Publication Abstract

Temporal changes in allele frequencies but stable genetic diversity over the past 40 years in the Irish Sea population of thornback ray, Raja clavata

Temporal changes in allele frequencies but stable genetic diversity over the last 40 years in the Irish Sea population of thornback ray.

M. Chevolot, J.R. Ellis, A.D. Rijnsdorp, W.T. Stam and J.L. Olsen

The effective population size (Ne) and temporal changes in the genetic diversity were estimated for the population of thornback ray (Raja clavata) in the Irish Sea and Bristol Channel. Using five highly polymorphic microsatellite loci and a temporal method examining archived (1965) and contemporary (2003–2004) samples, Ne was estimated at 399 individuals [95% CI = 113–2213 individuals] with an Ne/N ratio between 1.3 x 10–4 and 8 x 10-4. Although the ratio is low, showing that few individuals contribute to the next generation, it is higher than that reported for teleosts.  Differences in reproductive success, due to differences in life history traits (fecundity, egg and juvenile mortality) may explain the higher Ne/N ratio in skates. However the Ne/N ratio in skates remains small and other factors, such as mating systems and fluctuations in population size, may play a major role in lowering this ratio. There was no evidence for a loss of genetic diversity over the 40-yr timeframe. These results suggest that thornback ray populations may be at genetic risk over the long but not in the short term.

Reference

M. Chevolot, J.R. Ellis, A.D. Rijnsdorp, W.T. Stam and J.L. Olsen  (2008) Low effective population size but stable genetic diversity in the Irish Sea population of thornback ray Raja clavata. Heredity, 101; 120-126

M. Chevolot, J.R. Ellis*, A.D. Rijnsdorp, W.T. Stam and J.L. Olsen

Heredity, 101; 120-126