Spatial genetic subdivision among populations of Pampus chinensis between China and Pakistan: testing the barrier effect of the Malay Peninsula

Tissue samples from 84 Pampus chinensis individuals were collected from four geographic regions within the Indo–Pacific Ocean and analyzed using mitochondrial and nuclear DNA markers. Distinct genetic heterogeneity was found for both types of markers between Chinese and Pakistani populations, while the diversity of this species was high in all populations. In combination with published information on marine species with similar distributions, these results suggested that the Malay Peninsula, or a less effective supplement, played a role in shaping the contemporary genetic structure. This population structure was presumably reflected in P. chinensis, whose populations were genetically isolated during Pleistocene glaciations and then did not experience secondary contact between previous refuge populations. However, P. chinensis showed genetic continuity in China or Pakistan, which indicated that the populations in different geographical regions constituted a single panmictic stock with high gene flow, respectively. The spatial genetic subdivision evident among populations indicates that P. chinensis in this Indo–Pacific region should be managed as different independent stocks to guide the sustainability of this fisheries resource.

Wnt controls the medial–lateral subdivision of the Drosophila head

In insects, the subdivision of the head into a lateral region, harbouring the compound eyes (CEs), and a dorsal (medial) region, where the ocelli localize, is conserved. This organization might have been already present in the insects' euarthropodan ancestors. In Drosophila, the Wnt-1 homologue wingless (wg) plays a major role in the genetic subdivision of the head. To analyse specifically the role of wg signalling in the development of the dorsal head, we attenuated this pathway specifically in this region by genetic means. We find that loss of wg signalling transforms the dorsal/medial head into lateral head structures, including the development of ectopic CEs . Our genetic analysis further suggests that wg signalling organizes the dorsal head medial–lateral axis by controlling, at least in part, the expression domains of the transcription factors Otd and Ey/Pax6.