Data from: Habitat segregation and ecological character displacement in cryptic African malaria mosquitoes
Tene Fossog, Billy et al. (2014), Data from: Habitat segregation and ecological character displacement in cryptic African malaria mosquitoes, Dryad, Dataset, https://doi.org/10.5061/dryad.61m2s
Understanding how divergent selection generates adaptive phenotypic and population diversification provides a mechanistic explanation of speciation in recently separated species pairs. Toward this goal, we sought ecological gradients of divergence between the cryptic malaria vectors Anopheles coluzzii and An. gambiae, and then looked for a physiological trait that may underlie such divergence. Using a large set of occurrence records and eco-geographical information, we built a distribution model to predict the predominance of the two species across their range of sympatry. Our model predicts two novel gradients along which the species segregate: distance from the coastline and altitude. Anopheles coluzzii showed a ‘bimodal’ distribution, predominating in xeric West African savannas and along the western coastal fringe of Africa. To test whether differences in salinity tolerance underlie this habitat segregation, we assessed the acute dose-mortality response to salinity of thirty-two larval populations from Central Africa. In agreement with its coastal predominance, Anophels coluzzii was overall more tolerant than An. gambiae. Salinity tolerance of both species, however, converged in urban localities, presumably reflecting an adaptive response to osmotic stress from anthropogenic pollutants. When comparing degree of tolerance in conjunction with levels of syntopy, we found evidence of character displacement in this trait.