Demographic changes in Pleistocene sea turtles were driven by past sea level fluctuations affecting feeding habitat availability

Jurjan P. van der Zee*, Marjolijn J.A. Christianen, Martine Bérubé, Mabel Nava, Sietske van der Wal, Jessica Berkel, Tadzio Bervoets, Melanie Meijer zu Schlochtern, Leontine E. Becking, Per J. Palsbøll

*Corresponding author for this work

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Abstract

Pleistocene environmental changes are generally assumed to have dramatically affected species’ demography via changes in habitat availability, but this is challenging to investigate due to our limited knowledge of how Pleistocene ecosystems changed through time. Here, we tracked changes in shallow marine habitat availability resulting from Pleistocene sea level fluctuations throughout the last glacial cycle (120–14 thousand years ago; kya) and assessed correlations with past changes in genetic diversity inferred from genome-wide SNPs, obtained via ddRAD sequencing, in Caribbean hawksbill turtles, which feed in coral reefs commonly found in shallow tropical waters. We found sea level regression resulted in an average 75% reduction in shallow marine habitat availability during the last glacial cycle. Changes in shallow marine habitat availability correlated strongly with past changes in hawksbill turtle genetic diversity, which gradually declined to ~1/4th of present-day levels during the Last Glacial Maximum (LGM; 26–19 kya). Shallow marine habitat availability and genetic diversity rapidly increased after the LGM, signifying a population expansion in response to warming environmental conditions. Our results suggest a positive correlation between Pleistocene environmental changes, habitat availability and species’ demography, and that demographic changes in hawksbill turtles were potentially driven by feeding habitat availability. However, we also identified challenges associated with disentangling the potential environmental drivers of past demographic changes, which highlights the need for integrative approaches. Our conclusions underline the role of habitat availability on species’ demography and biodiversity, and that the consequences of ongoing habitat loss should not be underestimated.

Original languageEnglish
Pages (from-to)1044-1056
Number of pages13
JournalMolecular Ecology
Volume31
Issue number4
DOIs
Publication statusPublished - Feb-2022

Keywords

  • ddRAD sequencing
  • demographic change
  • habitat availability
  • Pleistocene sea turtles
  • sea level change

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