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2 resultados encontrados para: AUTOR: Emerson, Brent C.
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1.
Artículo
Introgressive hybridization in a Spiny-Tailed Iguana, Ctenosaura pectinata, and its implications for taxonomy and conservation
Zarza Franco, Guadalupe Eugenia (autora) ; Reynoso, Víctor H. (autor) ; Faria, Christiana M. A. (autora) ; Emerson, Brent C. (autor) ;
Disponible en línea
Contenido en: PeerJ Volumen 7, número e6744 (2019), p. ISSN: 2167-8359
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Resumen en: Inglés |
Resumen en inglés

Introgression, the transmission of genetic material of one taxon into another through hybridization, can have various evolutionary outcomes. Previous studies have detected signs of introgression between western populations of the Mexican endemic and threatened spiny-tailed iguana, Ctenosaura pectinata. However, the extent of this phenomenon along the geographic distribution of the species is unknown. Here, we use multilocus data together with detailed geographic samplingto (1) define genotypic clusters within C. pectinata; (2) evaluate geographic concordance between maternally and biparentally inherited markers; (3) examine levels of introgression between genotypic clusters, and (4) suggest taxonomic modifications in light of this information. Applying clustering methods to genotypes of 341 individuals from 49 localities of C. pectinata and the closely related C. acanthura, we inferred the existence offive genotypic clusters. Contact zones between genotypic clusters with signatures of interbreeding were detected, showing different levels of geographic discordance with mtDNA lineages. In northern localities, mtDNA and microsatellites exhibit concordant distributions, supporting the resurrection of C. brachylopha. Similar concordance is observed along the distribution of C. acanthura, confirming its unique taxonomic identity. Genetic and geographic concordance is also observed for populations within southwestern Mexico, where the recognition of a new species awaits in depth taxonomic revision. In contrast, in western localities a striking pattern of discordance was detected where up to six mtDNA lineages co-occur with only two genotypic clusters. Given that the type specimen originated from this area, we suggest that individuals from western Mexico keep the name C. pectinata. Our results have profound implications for conservation, management, and forensics of Mexican iguanas.


2.
Artículo
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Diversification in the northern neotropics: mitochondrial and nuclear DNA phylogeography of the iguana Ctenosaura pectinataand related species
Zarza Franco, Guadalupe Eugenia (autora) ; Reynoso, Víctor H. (autor) ; Emerson, Brent C. (autor) ;
Contenido en: Molecular Ecology Vol. 17 (2008), p. 3259–3275 ISSN: 1365-294X
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Resumen en: Inglés |
Resumen en inglés

While Quaternary climatic changes are considered by some to have been a major factor promoting speciation within the neotropics, others suggest that much of the neotropical species diversity originated before the Pleistocene. Using mitochondrial and nuclear sequence data, we evaluate the relative importance of Pleistocene and pre-Pleistocene events withinthe evolutionary history of the Mexican iguana Ctenosaura pectinata, and related species. Results support the existence of cryptic lineages with strong mitochondrial divergence(> 4%) among them. Some of these lineages form zones of secondary contact, with one of them hybridizing with C. hemilopha. Evolutionary network analyses reveal the oldest populations of C. pectinata to be those of the northern and southern Mexican coastal regions. Inland and mid-latitudinal coastal populations are younger in age as a consequence of a history of local extinction within these regions followed by re-colonization. Estimated divergence times suggest that C. pectinata originated during the Pliocene, whereas geographically distinct mitochondrial DNA lineages first started to diverge during the Pliocene, with subsequent divergence continuing through the Pleistocene. Our results highlight the influence of both Pliocene and Pleistocene events in shaping the geographical distributionof genetic variation within neotropical lowland organisms. Areas of high genetic diversityin southern Mexico were detected, this finding plus the high levels of genetic diversity within C. pectinata, have implications for the conservation of this threatened species.