Potential contribution of ancient introgression to the evolution of a derived reproductive strategy in ricefishes

Transitions from no parental care to extensive care are costly and involve major changes in life history, behaviour and morphology. Nevertheless, in Sulawesi ricefishes, pelvic brooding evolved from transfer brooding in two distantly related lineages within the genera Adrianichthys and Oryzias, respectively. Females of pelvic brooding species carry their eggs attached to their belly until the fry hatches. Despite their phylogenetic distance, both pelvic brooding lineages share a set of external morphological traits. A recent study found no direct gene flow between pelvic brooding lineages, suggesting independent evolution of the derived reproductive strategy. Convergent evolution can, however, also rely on repeated sorting of pre-existing variation of an admixed ancestral population, especially when subjected to similar external selection pressures. We thus used a multi-species coalescent (MSC) model and D-statistics to identify gene-tree - species-tree incongruencies, to evaluate the evolution of pelvic brooding with respect to inter-specific gene flow not only between pelvic brooding lineages, but between pelvic brooding lineages and other Sulawesi ricefish lineages. We found a general network-like evolution in Sulawesi ricefishes and as previously reported, no gene flow between the pelvic brooding lineages. Instead, we found hybridization between the ancestor of pelvic brooding Oryzias and the common ancestor of the Oryzias species from the Lake Poso area. We further detected signs of introgression within the confidence interval of a quantitative trait locus (QTL) associated with pelvic brooding in O. eversi. Our results hint towards a contribution of ancient standing genetic variation to the evolution of pelvic brooding in Oryzias

Lokasi Baru Spesies Grup Oryzias Woworae (Adrianichthyidae) Di Sulawesi Tenggara [ New Localities of the Oryzias Woworae Species Group (Adrianichthyidae) ]

The Oryzias woworae species group, composed of O. asinua, O. wolasi, and O. woworae, is a group of the family Adrianichthyidae endemic to Sulawesi Tenggara (Southeast Sulawesi). Here, we report new localities of each of the three species in this group, which were collected during our field expeditions in 2014-2015. In total, six new localities were discovered throughout Sulawesi Tenggara, including Muna Island, suggesting that they may have wider species ranges than currently recognized. Some of the new localities were independent of the river systems of the known localities, suggesting that each species is genetically structured, and that the unit for conservation should be considered not as each species but as each local population