Original Research ARTICLE
Global patterns of species richness in coastal cephalopods
- 1University of Lisbon, Portugal
- 2University of Coimbra, Portugal
- 3Tohoku University, Japan
- 4Kazan Federal University, Russia
- 5Independent researcher, Italy
- 6Severtsov Institute of Ecology and Evolution (RAS), Russia
- 7Institute of Marine Research (CSIC), Spain
- 8University of South Florida St. Petersburg, United States
- 9Universidad Andrés Bello, Chile
- 10GEOMAR Helmholtz Center for Ocean Research Kiel, Germany
- 11Smithsonian National Museum of Natural History (SI), United States
Within the context of global climate change and overfishing of fish stocks, there is some evidence that cephalopod populations are benefiting from this changing setting. These invertebrates show enhanced phenotypic flexibility and are found from polar regions to the tropics. Yet, the global patterns of species richness in coastal cephalopods are not known. Here, among the 370 identified-species, 164 are octopuses, 96 are cuttlefishes, 54 are bobtails and bottletails, 48 are inshore squids and 8 are pygmy squids. The most diverse ocean is the Pacific (with 213 cephalopod species), followed by the Indian (146 species) and Atlantic (95 species). The least diverse are the Southern (15 species) and the Arctic (12 species) Oceans. Endemism is higher in the Southern Ocean (87%) and lower in the Arctic (25%), which reflects the younger age and the “Atlantification” of the latter. The former is associated with an old lineage of octopuses that diverged around 33 Ma. Within the 232 ecoregions considered, the highest values of octopus and cuttlefish richness are observed in the Central Kuroshio Current ecoregion (with a total of 64 species), followed by the East China Sea (59 species). This pattern suggests dispersal in the Central Indo-Pacific (CIP) associated with the highly productive Oyashio/Kuroshio current system. In contrast, inshore squid hotspots are found within the CIP, namely in the Sunda Shelf province, which may be linked to the occurrence of an ancient intermittent biogeographic barrier: a land bridge formed during the Pleistocene which severely restricted water flow between the Pacific and Indian Oceans, thereby facilitating squid fauna differentiation. Another marked pattern is a longitudinal richness cline from the Central (CIP) towards the Eastern Indo-Pacific (EIP) realm, with central Pacific archipelagos as evolutionary dead ends. In the Atlantic Ocean, closure of the Atrato Seaway (at the Isthmus of Panama) and Straits of Gibraltar (Mediterranean Sea) are historical processes that may explain the contemporary Caribbean octopus richness and Mediterranean sepiolid endemism, respectively. Last, we discuss how the life cycles and strategies of cephalopods may allow them to adapt quickly to future climate change and extend the borealization of their distribution.
Keywords: biogeography, mollusk, cephalopod, cuttlefish, Squid, octopus, species richness
Received: 06 May 2019;
Accepted: 11 Jul 2019.
Edited by:Sophie Von Der Heyden, Stellenbosch University, South Africa
Reviewed by:Luisa F. Dueñas, Universidad Nacional de Colombia, Colombia
Xiubao Li, Hainan University, China
Brian Bowen, University of Hawaii, United States
Copyright: © 2019 Rosa, Pissarra, Borges, Xavier, Gleadall, Golikov, Bello, Morais, Lishchenko, Roura, Judkins, Ibáñez, Piatkowski, Vecchione and Villanueva. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Mx. Rui Rosa, University of Lisbon, Lisbon, Portugal, firstname.lastname@example.org