Breeding Pool Segregation by the Mole Salamanders, Ambystoma Jeffersonianum and A. Maculatum, in a Region of Sympatry

Abstract

During 1977 and 1978, 85 ambystomatid breeding pools were identified in the 4 western counties in Maryland, USA. Twenty pools were used solely by A. jeffersonianum, 31 by A. maculatum and 34 by the 2 spp. Fifteen variables measured at each of these pools were used in a multiple stepwise discriminant function analysis. Thirteen variables were important in segregating breeding pools, and several contributed highly to pool discrimination. Pools harboring the 2 spp. were lower in elevation, larger, with less bottom in mud than the other 2 pool types and intermediate in percent pool bottom in emergent vegetation, percent shoreline in fields and water turbidity and temperature. Sites with only A. jeffersonianum had a higher percent of the pool bottom in emergent vegetation, a lower percent shoreline in fields, a higher water turbidity and a lower water temperature. A. maculatum sites were at the other end of this continuum. The observed positions of the pool types along the discriminant axes could be due to one or the other species having a competitive advantage under certain environmental conditions and/or to differences in environmental tolerances.