Evidencias moleculares de hibridación entre Serinus canaria domestica (L., 1758) y Spinus barbatus (Molina, 1782) (Aves: Fringillidae)

Resumen En este estudio se muestran evidencias moleculares de éxito en la hibridación entre Serinus canaria domestica (linnaeus, 1758) y Spinus barbatus (molina, 1782). Como parte de una secuencia de retrocruzamiento, se logró reproducir híbridos F2 a partir de hembras híbridas fértiles viables F1 x S. c. domestica. La F1 fue la descendencia entre P0 = Serinus c. domestica x Spinus barbatus. Las secuencias de nucleótidos de dos segmentos de ADN, citocromo b mitocondrial (Cyt b) y el receptor de tirosina quinasa muscular (MuSK) del ADN nuclear se obtuvieron de tres especímenes híbridos F2. Tanto las secuencias de Cyt b como de MuSK señalaron fuerte soporte filogenético a la condición genética híbrida de los tres embriones F2. De esta manera la evidencia molecular refleja el éxito en el cruce interespecífico entre S. barbatus con S. c. domestica y que es posible obtener híbridos fértiles viables F1 (en este caso hembras) y F2 entre estos dos linajes en poblaciones naturales. Abstract In this study we show molecular evidences of success in hybridization between Serinus canaria domestica and Spinus barbatus. As part of a sequence of backcrossing we have achieved to reproduce F2 hybrids of fertile hybrid females F1 with parental S. c. domestica. F1 was the offspring between, P0 = S. c. domestica x S. barbatus. In this study the space where the observations and the breeding success are carried out between these species, they are described: is a room with the following measures; 4,45 m (lenghty) x 1,60 m (width) x 2,30 m (high), located in an urban building; specifically, glassed-balcony at a height of 10,60 m above ground level, facing some ornamental and exuberant canopy trees of Platanus orientalis (L., 1753) and with direct entrance of natural sunlight, in urban city of Santiago, Chile, where his perceptual world develops. We took care to keep the biotic and abiotic factors under control; specifically, incoming natural light, ambient vegetation and temperature. On the other hand, we fed the individuals appropriately and provided them with plenty of clean water to drink and get clean, where there were no predators. In sum, the individuals were kept in a healthy environment. The backcrossing between the male S. c. domestica (generation 0) bred with two viable hybrid F1 offspring females, it gave as resulted in a total of three independent generations of F2 hybrids (n = 12). All the individuals came out healthy, and none of them died, despite being inbred lineages. Three embryos representative of the F2 hybrids were sacrificed and deposited in 99% alcohol. Nucleotide sequences of two DNA segments, mitochondrial cytochrome b (Cyt b) and muscle-specific receptor tyrosine kinase (MuSK) gene of the nuclear DNA were obtained from three F2 hybrid specimens. The model of molecular evolution with the greatest adjustment to the data obtained by jModeltest was GTR + I + G (I = 0,1450, G = 0,0930), according to the phylogenetic analysis of mitochondrial DNA (Fig. 1a), the female progenitor P0 is S.c.domestica. This conclusion is based on the evi- dence that mitochondrial DNA in birds, as well as in most animal groups, is exclusively inherited through the maternal ways. The same analysis carried out with the nuclear MuSK gene shows that the parental male P0 of the embryos analyzed is very much related to S. barbatus (Fig. 1b). The Cyt b and MuSK region show strongly support to hybrids genetic condition of the three F2 embryos. Intergeneric hybrids are usually sterile, but it is worth noting that genera of Fringillidae are very closely related (the Family as a whole is only 12 million years old, and most genera in the terminal canary-siskin group are <5 million years old). This is simply a case of poor classification with oversplitting or maybe the nature of these lineages are fractals, since in most of the Passeriformes, family-level taxa are more than 20 million years old, and in other groups of Aves families and genera are even older. Then hybridization takes place more easily in captivity. Many authors considered that hybridization in birds is not important because hybrids are formed in proportion 1/50,000 specimens. Despite this, many bird hybrids have been created in captivity. In addition, hybrids produced ex situ under controlled conditions would play an important role for reproductive success and subsequent interspecific viability. The main conclusions derived from this study are as follows: 1) The present report strongly indicates that hybridizations have occurred among S. c. canary x S. barbatus. 2) In this way the molecular evidence reflects and justifies the success in interspecific reproduction between S. barbatus with S. c. domestica and that it is possible to obtain viable fertile hybrids F1 (in this case females) and F2 between these two lineages, 3) And consequently the close genetic affinity between these two genera and the formation of hybrids in natural populations should not discard.