Search results for "Sympatry"
showing 6 items of 56 documents
Morphological variation and the recent evolution of wing length in the icterine Warbler: A case of unidirectional introgression?
1999
Icterine Warbler Hippolais icterina and Melodious Warbler H. polyglotta are closely related species with parapatric breeding ranges. Their breeding ranges overlap only in a narrow zone in western Europe, where the Icterine Warbler population is presently declining and the Melodious Warbler population expanding. In eastern Burgundy (France), both species have bred in sympatry for at least forty years, but the Icterine Warbler started to decline in the mid-seventies. The two species differ in wing length and wing formula. Morphological variations of the wing were compared for the Icterine Warbler population in eastern Burgundy between 1965/76 and 1985/96. In the second period, wing length and…
Review paper: Ecological genetics of Brachionus sympatric sibling species
1998
In this paper we review previous studies on sympatric Brachionus populations in Torreblanca Marsh as a model of evolutionary and ecological relationships between closely related species. The marsh is a wetland on the Mediterranean coast of Spain with high spatial and temporal heterogeneity. Allozyme and morphometric analysis showed that Brachionus group plicatilis (formerly, Brachionus plicatilis and currently split into B. plicatilis and B. rotundiformis) was composed of three groups of genotypes with no evidence of gene flow between them (B. plicatilis, B. rotundiformis SM and B. rotundiformis SS). Correlations between seasonal and spatial distributions, on one hand, and temperature and s…
Crossed induction of sex in sympatric congeneric rotifer populations
2009
The transition from asexual to sexual reproduction in rotifers of the genus Brachionus (Monogononta) is triggered by a chemical signal produced and released by the rotifers themselves; the signal accumulates in the environment as population density increases. The response to this signal has been hypothesized to be speciesspecific. If not, the timing of sex and final diapausing egg production of a species might not be optimized. In this study, a set of experiments—based on individual and mass culture approaches—was carried out to investigate the differentiation in sex induction signals between sympatric and allopatric congeneric Brachionus populations by analyzing the capability of the mediu…
Molecular inference of a Late Pleistocene diversification shift inNigellas. lat. (Ranunculaceae) resulting from increased speciation in the Aegean ar…
2009
Aim To infer the temporal course and geographical mode of speciation in Mediterranean/Southwest Asian Nigella s. lat. Location Mediterranean Basin, Aegean archipelago. Methods Phylogenies for Nigella L. and Garidella L. (= Nigella s. lat.) were obtained from maximum-likelihood analyses of internal transcribed spacer (ITS) sequences. Diversification through time was analysed by log lineages-through-time (LTT) plots and survival analyses. Relative node age estimates were regressed against the degree of sympatry between sister clades to infer the predominant mode of geographical speciation in Nigella s. lat. Results The Late Pleistocene radiation of the Nigella arvensis complex in the Aegean r…
Speciation via Differential Host–Plant Use in the Tephritid Fly Tephritis conura
2010
The close association between phytophagous insects and host plants and the possibility for specialization on new plants make phytophagous insects prime candidates for sympatric speciation via host-race evolution. In this chapter, we summarize results addressing host-race evolution in the tephritid fly Tephritis conura (Tephritidae) infesting Cirsium heterophyllum and C. oleraceum (Asteraceae). Host plant distributions in allopatry, sympatry and parapatry, and different infestation patterns enabled us to test geographic speciation scenarios, investigate adaptations, and address the importance of plant population history for diversification of T. conura.
Strength of sexual and postmating prezygotic barriers varies between sympatric populations with different histories and species abundances
2019
The impact of different reproductive barriers on species or population isolation may vary in different stages of speciation depending on evolutionary forces acting within species and through species’ interactions. Genetic incompatibilities between interacting species are expected to reinforce prezygotic barriers in sympatric populations and lead to cascade reinforcement between conspecific populations living within and outside the areas of sympatry. We tested these predictions and studied whether and how the strength and target of reinforcement between Drosophila montana and Drosophila flavomontana vary between sympatric populations with different histories and species abundances. All barri…