Effects of genetic drift in a small population of Atlantic cod (Gadus morhua kildinensis Derjugin) landlocked in a meromictic lake: genetic variation and conservation measuresстатья
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Дата последнего поиска статьи во внешних источниках: 17 февраля 2016 г.
Аннотация:Landlocked populations of normally salt-water,
bottom-dwelling Atlantic cod exist in a few circumpolar
meromictic lakes. One such population, the Kildin cod,
inhabits Mogilnoe Lake (Kildin Island, the Barents Sea)
that is listed among regional nature reserves. The lake has
three main strata of water of about 5 m each: an upper level
with nearly fresh water, a saline layer, and an anaerobic
zone at the bottom. The fish lives in the saline stratum and
appears in the fresh layer as well. Available food is poor,
the adults heavily prey on cod juveniles. The Kildin cod
has distinct morphological features, faster growth rate,
earlier age of maturation, and shorter longevity that likely
developed in response to the unusual lake environment.
Genetic and capture-mark-recapture data show that the
Kildin cod greatly differs from its marine counterparts: It
has an effective population size of about one hundred and
an average adult census size of about half a thousand,
reproductively isolated from a parental marine population
around 1800 years ago, lost a large portion of microsatellite
and mitochondrial DNA variation due to long-term
genetic drift, but still maintains variation at allozyme loci.
DNA markers of the Kildin cod do not carry novel mutations,
but their multilocus genotypes seem to be unique to
the lake population. The suggested conservation strategy
includes: (1) the lake and its drainage area should be
strongly protected from any detrimental human activities;
(2) the transplantation of any genetic material into the cod
population of Mogilnoe Lake should be strongly
prohibited.