate with, a female had a similar effect, suggesting that chemo-tactile cues from the female are sufficient to elicit this change in aggression.     

In vitro corm production in the saffron crocus (Crocus sativus L.)

Means to increase the reproductive capacity of Crocus sativus L., in vitro, are described. Cytokinins and auxin were found to be essential for development of bud explants. Ethylene and ethaphon pretreatments inhibited leaf development but induced corm production. Microsurgery of the apical bud combined with ethylene pretreatment increased both sprouting and corm production.     

Social dominance in female bighorn sheep

A group of six individually identified bighorn ewes (Ovis canadensis canadensis) in the Denver Zoo, Denver, Colorado, was studied to determine the existence of a dominance hierarchy. Using success in displacement interactions as an index to rank, a very linear, age-related hierarchy was found.     

Reciprocal allopolyploid grasses (Festuca × Lolium) display stable patterns of genome dominance

Allopolyploidization entailing the merger of two distinct genomes in a single hybrid organism, is an important process in plant evolution and a valuable tool in breeding programs. Newly established hybrids often experience massive genomic perturbations, including karyotype reshuffling and gene expression modifications. These phenomena may be asymmetric with respect to the two progenitors, with one of the parental genomes being “dominant.” Such “genome dominance” can manifest in several ways, including biased homoeolog gene expression and expression level dominance. Here we employed a k-mer–based approach to study gene expression in reciprocal Festuca pratensis Huds. × Lolium multiflorum Lam. allopolyploid grasses. Our study revealed significantly more genes where expression mimicked that of the Lolium parent compared with the Festuca parent. This genome dominance was heritable to successive generation and its direction was only slightly modified by environmental conditions and plant age. Our results suggest that Lolium genome dominance was at least partially caused by its more efficient trans-acting gene expression regulatory factors. Unraveling the mechanisms responsible for propagation of parent-specific traits in hybrid crops contributes to our understanding of allopolyploid genome evolution and opens a way to targeted breeding strategies.     

Ecological validity of social interaction tests in rats and mice

Different rat and mouse models are used in studies of social interactions. Simple behavioral measures, which are commonly used in the laboratory, allow to perform relatively short experiments and to use multiple brain manipulation techniques. However, too much focus on the simplest behavioral models generates a serious risk of reducing ecological validity or even studying phenomena which would never happen outside of the laboratory. In this review, we discuss the suitability of mice and rats as model organisms for studying social behaviors, with focus on social transmission of fear paradigms. First, we briefly introduce the concept of domestication and what impact it had on laboratory rodents. Then, we present two aspects of social behaviors, sociability and dominance, which are crucial for social organization in these species. Finally, we present experimental models used for studying how animals transmit information about danger between each other, and how these models may reflect what happens in the natural environment. We discuss the difficulties that arise from our limited knowledge of rat and mouse ecology, especially their social life. We also explore the subject of balancing ecological validity and controllability in rodent models of social behaviors, the latter being particularly important for studying brain activity. Although it is very challenging, an efficient program for social neuroscience research should, in our opinion, aim at bridging the gap between laboratory and field studies.     

基于SSR标记的不同优势等级云南松遗传多样性分析

基于SSR分子标记技术,按树高和胸径（地径）因子将样地内的植株分为优势木、中等木和劣势木3类,对不同生长优势等级云南松林木的遗传多样性变异特征进行了研究。结果表明：在林冠层,优势木的有效等位基因数、Shannon's信息指数、观测杂合度和期望杂合度分别为2.083、0.762、0.290和0.423,略高于中等木和劣势木;在更新层,有效等位基因数、Shannon's信息指数、观测杂合度和期望杂合度分别为2.063、0.774、0.272和0.410,除观测杂合度外,其余3个指标也均表现为优势木略高于中等木和劣势木。从差异显著性检验来看,不同生长优势等级云南松林木间的遗传多样性差异不显著,即林木生长分化对遗传多样性的影响不明显。