DOI: 10.5061/dryad.p0q25
title: Data from: Unifying latitudinal gradients in range size and richness across marine and terrestrial systems

description: Many marine and terrestrial clades show similar latitudinal gradients in
 species richness, but opposite gradients in range size—on land, ranges are
 the smallest in the tropics, whereas in the sea, ranges are the largest in
 the tropics. Therefore, richness gradients in marine and terrestrial
 systems do not arise from a shared latitudinal arrangement of species
 range sizes. Comparing terrestrial birds and marine bivalves, we find that
 gradients in range size are concordant at the level of genera. Here, both
 groups show a nested pattern in which narrow-ranging genera are confined
 to the tropics and broad-ranging genera extend across much of the
 gradient. We find that (i) genus range size and its variation with
 latitude is closely associated with per-genus species richness and (ii)
 broad-ranging genera contain more species both within and outside of the
 tropics when compared with tropical- or temperate-only genera.
 Within-genus species diversification thus promotes genus expansion to
 novel latitudes. Despite underlying differences in the species range-size
 gradients, species-rich genera are more likely to produce a descendant
 that extends its range relative to the ancestor's range. These
 results unify species richness gradients with those of genera, implying
 that birds and bivalves share similar latitudinal dynamics in net species
 diversification.
description: Latitudinal range limits
 of birds at global scalesLatitudinal range limits
 of bird genera and species at global scales defined on the basis of
 2,785,600 occurrences from published literature, sightings, and from
 museum specimens (Rahbek and Graves 2001; Rahbek et al. 2012). Ranges were
 compiled at a resolution of 1° x 1°. References: Rahbek, C. & Graves,
 G. R. 2001 Multiscale assessment of patterns of avian species richness.
 Proc. Natl. Acad. Sci. USA 98, 4534-4539. Rahbek, C., Hansen, L. A. &
 Fjelds, J. 2012. One degree resolution database of the global distribution
 of birds. Natural History Museum of Denmark, University of Copenhagen,
 Denmark.Global bird range
 limits.xlsLatitudinal range limits
 of birds in the New WorldLatitudinal range limits
 of bird genera and species in the New World defined on the basis of
 occurrences from published literature, sightings, and from museum
 specimens (Rahbek and Graves 2001; Rahbek et al. 2012). Ranges were
 compiled at a resolution of 1° x 1°. References: Rahbek, C. & Graves,
 G. R. 2001 Multiscale assessment of patterns of avian species richness.
 Proc. Natl. Acad. Sci. USA 98, 4534-4539. Rahbek, C., Hansen, L. A. &
 Fjelds, J. 2012. One degree resolution database of the global distribution
 of birds. Natural History Museum of Denmark, University of Copenhagen,
 Denmark.New
 World bird range limits.xlsLatitudinal range limits
 of bivalves at global scalesLatitudinal range limits
 of bivalve genera and species at global scales, occurring at depths &lt;
 200 m. They were compiled from both the literature and museum collections.
 Reference: Jablonski, D., Belanger, C. L., Berke, S. K., Huang, S., Krug,
 A. Z., Roy, K., Tomasovych, A. & Valentine, J. W. 2013 Out of the
 tropics, but how? Fossils, bridge species, and thermal ranges in the
 dynamics of the marine latitudinal diversity gradient. Proc. Natl. Acad.
 Sci. USA 110, 10487-10494.Global bivalve range
 limits.xlsLatitudinal range limits
 of bivalves in the Eastern PacificLatitudinal range limits
 of bivalve genera and species in the Eastern Pacific, occurring at depths
 &lt; 200 m. They were compiled from both the literature and museum
 collections. Reference: Jablonski, D., Belanger, C. L., Berke, S. K.,
 Huang, S., Krug, A. Z., Roy, K., Tomasovych, A. & Valentine, J. W.
 2013 Out of the tropics, but how? Fossils, bridge species, and thermal
 ranges in the dynamics of the marine latitudinal diversity gradient. Proc.
 Natl. Acad. Sci. USA 110, 10487-10494.Eastern Pacific bivalve range
 limits.xlsLatitudinal range limits
 of bivalves in the Western AtlanticLatitudinal range limits
 of bivalve genera and species in the Western Atlantic, occurring at depths
 &lt; 200 m. They were compiled from both the literature and museum
 collections. Reference: Jablonski, D., Belanger, C. L., Berke, S. K.,
 Huang, S., Krug, A. Z., Roy, K., Tomasovych, A. & Valentine, J. W.
 2013 Out of the tropics, but how? Fossils, bridge species, and thermal
 ranges in the dynamics of the marine latitudinal diversity gradient. Proc.
 Natl. Acad. Sci. USA 110, 10487-10494.Western Atlantic bivalve range
 limits.xls