Search results for "hybrid zone"
showing 7 items of 17 documents
The fire salamander, Salamandra salamandra L., in central Europe: subspecies distribution and intergradation
1992
AbstractAllozyme electrophoresis of 14 loci provided information on the distribution of the two central European subspecies of the fire salamander, Salamandra salamandra salamandra (dotted taxon) and S.s.terrestris (striped taxon), along an east-west-transect in Germany. 2183 larvae from 48 populations situated in 14 mountain ranges were studies. A broad (about 140 km wide) zone of intergradition between the two forms is described, ranging from the Hunsrück Mountains in the west to the Spessart in the east. Within this hybrid zone the populations are panmictic. Focussing on the Rhenish Slate Mountains, the western border of the hybrid zone is described in detail. A comparison between allozy…
Characterizing a hybrid zone between a cryptic species pair of freshwater snails.
2015
Characterizing hybrid zones and their dynamics is a central goal in evolutionary biology, but this is particularly challenging for morphologically cryptic species. The lack of conspicuous divergence between parental types means intermediate hybrid forms often go undetected. We aimed to detect and characterize a suspected hybrid zone between a pair of morphologically cryptic lineages of the freshwater snail, Radix. We sampled Radix from across a contact zone between two mitochondrial lineages (Radix balthica and an undescribed lineage termed 'MOTU3') and detected admixture between two nuclear genotype clusters, which were significantly but not categorically associated with the mitochondrial …
Pre- and post-mating reproductive barriers drive divergence of five sympatric species of Naryciinae moths (Lepidoptera: Psychidae)
2014
The biological species concept suggests that species can be separated on the basis of reproductive isolation. However, because natural interbreeding capabilities are often unknown, differences in morphology are generally used to separate species. Alternatively, genetic dissimilarity is used to separate morphologically similar species. Many genetic markers, including the maternally inherited mitochondrial cytochrome oxidase I sequence, cannot show interbreeding and therefore species status of groups may remain unresolved. In species of the genera Dahlica and Siederia (Lepidoptera: Psychidae: Naryciinae) the lack of morphological distinction and unknown interbreeding has led to unclear and un…
Species-specific song convergence in a moving hybrid zone between two passerines
2003
Moving hybrid zones are receiving increasing attention. However, so far little is known about the proximate mechanisms underlying these movements. Signalling behaviour, by individuals engaged in interspecific sexual and aggressive interactions, may play a crucial role. In this study, we investigated song variation within a moving hybrid zone between two warblers, Hippolais polyglotta and H. icterina. In these species, song is involved in interspecific territoriality and, probably, in mixed pairings. We showed that allopatric populations of the two species are clearly acoustically differentiated. However, interspecific differences faded out in sympatry as a result of an overall pattern of co…
Maintenance of male reaction to the congeneric song in the Hippolais warbler hybrid zone
1999
Both hybridization and competition may induce character shift on communication systems in hybrid zones, leading either to convergence or divergence. Melodious warblers Hippolais polyglotta and Icterine warblers H. icterina are interspecifically territorial and hybridize along a narrow contact zone. This spatial distribution is favoured by a reaction to the congeneric song. A character displacement, e.g. a decrease of the reaction, was expected within the hybrid zone because of reproduction costs lower than in allopatry. We investigated the pattern of variation of the interspecific reaction by comparing allopatric and sympatric populations. However, our data did not support the hypothesis ch…
Who threatens who? Natural hybridization between Lotus dorycnium and the island endemic Lotus fulgurans (Fabaceae)
2010
In contrast to its creative role in plant evolution, hybridization may be a cause for concern in efforts to preserve rare and endangered species. Threats can be more acute when population sizes are unequal and when barriers to introgression are weak. Lotus fulgurans is an endangered Balearic Islands endemic shrub related to the widespread Mediterranean species Lotus dorycnium. Both species are morphologically distinct when they grow together. However, morphologically intermediate individuals have been observed on the island of Minorca, in a single, narrowly localized, and apparently stable hybrid zone. Morphological and molecular markers suggest that gene flow between these two Lotus specie…