Equatorward increase in naticid gastropod drilling predation on infaunal bivalves from Brazil with paleontological implications Christy C. Visaggi a,b, ⁎, Patricia H. Kelley c a Department of Biology and Marine Biology, University of North Carolina Wilmington, 601 S. College Road, Wilmington, NC, 28403 USA b Department of Geosciences, Georgia State University, P.O. Box 3965, Atlanta, GA, 30302 USA c Department of Geography and Geology, University of North Carolina Wilmington, 601 S. College Road, Wilmington, NC, 28403 USA abstract article info Article history: Received 17 February 2015 Received in revised form 25 July 2015 Accepted 27 July 2015 Available online 5 August 2015 Keywords: Naticidae Drilling predation Latitudinal variation South America Understanding the influence of spatial variation on temporal trends is important for interpreting evolutionary patterns of predation in the fossil record. Geographic data on naticid gastropod drilling predation are contra- dictory and mostly limited to the Northern Hemisphere. This study examines latitudinal variation in drilling on ~24,000 beach-collected Recent bivalves from 6°S to 34°S in Brazil. Twenty-eight localities representing 16 latitudes were sampled in the Brazilian and Argentinean provinces, further subdivided into four smaller ecoregions (Northeastern Brazil, Eastern Brazil, Southeastern Brazil, Rio Grande). Analyses focused on bivalves exhibiting infaunal life habits. Increased drilling equatorward was observed at the assemblage-level across several spatial scales (localities, latitudes, ecoregions, provinces). Taxon-level analyses for eight genera drilled across multiple ecoregions generally indicated greater drilling among lower latitudes; size standardization did not affect patterns at the genus level. An equatorward increase in drilling was documented also upon restricting the data to localities characterized primarily by softer substrates, fine- to medium-grained sediments, and in limiting data to samples obtained by a single collecting strategy, minimizing concerns regarding the influence of local environmental variation and different methodologies on latitudinal patterns in drilling. Latitudinal pat- terns in drilling may be related to temperature and seasonality in influencing metabolic rates, as well as diversity and predator–prey size distributions. The results of this study do not correspond to existing patterns previously described for Western Atlantic molluscan assemblages of the Northern Hemisphere. However, they may help explain temporal patterns in the fossil record of naticid predation. © 2015 Elsevier B.V. All rights reserved. 1. Introduction Understanding patterns and processes that operate over broad spatial and temporal scales has become increasingly important in ad- dressing large-scale environmental problems impacting global habitats and the species therein (Sanford and Bertness, 2009; Schemske et al., 2009). Local studies have offered insight into the dynamics of marine ecosystems and the importance that factors such as predation have on communities (e.g., Menge, 1976), but how these results scale up in space or time remains unresolved (e.g., Bennington et al., 2009). Im- proved understanding is needed of how abiotic and biotic variables influence species interactions on a macroecological scale (Sanford and Bertness, 2009) and of the role of such species interactions in evolution (Jablonski and Sepkoski, 1996; Jablonski, 2008). In particular, predator– prey interactions have been considered as potentially important in evolution, either through coevolution (reciprocal adaptation; Ehrlich and Raven, 1964; Futuyma and Slatkin, 1983), or escalation, involving enemy-driven adaptation (Vermeij, 1987, 1994). Escalation claims that the intensity of, and adaptations to, biological hazards such as predation and competition has increased throughout geologic time (Vermeij, 2002). Much of the history of life thus can be interpreted as the result of arms races in which prey evolve in response to their predators, but then predators evolve in response to their enemies (Dietl and Kelley, 2002). Substantial evidence for escalation consists of drillholes preserved in fossil mollusk shells, providing a record of ancient predator–prey interactions. Beveled drillholes usually can be attributed to predatory naticid gastropods (moon snails). Because naticids most often prey upon shallow-burrowing marine bivalves and gastropods, evidence of drilling predation is readily preserved in both modern shells and paleontological assemblages. Based on a limited literature survey, Vermeij (1987) stated that drilling frequencies were low in the Cretaceous and reached modern levels by the Eocene. Kelley and Hansen (1993, 1996, 2003, 2006) reported instead that escalation appeared to be episodic, based on their database on naticid drilling from collections of N 150,000 mollusk speci- mens from the U.S. Coastal Plain Cretaceous through Pleistocene. Kelley and Hansen (2007) suggested that the fluctuations in drilling frequency may be linked to variations in climate, in part because samples from Palaeogeography, Palaeoclimatology, Palaeoecology 438 (2015) 285–299 ⁎ Corresponding author at: Department of Geosciences, Georgia State University, P.O. Box 3965, Atlanta, GA, 30302 USA. E-mail addresses: cvisaggi@gsu.edu (C.C. Visaggi), kelleyp@uncw.edu (P.H. Kelley). Contents lists available at ScienceDirect Palaeogeography, Palaeoclimatology, Palaeoecology journal homepage: www.elsevier.com/locate/palaeo http://dx.doi.org/10.1016/j.palaeo.2015.07.045 0031-0182/© 2015 Elsevier B.V. All rights reserved.