Search results for "Evolution"

2021

Most species are either parasites or exploited by parasites, making parasite–host interactions a driver of evolution. Parasites with complex life cycles often evolve strategies to facilitate transmission to the definitive host by manipulating their intermediate host. Such manipulations could explain phenotypic changes in the ant Temnothorax nylanderi, the intermediate host of the cestode Anomotaenia brevis. In addition to behavioral and morphological alterations, infected workers exhibit prolonged lifespans, comparable to that of queens, which live up to two decades. We used transcriptomic data from cestodes and ants of different castes and infection status to investigate the molecular unde…

Adaptive Evolution and Epigenetics

2023

Epigenetic changes, such as DNA methylation and certain histone modifications, can be inherited but in many cases they do not follow Mendelian inheritance patterns and their stability appears to be lower than for changes in DNA sequence. Adaptive evolution by natural selection requires that differences among individuals are heritable to some degree. Epigenetic changes can be incorporated into evolutionary theory, and given that properties of epigenetic variation are distinct from genetic variation, spontaneous epigenetic changes can affect evolutionary dynamics in interesting ways. In this chapter, I review the properties of epigenetic variation and how they relate to the main parameters of…

2016

Sex differences in ageing rates and lifespan are common in nature, and an enduring puzzle for evolutionary biology. One possibility is that sex-specific mortality rates may result from recessive deleterious alleles in ‘unguarded’ heterogametic X or Z sex chromosomes (the unguarded X hypothesis). Empirical evidence for this is, however, limited. Here, we test a fundamental prediction of the unguarded X hypothesis in Drosophila melanogaster , namely that inbreeding shortens lifespan more in females (the homogametic sex in Drosophila ) than in males. To test for additional sex-specific social effects, we studied the lifespan of males and females kept in isolation, in related same-sex groups, …

Chironomus riparius(Diptera) genome sequencing reveals the impact of minisatellite transposable elements on population divergence

2016

AbstractActive transposable elements (TEs) may result in divergent genomic insertion and abundance patterns among conspecific populations. Upon secondary contact, such divergent genetic backgrounds can theoretically give rise to classical Dobzhansky-Muller incompatibilities (DMI), a way how TEs can contribute to the evolution of endogenous genetic barriers and eventually population divergence. We investigated whether differential TE activity created endogenous selection pressures among conspecific populations of the non-biting midgeChironomus riparius,focussing on aChironomus-specific TE, the minisatellite-likeCla-element, whose activity is associated with speciation in the genus. Using an …

The complete plastid genome of the middle Asian endemic of Stipa lipskyi (Poaceae)

2016

AbstractThe structure of the Stipa lipskyi (GenBank accession no. KT692644) plastid genome is similar to that of closely related Poaceae species: it has a total length of 137 755 bp, the base composition of the plastome is the following: A (30.7%), C (19.3%), G (19.4%) and T (30.5%). The S. lipskyi plastid genome contains 71 genes, excluding second IR region. A complete plastome sequence of S. lipskyi will help the development of primers for examining phylogeny and hybridization events in this taxonomically difficult genus.

Application of high resolution melting assay (HRM) to study temperature-dependent intraspecific competition in a pathogenic bacterium

2017

AbstractStudies on species’ responses to climate change have focused largely on the direct effect of abiotic factors and in particular temperature, neglecting the effects of biotic interactions in determining the outcome of climate change projections. Many microbes rely on strong interference competition; hence the fitness of many pathogenic bacteria could be a function of both their growth properties and intraspecific competition. However, due to technical challenges in distinguishing and tracking individual strains, experimental evidence on intraspecific competition has been limited so far. Here, we developed a robust application of the high-resolution melting (HRM) assay to study head-to…

Host infection history modifies co-infection success of multiple parasite genotypes.

2015

Co-infections by multiple parasite genotypes are common and have important implications for host-parasite ecology and evolution through within-host interactions. Typically, these infections take place sequentially, and therefore, the outcome of co-infection may be shaped by host immune responses triggered by previous infections. For example, in vertebrates, specific immune responses play a central role in protection against disease over the course of life, but co-infection research has mostly focused on previously uninfected individuals. Here, we investigated whether sequential exposure and activation of host resistance in rainbow trout Oncorhynchus mykiss affects infection success and inte…

Repeated evolution of camouflage in speciose desert rodents

2017

AbstractThere are two main factors explaining variation among species and the evolution of characters along phylogeny: adaptive change, including phenotypic and genetic responses to selective pressures, and phylogenetic inertia, or the resemblance between species due to shared phylogenetic history. Phenotype-habitat colour match, a classic Darwinian example of the evolution of camouflage (crypsis), offers the opportunity to test the importance of historical versus ecological mechanisms in shaping phenotypes among phylogenetically closely related taxa. To assess it, we investigated fur (phenotypic data) and habitat (remote sensing data) colourations, along with phylogenetic information, in t…

Multi-modal defences in aphids offer redundant protection and increased costs likely impeding a protective mutualism.

2017

The pea aphid, Acyrthosiphon pisum, maintains extreme variation in resistance to its most common parasitoid wasp enemy, Aphidius ervi, which is sourced from two known mechanisms: protective bacterial symbionts, most commonly Hamiltonella defensa, or endogenously encoded defences. We have recently found that individual aphids may employ each defence individually, occasionally both defences together, or neither. In field populations, Hamiltonella-infected aphids are found at low to moderate frequencies and while less is known about the frequency of resistant genotypes, they show up less often than susceptible genotypes in field collections. To better understand these patterns, we sought to co…

From microbial eukaryotes to metazoan vertebrates: Wide spectrum paleo-diversity in sedimentary ancient DNA over the last ~14,500 years

2018

Most studies that utilize ancient DNA have focused on specific groups of organisms or even single species. Instead, the whole biodiversity of eukaryotes can be described using universal phylogenetic marker genes found within well-preserved sediment cores that cover the post-glacial period. Sedimentary ancient DNA samples from Lake Lielais Svētiņu, eastern Latvia, at a core depth of 1,050 cm in ~150 year intervals were used to determine phylotaxonomy in domain Eukaryota. Phylotaxonomic affiliation of >1,200 eukaryotic phylotypes revealed high richness in all major eukaryotic groups-Alveolata, Stramenopiles, Cercozoa, Chlorophyta, Charophyta, Nucletmycea, and Holozoa. The share of organisms t…