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Harvard Forest Symposium Abstract 2018

  • Title: Among-species overlap in rodent body size distributions predicts species richness along a temperature gradient
  • Primary Author: Sydne Record (Bryn Mawr College)
  • Additional Authors: John Grady (University of New Mexico - Main Campus)
  • Abstract:

    Additional co-authors: Quentin Read (Michigan State University), Phoebe Zarnetkse (MSU), Ben Baiser (University of Florida Gainesville), Jonathan Belmaker (Tel Aviv University), Mao-Ning Tuanmu (Academica Sinica), Angela Strecker (Portland State University), Lydia Beaudrot (University of Michigan), and Katherine Thibault (NEON).

    Temperature is widely regarded as a major driver of species richness, but the
    mechanisms are debated. Niche theory suggests temperature may affect richness
    by filtering traits and species in colder habitats while promoting specialization in
    warmer ones. However, tests of this theory are rare because niche dimensions are
    challenging to quantify along broad thermal gradients. Here, we use individuallevel
    trait data from a long-term monitoring network spanning a large geographic
    extent to test niche-based theory of community assembly in small mammals. We
    examined variation in body size among 23 communities of North American rodents
    sampled across the National Ecological Observatory Network (NEON), ranging
    from northern hardwood forests to subtropical deserts. We quantified body size
    similarity among species using a metric of overlap that accounts for individual
    variation, and fit a structural equation model to disentangle the relationships
    between temperature, productivity, body size overlap, and species richness. We
    document a latitudinal gradient of declining similarity in body size among species
    towards the tropics and overall increase in the dimensions of community-wide trait
    space in warmer habitats. Neither environmental temperature nor net primary
    productivity directly affect rodent species richness. Instead, temperature determines
    the community-wide niche space that species can occupy, which in turn alters
    richness. We suggest a latitudinal gradient of trait space expansion towards the
    tropics may be widespread and underlie gradients in species diversity.

  • Research Category: Physiological Ecology, Population Dynamics, and Species Interactions; Large Experiments and Permanent Plot Studies; Biodiversity Studies