Kernels and Ecological Niche Modeling

Abstract

Photographs by Mathieu Denoël Kernel density estimators (KDEs) are a powerful tool to delineate conservation areas, but they have not been applied at the population level on patch-distributed organisms. This would be particularly worthy for species that need broad habitats beyond those where they can be sampled, such as terrestrial lands for pond-breeding amphibians. The aim of this study was to compare different approaches for the identification of suitable areas for conservation: KDE, ecological niche modelling, and a combination of KDE and niche models. Paedomorphosis in newts was chosen as a model system because this is an important form of intraspecific variation that is present in numerous taxa, but geographically localized within species and globally endangered. Overall, the best results were observed by the KDE integrating ecological barriers, and by the combination between KDE and niche modelling. This study highlights that KDEs are a pertinent tool in providing quantitative spatial measurements to delineate conservation areas based on patch-abundance data with a specific focus to connectivity. Paedomorphic palmate newt (Lissotriton helveticus) from Southern Larzac (St-Michel “Le Laquet,” France). In contrast to the dispersal metamorphosed phenotype, paedomorphs are fully aquatic organisms that retain larval traits such as gills at the adult stage. A typical pond of Southern Larzac (Le Coulet “Tournant,” France) where paedomorphic and metamorphic palmate newts (Lissotriton helveticus) can be found. The terrestrial environment is necessary for allowing population persistence and connectivity between sites by metamorphosed dispersers. A cartographic representation of Kernel Density Estimators (KDEs) for paedomorphic palmate newts (Lissotriton helveticus) in southern Larzac (France). The average number of paedomorphs caught per pond is proportional to the size of full circles. KDEs from 10 to 95% are shown. These photographs illustrate the article “Using kernels and ecological niche modeling to delineate conservation areas in an endangered patch-breeding phenotype” by Mathieu Denoël and Gentile Francesco Ficetola, tentatively scheduled to appear in Ecological Applications 25(7), October 2015. http://dx.doi.org/10.1890/14-1041.1