Meeting Abstract

P2.119  Saturday, Jan. 5  Can members of the imperiled Gila species-complex be identified as morphologically distinct across life history stages? MORAN, C.J.*; LERMA, C; JIMENEZ, J; GIBB, A.C.; Northern Arizona University cmoran.mlml@gmail.com

Imperiled cyprinid species in the genus Gila (Teleostei, Cypriniformes) from the southwestern United States are of critical concern to conservation biologists and management agencies, but difficult to identify—especially at juvenile and young adult life history stages, when different species demonstrate very similar body designs. Species identification within the genus is further complicated by hybridization between coexisting species and putative morphological differences within a species between drainages. Because fishes at later life history stages are more clearly morphologically distinct from one another, we sought to determine which morphological characteristics (if any) can be used distinguish species at juvenile and young adult stages using standard meristic traits and measurements of body proportions taken from digital images of preserved specimens and from live specimens collected in the field. We found that several morphological characteristics varied among young individuals of representative Gila species including: caudal peduncle depth, caudal peduncle length and dorsal fin-base length. We note that these characteristics may have functional consequences for aquatic locomotor behaviors; however, further investigation will be necessary determine the biomechanical significance of morphological variation in these traits. In addition, although we noted variability within a species among waterways, it is not yet clear if this variability is genetic, or the result of developmental plasticity. These results could aid in interpreting morphological variability within members of the genus Gila, as well as assisting with field identification of these rare and threatened fishes.