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Climate, niche evolution, and diversification of the “bird‐cage” evening primroses (Oenothera, sections Anogra and Kleinia)
Margaret Evans, Post-doc; YIBS, EEB, Yale UniversityStephen Smith, PhD student; EEB, Yale UniversityRachel Flynn, Undergraduate; Yale UniversityMichael Donoghue, Professor; Peabody Museum, EEB,
Yale University
plant diversity~300,000 species
Explanations for plant diversity:Evolutionary vs.Climatic
High elevation or latitude,meadows, prairies
evening primroses (Oenothera, sections Anogra and Kleinia)
Low elevation, Sonoran Desert
Mid elevation, foothills
19 taxaWestern North America
two endangered species
Oenothera californica ssp. eurekensisEureka Dunes, Death Valley National Park
Origins?
Stem date ~ 9 my
Evolutionary radiation during the Quaternary, Pleistocene
glacial-interglacial climatic fluctuations, migration, vicariance
Crown date ~ 0 my
…How old is this diversity?
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
Origins?How has the evolution of this group been influenced by climate?
Step 1:Characterize extant species’ climatic tolerances
locality data from herbarium specimen
Quantify and visualize niche evolution
Georeferenced locality data
+
Environmental layers
herbarium specimens
19 Bioclim variables (temperature, precipitation)
Predicted species distribution
algorithm
Where the species is
What the environment is like there
Where you should find the species on the landscape
Species Distribution Modeling
Maxent
Maxent output
Probability Distribution -predicted suitability of the landscape
cumulative probability of occurrence
Probability Distribution -predicted suitability of the landscape
Characterize extant species’ climatic tolerances
predicted occupancy of a climatic niche dimension
sum probabilities according to the
climate data
niche occupancy profiles
Characterize extant species’climatic tolerances
Step 2:Phylogenetic relationships?
Step 1:Characterize extant species’ climatic tolerances
6 gene regions(one nuclear, five cp)~6500 bpBayesian analysis
Phylogeny (topology) Dating (time scale)
Step 2: Phylogenetic relationshipsStep 1: Characterize extant species’ climatic tolerances
Step 3: Reconstruct evolution of climatic tolerances
Brownian motion model of evolution•weighted mean of daughters•(weights inversely proportional to the branch lengths)
3 2 9 5 2
3
22
11
4 46
2.5
75.9
5.3
Step 2: Phylogenetic relationshipsStep 1: Characterize extant species’ climatic tolerances
Step 3: Reconstruct evolution of climatic tolerances
Brownian motion model of evolution•weighted mean of daughters•(weights inversely proportional to the branch lengths)
Two issues:Intraspecific variabilityPhylogenetic uncertainty
samples from climate profiles
samples from posterior distribution of trees
3 2 9 5 2
3
22
11
4 46
2.5
75.9
5.3
reconstruct the evolution of ecological niches
ecological radiation
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 droughtfreezing temperatures
Climatic heterogeneity of WNA has been template for niche evolutionThis 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. arizonicaO. californica ssp. eurekensisO. californica ssp. californica
Other hotspots of plant diversity explained by spatio-climatic heterogeneity??
Explanations for plant diversity:Evolution andClimate
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.
Summary
Might evolution in response to climate change mitigate predictions about biodiversity loss?
slope=rate
Evans, Smith, Sytsma and Donoghue. in prep.
How fast must evolution be, and how does that compare to past rates of evolution?