DOI: 10.5061/dryad.7jq72gr4
title: Data from: Increased energy promotes size-based niche availability in marine mollusks

description: Variation in chemical energy, i.e., food, availability is posited to cause
 variation in body size. However, examinations of the relationship are rare
 and primarily limited to amniotes and zooplankton. Moreover, the
 relationship between body size and chemical energy may be impacted by
 phylogenetic history, clade specific ecology, and heterogeneity of
 chemical energy in space and time. Considerable work remains to both
 document patterns in body size over gradients in food availability and
 understanding the processes potentially generating them. Here, we examine
 the functional relationship between body size and chemical energy
 availability over a broad assortment of marine mollusks varying in habitat
 and mobility. We demonstrate that chemical energy availability is likely
 driving body size patterns across habitats. We find that lower food
 availability decreases size-based niche availability by setting hard
 constraints on maximum size and potentially on minimum size depending on
 clade-specific ecology. Conversely, higher food availability promotes
 greater niche availability and potentially promotes evolutionary
 innovation with regard to size. We posit based on these findings and
 previous work that increases in chemical energy are important to the
 diversification of Metazoans through size-mediated niche processes.
description: McClainetal(2011)Data for bivalves from the Northeast Pacific and Northwest Atlantic were collected through an extensive search of the primary literature and online databases resulting in complete information for 1,578 species from 75 families. Substantial information came from Desbruyeres et al. (2006), Malacolog v. 4.1.1 (Rosenberg 2009), and Coal et al. (2000). The data collected include: taxonomic information from the subclass to species; synonymies; maximum and minimum water depth in meters; maximum and minimum latitude; maximum reported shell length, width, and height in millimeters; habitat type; and ocean basin. Habitat type was broken into fine grain, coarse grain, sediment generalist, hard substrate, hydrothermal vent, methane seep, seamount, wood fall, whale fall, reducing generalist (a generalist on vents, seeps, wood falls, or whale falls) and other, which were primarily made up of commensal bivalves. | Data for gastropods of the Northwest Atlantic were derived from Malacolog v. 4.1.1 (Rosenberg 2009) resulting in data for 3,350 species from 112 families. The data collected included: taxonomic information from the subclass to species; maximum and minimum water depth in meters; maximum and minimum latitude; and maximum reported shell length. | Approximate biovolume for each species was calculated as length*height2 of the shell. In the absence of both length and height measurements, missing measurements were calculated from length:height ratios based on raw measurements from ImageJ v. 1.42 taken from the best available picture for each species from the literature or online collections. | The chemical energy available to the mollusks was estimated as particulate organic carbon (POC) flux (g of C m-2 year-1) based on the Lutz et al. (2007) model. The model utilizes empirically derived sediment trap POC flux estimates compared to remotely sensed estimates of net primary production (NPP) and sea surface temperature (SST). For each species, we quantified the mean, median, and standard deviation of carbon flux over their known latitudinal and depth ranges. Data from each species were manipulated using ArcGIS Workstation 10. We created a GIS coverage for each species’ north-south range extent. This was overlaid upon bathymetry data (GEBCO 08, 30 arc-second grid, September 2010 release, www.gebco.org) to limit each species’ distribution to their recorded depth range. To obtain the carbon flux values, each species’ range was overlaid upon the Lutz et al. (2007) model, with values exported to a text file. Values from each species were compiled into a single data file. | In some cases, because of the coarseness of the depth and carbon flux GIS grids and the small biogeographic ranges of some of the bivalves here, we slightly extended species ranges in order to obtain carbon flux data. This ensured that matching cells in the GIS grids would be found for each species. The smallest latitudinal extent for any species with small ranges was set at 1 degree. Species recorded from a single depth, or very narrow depths were also expanded. All species found at depths less than 10 m were adjusted to a minimum depth range of 10 m. Species at depths up to 20 m were adjusted so that their minimum depth range was 10 m, with an equal amount added to the minimum and maximum depth. Depth ranges from 20-49 m were adjusted to have a 20 m minimum depth range, 50-199 m to 40 m, 200-999 to 100 m, and &gt;1000 m to 200 m. The grade of the continental shelf is low and thus depth ranges changes were limited to shorter intervals to prevent making biogeographic ranges substantially larger.