Experimental hybridization in allopatric species of desert Drosophila: implications for the model of speciation.

COLINES BETINA; SOTO, IGNACIO M; DE PANIS D; PADRÓ, JULIÁN

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2018

0024-4066

The Pleistocene refugia theory proposes that recurrent expansions and contractions of xerophytic vegetation overperiods of climate change affected the evolution of cactophilic Drosophila in South America. The resulting demographicfluctuations linked to the available patches of vegetation should have been prone to bottlenecks and founderevents, affecting the fate of gene pool dynamics. However, these events also promoted the diversification of cacti,creating an ecological opportunity for host specialization. We tested the hypothesis of ecological speciation in theDrosophila buzzatii group. We assessed adaptive footprints and examined the genetic architecture of fitness-relatedtraits in the sibling allopatric species D. koepferae and D. antonietae. The results are in line with the idea that thesespecies evolved under different ecological scenarios. Joint-scaling analysis comparing both species and their hybridsrevealed that additive genetic variance was the major contributor to phenotypic divergence, but dominance, epistasisand maternal effects were also important factors. Correlation analysis among functionally related traits suggesteddivergent selection on phenotypic integration associated with fitness. These findings support the hypothesis of adaptiveevolution driving the phylogenetic radiation of the group through independent events of host shifts to chemicallycomplex columnar cacti.