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Phylogenetic relationships in Pterodroma petrels are obscured by recent secondary contact and hybridization.

Brown RM, Jordan WC, Faulkes CG, Jones CG, Bugoni L, Tatayah V, Palma RL, Nichols RA - PLoS ONE (2011)

Bottom Line: The classification of petrels (Pterodroma spp.) from Round Island, near Mauritius in the Indian Ocean, has confounded researchers since their discovery in 1948.The breakdown of species boundaries in Round Island petrels followed environmental change (deforestation and changes in species composition due to hunting) within their overlapping ranges.Such multi-species interactions have implications not only for conservation, but also for our understanding of the processes of evolutionary diversification and speciation.

View Article: PubMed Central - PubMed

Affiliation: Institute of Zoology, Zoological Society of London, London, United Kingdom. rthbwn@bas.ac.uk

ABSTRACT
The classification of petrels (Pterodroma spp.) from Round Island, near Mauritius in the Indian Ocean, has confounded researchers since their discovery in 1948. In this study we investigate the relationships between Round Island petrels and their closest relatives using evidence from mitochondrial DNA sequence data and ectoparasites. Far from providing clear delimitation of species boundaries, our results reveal that hybridization among species on Round Island has led to genetic leakage between populations from different ocean basins. The most common species on the island, Pterodroma arminjoniana, appears to be hybridizing with two rarer species (P. heraldica and P. neglecta), subverting the reproductive isolation of all three and allowing gene flow. P. heraldica and P. neglecta breed sympatrically in the Pacific Ocean, where P. arminjoniana is absent, but no record of hybridization between these two exists and they remain phenotypically distinct. The breakdown of species boundaries in Round Island petrels followed environmental change (deforestation and changes in species composition due to hunting) within their overlapping ranges. Such multi-species interactions have implications not only for conservation, but also for our understanding of the processes of evolutionary diversification and speciation.

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Bayesian phylogenetic tree based on cyt-b                            haplotypes.Four distinct phylogroups (red, blue, green, purple) are visible.                            Posterior probability support values are shown above branches. Average                            sequence divergence between phylogroups ranges from 0.70% to                            1.35%. A1–A6, B1–B8 and C1 sequenced during this                            study; BRA–BRI from [5]; BT from [7].                            Columns show distribution of haplotypes between species/populations                                (▴ = P. arminjoniana (or                            dark-shafted birds), ▪ = P.                                neglecta (or white-shafted birds)                                • = P. heraldica,                                ★ = P. atrata,                            ♦ = intermediate). Frequency of each                            haplotype is also shown.
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pone-0020350-g002: Bayesian phylogenetic tree based on cyt-b haplotypes.Four distinct phylogroups (red, blue, green, purple) are visible. Posterior probability support values are shown above branches. Average sequence divergence between phylogroups ranges from 0.70% to 1.35%. A1–A6, B1–B8 and C1 sequenced during this study; BRA–BRI from [5]; BT from [7]. Columns show distribution of haplotypes between species/populations (▴ = P. arminjoniana (or dark-shafted birds), ▪ = P. neglecta (or white-shafted birds) • = P. heraldica, ★ = P. atrata, ♦ = intermediate). Frequency of each haplotype is also shown.

Mentions: Twenty-three unique haplotypes were identified within the data set (Table 1). Haplotypes sequenced during this study were named A1–A6, B1–B8 and C1. The P. neglecta haplotype downloaded from Genbank was identical to haplotype B4 sequenced during this study. Haplotypes from [5] and [7] were named A–I and T following the original publications. Two of the short haplotype fragments published by [7] were identical to the corresponding section of two longer haplotypes sequenced during this study. These matching long and short haplotypes were therefore considered to be identical. A mitochondrial DNA-based phylogenetic tree for the Round Island birds, together with data from petrels originating from the historical ranges of P. arminjoniana, P. neglecta and P. heraldica, revealed four distinct phylogroups within the data set (Fig. 2). The phylogeny provides evidence of a genetic contribution from three species (P. arminjoniana, P. neglecta and P. heraldica) into the Round Island population. Atlantic P. arminjoniana haplotypes (blue phylogroup) are shared with dark-shafted and intermediate birds from Round Island. Pacific P. neglecta haplotypes (red phylogroup) are shared with dark-shafted, intermediate and white-shafted Round Island birds. Similarly, one Pacific P. heraldica haplotype (purple phylogroup) is shared with haplotypes from dark-shafted and white-shafted birds, and the P. heraldica sampled on Round Island.


Phylogenetic relationships in Pterodroma petrels are obscured by recent secondary contact and hybridization.

Brown RM, Jordan WC, Faulkes CG, Jones CG, Bugoni L, Tatayah V, Palma RL, Nichols RA - PLoS ONE (2011)

Bayesian phylogenetic tree based on cyt-b                            haplotypes.Four distinct phylogroups (red, blue, green, purple) are visible.                            Posterior probability support values are shown above branches. Average                            sequence divergence between phylogroups ranges from 0.70% to                            1.35%. A1–A6, B1–B8 and C1 sequenced during this                            study; BRA–BRI from [5]; BT from [7].                            Columns show distribution of haplotypes between species/populations                                (▴ = P. arminjoniana (or                            dark-shafted birds), ▪ = P.                                neglecta (or white-shafted birds)                                • = P. heraldica,                                ★ = P. atrata,                            ♦ = intermediate). Frequency of each                            haplotype is also shown.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3105042&req=5

pone-0020350-g002: Bayesian phylogenetic tree based on cyt-b haplotypes.Four distinct phylogroups (red, blue, green, purple) are visible. Posterior probability support values are shown above branches. Average sequence divergence between phylogroups ranges from 0.70% to 1.35%. A1–A6, B1–B8 and C1 sequenced during this study; BRA–BRI from [5]; BT from [7]. Columns show distribution of haplotypes between species/populations (▴ = P. arminjoniana (or dark-shafted birds), ▪ = P. neglecta (or white-shafted birds) • = P. heraldica, ★ = P. atrata, ♦ = intermediate). Frequency of each haplotype is also shown.
Mentions: Twenty-three unique haplotypes were identified within the data set (Table 1). Haplotypes sequenced during this study were named A1–A6, B1–B8 and C1. The P. neglecta haplotype downloaded from Genbank was identical to haplotype B4 sequenced during this study. Haplotypes from [5] and [7] were named A–I and T following the original publications. Two of the short haplotype fragments published by [7] were identical to the corresponding section of two longer haplotypes sequenced during this study. These matching long and short haplotypes were therefore considered to be identical. A mitochondrial DNA-based phylogenetic tree for the Round Island birds, together with data from petrels originating from the historical ranges of P. arminjoniana, P. neglecta and P. heraldica, revealed four distinct phylogroups within the data set (Fig. 2). The phylogeny provides evidence of a genetic contribution from three species (P. arminjoniana, P. neglecta and P. heraldica) into the Round Island population. Atlantic P. arminjoniana haplotypes (blue phylogroup) are shared with dark-shafted and intermediate birds from Round Island. Pacific P. neglecta haplotypes (red phylogroup) are shared with dark-shafted, intermediate and white-shafted Round Island birds. Similarly, one Pacific P. heraldica haplotype (purple phylogroup) is shared with haplotypes from dark-shafted and white-shafted birds, and the P. heraldica sampled on Round Island.

Bottom Line: The classification of petrels (Pterodroma spp.) from Round Island, near Mauritius in the Indian Ocean, has confounded researchers since their discovery in 1948.The breakdown of species boundaries in Round Island petrels followed environmental change (deforestation and changes in species composition due to hunting) within their overlapping ranges.Such multi-species interactions have implications not only for conservation, but also for our understanding of the processes of evolutionary diversification and speciation.

View Article: PubMed Central - PubMed

Affiliation: Institute of Zoology, Zoological Society of London, London, United Kingdom. rthbwn@bas.ac.uk

ABSTRACT
The classification of petrels (Pterodroma spp.) from Round Island, near Mauritius in the Indian Ocean, has confounded researchers since their discovery in 1948. In this study we investigate the relationships between Round Island petrels and their closest relatives using evidence from mitochondrial DNA sequence data and ectoparasites. Far from providing clear delimitation of species boundaries, our results reveal that hybridization among species on Round Island has led to genetic leakage between populations from different ocean basins. The most common species on the island, Pterodroma arminjoniana, appears to be hybridizing with two rarer species (P. heraldica and P. neglecta), subverting the reproductive isolation of all three and allowing gene flow. P. heraldica and P. neglecta breed sympatrically in the Pacific Ocean, where P. arminjoniana is absent, but no record of hybridization between these two exists and they remain phenotypically distinct. The breakdown of species boundaries in Round Island petrels followed environmental change (deforestation and changes in species composition due to hunting) within their overlapping ranges. Such multi-species interactions have implications not only for conservation, but also for our understanding of the processes of evolutionary diversification and speciation.

Show MeSH
Related in: MedlinePlus