Molecular taxonomy of Brazilian tyrant-flycatchers (Passeriformes: Tyrannidae).

The tyrannids are one of the most diverse groups of birds in the world, and the most numerous suboscine family in the Neotropics. Reflecting such diversity, many taxonomic issues arise in this group, mainly due to morphological similarities, even among phylogenetically distant species. Other issues appear at higher taxonomic levels, mostly brought up by genetic studies, making systematics a rather inconclusive issue. This study looks into the use of DNA barcodes method to discriminate and identify Tyrannidae species occurring in the Atlantic Forest and Cerrado biomes of Brazil. We analysed 266 individuals of 71 tyrant-flycatcher species from different geographical locations by sequencing 542 bp of the mtDNA COI gene. The great majority of the analysed species showed exclusive haplotypes, usually displaying low intraspecific diversity and high interspecific divergence. Only Casiornis fuscus and Casiornis rufus, suggested in some studies to belong to a single species, could not be phylogenetically separated. High intraspecific diversity was observed among Elaenia obscura individuals, which can suggest the existence of cryptic species in this taxon. The same was also observed for Suiriri suiriri, considered by some authors to comprise at least two species, and by others to be divided into three subspecies. Additionally, the use of sequences from voucher specimens allowed us to correct four misidentifications that had happened in the field. Our findings suggest a great power of the COI barcodes to discriminate species of the Tyrannidae family that are found in Brazil.

Mitochondrial DNA corroborates the species distinctiveness of the Planalto (Thamnophilus pelzelni Hellmayr, 1924) and the Sooretama (T. ambiguus Swainson, 1825) Slaty-antshrikes (Passeriformes: Thamnophilidae)

The Thamnophilus punctatus complex has been recently reviewed on the basis of morphological and vocal characters, and is divided in six different species. Two of the new species, although well defined on the basis of morphological differences, could not be unambiguously distinguished through their loudsongs. The Planalto Slaty-antshrike (Thamnophilus pelzelni) and the Sooretama Slaty-antshrike (T. ambiguus) are most easily distinguished by subtle and localized changes in plumage colors of males and females. In the present study we used sequences of the control region, Cytochrome b, and ND2 genes, of the mitochondrial DNA (mtDNA) to evaluate the levels of molecular differentiation between these two species. The mean pairwise distance between the two species was 3.8 percent, while it varied from 2.7 percent to 4.9 percent for each mtDNA region. Although extensive variation was also detected among haplotypes within species, especially for T. ambiguus, we suggest that the genetic divergence found between T. ambiguus and T. pelzelni is high enough to corroborate the separate species status of these two antbird taxa.

O complexo Thamnophilus punctatus foi recentemente revisado, com base em caracteres morfológicos e vocais, sendo dividido em seis diferentes espécies. Duas dessas novas espécies, embora bem definidas com base em distinções morfológicas, não puderam ser definitivamente diferenciadas por seus cantos. Thamnophilus pelzelni (choca-do-planalto) e T. ambiguus (choca-de-sooretama) são mais facilmente diferenciadas por sutis e localizadas mudanças de coloração da plumagem de machos e fêmeas. Neste estudo, foram utilizadas seqüências de DNA mitocondrial (região controle, Citocromo b e ND2) a fim de avaliar os níveis de diferenciação molecular entre estas duas espécies. A divergência genética média entre as duas espécies foi de 3,8 por cento, enquanto para cada região mitocondrial esta variou entre 2,7 por cento e 4,9 por cento. Embora tenha sido observada grande variabilidade entre haplótipos dentro das espécies, especialmente para T. ambiguus, os resultados sugerem que a divergência genética observada entre T. ambiguus e T. pelzelni é suficientemente elevada para corroborar o status de espécies separadas destes dois Thamnophilidae.

Mitochondrial DNA corroborates the species distinctiveness of the Planalto (Thamnophilus pelzelni Hellmayr, 1924) and the Sooretama (T. ambiguus Swainson, 1825) Slaty-antshrikes (Passeriformes: Thamnophilidae).

The Thamnophilus punctatus complex has been recently reviewed on the basis of morphological and vocal characters, and is divided in six different species. Two of the new species, although well defined on the basis of morphological differences, could not be unambiguously distinguished through their loud songs. The Planalto Slaty-antshrike (Thamnophilus pelzelni) and the Sooretama Slaty-antshrike (T. ambiguus) are most easily distinguished by subtle and localized changes in plumage colors of males and females. In the present study we used sequences of the control region, Cytochrome b, and ND2 genes, of the mitochondrial DNA (mtDNA) to evaluate the levels of molecular differentiation between these two species. The mean pairwise distance between the two species was 3.8%, while it varied from 2.7% to 4.9% for each mtDNA region. Although extensive variation was also detected among haplotypes within species, especially for T. ambiguus, we suggest that the genetic divergence found between T. ambiguus and T. pelzelni is high enough to corroborate the separate species status of these two antbird taxa.

Genetic diversity and structure of natural populations of Plathymenia reticulata (Mimosoideae), a tropical tree from the Brazilian Cerrado.

Plathymenia reticulata is a tropical tree native to the Brazilian Cerrado, one of the most important and endangered ecosystems in Brazil. This species presents high-quality wood and potential for recovery of degraded areas. Despite its importance, almost nothing is known about its genetic or ecological features. Random amplified polymorphic DNA (RAPD) markers were used to investigate the genetic diversity and structure of six natural populations of P. reticulata. DNAs from 117 adult individuals were amplified with 10 random primers and Shannon's index and amova were used to evaluate the levels of genetic diversity within and among populations. Through 72 markers, 70.8% of which were polymorphic, it was possible to obtain 117 unique RAPD phenotypes. The levels of genetic variability found in the six populations of P. reticulata were considerable and most of the genetic variation was found between individuals within populations, although pairwise PH(ST) values indicated significant divergence between populations. The among-population component accounted for, respectively, 12.3% and 16% of the genetic variation, according to amova and Shannon's index. These results were compared with other genetic studies on plant species and such a level of differentiation among populations corresponds to that which has usually been observed for outcrossing plants. The importance of maintenance of the P. reticulata populations and implications of the analysis of adult individuals, considering the longevity of this species and the relatively recent Cerrado fragmentation, are discussed.