Species limits in the Le Conte's thrasher

We studied patterns of mitochondrial DNA (mtDNA) and colorimetric variation in the Le Conte's Thrasher (Toxostomsa lecontei) to determine patterns of geographic variation, and to clarify subspecific and species limits. We sequenced 619 base pairs of mtDNA (parts of cytochrome b and ND6) for 14 Le Conte's Thrashers from 9 localities representing the three putative subspecies (leconrei, macmillanorum, and arenicola). Haplotypes were shared between leconrei and macmillanorum, and we do not support recognition of the latter. However, haplotypes of arenicola differed bq 3.5% sequence divergence from those of lecontei and macmillanorum, and we suggest that arenicola be recognized as a species. Colorimetric analyses of 105 specimens indicated that arenicola differed consistently from lecontei and macmillanorum, corroborating the mtDNA results

Systematics and bird conservation policies: the importance of species limits

The taxonomic criteria used as bases for endangered species lists can affect conservation policy decisions. We emphasize that the use of different taxonomic units affects the baselines of such lists. Recent taxonomic reviews for the Mexican avifauna provided the tools for assessing this effect on a highly diverse avifauna which is currently in need of serious conservation actions. Most ornithologists have used a taxonomy based on the biological species concept (BSC) to make decisions on species limits and therefore to set them into endangered species lists. However, the application of the phylogenetic species concept (PSC) as an alternative for delimiting species, results in a different panorama of what should be protected. Our analysis shows that the current official Mexican endangered species list, BSC based, encompasses 371 birds, ranked as 277 species and 94 subspecies. The same list of protected forms changes under the phylogenetic species concept because 47 of them are not recognized as valid species, while another 28 forms merit higher levels of protection. Additionally, under this concept another :11 forms should be candidates for inclusion based on their restricted distribution. We call attention to the fact that the use of one or another species concept affects endangered species lists

Blackpoll warbler (Dendroica striata) and other records of birds from Guerrero, Mexico

We present a list of noteworthy distributional records for 12 species of birds in the Mexican state of Guerrero. One (Dendroica striata) is new for the state, and the remaining either significantly expand their known geographic and seasonal distribution or add information about their presence in the state

Recent speciation in the orchard oriole group: Divergence of Icterus spurius spurius and Icterus spurius fuertesi

New World orioles (Icterus) include several closely related species and subspecies pairs that provide excellent opportunities for studying recent speciation. We examined a subspecies pair in the Orchard Oriole group: Orchard Oriole (l. spurius spurius), a longdistance migrant that breeds in eastern North America, and Fuertes's Oriole (l. s. fuertesi), a shortdistance migrant that breeds in a restricted range in Veracruz, Mexico. We sequenced parts of the mitochondrial cytochromeb gene (925 base pairs) and control region (344 base pairs) freom 23 Orchard Orioles and 7 Fuertes's Orioles. Subspecies are not reciprocally monophyletic. Instead, our data suggest that at least one taxon is paraphyletic or polyphyletic. We found little support for any further phylogenetic structure, including whether one subspecies might be derived freom the other. However, haplotype freequency analysis suggests that there is little or no current gene flow between the taxa. The phylogenetic relationship between Orchard and Fuertes's orioles is likely a result of recent divergence and incomplete lineage sorting. That interpretation is consistent with theoretical models of speciation, which predict patterns of nonmonophyly at early stages of taxon divergence. Our findings suggest that Orchard and Fuertes's orioles are separate species and provide a case study for evaluating the importance of monophyly in defining species limits

Modeling distributions of disjunct populations of the Sierra Madre Sparrow

models based on the reduced dataset indicated that the two populations occur in areas with similar ecological conditions. Our models also suggest that southern population of Sierra Madre Sparrows covers most of their potential range in that region. The potential range of the northern population, however, extends beyond known points of occurrence. To clarify the distribution of Sierra Madre Sparrows and evaluate their status and conservation opportunities, detailed searches for additional populations in areas identified by the model are needed