Cenozoic climate change and diversification on the continental shelf and slope: evolution of gastropod diversity in the family Solariellidae (Trochoidea)

Abstract

Recent expeditions have revealed high levels of biodiversity in the tropical deep-sea, yet little is known about the age or origin of this biodiversity, and large-scale molecular studies are still few in number. In this study, we had access to the largest number of solariellid gastropods ever collected for molecular studies, including many rare and unusual taxa. We used a Bayesian chronogram of these deep-sea gastropods (1) to test the hypothesis that deep-water communities arose onshore, (2) to determine whether Antarctica acted as a source of diversity for deep-water communities elsewhere and (3) to determine how factors like global climate change have affected evolution on the continental slope. We show that although fossil data suggest that solariellid gastropods likely arose in a shallow, tropical environment, interpretation of the molecular data is equivocal with respect to the origin of the group. On the other hand, the molecular data clearly show that Antarctic species sampled represent a recent invasion, rather than a relictual ancestral lineage. We also show that an abrupt period of global warming during the Palaeocene Eocene Thermal Maximum (PETM) leaves no molecular record of change in diversification rate in solariellids and that the group radiated before the PETM. Conversely, there is a substantial, although not significant increase in the rate of diversification of a major clade approximately 33.7 Mya, coinciding with a period of global cooling at the Eocene–Oligocene transition. Increased nutrients made available by contemporaneous changes to erosion, ocean circulation, tectonic events and upwelling may explain increased diversification, suggesting that food availability may have been a factor limiting exploitation of deep-sea habitats. Tectonic events that shaped diversification in reef-associated taxa and deep-water squat lobsters in central Indo-West Pacific were also probably important in the evolution of solariellids during the Oligo-Miocene.

First glimpse into Lower Jurassic deep-sea biodiversity: in situ diversification and resilience against extinction

“…Debates have focused on the impact of variations in temperature, oxygenation and circulation mode on the colonization of deep habitats, and at least for the late Cenozoic, deep-sea sediment cores have provided extensive benthic foraminifer and ostracod microfossil evidence in this respect [3,4]. Biogeographic patterns and molecular clock estimates have yielded dates which predominantly converge to a latest Mesozoic or early Cenozoic origin of the modern deep-sea fauna [5][6][7][8][9]. Testing these hypotheses and exploring older deep-sea biodiversity using direct fossil evidence, however, has been hampered so far by the sparse record of & 2014 The Author(s) Published by the Royal Society.…”

Repeated eye reduction events reveal multiple pathways to degeneration in a family of marine snails

“…Solariellidae is a family of small marine vetigastropods found worldwide from littoral to abyssal depths, and eye loss has been reported in several species across the family (Marshall ; Williams et al. ). This group provides an excellent opportunity to study the potential for anatomical determinism in eye loss and to draw comparisons among eyeless taxa, and offers a larger sample of eye reduction events than more commonly studied cavernicolous groups (Jeffery ; Tierney et al.…”

An annotated catalogue and bibliography of the taxonomy, synonymy and distribution of the Recent Vetigastropoda of South Africa (Mollusca)

“…Kensley, 1973 Notes. Molecular sequence data has demonstrated that the material studied by and Herbert (1987c) is composite, containing at least one additional cryptic species (Williams et al 2013). Further studies are needed to resolve the taxonomy of this complex.…”

“…At that time, however, the solariellid fauna of the central Indo-West Pacific was little known and, erring on the side of caution, I was reluctant to definitively conclude that Margarita bicarinata was in fact a South African rather than an oriental species. In the intervening years the solariellid fauna the 'Eastern Seas' has become better documented Poppe & Tagaro 2008c;Vilvens 2009;Williams et al 2013;Vilvens, Williams & Herbert 2014;Vilvens & Williams in press), but no species resembling Margarita bicarinata has been encountered. As a result, I believe it can be justifiably concluded that Margarita bicarinata was originally mislocalised and that it is in fact the Agulhas Bank taxon currently known by the name Ilanga undata undata.…”

“…The morphology of the shell and radula of this species (Herbert 1987c) strongly suggest that it is referable to Zetela rather than Solariella (cf. Marshall 1999;Williams et al 2013).…”