Neotropical crocodiles inhabit a broad geographical area, with populations found in coastal, inland, and island settings. Recent research has uncovered significant genetic diversity within this group and identified two new island species: one residing on Cozumel Island and the other on the Bancochinchoro atoll off the Yucatan Peninsula.
Adult American Crocodile (Crocodylus acutus) in La Manzanilla, Jalisco, Mexico. Image credit: Tomás Castelazo.
Crocodiles made their way from Africa to the neotropics approximately 5 million years ago, evolving into four recognized living species today.
American crocodile (Crocodylus acutus) thrives in various environments, including brackish and freshwater areas on mainlands, islands, and coral and diatomaceous atolls along the Pacific and Caribbean coasts of the neotropics, coexisting with three other species.
Meanwhile, Morelet’s Crocodile (Crocodylus moreletii) is classified as a species of least concern, while American crocodiles are listed as vulnerable, along with the other two species, which are considered critically endangered according to the International Union for Conservation of Nature Red List.
“Biodiversity is vanishing more quickly than we can comprehend what we are losing,” stated Professor Hans Larson, a researcher at McGill University.
“Many crocodile species are already endangered, and rapid coastal development poses a threat to nearly all populations.”
“Our research seeks to uncover the true diversity of alligators on these remote islands.”
Professor Larson and his team conducted a genetic analysis of the crocodile populations on Cozumel and Banco Chinchoro.
By comparing these genetic sequences to those from crocodiles in the Caribbean, Central America, and Mexico, they uncovered significant genetic differentiation, concluding that these populations are not simply variations of the American crocodile.
“These findings were entirely surprising,” remarked Dr. José Avila-Cervantes of McGill University.
“We believed Crocodylus acutus was a single species extending from Baja California to Venezuela and the Caribbean.”
“Our study is the first to thoroughly investigate the genome and anatomical differences of these animals.”
The two newly identified species are found in small, isolated populations, each consisting of fewer than 1,000 breeding individuals.
Both populations seem stable, yet are at risk due to their small numbers and habitat limitations.
“The rapid decline in biodiversity can only be mitigated if we identify which species are most at risk,” Professor Larson noted.
“Recognizing these crocodiles as separate species emphasizes the need to safeguard their habitats.”
“Limiting land development and implementing careful conservation measures in Cozumel and Banco Chinchoro will be crucial for their survival.”
The team’s paper was published in the journal Molecular Phylogeny and Evolution.
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Jose Avila Acervantes et al. 2025. New island species elucidate neotropical crocodile species complexes. Molecular phylogeny and evolution 207:108341; doi:10.1016/j.ympev.2025.108341
Source: www.sci.news
