Climate, niche evolution, and diversification of the bird cage evening primroses (Oenothera, sections Anogra and Kleinia) Margaret Evans, Post-doc; YIBS, EEB, Yale University Stephen Smith, PhD student; EEB, Yale University Rachel Flynn, Undergraduate; Yale University Michael Donoghue, Professor; Peabody Museum, EEB, Yale University
plant diversity ~300,000 species
Explanations for plant diversity: Evolutionary vs. Climatic
evening primroses (Oenothera, sections Anogra and Kleinia) 19 taxa Western North America High elevation or latitude, meadows, prairies Low elevation, Sonoran Desert Mid elevation, foothills
two endangered species Oenothera californica ssp. eurekensis Eureka Dunes, Death Valley National Park
Origins? How old is this diversity? Stem date ~ 9 my Crown date ~ 0 my Evolutionary radiation during the Quaternary, Pleistocene glacial-interglacial climatic fluctuations, migration, vicariance
Origins? How has the evolution of this group been influenced by climate? Qualitatively, Occupy a diversity of habitats/climates (deserts to alpine meadows) Radiated in the last ~1 million years Approach: Combine niche models phylogenetic information time scale Quantify and visualize niche evolution To understand speciation/diversification in relation to climate
Quantify and visualize niche evolution Step 1: Characterize extant species climatic tolerances locality data from herbarium specimen
Species Distribution Modeling Georeferenced locality data + Environmental layers algorithm Maxent Where the species is herbarium specimens What the environment is like there 19 Bioclim variables (temperature, precipitation) Predicted species distribution Where you should find the species on the landscape
Maxent output Probability Distribution - predicted suitability of the landscape cumulative probability of occurrence
Characterize extant species climatic tolerances Probability Distribution - predicted suitability of the landscape sum probabilities according to the climate data predicted occupancy of a climatic niche dimension
Characterize extant species climatic tolerances niche occupancy profiles
Step 1: Characterize extant species climatic tolerances Step 2: Phylogenetic relationships? 6 gene regions (one nuclear, five cp) ~6500 bp Bayesian analysis Phylogeny (topology) Dating (time scale)
Step 1: Characterize extant species climatic tolerances Step 2: Phylogenetic relationships Step 3: Reconstruct evolution of climatic tolerances 3 2 9 5 2 Brownian motion model of evolution weighted mean of daughters (weights inversely proportional to the branch lengths) 2 2.5 3 2 5.9 1 4 4 7 1 5.3 6
Step 1: Characterize extant species climatic tolerances Step 2: Phylogenetic relationships Step 3: Reconstruct evolution of climatic tolerances 3 2 9 5 2 Brownian motion model of evolution weighted mean of daughters (weights inversely proportional to the branch lengths) 2 2.5 3 2 5.9 1 4 4 7 1 5.3 6 Two issues: Intraspecific variability Phylogenetic uncertainty samples from climate profiles samples from posterior distribution of trees
ecological radiation reconstruct the evolution of ecological niches
evolution of ecological niches ecological radiation summer rain vs. summer drought
evolution of ecological niches ecological radiation summer rain vs. summer drought freezing temperatures
Niches have evolved quite a bit: summer rain vs. summer drought freezing temperatures Climatic heterogeneity of WNA has been template for niche evolution This niche evolution and diversification occurred in last 1 my spatio temporal climatic heterogeneity, and adaptation to it, probably played a role in generating diversity Evans, Smith, Flynn, and Donoghue. in revision. The American Naturalist.
conceptual models for speciation in response to climate change
conceptual models for speciation in response to climate change
Biodiversity pump hypothesis
Migration of an ancestor similar to O. californica ssp. avita or O. neomexicana Leaving behind O. arizonica O. californica ssp. eurekensis O. californica ssp. californica
Other hotspots of plant diversity explained by spatio-climatic heterogeneity??
Explanations for plant diversity: Evolution and Climate
Summary We can use niche modeling and phylogenetic information to estimate or reconstruct evolution of climatic tolerances (niche evolution). Infer: what were the climatic tolerances of ancestors? Make inference on the role of climate in diversification, speciation.
Might evolution in response to climate change mitigate predictions about biodiversity loss? How fast must evolution be, and how does that compare to past rates of evolution? slope=rate Evans, Smith, Sytsma and Donoghue. in prep.