Meeting Abstract

P3.24  Jan. 6  The Pattern of Evolution of Saline-Tolerance in Mosquito Larvae ALBERS, Melissa A*; BRADLEY, Timothy J; Univ. of California, Irvine; Univ. of California, Irvine malbers@uci.edu

We examined the evolution of saline-tolerance in mosquito larvae of the genus, Ochlerotatus. The mosquito larvae of this genus are strict osmoregulators. Some species are restricted to freshwater habitats while others can successfully osmoregulate in saline waters that greatly exceed the concentration of seawater. This physiological differentiation between the freshwater and saline-tolerant forms is associated with a morphological difference in the larval rectum, an organ that serves an osmoregulatory function. We are interested in where the evolution of saline-tolerance evolved in this lineage. We characterized the larval osmoregulatory capabilities of several mosquito species in both physiological and morphological aspects. We used these freshwater and saline-tolerant Ochlerotatus mosquitoes to construct a phylogenetic tree using molecular data. These data were obtained by PCR amplifying and sequencing mitochondrial and ribosomal DNA genes. When we superimposed saline-tolerance characteristics of the larval stages onto the tree, we showed that the evolution of saline-tolerance within the Ochlerotatus genus is homoplasic. Our data suggest saline-tolerance has evolved independently multiple times in this genus. It appears that it may also have been lost in some lineages.