Divergent Crossover Patterns among Galloanserae in spite of Conserved Karyoptype Structure

DEL PRIORE LUCIA; PIGOZZI M.I.; DEL PRIORE LUCIA; PIGOZZI M.I.

Foz do Igaucu

Congreso; 21st International Chromosome Conference (ICC); 2016

Poster Honorable Mention Awarded to Lucía de Priore.It is known that the pattern of crossover (CO) distribution is affected by karyotypic features such as chromosome size, centromere position, and heterochromatic content. Birds are comparatively less variable than mammals in this regard, so it could be predicted that their recombination landscapes will be less variable as well. In order to test this prediction, we investigated the CO rates and distribution in 5 species of domestic Galloanserae that show conserved karyotype structure and genome sizes. To this end, we used immunolocalization of the mismatch-repair protein MLH1 that labels CO sites along the synaptonemal complexes during pachytene. We found that the total genetic maps are in the range of 2,655 to 3,105 cM, and in most cases, MLH1 foci on macrobivalents show a multimodal profile along chromosome arms. A departure from this general feature was found in the helmeted guinea fowl (Numida meleagris), a species that diverged from the chicken about 30 MYA. In this species, the genetic map spans only 2,220 cM and MLH1 foci are strongly localized towards opposite ends of the bivalents. Furthermore, the global CO rate in the guinea fowl (1.8 cM/Mb) is very similar to that of certain passerines, but lower compared to other species of Galliformes investigated so far. The present data suggest that broad-scale recombination patterns can be significantly modified in the absence of drastic karyotype rearrangements, and that, in contrast to mammals, CO rates might not show a strong phylogenetic signal in birds.