Does segregated spawning time prevent the introgression of stocked whitefish species into native species? A morphometric and genetic study in Lake Mondsee, Austria
Pamminger-Lahnsteiner, B.; Winkler, K.A.; Weiss, S.; Wanzenböck, J.
Ecological niche differentiation, as well as temporal or spatial differences in spawning activity, could lead to reproductive isolation between stocked and native lineages of fish. In the Austrian Lake Mondsee, the distinct spawning times of indigenous and stocked whitefish stemming from the Baltic area might be an example for such a mechanism. Fourteen morphometric and seven meristic characters were used to characterize whitefish in Mondsee. Characters involving the head of the fish contributed predominantly to the discrimination of two population groups associated with early and late spawning activity in Mondsee. The extent of genetic differentiation was evaluated using four newly developed tetra-nucleotide microsatellite DNA markers, comprising the motifs GACA and GATA. These data also supported the existence of multiple population units within the lake and were largely congruent with two groups defined with morphological characters. However, some overlap in the data sets is seen, suggesting some level of hybridization and introgression. Thus, the temporally segregated spawning of native and stocked populations promotes reproductive isolation of the two groups in Lake Mondsee, although the extent of introgression cannot yet be quantified.