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 , ~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 Euphorbia L.

• ca. 2000 species. Cosmopolitan genus. Particularly diversified in (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 Geophytes

Pencil like Thorny 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 ~ 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 Mediusella Pentachlaena Xyloolaena Thanks!

…to all who have contributed to the development of the data sets

…and for your attention !