Comparative studies of niche evolution and diversification ... · PDF filedudi.pca {ade4} OMI Axis 1 OMI Axis 2. Multivariate approach - OMI . Leaves poorly or non succulent . Leaves

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

traitgram {picante}

phylogeny phylogeny in climate space

mea

n an

nual

tem

pera

ture

traitgram {picante}

phylogeny phylogeny in climate space

mea

n an

nual

pre

cipi

tatio

n

• 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 (???)

Purvis & Cooper. 2009. J Evol Biol.

Estimating the rate of evolution of the niche

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

Thanks! …to all who have contributed to the development of the data sets …and for your attention !