Climate-driven habitat size determines the latitudinal diversity gradient in temporary ponds

Abstract

The latitudinal diversity gradient (LDG) has been one of the most documented patterns in ecology, typically showing decreasing species diversity with increasing latitude. Studies of these patterns also used different spatial scales and dispersal traits to better understand the underpinning ecological factors. Seasonal freshwater ecosystems are less studied and may exhibit different patterns because they are more sensitive to climatic variation, which result in an inundation-desiccation cycle. In California, precipitation increases and temperature decreases with increasing latitude and thus the LDG pattern may be associated with this climatic gradient. Using collected data and United States Fish and Wildlife Service reports across seven degrees of latitude, analysis of California vernal pool invertebrate community (total richness and richness of passive and active dispersers) was conducted using correlations (Spearman rank and partial). Alpha diversity (total and passive dispersers) increased and beta diversity (passive dispersers) decreased with increasing latitude. Vernal pool surface area was correlated with active disperser alpha and passive disperser beta diversity. This suggests that climate-driven habitat size influences alpha and beta diversity patterns depending on dispersal ability. Active dispersers and predators exhibited higher beta diversity than passive dispersers and prey, respectively. Species composition differed among counties and some of these differences were correlated with pool depth and temperature. These results suggest that seasonal habitats will have diversity patterns strongly associated with local scale characteristics (habitat size and hydroperiod) determined by climate variation along the latitudinal gradient. Understanding these diversity patterns along the gradient will also contribute to management and restoration of these ecosystems with high endemism and diversity.

Do active‐dispersing insects dominate the invertebrate fauna of rock pools in the wet–dry tropics, Kimberley, Australia?

“…Brendonck, Jocqué, Tuytens, Timms, and Vanshoenwinkel () found that hydrological stability (defined as frequency and length of hydroperiod) strongly determined FRP invertebrate richness, both locally and regionally. Richness declined along an 800‐km transect, from south to north, in south‐western Australia, corresponding to increased aridity (and thus to hydrological instability, similar to findings in Kneitel () and Timms ()). Brendonck et al () predicted that this trend would reverse, moving further northwards from the arid zone to the tropical Kimberley region, yet high species richness was not observed in the present study.…”

Occupancy and environmental responses of habitat specialists and generalists depend on dispersal traits

“…This also reflected previous patterns in which active dispersers had greater beta diversity than passive dispersers (Soininen et al. , Kneitel ). There are several non‐mutually exclusive explanations for these results.…”

“…California vernal pools are seasonal ponds or wetlands whose hydro‐regime is determined by rainfall patterns in this Mediterranean climate (Boix et al. , Kneitel ). The pools typically fill during winter and dry by late spring, but the amount, timing, and distribution of this rainfall are highly variable (Boix et al.…”

“…Large branchiopods were identified to species, but most of the other groups were broader taxonomic groups (Table ). Details of the data sources and sites can be found in Kneitel (). The 30 taxa were categorized into four groups based on specialization and dispersal modes, specialist‐passive, specialist‐active, generalist‐passive, and generalist‐active, and percent occupancy was used along the latitudinal gradient (Table ).…”

“…The purpose of this study was to assess specialist (vernal pool endemics) and generalist (widespread wetland) taxa found in California vernal pools along a latitudinal gradient and their responses to environmental variation. Using taxonomically diverse invertebrate data from two separate studies (Kneitel , Kneitel et al. ), the goal was to test niche‐based predictions using species occupancy and environmental responses.…”