“Evidence for trait-based dominance in occupancy among fossil taxa and the decoupling of macroecological and macroevolutionary success”

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Peter Wagner, Roy E. Plotnick, and S. Kathleen Lyons (Sep 2018)

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Fossil marine genera suggest that traits shared by related species encourage denser occupancy of geographic ranges

Abstract

Biological systems provide examples of differential success among taxa, from ecosystems with a few dominant species (ecological success) to clades that possess far more species than sister-clades (macroevolutionary success). “Macroecological success,” the occupation by a species or clade of an unusually high numbers of areas, has received less attention. If macroecological success reflects heritable traits, then successful species should be related. Genera comprised of species possessing those traits should occupy more areas than genera with comparable species richness that lack the traits. Alternatively, if macroecological success reflects autapomorphic traits, then generic occupancy should be a byproduct of species richness among genera and occupancy of constituent species. We test this using Phanerozoic marine invertebrates. Although temporal patterns of species and generic occupancy are strongly correlated, inequality in generic occupancy typically is greater than expected. Genus-level patterns cannot be explained solely with species level patterns. Within individual intervals, deviations between observed and expected generic occupancy correlate with the number of lithological units (stratigraphic formations), particularly after controlling for geographic range and species-richness. However, elevated generic occupancy is unrelated or negatively associated with either generic geographic ranges or within genus species-richness. Our results suggest that shared traits among congeneric species encourage short term macroecological success without generating short-term macroevolutionary success. A broad niche may confer high occupancy, but does not necessarily promote speciation.