Hybridization between two recently diverged Neotropical passerines: The Pearly-bellied Seedeater Sporophila pileata, and the Copper Seedeater S. bouvreuil (Aves, Passeriformes, Thraupidae)

Abstract

The small Neotropical finches called capuchinos are outstanding because they have experienced one of the most recent and explosive avian radiations ever documented for birds. Despite very low morphological and niche divergence among species, many of them are reproductively isolated when in sympatry due to strong sexual selection in plumage traits. However, a specific pair of mostly parapatric species, the Pearly-bellied, Sporophila pileata, and the Copper Seedeaters, S. bouvreuil, has confounded taxonomists because individuals with intermediate color patterns can be found. By analyzing diagnostic COI mtDNA sequences and adult male plumage we provide evidence for hybridization. Paternity tests using microsatellites also indicated that representatives with intermediate plumage pattern can be fertile. Our findings are consistent with the classification of S. bouvreuil and S. pileata as distinct taxa, but we demonstrate that the sexual selection mechanisms involved in the isolation of other reproductively sympatric capuchinos are not applicable to this pair of species, likely because of reduced barriers to mate recognition.

Rapid speciation via the evolution of pre-mating isolation in the Iberá Seedeater

“…Field experiments suggest that divergent male traits govern conspecific recognition and territorial defense (14). Nonetheless, viable hybrids between capuchino species are readily produced in the field (15) and in captivity (16), suggesting a lack of genetic incompatibilities.…”

Genetic Variability and Kinship Analyses of Seized Red-Browed Amazon, Amazona rhodocorytha (Aves, Psittacidae)

“…The past fragmentation cause is unknown, but post-decline rebound could affect genetic diversity over space and time, especially if the rebound is recent and localized, since the complex formed by the Vale Reserve and the Sooretama Biological Reserve is relatively new and surrounded by agricultural land, perhaps representing a site of rebounding for the Red-browed Amazons present in the region. For this reason, two alternative patterns of contemporary spatial genetic variability distribution are possible: (i) the current populations of the Red-browed Amazon have experienced total admixture in such a way that the genetic signatures of the past isolation no longer correspond to the geographic regions where they were originated, or (ii) the diagnosable genetic lineages are still associated with the past areas of isolation and the region of the Sooretama Biological Reserve represents a contact zone (see also [58]). Amazona parrots' high displacement ability, the absence of geographic barriers capable of isolating birds across the Atlantic Forest distribution, and the co-occurrence of five individuals of unknown, and likely different, origins that also had representatives in the two main genetic clusters, provide compelling evidence for widespread genetic introgression.…”

Systematics of Thraupis (Aves, Passeriformes) reveals an extensive hybrid zone between T. episcopus (Blue-gray Tanager) and T. sayaca (Sayaca Tanager)

“…However, the underlying mechanisms leading to either outcome remain partially unclear. Hybridization often occurs in nature between closely-related species, and it has been widely reported in various bird families within songbirds (Passeriformes) [26][27][28][29][30][31][32]. Currently, one of the reasons that can lead to hybridization is human-induced habitat transformation [33,34], which in the episcopus-sayaca complex might be relevant.…”