Líffræðifélag Íslands
Líffræðiráðstefnan 2015
Erindi/veggspjald / Talk/poster V60
Guðni Magnús Eiríksson, Einar Árnason
Háskóli Íslands, Líf- og umhverfisvísindadeild
Kynnir / Presenter: Einar Árnason
Tengiliður / Corresponding author: Guðni Magnús Eiríksson (gme@hi.is)
Genetic variation in spawning Atlantic cod, Gadus morhua, around Iceland was examined using mitochondrial DNA sequence information. A 328 base pair fragment of the cytochrome b gene in 2656 individuals sampled all around Iceland was examined. Variation was found at 70 sites defining 128 haplotypes. The observed polymorphism was mostly synonymous, suggesting weak or no natural selection acting on it. Demographic analysis of the genetic variation suggest sudden expansion of the Atlantic cod population estimated to have taken place 96 Kyr ago. Rapid changes in allele frequency observed in the present study, particularly in cod from NE-Iceland, suggest that the mtDNA sequence variation is an ideal marker for detecting recent population divergence. Temporal genetic analysis showed heterogenity in haplotype frequency change between NE- and SW-Iceland. This is in accordance with earlier findings that have shown temporal and spatial variation in the contribution of different spawning grounds to each cohort. The variation is likely to be attributed to strength of the warm Atlantic ocean current, but temporal variation in spawning success in different spawning grounds may also be important. Our analysis does not suggest the Atlantic cod around Iceland is divided into distinct historical populations as has been suggested in earlier studies. On the contrary it supports the view of high levels of gene flow in Atlantic cod around Iceland. We suggest that the mixing of cod at times when ocean currents allow high levels of embryo/larvae drift, prevents the evolution of distinct populations.