MSGID: 1:317/3 63f83d76   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    A labyrinth lake provides surprising benefits for an endangered seal   
      
      
     Date:   
         February 23, 2023   
     Source:   
         University of Helsinki   
     Summary:   
         The endangered Saimaa ringed seal is an Ice Age relict living in   
         the highly labyrinthine Lake Saimaa, Finland. The newly published   
         work shows that although individual seals have greatly reduced   
         genetic variation, the loss of variation has been complementary,   
         preserving the adaptive potential of the whole population.   
      
      
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   FULL STORY   
   ==========================================================================   
   The endangered Saimaa ringed seal is an Ice Age relict living in the   
   highly labyrinthine Lake Saimaa, Finland. The newly published work shows   
   that although individual seals have greatly reduced genetic variation,   
   the loss of variation has been complementary, preserving the adaptive   
   potential of the whole population.   
      
      
   ==========================================================================   
   Lake Saimaa, a highly labyrinthine lake in eastern Finland,   
   provides a unique opportunity for assessing the effects of population   
   fragmentation. The lake hosts a population of ringed seals (Pusa hispida   
   saimensis) that became landlocked as the land rebounded after the retreat   
   of the continental ice sheet 10,000 years ago. Today, the Saimaa ringed   
   seal, with some 400 individuals, is one of the world's most endangered   
   seals.   
      
   Researchers from the University of Helsinki together with colleagues   
   from the University of Eastern Finland and the University of Copenhagen   
   compared over 100 genomes of Saimaa ringed seals preserved in a tissue   
   bank.   
      
   "The Saimaa ringed seals have gone through a severe population size   
   contraction resulting in greatly reduced genetic variation. This   
   raises concerns about their ability to adaptively respond to ongoing   
   climate change," Petri Auvinen and Jukka Jernvall from the University   
   of Helsinki say.   
      
   The analyses revealed that the genomes of individual seals contained   
   long stretches of DNA sequences that were inherited identically from   
   both parents.   
      
   Comparisons of these homozygous regions among seals living in far-flung   
   nooks of the lake revealed something unexpected. "The good news is that   
   the labyrinthine shape of Lake Saimaa has generated three subpopulations   
   that are homozygous for largely different, complementary parts of their   
   genome. This means that the population as a whole has retained much   
   of its original genetic variation," explains Ari Lo"ytynoja from the   
   University of Helsinki.   
      
   Modelling the population history of the Saimaa ringed seals further   
   suggested that the intricate shape of Lake Saimaa has been optimal   
   in compensating for the detrimental effects of small population   
   size. Detailed analyses also revealed a beneficial genetic signature   
   of a seal individual that was translocated decades ago from one part of   
   the lake to another. For the conservation of other endangered species,   
   the lesson learned from the labyrinthine Lake Saimaa is the importance   
   of careful gene flow management among poorly connected populations.   
      
       * RELATED_TOPICS   
             o Plants_&_Animals   
                   # Zoology # Marine_Biology # Endangered_Animals #   
                   Evolutionary_Biology   
             o Earth_&_Climate   
                   # Ecology # Global_Warming # Ice_Ages # Biodiversity   
       * RELATED_TERMS   
             o Heritability o Common_Seal o Ice_age o Genetics o   
             Genetic_recombination o Evolution o Allele_frequency o Deciduous   
      
   ==========================================================================   
   Story Source: Materials provided by University_of_Helsinki. Note:   
   Content may be edited for style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Ari Lo"ytynoja, Pasi Rastas, Mia Valtonen, Juhana Kammonen,   
      Liisa Holm,   
         Morten Tange Olsen, Lars Paulin, Jukka Jernvall, Petri Auvinen.   
      
         Fragmented habitat compensates for the adverse effects of genetic   
         bottleneck. Current Biology, 2023; DOI: 10.1016/j.cub.2023.01.040   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/02/230223132910.htm   
      
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