Caught in the extinction vortex?
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Caught in the extinction vortex? Population dynamics and genetics in a metapopulation of dunlins. Donald Blomqvist Dept. Zoology, Univ. Gothenburg, Sweden. Small and isolated populations risk extinction for several reasons. Changes in demography and environment Genetic threats

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Donald Blomqvist Dept. Zoology, Univ. Gothenburg, Sweden

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Caught in the extinction vortex?

Population dynamics and genetics in a metapopulation of dunlins

Donald Blomqvist

Dept. Zoology, Univ. Gothenburg, Sweden


Small and isolated populations risk extinction for several reasons

  • Changes in demography and environment

  • Genetic threats

    - Inbreeding

    - Genetic drift

    - Mutation accumulation

  • Together form an ”extinction vortex”


Inbreeding

  • More immediate threat than other genetic factors

  • Related parents produce more homozygous offspring: expression of recessive, detrimental alleles

  • Reduction in individual fitness: inbreeding depression

  • Well documented in plants and animals


Influence of inbreeding and loss of genetic diversity on extinction risk

  • Theoretically expected

  • Supported by computer simulations, lab experiments, and studies of plants and butterflies in the wild

  • Still few studies of natural populations


Population

The aim of our study

Southern Dunlin Calidris alpina schinzii


The Dunlin

  • Circumpolar breeding distribution

  • Winters in temperate or tropical areas

  • Mean lifespan 5-7 years, max ~ 20 years

  • Socially monogamous

  • Several subspecies


The Southern Dunlin

  • Breeds in SE Greenland and NW Europe

  • In the Baltic Sea region, confined to wet pastures and meadows

  • Habitat loss - large population decline

  • Endangered


Study population


Several inter-connected, local populations form a meta-population


More extinctions than re-colonizations of local populations

The entire metapopulation is threatened by extinction


Questions

  • Population decline associated with more matings between related individuals?

  • Fitness consequences?

  • Is habitat management sufficient for preserving the Southern Dunlin?


Data

Long-term study:

Population, pedigree and individual fitness data

Two types of molecular markers:

  • DNA fingerprinting: Genetic similarity of mates

  • Microsatellite genotyping (7 loci): Individual genetic diversity


Questions

  • Population decline associated with more matings between related individuals?

  • Fitness consequences?

  • Is habitat management sufficient for preserving the Southern Dunlin?


Increased frequency of matings between related individuals

Pedigrees (141 pairs)

DNA fingerprinting

p = 0.038, 40 pairs


Questions

  • Population decline associated with more matings between related individuals?

  • Fitness consequences?

  • Is habitat management sufficient for preserving the Southern Dunlin?


Related parents suffer increased hatching failure

p = 0.024

36 pairs


Morehomozygouschicksdie earlier

p = 0.023


Homozygous chicks are less likely to survive to breeding age

p = 0.032


Questions

  • Population decline associated with more matings between related individuals?

  • Fitness consequences?

  • Is habitat management sufficient for preserving the Southern Dunlin?


Protective nest cages 2001-2004


...yet the population continues to decline

Cages improve nest survival...

p = 0.048, 86 nests


Conclusions

  • The population decline of the Southern Dunlin has serious genetic consequences

  • Habitat management seems insufficient for preserving the Southern Dunlin

  • Ignoring genetics will underestimate extinction risks and may lead to inappropriate conservation measures


Financial support

Swedish Research Council (Formas)

County Administration Board of Halland, Sweden

THANKS!

Co-workers

L.-Å. Flodin

H. Hirsimäki

O. C. Johansson

M. Larsson

A. Pauliny

U. Unger

J. Wallander


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