Comparative studies of niche evolution and diversification in malagasy Euphorbia and Sarcolaenaceae
Thomas HAEVERMANS (MNHN, UMR 7205)
Margaret Evans, Xavier Aubriot, Maxime Lanciaux, Annaëlle Soulebeau, Porter P. Lowry Département Systématique et Evolution, UMR 7205 MNHN/CNRS Origine Structure et Evolution de la Biodiversité
Rencontres IRD / MNHN, 20- 21 septembre 2012 Sarcolaenaceae
Euphorbia
total # Phylogeny locality rates Predictors taxa data of rates
Euphorbia ~130 58 species, ~550 not yet Sections species Xavier points attempted Goniostema, Aubriot (9/species) but good Denisophorbia, Xavier Aubriot Deuterocalli candidates
Sarcolaenaceae ~70 47 species, ~2100 predictors species, Thomas points ??? (10 Haevermans (44/species) genera) General information about the genus Euphorbia L.
• ca. 2000 species. Cosmopolitan genus. Particularly diversified in Africa (800 taxa) and in Madagascar (> 200 taxa)
Euphorbia L. in Madagascar (1) Herbs Euphorbia intisy Drake Euphorbia primulifolia var. begardii G. Cremers
Euphorbia emirnensis Baker Pencil like trees Geophytes
Pencil like Thorny shrubs trees Monocaulus and cactiform
Euphorbia cf. milii (natural hybrid)
Euphorbia stenoclada Baill.
Euphorbia viguieri Denis Euphorbia alluaudii Drake Spiny trees Euphorbia L. in Madagascar (2)
Unarmed shrubs Lianas Unarmed shrubs
Euphorbia sp. Euphorbia denisii Oudejans Euphorbia orthoclada Baker
Euphorbia plagiantha Drake
Euphorbia antso Denis Euphorbia mandravioky Leandri
Large pachycaulous Trees
trees © Genève, L.Gauthier et al. Trees Euphorbia L. in Madagascar (3)
• Present everywhere in Madagscar, in every type of climate, vegetation and substrate
Karstic cliffs Tropical rainforest
Arid haut-plateaux
Quartzite formations
Inland karstic formations Euphorbia L. in Madagascar (4)
• Major diversity hot spots: dry area of the North (Antsiranana), of the West (Mahajanga) and of the South (Fort-Dauphin, Tulear) of Madagascar
Species richness of Euphorbia spp. in Madagascar (Kew, GIS lab, Justin Moat and Thomas Haevermans; based on all the georeferenced herbaria specimens of K, HED and P), 2003 Euphorbia L. in Madagascar (5)
• Micro-endemism common. 80% of the species being threatened (IUCN). All succulent species are listed in annexes I and II of CITES convention
Succinct phylogeny of Euphorbia L.
• Malagasy Euphorbia are polyphyletic (6-7 radiations in Madagascar) • Malagasy Euphorbia clades are unequal in terms of species diversity
~ 57% ~ 76%
Bayesian Inference of Euphorbia phylogeny based on 500 ITS sequences (GenBank plus unpublished data) We wish to explain the morphological diversity found in Euphorbia Sects Goniostema, Denisophorbia, and Deuterocalli (GDD)
succulence: leaves stems Index 1 (quantitative, # organs succulent) Index 2 (qualitative, 5 categories)
growth form: caudex (thickened stem below/at ground level) Index (5 categories)
spines
cyathia: reduced enveloped We wish to explain the morphological diversity found in Euphorbia Sects Goniostema, Denisophorbia, and Deuterocalli (GDD)
Can climate explain the evolution of some of this morphological diversity?
Hypothesis Prediction
Succulence Succulence is an adaptation should be for arid conditions associated with High temperature arid conditions Low precipitation We wish to explain the morphological diversity found in Euphorbia Sects Goniostema, Denisophorbia, and Deuterocalli (GDD)
Two approaches
Multivariate approach: OMI (outlying mean index; Doldec et al. 2000) a form of discriminant analysis, which, like PCA, generates orthogonal (uncorrelated) axes of climate that are linear combinations of the original variables
Univariate approach: single or small numbers of climate variables (untransformed, no ordination)
Both tested with phylogenetic logistic regression (MCMCglmm): Predictors = climate variables (either OMI or original climate variables) Response = traits expressed as 0/1 Working phylogeny for Euphorbia Sects Goniostema, Denisophorbia, and Deuterocalli (GDD)
268 tips
Reduced to 58 taxa (OTU’s)
Some nodes with poor resolution
Non monophyly of some species (E. primulifolia, E. alluaudii)
Bayesian inference (Beast) based on 8 DNA regions (2 nuclear, 6 cp) using two secondary calibration points. One run of 6 x 107 generations Locality data: sparse ~550 points total (on average, 9 points/species). many species for which the number of points is 1 or 2 or 3...because of microendemism
Climate data: 19 bioclim variables from worldclim ~1 km resolution phylogeny phylogeny in climate space meanannualtemperature
traitgram {picante} phylogeny phylogeny in climate space
meanannualprecipitation
traitgram {picante} Warm and dry mean annual temperaturemean
meanannualprecipitation
Cool and wet
• Considerable evolution of climatic niche in the ~10-15 million years of the GDD radiation
• Tend to be found in warm, dry places (23-27 degrees C, 500-1500 mm/year)
• A few species have adapted to cold or wet places Multivariate approach - OMI
Cool and wet
High Moist temperature
OMI Axis 2 seasonality
OMI Axis 1 dudi.pca {ade4} Warm and High precipitation seasonality Leaf succulence
Leaves Leaves Leaves poorly or non thickened very succulent succulent
Cool and wet OMI Axis 2 Axis OMI
High temperature Moist seasonality • OMI Axis 1 positively correlated with OMI Axis 1 the evolution of leaf succulence
• Evolution of leaves towards succulence associated with high temperature dudi.pca {ade4} Warm and High precipitation seasonality seasonality and aridity Growth form
~ 2/3 of the plant ~ 1/2 of the plant More than 1/3 of the plant below the soil below the soil above the soil
Cool and wet OMI Axis 2 Axis OMI
High temperature Moist seasonality OMI Axis 1 • OMI Axis 1 negatively correlated with the evolution of the growth form
• Evolution of growth form towards geophytic habit associated with high dudi.pca {ade4} temperature seasonality and aridity Warm and High precipitation seasonality Phylogeny in climate space + trait mapping
Leaves poorly or non succulent + Leaves coriaceous
Precipitationof the wettest month(Bio13) Leaves very succulent
phenogram {phytools}
Phylogeny in climate space + trait mapping
More than 1/3 of the plant above the soil
Between 1/2 and 2/3 of the plant below the soil mean annual temperature (Bio1) meanannualtemperature
phenogram {phytools}
Temperature of the wettest quarter
Temperature annual range
Temperature seasonality
Evolution of leaf succulence: Precipitation of the • Positively correlated with warmest quarter temperature seasonality and temperature annual range Precipitation of the wettest quarter
• Negatively correlated with Precipitation of several precipitation the wettest month parameters Mean annual precipitation Temperature of the coldest quarter
Temperature of the warmest quarter
Temperature of the wettest quarter
Mean annual temperature
Evolution towards above- ground growth forms:
• Positively correlated with several temperature parameters
• No correlation with precipitation parameters Perspective:
Other predictors might better explain some of these traits?
Leaf succulence associated with low precipitation high T variation (???)
Substrate (working on this, data from Kew) Wind (reliable source ?) Slope (high-res layers needed) Estimating the rate of evolution of the niche
Purvis & Cooper. 2009. J Evol Biol. Estimating the rate of evolution of the niche
Purvis & Cooper. 2009. J Evol Biol.
rate of evolution of mean annual temperature (Euphorbia clade GDD) Sarcolaenaceae
Euphorbia
total # Phylogeny locality rates Predictors taxa data of rates
Euphorbia ~130 58 species, ~550 not yet Sections species Xavier points attempted Goniostema, Aubriot (9/species) Denisophorbia, Xavier Aubriot Deuterocalli
Sarcolaenace ~70 47 species, ~2100 predictors ae species, Thomas points ??? (10 Haeverman (44/species) genera) s Phylogeny in climate space – macroevolution of climatic niche
Sarcolaenaceae Ermolaena Rhodolaena Leptolaena Sarcolaena Mediusella Schizolaena Pentachlaena Xerochlamys Perrierodendron Xyloolaena Thanks!
…to all who have contributed to the development of the data sets
…and for your attention !