Environmental controls on geographic range size in marine animal genera Author(s): Michael Foote Source: Paleobiology, 40(3):440-458. 2014. Published By: The Paleontological Society DOI: http://dx.doi.org/10.1666/13056 URL: http://www.bioone.org/doi/full/10.1666/13056 BioOne (www.bioone.org) is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne’s Terms of Use, available at www.bioone.org/page/ terms_of_use. Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. Paleobiology, 40(3), 2014, pp. 440–458 DOI: 10.1666/13056 Environmental controls on geographic range size in marine animal genera Michael Foote Abstract.—Here I test the hypothesis that temporal variation in geographic range size within genera is affected by the expansion and contraction of their preferred environments. Using occurrence data from the Paleobiology Database, I identify genera that have a significant affinity for carbonate or terrigenous clastic depositional environments that transcends the Database’s representation of these environments during the stratigraphic range of each genus. These affinity assignments are not a matter of arbitrarily subdividing a continuum in preference; rather, genera form distinct, nonrandom subsets with respect to environmental preference. I tabulate the stage-by-stage transitions in range size within individual genera and the stage-by-stage changes in the extent of each environment. Comparing the two shows that genera with a preference for a given environment are more likely to increase in geographic range, and to show a larger average increase in range, when that environment increases in areal extent, and likewise for decreases in geographic range and environmental area. Similar results obtain for genera with preferences for reefal and non-reef settings. Simulations and subsampling experiments suggest that these results are not artifacts of methodology or sampling bias. Nor are they confined to particular higher taxa. Genera with roughly equal preference for carbonates and clastics do not have substantially broader geographic ranges than those with a distinct affinity, suggesting that, at this scale of analysis, spatial extent of preferred environment outweighs breadth of environmental preference in governing geographic range. These results pertain to changes over actual geologic time within individual genera, not overall average ranges. Recent work has documented a regular expansion and contraction when absolute time is ignored and genera are superimposed to form a composite average. Environmental preference may contribute to this pattern, but its role appears to be minor, limited mainly to the initial expansion and final contraction of relatively short-lived genera. Michael Foote. Department of the Geophysical Sciences, University of Chicago, Chicago, Illinois 60637, U.S.A. E-mail: [email protected] Accepted: 9 January 2014 Published online: 7 May 2014 Supplemental materials deposited at Dryad: doi: 10.5061/dryad.76082 What Governs Changes in Geographic graphic range reflects fluctuations in the Range Size? extent of its preferred habitat. It may seem Geographic ranges of species and genera are obvious that the answer must be affirmative. highly dynamic on both ecological and geo- There are reasons to suppose that the expec- logical time scales (Bennett 1997; Gaston 1998, tation may not be so clear, however. For 2008, 2009; Jackson and Overpeck 2000; example, barriers to dispersal (Webb 1991, Jernvall and Fortelius 2004; Jablonski et al. 2006; Holland and Patzkowsky 2007; Patz- 2006, 2013; Raia et al. 2006; Brett et al. 2007; kowsky and Holland 2007; Lessios 2008) and Foote 2007; Foote et al. 2007, 2008; Hendy and ecological incumbency (Rosenzweig and Kamp 2007; Liow and Stenseth 2007; Patz- McCord 1991; Sheehan 2008; Valentine et al. kowsky and Holland 2007; Krug et al. 2008; 2008), as well as biotic interactions more Hadly et al. 2009; Roy et al. 2009; Liow et al. generally (Jablonski 2008), may restrict taxa 2010; Willis and MacDonald 2011). Given the from areas that they would otherwise be quite evidence that species often track the locations capable of inhabiting. of their preferred environments (Bennett 1997; Using data from the Paleobiology Database, Jackson and Overpeck 2000; Holland et al. I will characterize occurrences of marine 2001; Brett et al. 2007; Hendy and Kamp 2007; animal genera as coming from carbonate Holland and Zaffos 2011; Willis and MacDon- versus terrigenous clastic environments, ald 2011), it is natural to ask whether temporal which reflect both substrate composition and variation in the magnitude of a taxon’s geo- consistency and aspects of the broader depo- Ó 2014 The Paleontological Society. All rights reserved. 0094-8373/14/4003-00/$1.00 ENVIRONMENT AND GEOGRAPHIC RANGE 441 sitional system such as nutrient levels, turbid- genus that are assigned to carbonate and ity, and temperature (Wilson 1975; Peters 2008; clastic lithologies. These proportions were Foote and Miller 2013: Appendix 1), as well as treated as the null expectation for the frequen- reefal versus non-reef settings. I will demon- cy of occurrence of the genus in either strate that changes in the geographic range lithology. Any genus that had significantly sizes of genera correlate with changes in the more occurrences than expected in either extent of their preferred environment. Subsid- lithology, using a one-tailed binomial proba- iary analyses suggest that these results are not bility of 0.05, was considered to have an likely to be artifacts of methodology or biased affinity for the corresponding environment. sampling of environments. (This is similar to the approach of Kiessling and Aberhan [2007a] except insofar as they Materials and Methods used the overall number of fossil occurrences Occurrence data for marine animal genera, rather than number of collections to set the with associated information on stratigraphy, probabilities for the null expectation; they note lithology, paleoenvironment, and geography, [p. 417] that they obtain similar results using were downloaded from the Paleobiology collections instead.) In addition, I stipulated Database (paleobiodb.org) on 23 February an arbitrary minimum of ten occurrences for a 2012. Details of the download and vetting genus to be included in this study. Other procedures are described by Foote and Miller protocols, such as using a different critical (2013). The data are available at Dryad (doi: probability, a different minimum number of 10.5061/dryad.76082). Collections were as- occurrences, or a null expectation of equal signed to a series of stratigraphic intervals, proportions carbonate and clastic (Foote 2006; primarily international stages (Foote and Miller and Foote 2009) yield comparable Miller 2013); collections that could not be results (Appendix 1). The variety of protocols resolved to a single time interval were used to assign affinity preferentially select for ignored. Lithologies of each marine collection longer-lived and more abundant genera. Thus, were categorized as either carbonate or clastic, there is little I can say about the determinants following Foote (2006), with minor modifica- of geographic range within rare taxa. The tion, and using only the primary lithology main analyses include about 21% of all genera, field in the Database. Collections with a mixed (carbonate and clastic) or unrecorded litholo- accounting for 70% of all occurrences. gy, and those not readily assignable to either Table 1 shows a few examples of the affinity category, were ignored. Results are consistent assignments. During the stratigraphic range of if secondary lithology and mixed lithologies the trilobite Acastella, 64% of the collections are are taken into consideration (Appendix 1). The from carbonates and 36% from clastics. This presence of a genus in a collection was genus has 44 occurrences, 30 of which are counted as a single occurrence, irrespective from clastics. The probability of observing 30 of the number of species. Although all or more clastic occurrences, if the true fre- À5 resulting occurrences were used in assigning quency is 36%, is only about 10 , so this lithologic affinities of genera, the analysis of genus is assigned a clastic affinity. The changes in geographic range focuses on the gastropod Acteonella is assigned a carbonate Ordovician through Pleistocene, mainly be- affinity, even though 52% of its occurrences cause of limited stratigraphic resolution in are from clastics. This is because its 48% parts of the Cambrian. occurrence rate in carbonates is significantly Environmental Affinities.—A genus could greater than the null expectation of 32%. occur primarily in a given environment Finally, the cephalopod Acrioceras has 78% of simply because that environment is dominant its occurrences in carbonates; it