Meeting Abstract

139.2  Monday, Jan. 7  Freshwater transitions and the evolution of osmoregulatory function in alewives (Alosa pseudoharengus) VELOTTA, J.P.*; MCCORMICK, S.D.; O’NEILL, R.J.; SCHULTZ, E.T.; University of Connecticut; United States Geological Survey; University of Connecticut; University of Connecticut jonathan.velotta@uconn.edu

Among fishes, ecological transitions into freshwater environments are often associated with episodes of diversification and adaptive radiation. The functional changes that accompany these transitions have rarely been characterized. In this research, we identify evolutionary shifts in osmoregulatory capacity and ion regulation associated with freshwater transitions in populations of alewife (Alosa pseudoharengus), some of which maintain the ancestrally anadromous migratory habit and some of which have become landlocked. Juvenile landlocked and anadromous alewives were experimentally challenged with a range of salinities both in situ and in the laboratory. We detected differentiation between population types in salinity tolerance and osmoregulatory performance, as well as in the expression of candidate genes for osmoregulation (Na⁺, K⁺, 2Cl^– cotransporter (NKCC), and cystic fibrosis transmembrane conductance regulator (CFTR)) and Na⁺, K⁺, ATPase activity. Overall, evolutionary changes upon restriction to freshwater include enhanced osmoregulatory function in freshwater and reduced osmoregulatory function in seawater, as well as a diminished response of several salt-secreting pathways.