Connectivity among populations plays a crucial role in maintaining genetic variation at a local scale, especially in small populations affected strongly by genetic drift. The negative consequences of ...population disconnection on allelic richness and gene diversity (heterozygosity) are well recognized and empirically established. It is not well recognized, however, that a sudden drop in local effective population size induced by such disconnection produces a temporary disequilibrium in allelic frequency distributions that is akin to the genetic signature of a demographic bottleneck. To document this effect, we used individual-based simulations and empirical data on allelic richness and gene diversity in six pairs of isolated versus well-connected (core) populations of European tree frogs. In our simulations, population disconnection depressed allelic richness more than heterozygosity and thus resulted in a temporary excess in gene diversity relative to mutation drift equilibrium (i.e., signature of a genetic bottleneck). We observed a similar excess in gene diversity in isolated populations of tree frogs. Our results show that population disconnection can create a genetic bottleneck in the absence of demographic collapse. La conectividad entre poblaciones juega un papel crucial en el mantenimiento de la variación genética a escala local, especialmente en poblaciones pequeñas afectadas por la deriva gènica. Las consecuencias negativas de la desconexión de la población sobre la riqueza alélica y la diversidad genética (heterocigosidad) están bien reconocidas y establecidas empíricamente. Sin embargo, no está bien reconocido que una disminución repentina en el tamaño poblacional efectivo inducida por tal desconexión produce un desequilibrio temporal en las distribuciones de frecuencias alélicas que es comparable con la firma genética de un cuello de botella demográfico. Para documentar este efecto, utilizamos simulaciones basadas en individuos y datos empíricos de la riqueza alélica y diversidad genética en seis pares de poblaciones aisladas de Hyla arborea versus poblaciones bien conectadas (núcleo). En nuestras simulaciones, la desconexión poblacional deprimió la riqueza alélica más que la heterocigosidad y por lo tanto resultó en un exceso temporal de diversidad genética en relación con el equilibrio por deriva mutacional (i. e., firma de un cuello de botella genético). Observamos un exceso similar en la diversidad genética en poblaciones aisladas de H. arbórea. Nuestros resultados muestran que la desconexión de la población puede crear un cuello de botella genético en la ausencia de un colapso demográfico.
We investigated sex-specific recombination rates in Hyla arborea, a species with nascent sex chromosomes and male heterogamety. Twenty microsatellites were clustered into six linkage groups, all ...showing suppressed or very low recombination in males. Seven markers were sex linked, none of them showing any sign of recombination in males (r=0.00 versus 0.43 on average in females). This opposes classical models of sex chromosome evolution, which envision an initially small differential segment that progressively expands as structural changes accumulate on the Y chromosome. For autosomes, maps were more than 14 times longer in females than in males, which seems the highest ratio documented so far in vertebrates. These results support the pleiotropic model of Haldane and Huxley, according to which recombination is reduced in the heterogametic sex by general modifiers that affect recombination on the whole genome.
We developed 11 new microsatellite markers for the European tree frog (Hyla arborea), and tested patterns of polymorphism in 54 adults (27 males and 27 females) from two ponds close to Lausanne ...(Western Switzerland). One marker was sex linked and two pairs displayed linkage disequilibrium. Comparisons of allele numbers with heterozygosity values support a stepwise‐mutation model at neutral equilibrium, with mutation rates spanning nearly two orders of magnitude. These markers will prove useful for population genetic studies and fine‐scale investigations requiring genetic assignment techniques.
Provider: - Institution: - Data provided by Europeana Collections- Frogs singing. Background: Bufo bufo ? and other amphibia.- All metadata published by Europeana are available free of restriction ...under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Several tree frogs singing. Background: Natterjacks, dog.- All metadata published by Europeana are available free of restriction ...under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Several tree frogs singing. Background: Mosquitoes.- All metadata published by Europeana are available free of restriction under ...the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Several tree frogs singing.- All metadata published by Europeana are available free of restriction under the Creative Commons CC0 ...1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Behaviour: Single frog calling at times, then others join in.- All metadata published by Europeana are available free of restriction ...under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Frogs singing. Background: Other amphibia.- All metadata published by Europeana are available free of restriction under the ...Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
Provider: - Institution: - Data provided by Europeana Collections- Behaviour : Advertising calls from the water. Participants: ca. 5. More in background- All metadata published by Europeana are ...available free of restriction under the Creative Commons CC0 1.0 Universal Public Domain Dedication. However, Europeana requests that you actively acknowledge and give attribution to all metadata sources including Europeana
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