Rates Of Climatic Niche Evolution Research Articles

Climatic niche evolution and species diversification in the Cape flora, South Africa

AbstractAimTo evaluate the evolutionary dynamics of the ecological niche by quantifying the modes and rates of ecological niche evolution (with a particular focus on climatic parameters) and species diversification.LocationGreater Cape Floristic Region, southern Africa.MethodsUsing the genus Babiana (Iridaceae) from the Cape flora, South Africa, we study the evolutionary dynamics of the ecological niche, which includes a characterization of the ecological niche, an assessment of phylogenetic signal, comparisons of different macroevolutionary models, and the estimation of rates of niche evolution (and their variation within and between clades) and lineage diversification, while accounting for phylogenetic uncertainty.ResultsA principal components analysis (PCA) identified mean annual precipitation and mean annual temperature as the most important climatic determinants differentiating species within Babiana. All parameters show significant phylogenetic signal, and the best‐fit model of evolution is the Ornstein–Uhlenbeck process with two distinct precipitation optima for two neighbouring biomes: the Fynbos and the Succulent Karoo. Evolutionary rates of climatic niches vary by more than an order of magnitude over the phylogeny, and rates of niche evolution and lineage diversification are both higher in the Fynbos biome than in the Succulent Karoo.Main conclusionsOur results show a possible link between rates of climatic niche evolution and rates of species diversification, indicating that rates of niche evolution might be driving diversification rates.

HOW IS THE RATE OF CLIMATIC-NICHE EVOLUTION RELATED TO CLIMATIC-NICHE BREADTH?

The rate of climatic-niche evolution is important to many research areas in ecology, evolution, and conservation biology, including responses of species to global climate change, spread of invasive species, speciation, biogeography, and patterns of species richness. Previous studies have implied that clades with higher rates of climatic-niche evolution among species should have species with narrower niche breadths, but there is also evidence suggesting the opposite pattern. However, the relationships between rate and breadth have not been explicitly analyzed. Here, we examine the relationships between the rate of climatic-niche evolution and climatic-niche breadth using phylogenetic and climatic data for 250 species in the salamander family Plethodontidae, a group showing considerable variation in both rates of climatic-niche evolution and climatic-niche breadths. Contrary to some expectations, we find no general relationship between climatic-niche breadth and the rate of climatic-niche evolution. Climatic-niche breadths for some ecologically important climatic variables considered separately (temperature seasonality and annual precipitation) do show significant relationships with the rate of climatic-niche evolution, but rates are faster in clades in which species have broader (not narrower) niche breadths. In summary, our results show that narrower niche breadths are not necessarily associated with faster rates of niche evolution.

Life history influences rates of climatic niche evolution in flowering plants

Across angiosperms, variable rates of molecular substitution are linked with life-history attributes associated with woody and herbaceous growth forms. As the number of generations per unit time is correlated with molecular substitution rates, it is expected that rates of phenotypic evolution would also be influenced by differences in generation times. Here, we make the first broad-scale comparison of growth-form-dependent rates of niche evolution. We examined the climatic niches of species on large time-calibrated phylogenies of five angiosperm clades and found that woody lineages have accumulated fewer changes per million years in climatic niche space than related herbaceous lineages. Also, climate space explored by woody lineages is consistently smaller than sister lineages composed mainly of herbaceous taxa. This pattern is probably linked to differences in the rate of climatic niche evolution. These results have implications for niche conservatism; in particular, the role of niche conservatism in the distribution of plant biodiversity. The consistent differences in the rate of climatic niche evolution also emphasize the need to incorporate models of phenotypic evolution that allow for rate heterogeneity when examining large datasets.