Distribution
The twist-necked turtle inhabits a large area throughout northern and central South America, from the southern Orinoco drainage in Venezuela to the Amazon basin in Brazil. However, Platemys platycephala, does not inhabit large rivers but instead prefers shallow creeks and forest floors.
Ernst (1983) surveyed the extensive geographical range of the twist-necked turtle and determined the presence of a dark subspecies in the western range of Platemys platycephala. The author uses the "Quaternary forest refuge theory" to explain the existence of this subspecies. The theory is based on significant climatic changes occurring in and around the equator during the Quaternary period. During these climatic changes of glaciation the northern rainforests of South America received less rainfall and deteriorated then subsequently expanded during interglaciation. This change caused allopatric speciation to occur among many species and gave rise to a new subspecies- Platemys platycephala melanonota.
Read more about this topic: Twist-necked Turtle
Famous quotes containing the word distribution:
“There is the illusion of time, which is very deep; who has disposed of it? Mor come to the conviction that what seems the succession of thought is only the distribution of wholes into causal series.”
—Ralph Waldo Emerson (1803–1882)
“Classical and romantic: private language of a family quarrel, a dead dispute over the distribution of emphasis between man and nature.”
—Cyril Connolly (1903–1974)
“The question for the country now is how to secure a more equal distribution of property among the people. There can be no republican institutions with vast masses of property permanently in a few hands, and large masses of voters without property.... Let no man get by inheritance, or by will, more than will produce at four per cent interest an income ... of fifteen thousand dollars] per year, or an estate of five hundred thousand dollars.”
—Rutherford Birchard Hayes (1822–1893)