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Out with the old, introgression with the new: Signals of ancient and recent admixture in hybridizing Mesoamerican crocodiles (Crocodylus acutus x Crocodylus moreletii)
  • Helen Sung,
  • Marisa Tellez,
  • F A Reed
Helen Sung
University of Hawai'i at Manoa College of Natural Sciences

Corresponding Author:[email protected]

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Marisa Tellez
Crocodile Research Coalition
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F A Reed
University of Hawai'i at Manoa
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Abstract

A central aim of conservation is to preserve existing biodiversity and understand the ecological and evolutionary processes that support it. Inter- and intra-specific hybridization in wildlife has been recognized as a common and naturally occurring phenomenon that facilitates species adaptation and evolution. However, hybridization still constitutes one of the most challenging problems for legal protection and species management due to its perceived biological risk, lack of regulatory oversight, and different case-by-case impacts. When considering rare or threatened hybridizing species with unequal legal protection, management strategies risk being inaccurate or unsuccessful unless contextualized with an informed understanding of the species’ genetic and evolutionary backgrounds. We investigated hybridization dynamics and genetic diversity of American crocodiles (Crocodylus acutus) and Morelet’s crocodiles (Crocodylus moreletii) from Belize to ascertain whether genetic exchange through admixture displayed signs of evolutionary significance. Using genomic reduced representation (3RAD) datasets from 242 wild crocodile samples, we found evidence of population structure among C. acutus, as well as ancient bidirectional gene flow that had occurred between C. acutus and C. moreletii. Notably, we also found evidence of high levels of recent admixture along the coastal Crocodylus populations in areas with extensive habitat modification due to human impact. These findings as well as a discovered disconnect between morphological and genetic species assignments used to identify populations have implications for conservation management practices and suggest a range of additional genetic investigations to understand the natural and anthropogenic role of hybridization in large long-lived tropical predators that span marine and terrestrial ecosystems.
29 May 2024Submitted to Molecular Ecology
05 Jun 2024Reviewer(s) Assigned
22 Jul 2024Review(s) Completed, Editorial Evaluation Pending
09 Aug 2024Editorial Decision: Revise Minor
28 Sep 20241st Revision Received
07 Oct 2024Submission Checks Completed
07 Oct 2024Assigned to Editor
07 Oct 2024Review(s) Completed, Editorial Evaluation Pending
23 Oct 2024Reviewer(s) Assigned