Search results for "DISPERSAL"
showing 10 items of 465 documents
Distortion of symmetrical introgression in a hybrid zone: evidence for locus-specific selection and uni-directional range expansion
2006
The fate of species integrity upon natural hybridization depends on the interaction between selection and dispersal. The relative significance of these processes may be studied in the initial phase of contact before selection and gene flow reach equilibrium. Here we study a hybrid zone of two salamander species, Lyciasalamandra antalyana and Lyciasalamandra billae, at the initial phase of hybridization. We quantify the degree and mode of introgression using nuclear and mtDNA markers. The hybrid zone can be characterized as an abrupt transition zone, the central hybrid zone being only c. 400 m, but introgressed genes were traced up to 3 km. Introgression was traced in both sexes but gene flo…
On the verge of extinction: genetics of the critically endangered Iberian plant species, Borderea chouardii (Dioscoreaceae) and implications for cons…
2005
Borderea chouardii is a relictual and dioecious, strictly sexually reproducing, long-living geophyte of the Dioscoreaceae family. Previous biological and demographic studies have indicated the existence of a uniformly distributed panmictic population of this taxon at the southernmost Spanish pre-Pyrenean mountain ranges where it occurs in rather inaccessible crevices of a single limestone cliff. However, individuals of B. chouardii are spatially subdivided into two subpopulations located, respectively, on the upper and lower parts of the cliff, and vertically separated 150 m. Because of its extreme rarity, B. chouardii was the first Iberian taxon to have a specific conservation plan and has…
The Genus Homo: Origin, Speciation and Dispersal
2011
The taxonomical interpretation of the fossil record of our own genus Homo is still highly controversial. In spite of obvious major advances concerning the acquisition, analysis and interpretation of the fossil specimens there currently remain unbridgeable disagreements concerning the origin, speciation and dispersal of our genus. The polarized positions result foremost from different methodological approaches for species recognition (e.g., Tattersall 1986; Wolpoff and Caspari 1997; Schwartz 2000a; Wiesemuller et al. 2003; Jobling et al. 2004; Rothe and Henke 2006). Beside the Multiregional Evolutionary Model (MRE) there are different Recent African Origin Models (RAOMs) with varying numbers…
Palaeozoogeographical connections of the Devonian vertebrate communities of the Baltica Province. Part II. Late Devonian
2010
Abstract Late Devonian vertebrate communities within the Baltica zoogeographical Province are analysed for intra- and interprovincial connections. Components within the category of provincial endemics are used to assign the communities to a particular zoogeographical province. Marine and continental, presumably freshwater types of vertebrate dispersal are outlined. During the Late Devonian marine dispersal is displayed by ptyctodonts, struniiforms, and some dipnoans, and continental dispersal by psammosteids, acanthodians, and some arthrodires. Isolation of communities is reflected by predominance of local and provincial endemics; the majority of polydemics and cosmopolitans records wider c…
Distribution and abundance patterns of a newly colonizing species in Tunisian oases: the Common Blackbird Turdus merula
2003
We investigated distribution and abundance patterns of a recently arrived species in the oases of southern Tunisia: the Common Blackbird Turdus merula. In this system, we expected that the vegetation structure and geographical locations of oases would have played an important part in shaping the patterns of oasis occupancy and local abundance. Using data collected at 53 oases during two breeding seasons, we found that Blackbird occurrence in a given oasis depended mainly on its presence at neighbouring oases. However, vegetation structure did not prove to be a relevant predictor of Blackbird occurrence. Within occupied oases, local abundance was associated with vegetation structure, namely …
Downy-oak woods of Italy: phytogeographical remarks on a controversial taxonomic and ecologic issue
2014
The importance of downy oak as an integral component of the "submediterranean" woods has been underscored by many studies. Nevertheless, terms like "submediterranean" and "downy oak" are some of the most poorly understood concepts in European phytogeographic and taxonomic research. Downy oak is well known to be a problematic taxon. The name "Quercus pubescens" (= Q. humilis) combines populations characterized by increasing phenotypic and genomic polymorphisms along north-south gradients, which is explained as the result of a "founder effect" produced by a relatively fast post-glacial re-colonization of the northern areas through rare long-distance dispersal events. On the other hand, polymo…
Towards a more mechanistic understanding of traits and range sizes
2012
Aim An important, unresolved question in macroecology is to understand the immense inter-specific variation in geographic range sizes. While species traits such as fecundity or body size are thought to affect range sizes, a general understanding on how multiple traits jointly influence them is missing. Here, we test the influence of a multitude of species traits on global range sizes of European passerine birds in order to better understand possible mechanisms behind macroecological relationships. Location Global. Methods We evaluated the effect of life-history traits (fecundity, dispersal ability), ecological traits (habitat niche, diet niche, migratory behaviour, migratory flexibility) an…
Offspring microbiomes differ across breeding sites in a panmictic species.
2019
High dispersal rates are known to homogenize host’s population genetic structure in panmictic species and to disrupt host local adaptation to the environment. Long-distance dispersal might also spread micro-organisms across large geographical areas. However, so far, to which extent selection mechanisms that shape host’s population genetics are mirrored in the population structure of the enteric microbiome remains unclear. High dispersal rates and horizontal parental transfer may homogenize bacterial communities between breeding sites (homogeneous hypothesis). Alternatively, strong selection from the local environment may differentiate bacterial communities between breeding sites (heterogene…
Rice fields as facilitators of freshwater invasions in protected wetlands: the case of Ostracoda (Crustacea) in the Albufera Natural Park (E Spain)
2014
Background: Previous studies have identified rice fields in the Mediterranean region as ‘hot spots’ for the introduction of alien freshwater organisms. Consequently, special attention should be paid when rice fields are located inside or near protected areas for the conservation of native, endangered species. To analyse the relationship between rice field environmental traits and the ecology of aquatic invaders, a study of zoobenthic communities was carried out in JulySeptember 2008 and May-August 2009 in ten rice fields located in the Albufera Natural Park (E Spain), with focus on Ostracoda. Results: A total of nine ostracod species were found including four considered exotic: Candonocypri…
The joint evolution of learning and dispersal maintains intraspecific diversity in metapopulations
2021
The evolution of dispersal tendencies and of cognitive abilities have both been intensely studied. Yet little attention has been given to the question of how these two aspects may relate to each other, as a result of their joint evolution. On the one hand, learning abilities may help dispersers to cope with their new habitat. On the other hand, dispersal may sometimes reduce the need for learning, because local environments may differ in how much there is to learn. To get a better understanding of this relationship, we built an individual‐based simulation in which both learning speed and dispersal tendency were free to evolve. We found that both positive and negative correlations could evol…