"Biogeography and origin of keynote anchialine fauna," by Thomas Iliffe (Pres 22: 5ISAE)
This presentation was a part of the 5th International Symposium on Anchialine Ecosystems (5ISAE), held in Kailua-Kona November 3-5, 2022.
Presentation 22: "Biogeography and origin of keynote anchialine fauna"
Presentation Authors: Thomas M. Iliffe, Fernando Calderón Gutiérrez (2), Brett Gonzalez (3), Alejandro Martínez García (4), Lauren Ballou (5)
Affiliations: (2) Department of Marine Biology, Texas A&M University at Galveston, Galveston, Texas, USA; (3) Department of Invertebrate Zoology, Smithsonian Institution, National Museum of Natural History, Washington, DC, USA; (4) Molecular Ecology Group, Water Research Institute, National Research Council of Italy, Pallanza, Italy; (5) Department of Biology, Florida International University-Biscayne Bay Campus, North Miami, FL, USA
Presentation Abstract: The present-day distribution of keynote and ancient anchialine taxa, class Remipedia and genus Humphreysella (Thaumatocyprididae, Ostracoda), show considerable overlap in their anomalous global distribution. Both groups have the greatest number of species and their biodiversity hotspot in the Lucayan Archipelago (Bahamas + Turks and Caicos Islands). Ten of the 12 remipede genera and 21 of the 30 described remipedes species inhabit the Lucayan Archipelago. Likewise, four of the 12 species of Humphreysella are endemic to this region.
Outside the Lucayan Archipelago, remipedes inhabit anchialine caves in the Yucatan Peninsula (Mexico + Belize), Cuba, Canary Islands, Dominican Republic, and Western Australia, while Humphreysella occurs in Lanzarote, Cuba, Jamaica, Yucatan Peninsula, Galapagos, and Christmas Island.
The high level of anchialine biodiversity in the Lucayan Archipelago results from numerous caves occurring on isolated shallow-water limestone platforms separated by wide channels reaching open ocean depths. As a consequence of geographic isolation, all remipede and Humphreysella species occur exclusively on single platforms. Furthermore, these limestone platforms formed at the same time as the Atlantic Ocean in the Jurassic. Thus, limestone caves could have existed in the Lucayan Archipelago for the last 120 million years.
Initially, the Atlantic Ocean would have been much narrower than it is now, such that the limestone platforms of the Bahamas would have been considerably closer to the volcanic precursors of the Canary Islands. This close connection between the two cave regions is evidenced by the remipede genus Morlockia containing species from both Lanzarote and the Dominican Republic on opposite sides of the Atlantic.
The Tethys Seaway provided communication between the Atlantic and Indian Oceans and the possible transport for ancestors of Indian Ocean remipedes and Humphreysella. Furthermore, before the closure of the Panama isthmus in the late Miocene, Humphreysella could have dispersed from the Caribbean into the Pacific.