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

Urmia Lake, the largest natural habitat of the brine shrimpArtemia urmiana, 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.Artemia urmianahas 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 ofA. urmianain 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 atITS1and an increase forNa+/K+ATPase. There was no notable difference in genetic variation detected forCOIand16Sgenes between the two periods. However, they represented distinctly different haplotypes.ITS1andCOIfollowed a population expansion model, whereasNa+/K+ATPaseand16Swere under demographic equilibrium without selective pressure in the 1994 samples. Neutrality tests confirmed the excess of rare historical and recent mutations present inCOIandITS1in both samples. It is evident that a short-term ecological disturbance has impacted the genetic diversity and structure ofA. urmiana.