Abstract
Extinctions and declines of large marine vertebrates have major ecological impacts and are of critical concern in marine environments. The Caribbean monk seal, Monachus tropicalis, last definitively reported in 1952, was one of the few marine mammal species to become extinct in historical times. Despite its importance for understanding the evolutionary biogeography of southern phocids, the relationships of M. tropicalis to the two living species of critically endangered monk seals have not been resolved. In this study we present the first molecular data for M. tropicalis, derived from museum skins. Phylogenetic analysis of cytochrome b sequences indicates that M. tropicalis was more closely related to the Hawaiian rather than the Mediterranean monk seal. Divergence time estimation implicates the formation of the Panamanian Isthmus in the speciation of Caribbean and Hawaiian monk seals. Molecular, morphological and temporal divergence between the Mediterranean and “New World monk seals” (Hawaiian and Caribbean) is profound, equivalent to or greater than between sister genera of phocids. As a result, we classify the Caribbean and Hawaiian monk seals together in a newly erected genus, Neomonachus. The two genera of extant monk seals (Monachus and Neomonachus) represent old evolutionary lineages each represented by a single critically endangered species, both warranting continuing and concerted conservation attention and investment if they are to avoid the fate of their Caribbean relative.
Highlights
M. tropicalis to the two living species of critically endangered monk seals have not been resolved
A western Atlantic origin with dispersal to the eastern Atlantic in the lineage leading to Monachus monachus would be parsimonious based on our results, and attempts to quantitatively assess these hypotheses using Dispersal-Extinction-Cladogenesis models (Ree and Smith 2008, data not shown) were equivocal regarding the center of origin of Monachus, Monachinae, and Phocidae
Based on phylogenetic analysis and divergence time estimation, we revealed that the Caribbean and Hawaiian monk seals form a well-supported monophyletic New
Summary
M. tropicalis to the two living species of critically endangered monk seals have not been resolved. The Hawaiian monk seal, Monachus schauinslandi Matschie, 1905, occurs throughout the Hawaiian island chain (Figure 1), with a current population of about 1000 animals (Lowry and Aguilar 2008, Schultz et al 2009). Both of these extremely endangered species are threatened by many anthropogenic stressors, including mortality from hunting, entanglement in fishing gear, competition with fisheries for food, loss and disturbance of coastal habitats and breeding sites, oceanic pollution, and emerging diseases (Lowry and Aguilar 2008, Aguilar and Lowry 2013, Kovacs et al 2012)
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