The old belief that climatic stability accounts for the high level of species diversity in the Amazon River basin of South America emerged, strangely enough, from observations of the deep sea. Sanders discovered high diversity among the mud-dwelling animals of the deep ocean. He argued that such diversity could be attributed to years in the Amazon basin, added to the absence of winter and glaciation, supports this view.
Recently, however, several observations have cast doubt on the validity of the stability hypothesis and suggest that the climate of the Amazon basin has fluctuated significantly in the past. Haffer noted that different species of birds inhabit different corners of the basin in spite of the fact that essentially unbroken green forest parts of the forest if the habitat in which they lived had a stable climate?
Haffer proposed a compelling explanation for the distribution of species. Observing that species found on high ground are different from those on low ground, and knowing that in the Amazon lowlands are drier than uplands, he proposed that during the ice ages the Amazon lowlands became a near-desert arid plain; meanwhile, the facilitated the development of new species as existing species on the lowlands adapted to changing climates.
Although no conclusive proof has yet been found to support Haffer’s hypothesis, it has led other researchers to gauge the effects of climatic changes, such as storms and flooding, on species diversity in the Amazon basin. Their research suggests splendid diversity of the Amazon rain forest today.
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