Wildlife of Madagascar

The composition of Madagascar's wildlife reflects the fact that the island has been isolated for about 88 million years. The prehistoric breakup of the supercontinent Gondwana separated the Madagascar-Antarctica-India landmass from the Africa-South America landmass around 135 million years ago. Madagascar later split from India about 88 million years ago, allowing plants and animals on the island to evolve in relative isolation. As a result of the island's long isolation from neighboring continents, Madagascar is home to an abundance of plants and animals found nowhere else on Earth. Approximately 90 percent of all plant and animal species found in Madagascar are endemic, including the lemurs (a type of strepsirrhine primate), the carnivorous fossa and many birds. This distinctive ecology has led some ecologists to refer to Madagascar as the "eighth continent", and the island has been classified by Conservation International as a biodiversity hotspot. As recent as 2021, the "smallest reptile on earth" was also found in Madagascar, Brookesia nana, also known as the nano-chameleon.

Fauna

Madagascar's isolation from other land masses throughout the Cenozoic Era has led to the evolution of a large proportion of endemic animal species and the absence of many taxa found on neighboring continents. Some of Madagascar's animals appear to represent lineages that have been present since the breakup of Gondwana, while many others, including all of the nonflying native mammals, are descendants of ancestors that survived rare rafting or swimming voyages from Africa (likely aided by currents). As of 2012 it has over 200 extant mammal species, including over 100 species of lemurs, about 300 species of birds, more than 260 species of reptiles, and at least 266 species of amphibians. The island also has a rich invertebrate fauna including earthworms, insects, spiders and nonmarine molluscs. Lemurs have been characterized as "Madagascar's flagship mammal species" by Conservation International. In the absence of monkeys and other competitors, these primates have adapted to a wide range of habitats and diversified into numerous species. As of 2012, there were officially 103 species and subspecies of lemur, 39 of which were discovered by zoologists between 2000 and 2008. They are almost all classified as rare, vulnerable, or endangered. Since the arrival of humans on Madagascar, at least 17 species of lemur have become extinct; all of them were larger than the surviving lemur species. A number of other mammals, including the cat-like fossa, are endemic to Madagascar. Over 300 have been recorded on the island, of which over 60 percent (including four families and 42 genera) are endemic. The few families and genera of reptile that have reached Madagascar have diversified into more than 260 species, with over 90 percent of these being endemic (including one endemic family). The island is home to two-thirds of the world's chameleon species, including the smallest known, and researchers have proposed that Madagascar may be the origin of all chameleons.

Endemic fish of Madagascar include two families, 15 genera and over 100 species, primarily inhabiting the island's freshwater lakes and rivers. Although invertebrates remain poorly studied on Madagascar, researchers have found high rates of endemism among the known species. All 651 species of terrestrial snail are endemic, as are a majority of the island's butterflies, scarab beetles, lacewings, spiders and dragonflies.

Flora

More than 80 percent of Madagascar's 14,883 plant species are found nowhere else in the world, including five plant families. There are several endemic families including the Asteropeiaceae, Sarcolaenaceae and Sphaerosepalaceae. The humid eastern part of the island was formerly covered in rainforest with many palms, ferns and bamboo, although much of this forest has been reduced by human activity. The west has areas of dry deciduous forest with many lianas and with tamarind and baobabs among the dominant trees. Subhumid forest once covered much of the central plateau but grassland is now the dominant vegetation type there. The family Didiereaceae, composed of four genera and 11 species, is limited to the spiny forests of southwestern Madagascar. Four-fifths of the world's Pachypodium species are endemic to the island. Three-fourths of Madagascar's 860 orchid species are found here alone, as are six of the world's eight baobab species. The island is home to around 170 palm species, three times as many as on all of mainland Africa; 165 of them are endemic. Many native plant species are used as herbal remedies for a variety of afflictions. The drugs vinblastine and vincristine, used to treat Hodgkin's disease, leukemia and other cancers, were derived from the Madagascar periwinkle. The traveler's palm, known locally as ravinala and endemic to the eastern rain forests, is highly iconic of Madagascar and is featured in the national emblem as well as the Air Madagascar logo.

Environmental issues

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