Ice Age effects on speciation and biodiversity:
<!--QuoteBegin-->QUOTE<!--QuoteEBegin-->Climate Change May be Responsible for Madagascar's Biodiversity
Why does Madagascar have so many unique animals?
... Using an analysis of watersheds in the context of paleoclimatic shifts, the authors provide a new mechanistic model to explain the process of explosive speciation on the island. Existing data show that substantial climatic shifts took place during the end of the Tertiary, as well as more recently during the Quaternary. The latter period is also known as âThe Age of Man.â
<b>When the climate was dry and cold, considerable portions of the Earth were covered by glaciers. </b>On Madagascar, habitats at higher elevations would have remained more humid, as compared to the drying-out of more lowland areas. Therefore, groups of animals tended to âretreatâ to higher elevations along riverine habitat that would have remained relatively humid during these periods of climatic change. The animals that did not âretreatâ tended to be left behind in small, limited geographic areas where river sources commenced at relatively low elevations. Since they were isolated, those populations that were able to survive were more likely to develop into new species.
<b>âRiver catchments with their sources at relatively low elevations were zones of isolation and hence led to the speciation of locally endemic taxa,â </b>the authors explain in a paper to be published as the cover story of Science on May 19, 2006. ...<!--QuoteEnd--><!--QuoteEEnd-->
<!--QuoteBegin-->QUOTE<!--QuoteEBegin-->The series of ice ages that occurred between 2.4 million and 10,000 years ago had a dramatic effect on the climate and the life forms in the tropics. During each glacial period the tropics became both cooler and drier, turning some areas of tropical rain forest into dry seasonal forest or savanna. For reasons associated with local topography, geography, and climate, some areas of forest escaped the dry periods, and acted as refuges for forest biota. <b>During subsequent interglacials, when humid conditions returned to the tropics, the forests expanded and were repopulated by plants and animals from the species-rich refuges.</b>
Ice Age and Biodiversity<!--QuoteEnd--><!--QuoteEEnd-->
<!--QuoteBegin-->QUOTE<!--QuoteEBegin-->Climate Change May be Responsible for Madagascar's Biodiversity
Why does Madagascar have so many unique animals?
... Using an analysis of watersheds in the context of paleoclimatic shifts, the authors provide a new mechanistic model to explain the process of explosive speciation on the island. Existing data show that substantial climatic shifts took place during the end of the Tertiary, as well as more recently during the Quaternary. The latter period is also known as âThe Age of Man.â
<b>When the climate was dry and cold, considerable portions of the Earth were covered by glaciers. </b>On Madagascar, habitats at higher elevations would have remained more humid, as compared to the drying-out of more lowland areas. Therefore, groups of animals tended to âretreatâ to higher elevations along riverine habitat that would have remained relatively humid during these periods of climatic change. The animals that did not âretreatâ tended to be left behind in small, limited geographic areas where river sources commenced at relatively low elevations. Since they were isolated, those populations that were able to survive were more likely to develop into new species.
<b>âRiver catchments with their sources at relatively low elevations were zones of isolation and hence led to the speciation of locally endemic taxa,â </b>the authors explain in a paper to be published as the cover story of Science on May 19, 2006. ...<!--QuoteEnd--><!--QuoteEEnd-->
<!--QuoteBegin-->QUOTE<!--QuoteEBegin-->The series of ice ages that occurred between 2.4 million and 10,000 years ago had a dramatic effect on the climate and the life forms in the tropics. During each glacial period the tropics became both cooler and drier, turning some areas of tropical rain forest into dry seasonal forest or savanna. For reasons associated with local topography, geography, and climate, some areas of forest escaped the dry periods, and acted as refuges for forest biota. <b>During subsequent interglacials, when humid conditions returned to the tropics, the forests expanded and were repopulated by plants and animals from the species-rich refuges.</b>
Ice Age and Biodiversity<!--QuoteEnd--><!--QuoteEEnd-->