Peter Kovalik
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Acrocephalidae (1 Viewer)
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Peter Kovalik
Well-known member
Melanie
Well-known member
Cape Verde Warbler
Genetic diversity and divergence in the endangered Cape Verde warbler Acrocephalus brevipennis
Batalha, H.R., Wright, D.J., Barr, I. et al. Conserv Genet (2016). doi:10.1007/s10592-016-0909-3
Genetic factors play an important role in the long-term persistence of populations and species, and conservation strategies should take such factors into account. We use neutral molecular markers to assess diversity and divergence between the three remaining island populations of a little-studied endemic passerine, the Cape Verde warbler Acrocephalus brevipennis. Variation at both microsatellite loci and the cytochrome b gene reveal low diversity within the species overall, but considerable divergence among the populations on Santiago, Fogo and São Nicolau islands. The genetic markers show a gradient of genetic diversity with population size, with the smallest population of S. Nicolau being the least diverse, and the largest, Santiago, the most diverse. The more geographically isolated population on S. Nicolau is also more divergent from Santiago and Fogo than these two are from each other. The Cape Verde warbler diverged from its sister species, the greater swamp warbler Acrocephalus rufescens, within the last million years, and the three populations became isolated from one another 165,000–199,000 years ago. There is also evidence of population bottlenecks, especially on S. Nicolau. This population seems to have decreased during the last century, with potential for further decreases and even extinction. As the three populations are genetically distinct, with no evidence of gene flow between them, we argue they should be treated as separate management units for the successful conservation of this species.
http://link.springer.com/article/10.1007/s10592-016-0909-3
Genetic diversity and divergence in the endangered Cape Verde warbler Acrocephalus brevipennis
Batalha, H.R., Wright, D.J., Barr, I. et al. Conserv Genet (2016). doi:10.1007/s10592-016-0909-3
Genetic factors play an important role in the long-term persistence of populations and species, and conservation strategies should take such factors into account. We use neutral molecular markers to assess diversity and divergence between the three remaining island populations of a little-studied endemic passerine, the Cape Verde warbler Acrocephalus brevipennis. Variation at both microsatellite loci and the cytochrome b gene reveal low diversity within the species overall, but considerable divergence among the populations on Santiago, Fogo and São Nicolau islands. The genetic markers show a gradient of genetic diversity with population size, with the smallest population of S. Nicolau being the least diverse, and the largest, Santiago, the most diverse. The more geographically isolated population on S. Nicolau is also more divergent from Santiago and Fogo than these two are from each other. The Cape Verde warbler diverged from its sister species, the greater swamp warbler Acrocephalus rufescens, within the last million years, and the three populations became isolated from one another 165,000–199,000 years ago. There is also evidence of population bottlenecks, especially on S. Nicolau. This population seems to have decreased during the last century, with potential for further decreases and even extinction. As the three populations are genetically distinct, with no evidence of gene flow between them, we argue they should be treated as separate management units for the successful conservation of this species.
http://link.springer.com/article/10.1007/s10592-016-0909-3
Peter Kovalik
Well-known member
Alice Cibois, Jean-Claude Thibault, Nicholas R. Friedman, Kevin E. Omland, Laure Desutter-Grandcolas, Tony Robillard & Eric Pasquet (2019) Reed warblers in the Marquesas Islands: song divergence and plumage convergence of two distinct lineages, Emu - Austral Ornithology, DOI: 10.1080/01584197.2019.1597633
Abstract:
The Pacific Ocean is the site of the most important diversification of insular reed warblers (Acrocephalus). In the Marquesas Islands (Eastern Polynesia), reed warblers belong to two distinct lineages that have reached the archipelago independently. We used mitochondrial sequences and microsatellite markers and found evidence of gene flow between the two lineages. One island in particular, Nuku Hiva, seems to act as the main contact zone between the two taxa. We then used reflectance spectrometry to evaluate the variation of carotenoid colouration among all populations. Marquesan reed warblers exhibit convergent evolution in carotenoid-based plumage colouration, but variation among islands was important. Having two different phylogenetic origins, the two lineages acquired their yellow colour independently and there is stochastic variation in plumage among islands. Finally, we analysed the songs of reed warblers from the main islands. Multifactorial analysis showed that vocalisations of Marquesan reed warblers differ slightly between species, significant differences between islands leading to different dialects. Vocal characteristics may act as the main pre-zygotic barriers when birds from different lineages come into contact. This study provides another example of convergence in plumage evolution in insular bird species. Furthermore, it highlights the importance of integrative analyses, using both genetic and phenotypical characters, for the study of the evolutionary history of the Pacific Ocean avifauna.
Abstract:
The Pacific Ocean is the site of the most important diversification of insular reed warblers (Acrocephalus). In the Marquesas Islands (Eastern Polynesia), reed warblers belong to two distinct lineages that have reached the archipelago independently. We used mitochondrial sequences and microsatellite markers and found evidence of gene flow between the two lineages. One island in particular, Nuku Hiva, seems to act as the main contact zone between the two taxa. We then used reflectance spectrometry to evaluate the variation of carotenoid colouration among all populations. Marquesan reed warblers exhibit convergent evolution in carotenoid-based plumage colouration, but variation among islands was important. Having two different phylogenetic origins, the two lineages acquired their yellow colour independently and there is stochastic variation in plumage among islands. Finally, we analysed the songs of reed warblers from the main islands. Multifactorial analysis showed that vocalisations of Marquesan reed warblers differ slightly between species, significant differences between islands leading to different dialects. Vocal characteristics may act as the main pre-zygotic barriers when birds from different lineages come into contact. This study provides another example of convergence in plumage evolution in insular bird species. Furthermore, it highlights the importance of integrative analyses, using both genetic and phenotypical characters, for the study of the evolutionary history of the Pacific Ocean avifauna.
CaliSteve
Living life in Paradise!
Confirmation of Acrocephalus scirpaceus avicenniae (Aves: Acrocephalidae) from mangroves on the Red Sea coast near Jazan, southwest Saudi Arabia.
https://www.tandfonline.com/doi/full/10.1080/09397140.2019.1604470
Melanie
Well-known member
Kearns, Anna M. et al. (2022). Conservation genomics and systematics of a near-extinct island radiation. Molecular Ecology 31(7): 1995-2012. https://doi.org/10.1111/mec.16382
albertonykus
Well-known member
Kubacka, J., A. Dubiec, J. Korb, V. Salewski, A. Dyrcz, J. Foucher, B. Giessing, B. Leisler, K. Schulze-Hagen, M. Wink, and H. Panagiotopoulou (2023)
Low genetic diversity and high gene flow in the Aquatic Warbler Acrocephalus paludicola, a threatened marshland songbird with a fragmented breeding range
Ibis (advance online publication)
doi: 10.1111/ibi.13250
Breeding habitat loss and depletion of genetic diversity can have critically negative impacts on species, and especially so for habitat specialists. The Aquatic Warbler Acrocephalus paludicola is a threatened European songbird that breeds in fens, which have been lost and fragmented over centuries. We used microsatellite loci to perform a spatial and longitudinal comparison, comparing samples collected recently (contemporary) with those from about two decades earlier (historical) from c. 25% of the breeding range (Biebrza and Polesie) of the Aquatic Warbler. With these data we explored changes in genetic diversity, expansions and reductions of population size, population structure, and gene flow. Allelic richness, expected heterozygosity, the number of effective and private alleles, and effective population size (NE ≈ 200) were low and comparable across time and space. We detected a genetic bottleneck in contemporary Biebrza, and a less certain reduction in both historical and contemporary population size in Polesie. Across space, Biebrza and Polesie were not genetically differentiated in either period. All the historical samples clustered together, but in the contemporary samples a small part of Polesie clustered separately (FST 0.011). Across time, Biebrza and Polesie showed low but significant differentiation (FST 0.026-0.064), and historical and contemporary groups clustered apart. A PCoA on genetic distance detected three groups, which spanned sampling locations. In the temporal comparison, the contemporary group and contemporary Biebrza had elevated mean within-group pairwise relatedness. We did not recover signals for sex-biased dispersal, asymmetric gene flow, or isolation-by-distance using the molecular data. Our results suggest that the studied populations show: (1) impoverished genetic diversity; (2) a change in allele frequencies over the past two decades; and (3) high gene flow between distant breeding sites, implying a high resilience to habitat fragmentation that should facilitate the success of habitat restoration in increasing the numbers of Aquatic Warbler and the retention of genetic diversity.
Low genetic diversity and high gene flow in the Aquatic Warbler Acrocephalus paludicola, a threatened marshland songbird with a fragmented breeding range
Ibis (advance online publication)
doi: 10.1111/ibi.13250
Breeding habitat loss and depletion of genetic diversity can have critically negative impacts on species, and especially so for habitat specialists. The Aquatic Warbler Acrocephalus paludicola is a threatened European songbird that breeds in fens, which have been lost and fragmented over centuries. We used microsatellite loci to perform a spatial and longitudinal comparison, comparing samples collected recently (contemporary) with those from about two decades earlier (historical) from c. 25% of the breeding range (Biebrza and Polesie) of the Aquatic Warbler. With these data we explored changes in genetic diversity, expansions and reductions of population size, population structure, and gene flow. Allelic richness, expected heterozygosity, the number of effective and private alleles, and effective population size (NE ≈ 200) were low and comparable across time and space. We detected a genetic bottleneck in contemporary Biebrza, and a less certain reduction in both historical and contemporary population size in Polesie. Across space, Biebrza and Polesie were not genetically differentiated in either period. All the historical samples clustered together, but in the contemporary samples a small part of Polesie clustered separately (FST 0.011). Across time, Biebrza and Polesie showed low but significant differentiation (FST 0.026-0.064), and historical and contemporary groups clustered apart. A PCoA on genetic distance detected three groups, which spanned sampling locations. In the temporal comparison, the contemporary group and contemporary Biebrza had elevated mean within-group pairwise relatedness. We did not recover signals for sex-biased dispersal, asymmetric gene flow, or isolation-by-distance using the molecular data. Our results suggest that the studied populations show: (1) impoverished genetic diversity; (2) a change in allele frequencies over the past two decades; and (3) high gene flow between distant breeding sites, implying a high resilience to habitat fragmentation that should facilitate the success of habitat restoration in increasing the numbers of Aquatic Warbler and the retention of genetic diversity.
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