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Population structure and plumage polymorphism: The intraspecific evolutionary relationships of a polymorphic raptor, Buteo jamaicensis harlani.

Hull JM, Mindell DP, Talbot SL, Kay EH, Hoekstra HE, Ernest HB - BMC Evol. Biol. (2010)

Bottom Line: Phenotypic and molecular genetic data often provide conflicting patterns of intraspecific relationships confounding phylogenetic inference, particularly among birds where a variety of environmental factors may influence plumage characters.Bayesian clustering analyses of nuclear microsatellite loci showed no significant differences between B. j. harlani and B. j. borealis.Differences observed between B. j. harlani and B. j. borealis in mitochondrial and microsatellite data were equivalent to those found between morphologically similar subspecies, B. j. borealis and B. j. calurus, and estimates of migration rates among all three subspecies were high.

View Article: PubMed Central - HTML - PubMed

Affiliation: Wildlife and Ecology Unit, Veterinary Genetics Laboratory, University of California, One Shields Avenue, Davis, CA 95616, USA. jmhull@ucdavis.edu

ABSTRACT

Background: Phenotypic and molecular genetic data often provide conflicting patterns of intraspecific relationships confounding phylogenetic inference, particularly among birds where a variety of environmental factors may influence plumage characters. Among diurnal raptors, the taxonomic relationship of Buteo jamaicensis harlani to other B. jamaicensis subspecies has been long debated because of the polytypic nature of the plumage characteristics used in subspecies or species designations.

Results: To address the evolutionary relationships within this group, we used data from 17 nuclear microsatellite loci, 430 base pairs of the mitochondrial control region, and 829 base pairs of the melanocortin 1 receptor (Mc1r) to investigate molecular genetic differentiation among three B. jamaicensis subspecies (B. j. borealis, B. j. calurus, B. j. harlani). Bayesian clustering analyses of nuclear microsatellite loci showed no significant differences between B. j. harlani and B. j. borealis. Differences observed between B. j. harlani and B. j. borealis in mitochondrial and microsatellite data were equivalent to those found between morphologically similar subspecies, B. j. borealis and B. j. calurus, and estimates of migration rates among all three subspecies were high. No consistent differences were observed in Mc1r data between B. j. harlani and other B. jamaicensis subspecies or between light and dark color morphs within B. j. calurus, suggesting that Mc1r does not play a significant role in B. jamaicensis melanism.

Conclusions: These data suggest recent interbreeding and gene flow between B. j. harlani and the other B. jamaicensis subspecies examined, providing no support for the historical designation of B. j. harlani as a distinct species.

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Results of full model migration matrix. We allowed all parameters to vary independently. We calculated migration direction and rates from: (A) 17 microsatellite loci and (B) mtDNA control region data. Nem and Nfm = estimate for number of migrants/females per generation based on nuclear microsatellites and mtDNA, respectively. Θ = population size (4Neμ; see text). 95% confidence intervals for parameter values are in parentheses. Arrow thickness is proportionate to estimated levels of gene flow (thicker arrows indicate higher relative gene flow).
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Figure 4: Results of full model migration matrix. We allowed all parameters to vary independently. We calculated migration direction and rates from: (A) 17 microsatellite loci and (B) mtDNA control region data. Nem and Nfm = estimate for number of migrants/females per generation based on nuclear microsatellites and mtDNA, respectively. Θ = population size (4Neμ; see text). 95% confidence intervals for parameter values are in parentheses. Arrow thickness is proportionate to estimated levels of gene flow (thicker arrows indicate higher relative gene flow).

Mentions: We observed asymmetrical gene flow among all subspecies and across both marker types. The full model (all parameters allowed to vary independently) had significantly higher likelihoods than the restricted island model (equal inter-group migration rate and equal θ across populations; microsatellite: LnLrestricted = -1078.32, LnLfull = -801.21, P < 0.0001; mtDNA: LnLrestricted = -527.48, LnLfull = 6.20, P < 0.0001). Nem and θ (4Neμ) values calculated in MIGRATE from microsatellite genotypes and mtDNA ranged from 2.56 -5.60 migrants per generation among subspecies, with θ ranging from 1.031 - 1.62 (Figure 4A), and <0.01 to 70.49 female migrants per generation among subspecies, with θ ranging from 0.004 - 0.007 (Figure 4B). The bias in the variances and the means indicate that, on average over generations, gene flow has been greater from B. j. borealis and B. j. harlani to B. j. calurus than B. j. calurus to the other two subspecies (Figure 4A, B). While gene flow estimates between B. j. harlani and B. j. borealis appear more symmetrical (overlapping confidence intervals) when based on microsatellite loci (Figure 4A), estimates based on mtDNA suggest significantly greater levels of gene flow from B. j. borealis to B. j. harlani than vice versa (Figure 4B). These estimates provide a rough estimation of the rate of gene exchange among subspecies and should not be viewed as precise measures. Rather, these results should be considered in the context of whether B. j. harlani is sufficiently isolated from other B. jamaicensis subspecies to be considered a full species.


Population structure and plumage polymorphism: The intraspecific evolutionary relationships of a polymorphic raptor, Buteo jamaicensis harlani.

Hull JM, Mindell DP, Talbot SL, Kay EH, Hoekstra HE, Ernest HB - BMC Evol. Biol. (2010)

Results of full model migration matrix. We allowed all parameters to vary independently. We calculated migration direction and rates from: (A) 17 microsatellite loci and (B) mtDNA control region data. Nem and Nfm = estimate for number of migrants/females per generation based on nuclear microsatellites and mtDNA, respectively. Θ = population size (4Neμ; see text). 95% confidence intervals for parameter values are in parentheses. Arrow thickness is proportionate to estimated levels of gene flow (thicker arrows indicate higher relative gene flow).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2927923&req=5

Figure 4: Results of full model migration matrix. We allowed all parameters to vary independently. We calculated migration direction and rates from: (A) 17 microsatellite loci and (B) mtDNA control region data. Nem and Nfm = estimate for number of migrants/females per generation based on nuclear microsatellites and mtDNA, respectively. Θ = population size (4Neμ; see text). 95% confidence intervals for parameter values are in parentheses. Arrow thickness is proportionate to estimated levels of gene flow (thicker arrows indicate higher relative gene flow).
Mentions: We observed asymmetrical gene flow among all subspecies and across both marker types. The full model (all parameters allowed to vary independently) had significantly higher likelihoods than the restricted island model (equal inter-group migration rate and equal θ across populations; microsatellite: LnLrestricted = -1078.32, LnLfull = -801.21, P < 0.0001; mtDNA: LnLrestricted = -527.48, LnLfull = 6.20, P < 0.0001). Nem and θ (4Neμ) values calculated in MIGRATE from microsatellite genotypes and mtDNA ranged from 2.56 -5.60 migrants per generation among subspecies, with θ ranging from 1.031 - 1.62 (Figure 4A), and <0.01 to 70.49 female migrants per generation among subspecies, with θ ranging from 0.004 - 0.007 (Figure 4B). The bias in the variances and the means indicate that, on average over generations, gene flow has been greater from B. j. borealis and B. j. harlani to B. j. calurus than B. j. calurus to the other two subspecies (Figure 4A, B). While gene flow estimates between B. j. harlani and B. j. borealis appear more symmetrical (overlapping confidence intervals) when based on microsatellite loci (Figure 4A), estimates based on mtDNA suggest significantly greater levels of gene flow from B. j. borealis to B. j. harlani than vice versa (Figure 4B). These estimates provide a rough estimation of the rate of gene exchange among subspecies and should not be viewed as precise measures. Rather, these results should be considered in the context of whether B. j. harlani is sufficiently isolated from other B. jamaicensis subspecies to be considered a full species.

Bottom Line: Phenotypic and molecular genetic data often provide conflicting patterns of intraspecific relationships confounding phylogenetic inference, particularly among birds where a variety of environmental factors may influence plumage characters.Bayesian clustering analyses of nuclear microsatellite loci showed no significant differences between B. j. harlani and B. j. borealis.Differences observed between B. j. harlani and B. j. borealis in mitochondrial and microsatellite data were equivalent to those found between morphologically similar subspecies, B. j. borealis and B. j. calurus, and estimates of migration rates among all three subspecies were high.

View Article: PubMed Central - HTML - PubMed

Affiliation: Wildlife and Ecology Unit, Veterinary Genetics Laboratory, University of California, One Shields Avenue, Davis, CA 95616, USA. jmhull@ucdavis.edu

ABSTRACT

Background: Phenotypic and molecular genetic data often provide conflicting patterns of intraspecific relationships confounding phylogenetic inference, particularly among birds where a variety of environmental factors may influence plumage characters. Among diurnal raptors, the taxonomic relationship of Buteo jamaicensis harlani to other B. jamaicensis subspecies has been long debated because of the polytypic nature of the plumage characteristics used in subspecies or species designations.

Results: To address the evolutionary relationships within this group, we used data from 17 nuclear microsatellite loci, 430 base pairs of the mitochondrial control region, and 829 base pairs of the melanocortin 1 receptor (Mc1r) to investigate molecular genetic differentiation among three B. jamaicensis subspecies (B. j. borealis, B. j. calurus, B. j. harlani). Bayesian clustering analyses of nuclear microsatellite loci showed no significant differences between B. j. harlani and B. j. borealis. Differences observed between B. j. harlani and B. j. borealis in mitochondrial and microsatellite data were equivalent to those found between morphologically similar subspecies, B. j. borealis and B. j. calurus, and estimates of migration rates among all three subspecies were high. No consistent differences were observed in Mc1r data between B. j. harlani and other B. jamaicensis subspecies or between light and dark color morphs within B. j. calurus, suggesting that Mc1r does not play a significant role in B. jamaicensis melanism.

Conclusions: These data suggest recent interbreeding and gene flow between B. j. harlani and the other B. jamaicensis subspecies examined, providing no support for the historical designation of B. j. harlani as a distinct species.

Show MeSH
Related in: MedlinePlus