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Selection and geographic isolation influence hummingbird speciation: genetic, acoustic and morphological divergence in the wedge-tailed sabrewing (Campylopterus curvipennis).

González C, Ornelas JF, Gutiérrez-Rodríguez C - BMC Evol. Biol. (2011)

Bottom Line: We present the results of genetic differentiation, and explore drift and selection effects in promoting acoustic and morphological divergence among populations of Campylopterus curvipennis, a lekking hummingbird with an extraordinary vocal variability across Mesoamerica.Coalescent simulations showed that fixation of song types has occurred faster than expected under neutrality but the hypothesis that morphological divergence resulted from drift was not rejected.These results highlight the importance of the Isthmus of Tehuantepec and more recent Pleistocene climatic events in driving isolation and population divergence.

View Article: PubMed Central - HTML - PubMed

Affiliation: Departamento de Biología Evolutiva, Instituto de Ecología AC, carretera antigua a Coatepec No, 351, El Haya, Xalapa, Veracruz 91070, Mexico.

ABSTRACT

Background: Mesoamerica is one of the most threatened biodiversity hotspots in the world, yet we are far from understanding the geologic history and the processes driving population divergence and speciation for most endemic taxa. In species with highly differentiated populations selective and/or neutral factors can induce rapid changes to traits involved in mate choice, promoting reproductive isolation between allopatric populations that can eventually lead to speciation. We present the results of genetic differentiation, and explore drift and selection effects in promoting acoustic and morphological divergence among populations of Campylopterus curvipennis, a lekking hummingbird with an extraordinary vocal variability across Mesoamerica.

Results: Analyses of two mitochondrial genes and ten microsatellite loci genotyped for 160 individuals revealed the presence of three lineages with no contemporary gene flow: C. c. curvipennis, C. c. excellens, and C. c. pampa disjunctly distributed in the Sierra Madre Oriental, the Tuxtlas region and the Yucatan Peninsula, respectively. Sequence mtDNA and microsatellite data were congruent with two diversification events: an old vicariance event at the Isthmus of Tehuantepec (c. 1.4 Ma), and a more recent Pleistocene split, isolating populations in the Tuxtlas region. Hummingbirds of the excellens group were larger, and those of the pampa group had shorter bills, and lineages that have been isolated the longest shared fewer syllables and differed in spectral and temporal traits of a shared syllable. Coalescent simulations showed that fixation of song types has occurred faster than expected under neutrality but the hypothesis that morphological divergence resulted from drift was not rejected.

Conclusions: Our phylogeographic analyses uncovered the presence of three Mesoamerican wedge-tailed sabrewing lineages, which diverged at different time scales. These results highlight the importance of the Isthmus of Tehuantepec and more recent Pleistocene climatic events in driving isolation and population divergence. Coalescent analyses of the evolution of phenotypic traits suggest that selection is driving song evolution in wedge-tailed sabrewings but drift could not be rejected as a possibility for morphological divergence.

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Phylogenetic relationships among mtDNA haplotypes based on Bayesian inference. Values above branches denote posterior probabilities, and numbers at the tip of the branches indicate distinct haplotypes. Outgroups were Campylopterus rufus, C. hemileucurus, and C. largipennis, and are shown collapsed into a single branch. Hummingbird illustrations were taken from color plates in the Handbook of the Birds of the World [32].
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Figure 1: Phylogenetic relationships among mtDNA haplotypes based on Bayesian inference. Values above branches denote posterior probabilities, and numbers at the tip of the branches indicate distinct haplotypes. Outgroups were Campylopterus rufus, C. hemileucurus, and C. largipennis, and are shown collapsed into a single branch. Hummingbird illustrations were taken from color plates in the Handbook of the Birds of the World [32].

Mentions: The consensus tree obtained from Bayesian inference clustered the haplotypes into two main well-supported clades (posterior probabilities of 1.0), corresponding to disjunct western (curvipennis, SMO) and eastern (pampa, YUC) groups on either side of the Isthmus of Tehuantepec (Figure 1). Haplotypes of the excellens group from the Tuxtlas region were clustered in a well-supported clade nested within the poorly resolved SMO clade.


Selection and geographic isolation influence hummingbird speciation: genetic, acoustic and morphological divergence in the wedge-tailed sabrewing (Campylopterus curvipennis).

González C, Ornelas JF, Gutiérrez-Rodríguez C - BMC Evol. Biol. (2011)

Phylogenetic relationships among mtDNA haplotypes based on Bayesian inference. Values above branches denote posterior probabilities, and numbers at the tip of the branches indicate distinct haplotypes. Outgroups were Campylopterus rufus, C. hemileucurus, and C. largipennis, and are shown collapsed into a single branch. Hummingbird illustrations were taken from color plates in the Handbook of the Birds of the World [32].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3045325&req=5

Figure 1: Phylogenetic relationships among mtDNA haplotypes based on Bayesian inference. Values above branches denote posterior probabilities, and numbers at the tip of the branches indicate distinct haplotypes. Outgroups were Campylopterus rufus, C. hemileucurus, and C. largipennis, and are shown collapsed into a single branch. Hummingbird illustrations were taken from color plates in the Handbook of the Birds of the World [32].
Mentions: The consensus tree obtained from Bayesian inference clustered the haplotypes into two main well-supported clades (posterior probabilities of 1.0), corresponding to disjunct western (curvipennis, SMO) and eastern (pampa, YUC) groups on either side of the Isthmus of Tehuantepec (Figure 1). Haplotypes of the excellens group from the Tuxtlas region were clustered in a well-supported clade nested within the poorly resolved SMO clade.

Bottom Line: We present the results of genetic differentiation, and explore drift and selection effects in promoting acoustic and morphological divergence among populations of Campylopterus curvipennis, a lekking hummingbird with an extraordinary vocal variability across Mesoamerica.Coalescent simulations showed that fixation of song types has occurred faster than expected under neutrality but the hypothesis that morphological divergence resulted from drift was not rejected.These results highlight the importance of the Isthmus of Tehuantepec and more recent Pleistocene climatic events in driving isolation and population divergence.

View Article: PubMed Central - HTML - PubMed

Affiliation: Departamento de Biología Evolutiva, Instituto de Ecología AC, carretera antigua a Coatepec No, 351, El Haya, Xalapa, Veracruz 91070, Mexico.

ABSTRACT

Background: Mesoamerica is one of the most threatened biodiversity hotspots in the world, yet we are far from understanding the geologic history and the processes driving population divergence and speciation for most endemic taxa. In species with highly differentiated populations selective and/or neutral factors can induce rapid changes to traits involved in mate choice, promoting reproductive isolation between allopatric populations that can eventually lead to speciation. We present the results of genetic differentiation, and explore drift and selection effects in promoting acoustic and morphological divergence among populations of Campylopterus curvipennis, a lekking hummingbird with an extraordinary vocal variability across Mesoamerica.

Results: Analyses of two mitochondrial genes and ten microsatellite loci genotyped for 160 individuals revealed the presence of three lineages with no contemporary gene flow: C. c. curvipennis, C. c. excellens, and C. c. pampa disjunctly distributed in the Sierra Madre Oriental, the Tuxtlas region and the Yucatan Peninsula, respectively. Sequence mtDNA and microsatellite data were congruent with two diversification events: an old vicariance event at the Isthmus of Tehuantepec (c. 1.4 Ma), and a more recent Pleistocene split, isolating populations in the Tuxtlas region. Hummingbirds of the excellens group were larger, and those of the pampa group had shorter bills, and lineages that have been isolated the longest shared fewer syllables and differed in spectral and temporal traits of a shared syllable. Coalescent simulations showed that fixation of song types has occurred faster than expected under neutrality but the hypothesis that morphological divergence resulted from drift was not rejected.

Conclusions: Our phylogeographic analyses uncovered the presence of three Mesoamerican wedge-tailed sabrewing lineages, which diverged at different time scales. These results highlight the importance of the Isthmus of Tehuantepec and more recent Pleistocene climatic events in driving isolation and population divergence. Coalescent analyses of the evolution of phenotypic traits suggest that selection is driving song evolution in wedge-tailed sabrewings but drift could not be rejected as a possibility for morphological divergence.

Show MeSH
Related in: MedlinePlus