Glacial refugia, haplotype distributions, and clonal richness of the Daphnia pulex complex in arctic Canada

Abstract

As part of a large international Arctic biodiversity expedition (Tundra Northwest '99), we examined the distribution of members of the arctic Daphnia pulex complex (Cladocera, Anomopoda) from 121 tundra ponds, spread across 16 sites spanning a large portion of arctic Canada (i.e. from 62 degrees 22' N to 79 degrees 01' N; 66 degrees 45' W to 139 degrees 37' W). Using allozyme electrophoresis and mitochondrial (mt)DNA analyses, we examined the population genetic (clonal) structure of these populations. The following taxa were detected in this complex: Daphnia pulicaria, D. middendorffiana and D. tenebrosa. Clear geographical differences in mean clonal richness and diversity were observed, with most western sites exhibiting higher clonal richness and diversity, than sites in the eastern Canadian Arctic. For both the pulicaria group (i.e. D. pulicaria and D. middendorffiana) and D. tenebrosa, the highest mean regional clonal richness was detected from the southern section of Banks Island, an unglaciated site situated on the edge or directly in the eastern fringe of the Beringian glacial refuge. A significant negative correlation was found between geographical distance from the Beringian edge, and overall regional clonal richness (i.e. sites closer to the edge harboured greater clonal richness). These results clearly indicate that more recently deglaciated regions (i.e. eastern Canadian Arctic) harbour lower levels of clonal richness than western regions nearer Beringia. We discuss the role that glacial refugia have played in influencing both biotic and genetic diversity in arctic taxa.

Effects of acid mine drainage on the genetic diversity and structure of a natural population of Daphnia longispina

“…Genetic diversity values found for the three studied populations were similar and within the range of other studies with Daphnia populations. Specifically, Nei's genetic diversity index in the present study ranged from 0.33 ± 0.16 to 0.36 ± 0.08 (mean ± standard deviation) while other studies with Daphnia populations reported values of 0.22 (Haag et al, 2005(Haag et al, , 2006 and from 0.10 to 0.50 (Weider and Hobaek, 2003). The values of observed heterozygosity here found ranged from 0.30 to 0.35, which were within the range of reported values of 0.42 ± 0.21 to 0.59 ± 0.28 (Giessler, 1997) and from 0.20 to 0.32 (Limburg and Weider, 2002).…”

Maximizing growth rate at low temperatures: RNA:DNA allocation strategies and life history traits of Arctic and temperate Daphnia

“…One temperate clone of Daphnia pulex was isolated in 1998 from a shallow pond at Nieuwersluis (The Netherlands: latitude 52°) and was cultured in laboratory prior to experiments. In 1998, polar Daphnia pulicaria was isolated from a pond close to Ny-Å lesund (Svalbard: latitude 79°; species have been identified according to Weider and Hobaek 2003). Microsatellite screening confirmed that the clone was polyploid as has previously also been inferred by the prevalence of unbalanced polymorphism (unpubl.…”

Goose-mediated nutrient enrichment and planktonic grazer control in arctic freshwater ponds

“…At Nordenskioldkysten, 23-27 individuals of Daphnia from each pond were randomly collected and stored in 80% ethanol, after which the species composition was determined according to Weider and Hobaek (2003).…”