title: Global biogeography and evolution of Cuvierina pteropods.
abstract: BACKGROUND
  Shelled pteropods are planktonic gastropods that are potentially good indicators of the effects of ocean acidification. They also have high potential for the study of zooplankton evolution because they are metazoan plankton with a good fossil record. We investigated phenotypic and genetic variation in pteropods belonging to the genus Cuvierina in relation to their biogeographic distribution across the world's oceans. We aimed to assess species boundaries and to reconstruct their evolutionary history.
  
  
  RESULTS
  We distinguished six morphotypes based on geometric morphometric analyses of shells from 926 museum and 113 fresh specimens. These morphotypes have distinct geographic distributions across the Atlantic, Pacific and Indian oceans, and belong to three major genetic clades based on COI and 28S DNA sequence data. Using a fossil-calibrated phylogeny, we estimated that these clades separated in the Late Oligocene and Early to Middle Miocene. We found evidence for ecological differentiation among all morphotypes based on ecological niche modelling with sea surface temperature, salinity and phytoplankton biomass as primary determinants. Across all analyses, we found highly congruent patterns of differentiation suggesting species level divergences between morphotypes. However, we also found distinct morphotypes (e.g. in the Atlantic Ocean) that were ecologically, but not genetically differentiated.
  
  
  CONCLUSIONS
  Given the distinct ecological and phenotypic specializations found among both described and undescribed Cuvierina taxa, they may not respond equally to future ocean changes and may not be equally sensitive to ocean acidification. Our findings support the view that ecological differentiation may be an important driving force in the speciation of zooplankton.
authors.affiliation: Naturalis Biodiversity Center, P.O. Box 9517, Leiden, 2300 RA, The Netherlands. Alice.Burridge@naturalis.nl.|Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O. Box 94248, Amsterdam, 1090 GE, The Netherlands. Alice.Burridge@naturalis.nl.
authors.forename: Alice K
authors.initials: AK
authors.lastname: Burridge
authors.affiliation: Department of Oceanography, University of Hawaii at Manoa, 1000 Pope Road, Honolulu, HI, 96822, USA. egoetze@hawaii.edu.
authors.forename: Erica
authors.initials: E
authors.lastname: Goetze
authors.affiliation: Naturalis Biodiversity Center, P.O. Box 9517, Leiden, 2300 RA, The Netherlands. Niels.Raes@naturalis.nl.
authors.forename: Niels
authors.initials: N
authors.lastname: Raes
authors.affiliation: Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O. Box 94248, Amsterdam, 1090 GE, The Netherlands. J.Huisman@uva.nl.
authors.forename: Jef
authors.initials: J
authors.lastname: Huisman
authors.affiliation: Naturalis Biodiversity Center, P.O. Box 9517, Leiden, 2300 RA, The Netherlands. k.t.c.a.peijnenburg@uva.nl.|Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, P.O. Box 94248, Amsterdam, 1090 GE, The Netherlands. k.t.c.a.peijnenburg@uva.nl.
authors.forename: Katja T C A
authors.initials: KT
authors.lastname: Peijnenburg
mesh_terms: D060105:Animal Shells / Q000033:anatomy & histology; D000818:Animals; D005075:Biological Evolution; D017753:Ecosystem; D005580:Fossils; D049851:Gastropoda / Q000033:anatomy & histology* / Q000145:classification / Q000235:genetics*; D014644:Genetic Variation; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009792:Oceans and Seas; D010802:Phylogeny