Search results for "Gene Flow"
showing 10 items of 177 documents
Genetic population structure of Epinephelus marginatus (Pisces, Serranidae) revealed by two molecular markers
2006
In this paper, data are presented regarding the population structure of dusky grouper (Epinephelus marginatus) which was sampled in the Mediterranean Sea and Atlantic Ocean using two different molecular markers, ND2 RFLP and cytochrome b (cyt b) sequence analysis. The main objective of the study is to analyse the genetic variability of E. marginatus in the Mediterranean Sea to define how the biological characteristics of the species, such as the dispersal capability of pelagic larvae and the benthonic-sedentary life style, can affect the genetic population structure or maintaining the gene flow or determining genetic differences. Furthermore, we considered an Atlantic sample to establish th…
How do freshwater organisms cross the “dry ocean”? A review on passive dispersal and colonization processes with a special focus on temporary ponds
2014
Lakes and ponds are scattered on Earth’s surface as islands in the ocean. The organisms inhabiting these ecosystems have thus developed strategies to pass the barrier represented by the surrounding land, to disperse and to colonize new environments. The evidences of a high potential for passive long-range dispersal of organisms producing resting stages inspired the idea that there were no real barriers to their actual dispersal, and that their distribution was only limited by the ecological characteristics of the available habitats. The development of genetic techniques allowed to criticize this view and revealed the existence of a more complex and diverse biological scenario governed by an…
Genetic structure in the Mediterranean seagrass Posidonia oceanica: disentangling past vicariance events from contemporary patterns of gene flow
2010
The Mediterranean Sea is a two-basin system, with the boundary zone restricted to the Strait of Sicily and the narrow Strait of Messina. Two main population groups are recognized in the Mediterranean endemic seagrass Posidonia oceanica, corresponding to the Western and the Eastern basins. To address the nature of the East-West cleavage in P. oceanica, the main aims of this study were: (i) to define the genetic structure within the potential contact zone (i.e. the Strait of Sicily) and clarify the extent of gene flow between the two population groups, and (ii) to investigate the role of present water circulation patterns vs. past evolutionary events on the observed genetic pattern. To achiev…
On the taxonomy of three sympatric sibling species of the Brachionus plicatilis (Rotifera) complex from Spain, with the description of B. ibericus n.…
2001
The accumulation of evidence during the last decade led to the splitting of the Brachionus plicatilis complex (Rotifera) into two morphologically recognizable species: B. plicatilis Muller and B. rotundiformis Tschugunoff, previously referred to as L- and S-type B. plicatilis (s.l.), respectively. However, recent population genetics and molecular studies have revealed that each of these taxa concern cryptic species complexes. In particular, in Torreblanca Marsh, a wetland on the Mediterranean coast of Spain, three genetically distinct groups in this rotifer complex have been shown to co-occur. Differences in genetic markers, ecological preferences, mixis responses, mating behaviour and no e…
Genetic evidence for divergent selection onOenanthe conioidesandOe. aquatica(Apiaceae), a candidate case for sympatric speciation
2014
The opportunity for habitat shift in sympatry is thought to be an important factor in sympatric speciation by facilitating assortative mating and offering opportunities for divergent selection. Oenanthe conioides (Apiaceae) is a narrow endemic from the lower Elbe river area (Germany) where it is restricted to areas experiencing fresh water tides inundating the plants twice a day. The species was shown to have originated from Oe. aquatica which is widely distributed in Europe and grows in still or slowly flowing fresh water. Reciprocal transplant experiments have previously shown that in both habitats the non-native species is less fit than the native, and several phenotypic traits have been…
What do we need to know about speciation?
2011
Speciation has been a major focus of evolutionary biology research in recent years, with many important advances. However, some of the traditional organising principles of the subject area no longer provide a satisfactory framework, such as the classification of speciation mechanisms by geographical context into allopatric, parapatric and sympatry classes. Therefore, we have asked where speciation research should be directed in the coming years. Here, we present a distillation of questions about the mechanisms of speciation, the genetic basis of speciation and the relationship between speciation and diversity. Our list of topics is not exhaustive; rather we aim to promote discussion on rese…
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…
Molecular and morphological patterns of introgression between two large white-headed gull species in a zone of recent secondary contact.
2007
Incomplete reproductive isolation promotes gene flow between diverging taxa. However, any gene encoding for traits involved in the reproductive barriers will be less prone to introgression than neutral markers. Comparing introgression rates among loci is thus informative of the number and functions of loci involved in the reproductive barriers. This study aimed at identifying possible mechanisms of restriction to gene flow across a zone of recent secondary contact between Larus argentatus and Larus cachinnans by comparing introgression patterns for nine microsatellite loci, a fragment of mitochondrial DNA and a set of phenotypic traits. The low linkage disequilibrium between neutral nuclear…
Expanding genetic graphs' potential to analyse ecological connectivity: assessment of graphs construction methods
2019
International audience; Dispersal movements are often constrained in human-shaped landscapes, thereby threatening species survival. Landscape genetics approaches are commonly used to analyse ecological connectivity because genetic data well reflect dispersal capacities. When species occupy discrete habitat patches, graph-theoretic methods are a particularly relevant approach to study dispersal-driven gene flow. The links of a genetic graph can be weighted using different genetic distances between populations (nodes). Similarly, graph pruning (link set selection) can rely on different criteria. However, despite growing interest in genetic graphs, the influence of these parameters remains mos…
Gene flow from oilseed rape to weedy species
2003
The assessment of the likelihood of transgene spread from cultivated species to their wild relatives is relevant for oilseed rape (Brassica napus, AACC, 2n=38) as it is partially allogamous and pre...