Transcript Week 7 Biodiversity Hotspot_Richa - Science-ed12

Biodiversity HotspotMadagascar & the Indian Ocean Islands
What is a Biodiversity Hotspot?
According to Conservation International, a biodiversity hotspot is
defined by the following 2 criteria:
1. It must have at least 1,500 species of endemic vascular plants
Endemism is the degree to which species are found only in a given place.
2. must have lost at least 70% of its original area.
34 hotspots have
been identified
worldwide
Our research is based onMadagascar & the Indian Ocean Islands Hotspot
Region: Madagascar, Seychelles (including Aldabra), the Comoros,
Mauritius (including Rodrigues), and the French overseas
departments of Réunion.
 Seychelles, Comoros & Mascarene islands in the Indian Ocean have many
critically endangered bird species.
 Seychelles are also home to the only endemic family of amphibians: the
Sooglossidae, and the Aldabra giant tortoise
Madagascar & the Indian Ocean Islands Hotspot
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1. Unique Biodiversity & Endemism
2. Hotspot Plant species
3. Hotspot Vertebrate speciesa) Birds
b) Mammals
c) Fishes
d) Reptiles & Amphibians
4. Hotspot Invertebrate species
1.Unique Biodiversity & Endemism
 Flora and fauna diversity extremely diverse & endemic.
 resulted from tens of millions of years of isolation from
the African mainland and from people, who didn't
arrive until 2,000 years ago.
 Endemism is marked not only at the species level, but
also at higher taxonomic levels.
 8 plant, 4 bird, and 5 primate families are endemic.
 70% of Madagascar’s species are endemic.
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2.Hotspot Plant species
More than 13,000 species of vascular plants, 90 % endemic
At least 310 endemic genera of plants. Local endemism is high as
well; some individual mountaintops have 150 to 200 endemic
plants.
Madagascar's signature endemic plant, traveler's tree
6 out of 8 species of the baobab, or bottle tree found
in drier regions of the west and south Madagascar.
bottle shaped trunks store large reserves of
water(adaptation)
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3a.Hotspot Vertebrates- Birds
Birds of Madagascar –low diversity but spectacular endemism.
More than 300 bird species,60% endemic. Over 55 endemic
species are currently threatened, and 32 have already gone
extinct, mainly from the Mascarenes.
Birds of the Indian Ocean islands10 bird species extinct in Réunion since 1500 & all the endemic
birds of Mauritius are threatened.
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3b.Hotspot Vertebrates- Mammals
Mammals in Madagascar
• Low diversity, 90% endemic
• more than 150 mammal species.
• Lemurs are unique to Madagascar. represented by 5 families of primates. 72
kinds of lemurs (species and subspecies), representing 15 genera
highest primate endemism in the world.
• One of the most unusual lemur species is the aye-aye
• more than 15 endemic bat species, including the Madagascar flying fox and
numerous endemic rodents, like the unusual giant jumping rat
• primary predator of lemurs is the carnivore fossa
• The endemic tenrecs, a unique family of insect-eating mammals, occupy the
ecological niche that shrews and moles occupy elsewhere.
3b.Hotspot Vertebrates- Mammals
(contd)
Mammals are thinly distributed elsewhere on the Indian Ocean
Islands, but include the world's largest bat, Livingstone's flying fox
(Pteropus livingstonii, CR) on the Comoros.
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3c.Hotspot Vertebrates- Fishes
 smaller islands are dominated by species with wide
marine distributions, which enter both brackish and
freshwater habitats.
 Madagascar's fish are mainly freshwater species of
continental origin that have evolved on the island.
nearly 100 endemic species of fish.
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3d.Hotspot VertebratesReptiles & Amphibians
Reptilesone endemic reptile family but high species diversity and endemism
96% of nearly 400 reptile species are endemic.
chameleon diversity- proposed that all the worlds' chameleons originated here.
 endemic reptile in the Indian Ocean islands is the Seychelles' Aldabra giant tortoise .
it is considered threatened by development, illegal trade, and natural disasters.
Amphibians- 2 endemic families of amphibians:
 Sooglossidae, found in the Seychelles
 Mantellidae, endemic to Madagascar and Mayotte.
Among the flagship amphibians are the beautiful frogs of the genera Mantella and
Scaphiophryne and the tomato frog , a bright red, bullfrog-sized animal found only in a
small corner of northeastern Madagascar.
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Hotspot Invertebrate fauna
Madagascar: 5,800 species, 86% are endemic
Some examples: terrestrial snails, dragonflies, tiger beetles,
scarab beetles, true butterflies ,freshwater crayfish and freshwater
shrimp.
Seychelles: estimated 5,100 species, 80% are endemic
• unique and amazing invertebrate flagship species is the
endemic giant tenebrionid beetle, restricted to 1 small island in
the Seychelles, and one of the largest terrestrial invertebrates in
the world.
• largest millipede and populations of the world's largest
terrestrial invertebrate, the coconut or robber
Hotspot- Food web & Food chain
Key species in this hotspot and their relationships with
other species Madagascar's signature endemic plant, the traveler's tree is pollinated by
the island's flagship vertebrate species, the lemurs.
 Grandidier's baobab, the largest baobab species, is pollinated by nocturnal
lemurs.
It is the most heavily exploited tree with the fruit, seeds, wood and
bark all being collected and used by local people for making rope and
medicines. The greatest threat to this tree comes from the
transformation of its habitat into agricultural land but it is also
threatened by fire, overgrazing and bark collection.
 Other Malagasy species are pollinated by fruit-eating bats.
Role of abiotic factors in the Hotspot
1. Soil- is very moist, which allows many plants to grow and
prosper there.
2. Sunlight-lot of sunlight because of the large quantities of tall
trees. These trees absorb all of the sunlight, which has caused
the plants to adapt to this.
3. Rainfall- abundant in the lowland rainforests, plants & animals
adapted to it.
4. Climate- of a lowland rainforest is hot and humid. If the climate
gets any colder and dryer, many of the plants & animals would
not be able to survive.
Human Impact on the Hotspot
 Demands from todays global markets threaten the
diversity brought about by the isolation that the
island of Madagascar has experienced.
 Deforestation, unsustainable agriculture and
erosion fueled by human population growth all
endanger the islands unique habitats.
 The result: several species such as lemurs and
chameleons that evolved over millions of years
may become extinct before the end of the century.

References
• http://www.eoearth.org/article/Biological_diversity_in_Madag
ascar_and_the_Indian_Ocean_Islands
• http://www.conservation.org/WHERE/PRIORITY_AREAS/HOTSP
OTS/Pages/hotspots_main.aspx
• http://www.environment.gov.au/biodiversity/hotspots/index.ht
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