Dataset Information

Latitudinal diversity gradients in Mesozoic non-marine turtles.

ABSTRACT: The latitudinal biodiversity gradient (LBG)-the pattern of increasing taxonomic richness with decreasing latitude-is prevalent in the structure of the modern biota. However, some freshwater taxa show peak richness at mid-latitudes; for example, extant Testudines (turtles, terrapins and tortoises) exhibit their greatest diversity at 25°?N, a pattern sometimes attributed to recent bursts of climatically mediated species diversification. Here, we test whether this pattern also characterizes the Mesozoic distribution of turtles, to determine whether it was established during either their initial diversification or as a more modern phenomenon. Using global occurrence data for non-marine testudinate genera, we find that subsampled richness peaks at palaeolatitudes of 15-30°?N in the Jurassic, 30-45°?N through the Cretaceous to the Campanian, and from 30° to 60°?N in the Maastrichtian. The absence of a significant diversity peak in southern latitudes is consistent with results from climatic models and turtle niche modelling that demonstrate a dearth of suitable turtle habitat in Gondwana during the Jurassic and Late Cretaceous. Our analyses confirm that the modern testudinate LBG has a deep-time origin and further demonstrate that LBGs are not always expressed as a smooth, equator-to-pole distribution.

SUBMITTER: Nicholson DB

PROVIDER: S-EPMC5180147 | biostudies-literature | 2016 Nov

REPOSITORIES: biostudies-literature

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Latitudinal diversity gradients in Mesozoic non-marine turtles.

Nicholson David B DB Holroyd Patricia A PA Valdes Paul P Barrett Paul M PM

Royal Society open science 20161123 11

The latitudinal biodiversity gradient (LBG)-the pattern of increasing taxonomic richness with decreasing latitude-is prevalent in the structure of the modern biota. However, some freshwater taxa show peak richness at mid-latitudes; for example, extant Testudines (turtles, terrapins and tortoises) exhibit their greatest diversity at 25° N, a pattern sometimes attributed to recent bursts of climatically mediated species diversification. Here, we test whether this pattern also characterizes the Mes ...[more]

PMID: 28018649

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Project description:AimThe latitudinal diversity gradient (LDG) - in which species richness decreases from the equator toward the poles - is among the most fundamental distributional patterns in ecology. Despite the expectation that the diversity of parasites tracks that of their hosts, available evidence suggests that many parasites exhibit reverse latitudinal gradients or no pattern, yet the rarity of large-scale datasets on host-parasite interactions calls into question the robustness of such trends. Here, we collected parasitological data from a host group of conservation importance - lentic-breeding amphibians - to characterize the form and direction of relationships among latitude, parasite richness, and parasite load.LocationThe contiguous USA.Time period2000 to 2014.Major taxa studiedLentic-breeding frogs and toads and their helminth parasites.MethodsWe collected information on parasite richness and infection load for 846 amphibian populations representing 31 species. We combined these data with environmental and biological data to test for LDGs and potential mechanisms.ResultsBoth parasite richness and abundance increased across 20 degrees of latitude - a reverse LDG. For parasite richness, this pattern was partially explained by latitudinal increases in wetland area, landcover diversity, and the richness of waterbirds - which function as definitive hosts for many amphibian parasites. Host body size also correlated positively with latitude and helminth richness, potentially reflecting increased habitat availability, greater host longevity, or a persistent phylogenetic signal. Parasite abundance associated positively with wetland area and landcover diversity, but negatively with amphibian taxonomic richness. Longitude exhibited non-linear relationships with parasite abundance and richness, which we suggest stem from large-scale variation in host availability (e.g., migratory bird flyways).Main conclusionsWith growing interest in the distribution of parasites and pathogens, these results highlight the importance of inverse latitudinal gradients while emphasizing the explanatory influence of host body size, habitat availability, and host diversity.

Dataset Information

Latitudinal diversity gradients in Mesozoic non-marine turtles.

Publications

Latitudinal diversity gradients in Mesozoic non-marine turtles.

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