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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Donald blomqvist dept zoology univ gothenburg sweden

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

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

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

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


Donald blomqvist dept zoology univ gothenburg sweden

Population

The aim of our study

Southern Dunlin Calidris alpina schinzii


The dunlin

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

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


Donald blomqvist dept zoology univ gothenburg sweden

Study population


Donald blomqvist dept zoology univ gothenburg sweden

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


Donald blomqvist dept zoology univ gothenburg sweden

More extinctions than re-colonizations of local populations

The entire metapopulation is threatened by extinction


Questions

Questions

  • Population decline associated with more matings between related individuals?

  • Fitness consequences?

  • Is habitat management sufficient for preserving the Southern Dunlin?


Donald blomqvist dept zoology univ gothenburg sweden

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


Questions1

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

Increased frequency of matings between related individuals

Pedigrees (141 pairs)

DNA fingerprinting

p = 0.038, 40 pairs


Questions2

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

Related parents suffer increased hatching failure

p = 0.024

36 pairs


More homozygous chicks die earlier

Morehomozygouschicksdie earlier

p = 0.023


Homozygous chicks are less likely to survive to breeding age

Homozygous chicks are less likely to survive to breeding age

p = 0.032


Questions3

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

Protective nest cages 2001-2004


Cages improve nest survival

...yet the population continues to decline

Cages improve nest survival...

p = 0.048, 86 nests


Conclusions

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


Donald blomqvist dept zoology univ gothenburg sweden

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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