Darwinisme

Résumé

thumb|Le naturaliste Charles Darwin, photographié en 1868. Le darwinisme désigne, en son sens strict, la théorie formulée en 1859 (dans L'Origine des espèces) par le naturaliste anglais Charles Darwin, qui explique . Il est aussi relativement courant d'entendre parler d'évolution darwinienne, pour parler de l'évolution autonome d'un pool quelconque (population et distribution de caractères) sur plusieurs générations. Les théories de l'évolution et le darwinisme Position du darwinisme dans les théories de l'évolution Au début du , l'existence d'espèces éteintes ne fait plus de doute dans la communauté scientifique, grâce notamment aux travaux de Georges Cuvier sur les mammouths et sur les mastodontes. C'est ainsi qu'en 1808 Jean-Baptiste Lamarck propose une théorie explicative de ce phénomène en mettant en jeu l'évolution des espèces, qu'il fonde en particulier sur l'affirmation des principes de la transmission des caractères acquis – déjà soutenue par Aristote

Source officielle

https://fr.wikipedia.org/wiki/Darwinisme

À propos de ce résultat

Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.

Publications associées (2)

Publications associées

Chargement

Personnes associées

Chargement

Unités associées

Chargement

Concepts associés (47)

Concepts associés

Chargement

Cours associés (7)

Cours associés

Chargement

Séances de cours associées (11)

Séances de cours associées

Chargement

Catch Me if You Can: Adaptation from Standing Genetic Variation to a Moving Phenotypic Optimum

Sebastian Matuszewski

Adaptation lies at the heart of Darwinian evolution. Accordingly, numerous studies have tried to provide a formal framework for the description of the adaptive process. Of these, two complementary modeling approaches have emerged: While so-called adaptive-walk models consider adaptation from the successive fixation of de novo mutations only, quantitative genetic models assume that adaptation proceeds exclusively from preexisting standing genetic variation. The latter approach, however, has focused on short-term evolution of population means and variances rather than on the statistical properties of adaptive substitutions. Our aim is to combine these two approaches by describing the ecological and genetic factors that determine the genetic basis of adaptation from standing genetic variation in terms of the effect-size distribution of individual alleles. Specifically, we consider the evolution of a quantitative trait to a gradually changing environment. By means of analytical approximations, we derive the distribution of adaptive substitutions from standing genetic variation, that is, the distribution of the phenotypic effects of those alleles from the standing variation that become fixed during adaptation. Our results are checked against individual-based simulations. We find that, compared to adaptation from de novo mutations, (i) adaptation from standing variation proceeds by the fixation of more alleles of small effect and (ii) populations that adapt from standing genetic variation can traverse larger distances in phenotype space and, thus, have a higher potential for adaptation if the rate of environmental change is fast rather than slow.

2015

Chargement

Language Evolution as a Darwinian Process: Computational Studies

Frédéric Kaplan

This paper presents computational experiments that illustrate how one can precisely conceptualize language evolution as a Darwinian process. We show that there is potentially a wide diversity of replicating units and replication mechanisms involved in language evolution. Computational experiments allow us to study systemic properties coming out of populations of linguistic replicators: linguistic replicators can adapt to specific external environments; they evolve under the pressure of the cognitive constraints of their hosts, as well as under the functional pressure of communication for which they are used; one can observe neutral drift; coalitions of replicators may appear, forming higher level groups which can themselves become subject to competion and selection.

2007

Chargement