Genetic variation within the Icelandic goat breed: assessment using population data and DNA analysis

The Icelandic goat breed is a very small closed population consisting of only about 500-600 animals kept in 45 herds. The breed is believed to have originated from Norway during the settlement of Iceland in the years 874-930 AD. Several population bottlenecks are known to have occurred and the population has at least twice declined to under 100 animals. In the present study the genetic diversity within the Icelandic goat population is estimated on the base of both pedigree information and DNA analysis. The estimate is based on three approaches. Firstly, pedigree information is used to calculate the rate of inbreeding, pedigree completeness, generation interval, effective population size, highest contributing ancestors and relationship within and between areas. Secondly, microsatellite markers were used for genotyping and various diversity measures were calculated as well as the effective population size. Thirdly, parts of the mtDNA D-loop were sequenced in order to estimate the genetic diversity and structure of the population. Genetic diversity of livestock is an important factor in animal breeding and it is the basis for all genetic adaptability. The major concern of Icelandic goat breeders is that the breed might become extinct, due to a small population size, extensive fragmentation and high levels of inbreeding. The findings presented here confirm their concern. The genetic diversity of the population is shown to be very low and the inbreeding levels high. Results from pedigree data show that the estimated annual rate of inbreeding is around 3% and the generation interval 3.5 years, corresponding to an increase in inbreeding of 9.9% per generation and the average inbreeding within the population in the year 2006 was 15.9% (PEC5 0.24). The estimated effective population size is 5.1 animals. The two most influential ancestors in the years 2002 and 2006 contributed 9.5% and 16.5% of the genetic material, respectively. Relationship calculations showed that there is relatively higher relationship within areas than between areas. Microsatellite analysis revealed a mean number of observed alleles per locus of 1.8, ranging from 1 to 4 for individual markers, six markers were monomorphic. The overall mean observed heterozygosity of 0.178 was lower than the mean overall expected heterozygosity of 0.185. The effective population size was estimated to be 4.1-8.8 individuals. Results from the mtDNA D-loop sequencing showed three haplotypes all representing the most common goat haplogroup A. Altogether, these results confirm that the Icelandic goat population is in a critical state with extremely low genetic diversity.

Author dc:creator

• Birna Kristín Baldursdóttir 1960-

Contributors dc:contributor

• Landbúnaðarháskóli Íslands

• Geitur
• Erfðabreytileiki
• Skildleikarækt
• Ísland

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/1946/7339

OAI identifier oai:identifier

oai:skemman.is:1946/7339