Search results for "Rift"

Regional coherency of boreal forest growth defines Arctic driftwood provenancing

2016

Arctic driftwood represents a unique proxy archive at the interface of marine and terrestrial environments. Combined wood anatomical and dendrochronological analyses have been used to detect the origin of driftwood and may allow past timber floating activities, as well as past sea ice and ocean current dynamics to be reconstructed. However, the success of driftwood provenancing studies depends on the length, number, and quality of circumpolar boreal reference chronologies. Here, we introduce a Eurasian-wide high-latitude network of 286 ring width chronologies from the International Tree Ring Data Bank (ITRDB) and 160 additional sites comprising the three main boreal conifers Pinus, Larix, a…

Spatio-temporal dynamics of genetic variation in the Iberian lynx along its path to extinction reconstructed with ancient DNA

2017

here is the tendency to assume that endangered species have been both genetically and demographically healthier in the past, so that any genetic erosion observed today was caused by their recent decline. The Iberian lynx (Lynx pardinus) suffered a dramatic and continuous decline during the 20th century, and now shows extremely low genome- and species-wide genetic diversity among other signs of genomic erosion. We analyze ancient (N = 10), historical (N = 245), and contemporary (N = 172) samples with microsatellite and mitogenome data to reconstruct the species' demography and investigate patterns of genetic variation across space and time. Iberian lynx populations transitioned from low but …

Demographic history has shaped the strongly differentiated corkwing wrasse populations in Northern Europe

2019

Understanding the biological processes involved in genetic differentiation and divergence between populations within species is a pivotal aim in evolutionary biology. One particular phenomenon that requires clarification is the maintenance of genetic barriers despite the high potential for gene flow in the marine environment. Such patterns have been attributed to limited dispersal or local adaptation, and to a lesser extent to the demographic history of the species. The corkwing wrasse (Symphodus melops) is an example of a marine fish species where regions of particular strong divergence are observed. One such genetic break occurred at a surprisingly small spatial scale (FST ~0.1), over a s…

Effects of the temporal scale of observation on the analysis of aquatic invertebrate metacommunities

2020

The development of metacommunity theory has boosted the implementation of numerous empirical tests with field data, mostly focused on the role of spatial and environmental gradients on metacommunity organization. These studies showed an important dependence of the results on the observational scale considered, i.e., spatial grain, sampling spacing, and extent. However, few works deal with time per se as a component explaining metacommunity structure, even when data from periodic sampling are available. We suggest adding time explicitly to metacommunity analysis, but taking into account that the temporal scale of observation could affect the estimation of the relative influence of environmen…

Disentangling structural genomic and behavioural barriers in a sea of connectivity

2019

18 pages, 4 tables, 3 figures.-- This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited

2016

AbstractPRDM9 is currently the sole speciation gene found in vertebrates causing hybrid sterility probably due to incompatible alleles. Its role in defining the double strand break loci during the meiotic prophase I is crucial for proper chromosome segregation. Therefore, the rapid turnover of the loci determining zinc finger array seems to be causative for incompatibilities. We here investigated the zinc finger domain-containing exon of PRDM9 in 23 tarsiers. Tarsiers, the most basal extant haplorhine primates, exhibit two frameshifting indels at the 5′-end of the array. The first mutation event interrupts the reading frame and function while the second compensates both. The fixation of thi…

POSTMATING ISOLATION ANALYSIS IN FOUNDER-FLUSH EXPERIMENTAL POPULATIONS OF DROSOPHILA PSEUDOOBSCURA.

1996

In this paper, we report a detailed analysis intended to detect postmating barriers in experimental populations of Drosophila pseudoobscura obtained through nine founderflush cycles. The number of offspring produced was determined in three consecutive generations of hybridization. It is found that the evolution of premating barriers, as shown by two of these populations, is not necessarily accompanied by the evolution of postmating ones. Under the founder-flush model of speciation proposed by Carson (1971), the first step in the speciation process is usually thought to be an incidental genetic change through founder effect affecting mating behavior so that sexual premating isolation evolves…

Diminishing returns of inoculum size on the rate of a plant RNA virus evolution

2017

[EN] Understanding how genetic drift, mutation and selection interplay in determining the evolutionary fate of populations is one of the central themes of Evolutionary Biology. Theory predicts that by increasing the number of coexisting beneficial alleles in a population beyond some point does not necessarily translates into an acceleration in the rate of evolution. This diminishing-returns effect of beneficial genetic variability in microbial asexual populations is known as clonal interference. Clonal interference has been shown to operate in experimental populations of animal RNA viruses replicating in cell cultures. Here we carried out experiments to test whether a similar diminishing-re…

Molecular phylogeography ofThymus herba-barona(Lamiaceae): Insight into the evolutionary history of the flora of the western Mediterranean islands

2011

Thymus herba-barona is endemic to Majorca, Corsica, and Sardinia. In order to gain insight into its evolutionary history, we examined the genetic diversity and phylogeography of the species using sequences of the trnT-trnL intergenic spacer from 106 individuals belonging to 15 populations. We detected high within-species genetic diversity and strong among- population differentiation, but no evidence for phylogeographic structure. A haplotype network supported the occurrence of three main clades, the ancestral one being geographically restricted to the Gennargentu massif in Sardinia, while the two derived ones were relatively widespread. Coalescent-based analyses indicated deep divergence ti…

FOUNDER-FLUSH SPECIATION IN DROSOPHILA PSEUDOOBSCURA: A LARGE-SCALE EXPERIMENT.

1993

A founder-flush-crash model of speciation has been proposed that may particularly apply to island and other colonizations. Previous laboratory experiments testing the model have given inconsistent results. We have conducted a large experiment with Drosophila pseudoobscura designed to meet the essential postulates of the model and to separately test some of the postulates. Forty-five experimental and 12 control populations have been studied during seven successive founder-flush-crash cycles, or about 50 generations. Sexual isolation tests yield significantly positive assortative mating in a few tests between pairs of experimental populations. Populations with fewer founders (N = 1 or 3) yiel…