Evaluating alternative study designs for optimal sampling of species’ climatic niches

Ecologists have traditionally studied intraspecific variation by sampling species across their geographic ranges. However, whether this classic approach produces samples that accurately represent species’ climatic niches is largely unknown. Alternative, niche-based study designs using species’ climatic niches to inform sampling locations should more efficiently and completely capture the breadth of the niche, but the magnitude of this difference and how it may vary is unclear. Here we use conifers as a model system to explore these issues and reach specific recommendations for future sampling designs. Using an independent dataset of high-quality species’ occurrences, we first show that recent publications examining variation across geographic space do a poor job of capturing the full breadth of species’ niches, such that on average, only 22% of species’ niche space was sampled. This was also true of a large compiled database, the International Tree-Ring Data Bank (ITRDB), which yielded ...