Mammalian evolution and the great american interchange.

摘要: A reciprocal and apparently symmetrical interchange of land mammals between North South America began about 3 million years ago, after the appearance Panamanian bridge. The number families in rose from 32 before to 39 it began, then back 35 at present. An equivalent experienced a comparable rise decline during same interval. These changes diversity are predicted by MacArthur-Wilson species equilibrium theory. greater American genera (24) initially entering than reverse (12) is proportions reservoir on two continents. However, later imbalance caused secondary immigrants (those which evolved initial immigrants) not expected