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Mascarenes islands : biogeographical features
Habitat diversity (Reunion island)
Endemism and geographical origin of biotas
Biological Conservation issues
blog.univ-reunion.fr/demin
Photo H. Douris. Parc National
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11 LECTURERS or PROFESSORS
20 PERMANENT SEARCHERS
45 TECHNICIANS
18 PhD
16 Postdoc
15 Permanent staff in crop biosecurity
and innovation
umr-pvbmt.cirad.fr
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• Mascarenes islands : Reunion, Mauritius and
Rodrigues
• Home of DODO, symbol of human caused
extinction and biodiversty loss
21°S 55.5°E
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The fauna experienced a HIGH EXTINCTION RATE
Despite a very RECENT human settlement : • Among 60 native birds sp. 2/3 extinct on Mascarenes Islands
J. Hume JJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJ...................................................... HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuummmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee Paintings J. Hume
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Native forest cover at Mauritius in 2015 : less than 2% is left
Main driver of extinction : habitat
transformation?
1988
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Extinction rate of Mauritius land snails 44%
(86 endemic species)
Plegma duponti Gibbus lyonetianus
Tropidophora carinata
Photos V. Florens
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Madagascar biodiversity hotspot
Marine and Terrestrial Biodiversity Hotspot
Number of endemic species / km2 is high
Mascarenes harbor 25 % of their original cover
http://runemerge.univ-reunion.fr
ANR-06-BDIV-0002
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VOLCANIC ORIGIN, Never connected to land mass
© Aline Peltier © observatoire © observatoire
considered as an analog to HAWAII
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Geographical features
PRESENT
FEATURES
Réunion Mauritius Rodrigues
AREA 2512 km2 1865 km2 110 km2
MAX
ELEVATION
3070 m 828 m 398 m
AGE 2.1 Myrs 7.8 Myrs 1.5 Myrs
3 ISLANDS
GEOLOGICALY YOUNG
(lava flows on surface even
younger, 0.2 M)
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Geographic
isolation
across time?
Geography when sea level
was 135 m BPSL
3,800 km
420 km
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Habitat
Diversity Photo H. Douris.
Parc National
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Past and
present
native
vegetation
20 BHU
30 % is left
Habitat diversity
on Reunion Island
Strasberg, Rouget, Richardson et al 2005
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Semi-dry forest
(Coastal Palm
forest)
Average annual Tp: 23°C
Precipitation: coast = 500- 1000 mm/year
Trees (7-20m) and lianas: 32
Small trees (1-6m): 32
Terrestrial herbs: 14
Epiphytes: 22 800
100
750 750
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Lowland
rainforest
Average annual Tp: 23-24°C
Precipitation: coast = 1500 mm/year
> 10 m in the E
Trees (7-20m) and lianas: 35
Small trees (1-6m): 18
Terrestrial herbs: 10
Epiphytes: 37
Hemiparasites: <1 800
1100
750
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Dense mountain cloud forest
Average annual Tp: 17°C
Precipitation: East around 4000 mm/year
W around 1500 mm
ETP reduced + Fog interception
Trees (7-15m) and lianas: 26
Small trees (1-6m): 20
Terrestrial herbs: 19
Epiphytes: 35
Hemiparasites: <1
800
1100
2000
1900
Photo S. Baret
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Disa borbonica
Hypericum lanceolatum
Stoebe passerinoides
Ericaceae , Asteraceae
Subalpine scrubland : grasslands and heathlands
2000
1900
3070
Average annual Tp: 10.9°C
Precipitation: East > 3000 mm/year
W from 1500 to 2500mm
No trees
Dominance by Shrubs
Terrestrial herbs: from 10 to 30%
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Habitat
diversity
a very rugged
topography
erosion records
Photo H. Douris. Parc National
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200
750 800
1100
2000
1900
3070 m NW
SE
Trade
winds
Lowland rainforest
Tropical mountain cloud forest
Subalpine vegetation
Semi-dry forest
a strong Elevation gradient 0-3070 m a.s.l.
Habitat Zonation, (Cadet 1977)
AVERAGE
RAINFALL
ranges
from 0.5 m to 12 m
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Which mechanisms control biodiversity patterns along elevation gradients, accross islands?
ERANET Biome funding, Conseil Regional, ANR
French Polynesia
Guadaloupe
Canary Is.
Açores
La Reunion
Madagascar
Kenya Kenynynynynynynynynynynynynynynynynynynynynynynynynynynynynynynynynynynya
Ah Peng et al 2015 moveclim.blogspot.com
moeclim.blogspot.com
MOVECLIM : montane vegetation as listening posts for climate
change
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20
Area: 400.6 km2
Top: 1,021 m
Pop.: 56,437
(141 /km2)
Geol. age: 1 MY
Area: 706 km2
Top: 2,426 m
Pop.: 21,145
(30/km2)
Geol. age: 3 MY
Area: 2,511 km2
Top: 3,070 m
Pop.: 840,974
(330/km2)
Geol. age: 2 MY
Area: 581,540 km2
Top: 2,876 m
Pop.: 22,005,222
(35.2/km2)
Geol. age: 88 MY
Area: 447,0 km2
Top: 2,350 m
Pop.: 14,806
(35.3 /km2)
Geol. age: 0,25 MY
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Endemism and Geographical origin of native biotas
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Endemism distribution among taxa
Thébaud, Warren, Strasberg & Cheke 2009
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« DISHARMONIC » vertebrate fauna with no terrestrial
mammals and no amphibians
Cheke & Hume 2008
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M. Attié
Main AFRICAN Origin,
+ EASTERN Origin implying
Long distance dispersal : Acacia heterophylla
And
several lineages of
plants, birds (Dodo), bats,
skinks, beetles, ….
Leroux et al. 2014
New Phytol.
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Crédits Photo : T. Pezet, F. Martos et J.F.
Bègue
How biodiversity has built up?
/ Anagenesis
Ex : orchid species richness (Micheneau et al. 2008)
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Daisy trees (Psiadia)
diversified into 26
endemic species
From 2 independent
colonisation events
1 Reunion clade (older)
1 Mauritian clade
> = to Madagascar
Cladogenesis and diversification
Strijk, Noyes, Strasberg et al. 2012
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Major Gaps in Systematic studies
And we know very few about processes!
speciation of orchids (Mallet et al. 2015)
Zosterops diversification
(Bertrand, Mila, Thébaud et al. 2014)
zoboscience sites.google
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Biological Conservation issues
The National Park covers 40% of Reunion area
+ World heritage site
Involving regional stakeholders in native Mascarenes habitats preservation
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Most impacting/abundant
introduced vertebrates in
Reunion native habitats
Main threat from biological invasions :
65 vertebrates species introduced to Reunion
25 invaders
Photos V. Florens
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FIRE FEQUENCY
FRAGMENTATION
ROAD BUILDING
promoted by landuse
and disturbances regime
changes
Alien plants invasions
In 250 yrs
More than 2500 introduced
835 naturalized
132 invasive
Baret et al. 2008
CBNM. 2014
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Rubus alceifolius recently « eradicated » from
the lowlands / biocontrol
Rosaceae
2000 1900
750
Research programs and biocontrol conducted
on one Bramble species
Cirad Réunion
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Psidium cattleianum
Syzygium jambos STRAWBERRY GUAVA the worst « transformer » in the
Mascarenes
the most appreciated fruit at Reunion
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Casuarina equisetifolia invading recent lava flows
altering ecosystem functioning
Potgieter et al 2014
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Fuchsia boliviana
F. x exoniensis
F. magellanica Mountain cloud forest
Photo S. Baret
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NEW INVASIVE SPECIES
RISK ANALYSIS
TO PREVENT INTRODUCTIONS,
Photo JM. Probst
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Active Invasive species management in protected areas at Mauritius
Lack of native community recovery
)
Photo V. Florens
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Breakdown of
plant x animal interactions
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Rewilding programs (?)
Photo J. Hume, B. Warren
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Thanks for your attention!