Search results for "Genetic drift"
showing 10 items of 73 documents
The population genetics and evolutionary epidemiology of RNA viruses.
2004
Key Points The authors discuss the main mechanisms of RNA virus evolution — mutation, recombination, natural selection, genetic drift and migration, and how these interact to shape the genetic structure of populations.The quasispecies model of RNA virus evolution is explained and the question of whether this model provides an accurate description of RNA virus evolution is discussed.Experiments that can be carried out to test the basic principles of evolutionary theory are briefly described. The authors review what such experiments have told us about virus evolution and, more widely, what these experiments have revealed in terms of general evolutionary principles.RNA viruses evolve quickly, …
GENETIC VARIABILITY AND DRIFT LOAD IN POPULATIONS OF AN AQUATIC SNAIL
2004
Population genetic theory predicts that in small populations, random genetic drift will fix and accumulate slightly deleterious mutations, resulting in reduced reproductive output. This genetic load due to random drift (i.e., drift load) can increase the extinction risk of small populations. We studied the relationship between genetic variability (indicator of past population size) and reproductive output in eight isolated, natural populations of the hermaphroditic snail Lymnaea stagnalis. In a common laboratory environment, snails from populations with the lowest genetic variability mature slower and have lower fecundity than snails from genetically more variable populations. This result s…
Pleistocene allopatric differentiation followed by recent range expansion explains the distribution and molecular diversity of two congeneric crustac…
2021
AbstractPleistocene glaciations had a tremendous impact on the biota across the Palaearctic, resulting in strong phylogeographic signals of range contraction and rapid postglacial recolonization of the deglaciated areas. Here, we explore the diversity patterns and history of two sibling species of passively dispersing taxa typical of temporary ponds, fairy shrimps (Anostraca). We combine mitochondrial (COI) and nuclear (ITS2 and 18S) markers to conduct a range-wide phylogeographic study including 56 populations of Branchinecta ferox and Branchinecta orientalis in the Palaearctic. Specifically, we investigate whether their largely overlapping ranges in Europe resulted from allopatric differe…
Do island plant populations really have lower genetic variation than mainland populations? Effects of selection and distribution range on genetic div…
2015
Ecological and evolutionary studies largely assume that island populations display low levels of neutral genetic variation. However, this notion has only been formally tested in a few cases involving plant taxa, and the confounding effect of selection on genetic diversity (GD) estimates based on putatively neutral markers has typically been overlooked. Here, we generated nuclear microsatellite and plastid DNA sequence data in Periploca laevigata, a plant taxon with an island–mainland distribution area, to (i) investigate whether selection affects GD estimates of populations across contrasting habitats; and (ii) test the long-standing idea that island populations have lower GD than their mai…
Systematics of European coastal anchovies (genus Engraulis Cuvier).
2021
Reports of morphological differences between European anchovy (Engraulis cf. encrasicolus) from coastal and marine habitats have long existed in the ichthyologic literature, and have given rise to a long-standing debate on their taxonomic status. More recently, molecular studies have confirmed the existence of genetic differentiation between the two anchovy ecotypes. Using ancestry-informative markers, we show that coastal anchovies throughout the Mediterranean share a common ancestry, and that substantial genetic differentiation persists in different pairs of coastal/marine populations despite the presence of limited gene flow. On the basis of genetic and ecological arguments, we propose t…
Genética de la conservación: la aplicación de los conceptos de la evolución a la conservación de la diversidad biológica
2013
La comprensión de las fuerzas de cambio evolutivo que actúan sobre las poblaciones, en conjunción con las técnicas más modernas de análisis genético, lleva aplicándose en los últimos veinte años al servicio de la conservación de la biodiversidad. Esta nueva aplicación de la genética ha recibido el nombre de genética de la conservación.
2014
Captive breeding for conservation purposes presents a serious practical challenge because several conflicting genetic processes (i.e., inbreeding depression, random genetic drift and genetic adaptation to captivity) need to be managed in concert to maximize captive population persistence and reintroduction success probability. Because current genetic management is often only partly successful in achieving these goals, it has been suggested that management insights may be found in sexual selection theory (in particular, female mate choice). We review the theoretical and empirical literature and consider how female mate choice might influence captive breeding in the context of current genetic…
Selection on life-history traits and genetic population divergence in rotifers
2009
A combination of founder effects and local adaptation – the Monopolization hypothesis – has been proposed to reconcile the strong population differentiation of zooplankton dwelling in ponds and lakes and their high dispersal abilities. The role genetic drift plays in genetic differentiation of zooplankton is well documented, but the impact of natural selection has received less attention. Here, we compare differentiation in neutral genetic markers (FST) and in quantitative traits (QST) in six natural populations of the rotifer Brachionus plicatilis to assess the importance of natural selection in explaining genetic differentiation of life-history traits. Five life-history traits were measur…
Evolutionary processes in a continental island system: molecular phylogeography of the Aegean Nigella arvensis alliance (Ranunculaceae) inferred from…
2005
Continental shelf island systems, created by rising sea levels, provide a premier setting for studying the effects of past fragmentation, dispersal, and genetic drift on taxon diversification. We used phylogeographical (nested clade) and population genetic analyses to elucidate the relative roles of these processes in the evolutionary history of the Aegean Nigella arvensis alliance (= ‘coenospecies’). We surveyed chloroplast DNA (cpDNA) variation in 455 individuals from 47 populations (nine taxa) of the alliance throughout its core range in the Aegean Archipelago and surrounding mainland areas of Greece and Turkey. The study revealed the presence of three major lineages, with largely nonove…
The interplay between metabolome, epigenome and metabolic syndrome in severe obesity: the influence of sex and age
2022
Antecedentes: la obesidad en adultos se define como una acumulación anormal o excesiva de grasa que representa un importante factor de riesgo para la salud, contribuyendo a aumentar la morbilidad y la mortalidad. Aunque las condiciones de salud subyacentes y la genética podrían ser en algunos casos las principales causas de la obesidad, en la mayoría de los casos es el resultado de estilos de vida poco saludables a largo plazo. En su forma más severa clínicamente (obesidad de Clase III), el tejido adiposo se convierte en el órgano endocrino metabólico más grande que interactúa fuertemente con el sistema endocrino y contribuye al desarrollo del síndrome metabólico (MetS). El MetS es consider…