GSA Annual Meeting in Seattle, Washington, USA - 2017

Paper No. 10-9
Presentation Time: 10:15 AM

EVALUATING THE INFLUENCES OF TEMPERATURE, PRODUCTIVITY, AND PHYLOGENETIC CONSTRAINT ON BIVALVE GROWTH RATES


SAULSBURY, James1, FINNEGAN, Seth2, LINDBERG, David R.3, MOSS, David K.4, IVANY, Linda C.5, GILOOLY, James F.6, GOODWIN, David7, HEIM, Noel A.8, KOWALEWSKI, Michal9, MCCLAIN, Craig R.10, PAYNE, Jonathan L.10, ROOPNARINE, Peter D.11 and SCHOENE, Bernd R.12, (1)Earth and Environmental Sciences, University of Michigan, Ann Arbor, 629 S Division St., Ann Arbor, MI 48104, (2)Department of Integrative Biology & Museum of Paleontology, University of California, Berkeley, 1005 Valley Life Sciences Building #3140, Berkeley, CA 94720, (3)Department of Integrative Biology and Museum of Paleontology, University of California, Valley Life Sciences Building, Berkeley, CA 94720-3140, (4)Department of Geological Sciences, University of South Carolina, Chapel Hill, NC 27599, (5)Department of Earth Sciences, Syracuse University, Syracuse, NY 13244, (6)Department of Biology, University of Florida, Gainesville, FL 32611, (7)Department of Geosciences, Denison University, FW Olin Science Hall, 100 Sunset Hill Drive, Granville, OH 43023, (8)Department of Geological Sciences, Stanford University, Stanford, CA 94305, (9)Florida Museum of Natural History, University of Florida, Gainesville, FL 32611, (10)Geological Sciences, Stanford University, 450 Serra Mall, Stanford, CA 94305, (11)Department of Invertebrate Zoology and Geology, California Academy of Sciences, San Francisco, CA 94118, (12)Geosciences, University of Mainz, Johann-Joachim-Becher-Weg 21, Mainz, 55128, Germany, jgsauls@umich.edu

One of the most striking features of the marine fossil record is the long-term increase in the mean body size and metabolic scope of fossil taxa. Numerous drivers, both biotic and abiotic, have been hypothesized to explain this trend, but evaluating them requires improved understanding of the controls on metabolic rates, growth rates, and longevities of marine invertebrates. Recent analyses have shown that among marine bivalves, lifespan increases, and growth rate decreases, with latitude. Here we dissect this pattern further by examining the influences of temperature and primary productivity on bivalve growth rates within a phylogenetically controlled framework. We integrated a global database of growth rates for 700 bivalve populations representing 202 species with satellite measurements of sea surface temperature (SST) and chlorophyll-a concentration. We extracted maximum and minimum monthly average SST and chlorophyll concentrations for 0.042-degree latitude-longitude cells based on satellite data from 2012 to 2016. Relationships between environmental variables and growth rates were evaluated using linear regression, quantile regression, and gradient boosting machines. In order to assess trends in a phylogenetically independent framework, we generated a phylogeny for the 96 species for which sequence data were available and tested for phylogenetic signal using Pagel’s lambda and Blomberg’s K. None of the evaluated predictors show a strong linear relationship to growth rate. The most important predictor is minimum temperature. Growth rates are uniformly low when winter temperatures are low, but vary widely when winter temperatures are high, implying that warm winter temperatures are a necessary but not sufficient condition for high growth rates. Maximum temperatures exhibit a narrower range than minimum temperatures, and have a weaker influence on growth rates. Chlorophyll concentration has little to no significant influence on growth rates at the global scale, but minimum chlorophyll concentration is a significant predictor of growth rates when considering only extratropical observations. Notably, growth rates exhibit no significant phylogenetic signal, suggesting that studies of growth rate variation in the fossil record should focus on potential environmental drivers.