title: Habitat size modulates the influence of heterogeneity on species richness patterns in a model zooplankton community.
abstract: Habitat heterogeneity is a primary mechanism influencing species richness. Despite the general expectation that increased heterogeneity should increase species richness, there is considerable variation in the observed relationship, including many studies that show negative effects of heterogeneity on species richness. One mechanism that can create such disparate results is the predicted trade-off between habitat area and heterogeneity, sometimes called the area-heterogeneity-trade-off (AHTO) hypothesis. The AHTO hypothesis predicts positive effects of heterogeneity on species richness in large habitats, but negative effects in small habitats. We examined the interplay between habitat size and habitat heterogeneity in experimental mesocosms that mimic freshwater ponds, and measured responses in a species-rich zooplankton community. We used the AHTO hypothesis and related mechanisms to make predictions about how heterogeneity would affect species richness and diversity in large compared to small habitats. We found that heterogeneity had a positive influence on species richness in large, but not small habitats, and that this likely resulted because habitat specialists were able to persist only when habitat size was sufficiently large, consistent with the predictions of the AHTO hypothesis. Our results emphasize the importance of considering context (e.g., habitat size in this case) when investigating the relative importance of ecological drivers of diversity, like heterogeneity.
authors.affiliation: Department of Biology, Washington University in St. Louis, St. Louis, Missouri, 63130, USA.
authors.forename: Matthew S
authors.initials: MS
authors.lastname: Schuler
authors.affiliation: German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscherplatz 5e, 04103, Leipzig, Germany.|Institute for Computer Science, Martin Luther University Halle-Wittenberg, Seckendorff-Platz 1, 06120, Halle (Saale), Germany.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Chase
authors.affiliation: German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Deutscherplatz 5e, 04103, Leipzig, Germany.|Institute of Biology, Martin Luther University Halle-Wittenberg, Am Kirchtor 1, 06108, Halle (Saale), Germany.|Department of Community Ecology, Helmholtz Centre for Environmental Research-UFZ, Theodor-Lieser-Straße 4, 06120, Halle (Saale), Germany.
authors.forename: Tiffany M
authors.initials: TM
authors.lastname: Knight
mesh_terms: D000818:Animals; D044822:Biodiversity; D017753:Ecosystem; D005618:Fresh Water; D008962:Models, Theoretical; D061005:Ponds; D015048:Zooplankton
keywords: gambusia affinis; habitat fragmentation; habitat loss; heterogeneity diversity relationship; homogenization; mesocosms