XXVI.3.2 Species selection can also explain evolutionary and ecological processes occurring at a local level

The phenomenon of species selection can be very important at a local level.A good example consists in the major change in fauna that occurred relatively recently, in the Tertiary, during the formation of the Isthmus of Panama, which connected North and South America approximately four million years ago and permitted migration of members of fauna from one continent to the other.This migration led to the slight enrichment of the fauna of North America by a relatively small number of species (opossum, armadillo) and major successful invasion of North American animals into South America, connected with elimination of a major portion of the original South American fauna.Traditionally, this event is interpreted in terms of replacement of the competitively weaker South American species, which evolved on a smaller, relatively isolated territory, by modern North American species that, as a result of the previous period of intense mutual competition over a much larger territory and greater range of competitors were competitively much stronger.More detailed analysis of the progress and result of the large intercontinental migration, however, showed that approximately the same percentage of species successfully moved from one continent to the other in both directions.While the originally North American species subsequently successfully and repeatedly underwent speciation in South America, the number of species of South American did not increase in North America.Thus, the North American fauna were victorious over the South American fauna in a competition based, not on ecological competition, but rather on speciation competition, i.e. in the field of species selection (Marshall & Hecht 1978).

Was this information useful for you?
The classical Darwinian theory of evolution can explain the evolution of adaptive traits only in asexual organisms. The frozen plasticity theory is much more general: It can also explain the origin and evolution of adaptive traits in both asexual and sexual organisms Read more
Draft translation from: Evoluční biologie, 2. vydání (Evolutionary biology, 2nd edition), J. Flegr, Academia Prague 2009. The translation was not done by biologist, therefore any suggestion concerning proper scientific terminology and language usage are highly welcomed. You can send your comments to flegratcesnet [dot] cz. Thank you.