Meeting Abstract
P2.76 Sunday, Jan. 5 15:30 Xiphophorus hellerii in toxic sulfide springs: patterns of adaptation like in other sulfide spring poeciliids? GREENWAY, R.S.*; TOBLER, M.; Oklahoma State University, Stillwater; Oklahoma State University, Stillwater ryan.greenway@okstate.edu
In Mexico, fish of the family Poeciliidae are common in the freshwater tributaries of the Río Grijalva. Within each tributary, there are also localized habitats with extreme environmental conditions in the form of springs rich in hydrogen sulfide (H2S), which is highly toxic for most organisms. Populations of the fish Poecilia mexicana have independently colonized these toxic habitats from ancestral freshwater habitats in three separate tributaries of the Río Grijalva. In one drainage, the Rio Pichucalco, additional species of poeciliid fish can be found in sulfidic springs, including a population of Xiphophorus hellerii (green swordtail), which occurs alongside Poecilia sulphuraria, a recently diverged sister species of Poecilia mexicana endemic to sulfidic habitats. This study aimed to determine if this population of X. hellerii has adapted to the toxic conditions in a similar fashion as P. sulphuraria and other populations of P. mexicana in sulfidic springs in the Río Grijalva system. To test this, X. hellerii from a sulfidic stream and a non-sulfidic stream were subjected to sulfide tolerance trials, and several morphological and physiological traits were compared between these populations. I predicted that X. hellerii originating from the sulfidic stream will have a higher tolerance to hydrogen sulfide as well as larger heads, gills, and livers when compared to fish from the non-sulfidic stream.
