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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
R e n c o n t r e s I R D / M N H N , 2 0 - 2 1 s e p t e m b r e 2 0 1 2
Comparative studies of niche evolution and diversification in
malagasy Euphorbia and Sarcolaenaceae
Euphorbia
total # taxa
Phylogeny locality data
rates Predictors of rates
Euphorbia Sections Goniostema, Denisophorbia, Deuterocalli
~130 species
58 species, Xavier Aubriot
~550 points (9/species) Xavier Aubriot
not yet attempted but good candidates
Sarcolaenaceae ~70 species, (10 genera)
47 species, Thomas Haevermans
~2100 points (44/species)
predictors???
Sarcolaenaceae
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)
Euphorbia emirnensis Baker
Euphorbia intisy Drake Euphorbia primulifolia var. begardii G. Cremers
Euphorbia alluaudii Drake
Euphorbia stenoclada Baill.
Euphorbia viguieri Denis
Euphorbia cf. milii (natural hybrid)
Herbs
Pencil like trees
Pencil like trees Geophytes
Thorny shrubs Monocaulus and cactiform
Spiny trees
Euphorbia denisii Oudejans Euphorbia sp.
Euphorbia mandravioky Leandri
Euphorbia plagiantha Drake
Euphorbia orthoclada Baker
Euphorbia antso Denis
© Genève, L.Gauthier et al.
Euphorbia L. in Madagascar (2)
Unarmed shrubs Lianas
Large pachycaulous trees
Unarmed shrubs
Trees Trees
• Present everywhere in Madagscar, in every type of climate, vegetation and substrate
Euphorbia L. in Madagascar (3)
Tropical rainforest
Arid haut-plateaux
Inland karstic formations
Karstic cliffs
Quartzite formations
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
• Major diversity hot spots: dry area of the North (Antsiranana), of the West (Mahajanga) and of the South (Fort-Dauphin, Tulear) of Madagascar
Euphorbia L. in Madagascar (4)
• Micro-endemism common. 80% of the species being threatened (IUCN). All succulent species are listed in annexes I and II of CITES convention
Euphorbia L. in Madagascar (5)
Bayesian Inference of Euphorbia phylogeny based on 500 ITS sequences (GenBank plus unpublished data)
Succinct phylogeny of Euphorbia L. • Malagasy Euphorbia are polyphyletic (6-7 radiations in Madagascar) • Malagasy Euphorbia clades are unequal in terms of species diversity
~ 76% ~ 57%
We wish to explain the morphological diversity found in Euphorbia Sects Goniostema, Denisophorbia, and
Deuterocalli (GDD)
succulence: growth form: spines cyathia:
leaves stems Index 1 (quantitative, # organs succulent) Index 2 (qualitative, 5 categories)
(thickened stem below/at ground level) caudex Index (5 categories)
reduced enveloped
Hypothesis Succulence is an adaptation for arid conditions
Can climate explain the evolution of some of this morphological diversity?
Prediction Succulence should be associated with arid conditions
High temperature 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
We wish to explain the morphological diversity found in Euphorbia Sects Goniostema, Denisophorbia, and
Deuterocalli (GDD)
Bayesian inference (Beast) based on 8 DNA regions (2 nuclear, 6 cp) using two secondary calibration points. One run of 6 x 107 generations
Reduced to 58 taxa (OTU’s)
Some nodes with poor resolution
268 tips
Non monophyly of some species (E. primulifolia, E. alluaudii)
Working phylogeny for Euphorbia Sects Goniostema, Denisophorbia, and Deuterocalli (GDD)
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
• 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
mea
n an
nual
pre
cipi
tatio
n m
ean annual temperature
Cool and wet
Warm and dry
High temperature seasonality
Moist
Warm and High precipitation seasonality
Cool and wet
dudi.pca {ade4} OMI Axis 1
OM
I Axi
s 2
Multivariate approach - OMI
Leaves poorly or non
succulent
Leaves thickened
Leaves very
succulent
Leaf succulence
dudi.pca {ade4}
Moist
Cool and wet
High temperature seasonality
Warm and High precipitation seasonality
OMI Axis 1
OM
I Axi
s 2
• OMI Axis 1 positively correlated with the evolution of leaf succulence
• Evolution of leaves towards succulence associated with high temperature seasonality and aridity
~ 2/3 of the plant
below the soil
~ 1/2 of the plant
below the soil
More than 1/3 of the plant
above the soil
Growth form
dudi.pca {ade4}
Moist
Cool and wet
High temperature seasonality
Warm and High precipitation seasonality
OMI Axis 1
OM
I Axi
s 2
• OMI Axis 1 negatively correlated with the evolution of the growth form
• Evolution of growth form towards geophytic habit associated with high temperature seasonality and aridity
Leaves poorly or non succulent + Leaves coriaceous
Leaves very succulent
Phylogeny in climate space + trait mapping
phenogram {phytools}
Pre
cipi
tatio
n of
the
wet
test
mon
th (B
io13
)
More than 1/3 of the plant above the soil
Between 1/2 and 2/3 of the plant below the soil m
ean
annu
al te
mpe
ratu
re (B
io1)
phenogram {phytools}
Phylogeny in climate space + trait mapping
Temperature seasonality
Temperature annual range
Precipitation of the wettest month
Mean annual precipitation
Precipitation of the wettest quarter
Precipitation of the warmest quarter
Evolution of leaf succulence:
• Positively correlated with temperature seasonality and temperature annual range
• Negatively correlated with several precipitation parameters
Temperature of the wettest quarter
Evolution towards above-ground growth forms:
• Positively correlated with several temperature parameters
• No correlation with precipitation parameters
Temperature of the coldest quarter
Temperature of the warmest quarter
Temperature of the wettest quarter
Mean annual temperature
Perspective: Other predictors might better explain some of these traits? Substrate (working on this, data from Kew) Wind (reliable source ?) Slope (high-res layers needed)
Leaf succulence associated with low precipitation high T variation (???)
rate of evolution of mean annual temperature (Euphorbia clade GDD)
Purvis & Cooper. 2009. J Evol Biol.
Estimating the rate of evolution of the niche
Euphorbia
total # taxa
Phylogeny locality data
rates Predictors of rates
Euphorbia Sections Goniostema, Denisophorbia, Deuterocalli
~130 species
58 species, Xavier Aubriot
~550 points (9/species) Xavier Aubriot
not yet attempted
Sarcolaenaceae
~70 species, (10 genera)
47 species, Thomas Haevermans
~2100 points (44/species)
predictors???
Sarcolaenaceae
Phylogeny in climate space – macroevolution of climatic niche
Sarcolaenaceae Ermolaena Leptolaena Mediusella Pentachlaena Perrierodendron
Rhodolaena Sarcolaena Schizolaena Xerochlamys Xyloolaena