Trapped in the extinction vortex? Strong genetic effects in a declining vertebrate population.
BACKGROUND
Inbreeding and loss of genetic diversity are expected to increase the extinction risk of small populations, but detailed tests in natural populations are scarce. We combine long-term population and fitness data with those from two types of molecular markers to examine the role of genetic effects in a declining metapopulation of southern dunlins Calidris alpina schinzii, an endangered shorebird.


RESULTS
The decline is associated with increased pairings between related individuals, including close inbreeding (as revealed by both field observations of parentage and molecular markers). Furthermore, reduced genetic diversity seems to affect individual fitness at several life stages. Higher genetic similarity between mates correlates negatively with the pair's hatching success. Moreover, offspring produced by related parents are more homozygous and suffer from increased mortality during embryonic development and possibly also after hatching.


CONCLUSIONS
Our results demonstrate strong genetic effects in a rapidly declining population, emphasizing the importance of genetic factors for the persistence of small populations.
Blomqvist
Donald
D
Department of Zoology, University of Gothenburg, Box 463, Gothenburg 40530, Sweden. donald.blomqvist@zool.gu.se
Pauliny
Angela
A
Larsson
Mikael
M
Flodin
Lars-Ake
LA
D000818:Animals; D001717:Birds / Q000235:genetics*; D003247:Conservation of Natural Resources; D056727:Endangered Species; D056084:Genetic Fitness; D014644:Genetic Variation; D005828:Genetics, Population; D007178:Inbreeding; D018895:Microsatellite Repeats; D010375:Pedigree; D017422:Sequence Analysis, DNA