The impact of one-decade ecological disturbance on genetic changes: a study on the brine shrimp from Urmia Lake, Iran.

Urmia Lake, the largest natural habitat of the brine shrimp , has progressively desiccated over the last two decades, resulting in a loss of 80% of its surface area and producing thousands of hectares of arid salty land. This ecological crisis has seriously affected the lake's native biodiversity. has lost more than 90% of its population during the decade from 1994 (rainy period) to 2004 (drought period) due to salinity increasing to saturation levels (∼300 g/l). We studied the influence of this ecological crisis on the genetic diversity of in Urmia Lake, based on one cyst collections in 1994 and 2004. AMOVA analysis on ISSR data demonstrated a 21% genetic variation and there was a 5.5% reduction of polymorphic loci between samples. PCoA showed that 77.42% and 68.75% of specimens clustered separately in 1994 and 2004, respectively. Our analyses of four marker genes revealed different genetic diversity patterns with a decrease of diversity at and an increase for . There was no notable difference in genetic variation detected for and genes between the two periods. However, they represented distinctly different haplotypes. and followed a population expansion model, whereas and were under demographic equilibrium without selective pressure in the 1994 samples. Neutrality tests confirmed the excess of rare historical and recent mutations present in and in both samples. It is evident that a short-term ecological disturbance has impacted the genetic diversity and structure of .