Selection: The Mechanism of Evolution

Thisbookhasbeenwritten tomake a pointand tofulfill a need. Thepoint is that the importance and the distinctiveness of the process of selection have been undervalued by most biologists. There is, consequently, the need for a book that describes the principles of selection in a simple but reasonably comprehensive way. Selection Is a Distinct Kind ofProcess Although we are now well into the second century of Darwinism, the theorythatDarwinand Wallaceannouncedin 1858hasnotyetmademuch progress beyond a small coterie of professional biologists. The reason is thatit isjarringlyunfamiliar toournormalexperienceofhow things come to be. Few ofus would be able to design a light bulb or a lathe, still fewer the computerand itsattendant softwarewithwhich this sentence is being written. But we all have a clear idea of what is meant by "design", and we readily, too readily, transfer this notion to the natural world. A light bulb or a lathe are prefigured in the mind, and constructed according to a plan. It is entirely reasonable to assume that beetles and daisies must be constructed after the same fashion, especially because they are much morecomplicatedthananythingthathumaningenuityhassofarmanaged to devise. There is, however, a second route to complex organization, throughtheselectionofrandomvariantsthatpropagatenearlyexactcopies ofthemselves. Itisofverylittleconsequenceinourdailylives,becauseifis somuchmorelaboriousandexpensivethandeliberatedesign. However,it isanotherwayofconstructingthings. Indeed, sofarasIknow, itistheonly other way of constructing things that we have ever been able to imagine. Simple selection; Selection on a single character; Single episode of selection; Selection of pre-existing variation; Continued selection; The Evolution of novelty; Selection on several characters; Selection acting on different components of fitness; Selection in several environments; Selection acting at different levels; Autoselection; Elements that utilize existing modes of transmission; Elements that modify existing modes of transmission; Social selection; Selection within a single uniform population; density-dependent selection; Selection within a single diverse population; frequency-dependent selection; Selection among populations; kin selection and group selection; Coevolution; Sexual selection.