Search results for "Biological Evolution"
showing 10 items of 522 documents
Predominance of outcrossing in Lymnaea stagnalis despite low apparent fitness costs of self-fertilization.
2007
We have quantified the natural mating system in eight populations of the simultaneously hermaphroditic aquatic snail Lymnaea stagnalis, and studied the ecological and genetic forces that may be directing mating system evolution in this species. We investigated whether the natural mating system can be explained by the availability of mates, by the differential survival of self- and cross-fertilized snails in nature, and by the effects of mating system on parental fecundity and early survival. The natural mating system of L. stagnalis was found to be predominantly cross-fertilizing. Density of snails in the populations had no relationship with the mating system, suggesting that outcrossing ra…
Intralocus tactical conflict: Genetic correlations between fighters and sneakers of the dung beetle Onthophagus taurus
2015
Males and females differ in their phenotypic optima for many traits, and as the majority of genes are expressed in both sexes, some alleles can be beneficial to one sex but harmful to the other (intralocus sexual conflict; ISC). ISC theory has recently been extended to intrasexual dimorphisms, where certain alleles may have opposite effects on the fitness of males of different morphs that employ alternative reproductive tactics (intralocus tactical conflict; ITC). Here, we use a half-sib breeding design to investigate the genetic basis for ISC and ITC in the dung beetle Onthophagus taurus. We found positive heritabilities and intersexual genetic correlations for almost all traits investigat…
Tracking Five Millennia of Horse Management with Extensive Ancient Genome Time Series
2019
Summary Horse domestication revolutionized warfare and accelerated travel, trade, and the geographic expansion of languages. Here, we present the largest DNA time series for a non-human organism to date, including genome-scale data from 149 ancient animals and 129 ancient genomes (≥1-fold coverage), 87 of which are new. This extensive dataset allows us to assess the modern legacy of past equestrian civilizations. We find that two extinct horse lineages existed during early domestication, one at the far western (Iberia) and the other at the far eastern range (Siberia) of Eurasia. None of these contributed significantly to modern diversity. We show that the influence of Persian-related horse …
Unmatedness promotes the evolution of helping more in diplodiploids than in haplodiploids
2014
The predominance of haplodiploidy (where males develop from unfertilized haploid eggs and females from fertilized diploid eggs) among eusocial species has inspired a body of research that focuses on the possible role of relatedness asymmetries in the evolution of helping and eusociality. Previous theory has shown that in order for relatedness asymmetries to favor the evolution of helping, there needs to be variation in sex ratios among nests in the population (i.e., split sex ratios). In haplodiploid species, unmated females can produce a brood of all males, and this is considered the most likely mechanism for split sex ratios at the origin of helping. In contrast, in diploidiploids unmated…
Using visual modelling to study the evolution of lizard coloration: sexual selection drives the evolution of sexual dichromatism in lacertids
2012
Sexual selection has been invoked as a major force in the evolution of secondary sexual traits, including sexually dimorphic colorations. For example, previous studies have shown that display complexity and elaborate ornamentation in lizards are associated with variables that reflect the intensity of intrasexual selection. However, these studies have relied on techniques of colour analysis based on human – rather than lizard – visual perception. Here, we use reflectance spectrophotometry and visual modelling to quantify sexual dichromatism considering the overall colour patterns of lacertids, a lizard clade in which visual signalling has traditionally been underrated. These objective method…
Sex change in plants and animals: a unified perspective
2014
The capacity of organisms to change their sex has evolved independently in several plant and animal lineages. Sex change has been widely studied, but research approaches have differed for plants and animals, and conclusions have often been taxon-specific. Although sex allocation theory provides a unifying framework for the study of sex change, this unity has not always been appreciated, especially in the botanical literature. Here, we review sex change with regard to its representation in relation to taxonomy and other sexual systems, with regard to its suggested adaptive benefits, and to the role of taxon-specific body architecture, such as modularity and gonadal structure. We highlight di…
The evolution of mating preferences for genetic attractiveness and quality in the presence of sensory bias.
2022
The aesthetic preferences of potential mates have driven the evolution of a baffling diversity of elaborate ornaments. Which fitness benefit—if any—choosers gain from expressing such preferences is controversial, however. Here, we simulate the evolution of preferences for multiple ornament types (e.g., “Fisherian,” “handicap,” and “indicator” ornaments) that differ in their associations with genes for attractiveness and other components of fitness. We model the costs of preference expression in a biologically plausible way, which decouples costly mate search from cost-free preferences. Ornaments of all types evolved in our model, but their occurrence was far from random. Females typically p…
Sexual conflict drives micro- and macroevolution of sexual dimorphism in immunity
2021
Abstract Background Sexual dimorphism in immunity is believed to reflect sex differences in reproductive strategies and trade-offs between competing life history demands. Sexual selection can have major effects on mating rates and sex-specific costs of mating and may thereby influence sex differences in immunity as well as associated host–pathogen dynamics. Yet, experimental evidence linking the mating system to evolved sexual dimorphism in immunity are scarce and the direct effects of mating rate on immunity are not well established. Here, we use transcriptomic analyses, experimental evolution and phylogenetic comparative methods to study the association between the mating system and sexua…
Bayesian modeling of the evolution of male height in 18th century Finland from incomplete data.
2012
Abstract Data on army recruits’ height are frequently available and can be used to analyze the economics and welfare of the population in different periods of history. However, such data are not a random sample from the whole population at the time of interest, but instead is skewed since the short men were less likely to be recruited. In statistical terms this means that the data are left-truncated. Although truncation is well-understood in statistics a further complication is that the truncation threshold is not known, may vary from time to time, and auxiliary information on the threshold is not at our disposal. The advantage of the fully Bayesian approach presented here is that both the …
Matters of scale: positive allometry and the evolution of male dimorphisms
2005
J.L.T. was funded by a Biotechnology and Biological Sciences Research Council research fellowship, J.S.K. by the Academy of Finland, and N.R.L. by a Natural Environment Research Council research fellowship. The developmental independence of alternative phenotypes is key to evolutionary theories of phenotypic plasticity and the origins of diversity. Male dimorphisms associated with alternative reproductive tactics are widely cited examples of such facultative expression of divergent fitness optima. Current models for the evolution of male dimorphisms invoke a size-dependent threshold at which the phenotype is reprogrammed. We use predictions derived from allometric modeling to test for the e…