Related Experiment Videos

The changing nationality composition of the Central Asian and Transcaucasian states

Post-Soviet Geography and Economics
|June 1, 1997
PubMed

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Speciation Rates01:07

Speciation Rates

Speciation can proceed at markedly different rates, and evolutionary biologists commonly describe these differences through the models of gradualism and punctuated equilibrium. Both patterns explain how new species arise, but they differ in the tempo and continuity of evolutionary change. In both cases, evolutionary change arises from heritable variation within populations, with natural selection often shaping traits that improve survival and reproduction under specific environmental conditions.
Mutation, Gene Flow, and Genetic Drift01:09

Mutation, Gene Flow, and Genetic Drift

In a population that is not at Hardy-Weinberg equilibrium, the frequency of alleles changes over time. Therefore, any deviations from the five conditions of Hardy-Weinberg equilibrium can alter the genetic variation of a given population. Conditions that change the genetic variability of a population include mutations, natural selection, non-random mating, gene flow, and genetic drift (small population size).Mechanisms of Genetic VariationThe original sources of genetic variation are mutations,...
Genetic Drift03:33

Genetic Drift

Natural selection—probably the most well-known evolutionary mechanism—increases the prevalence of traits that enhance survival and reproduction. However, evolution does not merely propagate favorable traits, nor does it always benefit populations.Life is not fair. A deer grazing contentedly in a field can have her meal cut tragically short by a bolt of lightning. If the doomed doe is one of only three in the population, 1/3 of the population’s gene pool is lost. Random events like this can...
Gene Flow02:39

Gene Flow

Gene flow is the transfer of genes among populations, resulting from either the dispersal of gametes or from the migration of individuals.
Ethnic Identity within a Larger Culture01:27

Ethnic Identity within a Larger Culture

Adolescents from ethnic minority backgrounds face a multifaceted journey in forming their identities, shaped by the intersections of cultural expectations and personal exploration. For these adolescents, identity formation involves not only typical developmental challenges but also navigating the perceptions and attitudes of the majority culture. As they grow, adolescents in ethnic minority groups often become increasingly aware of stereotypes, social biases, and discrimination, all of which...
Self-Esteem and Culture01:26

Self-Esteem and Culture

Self-esteem, a core psychological construct, is intricately shaped by cultural context and varies significantly between collectivist and individualistic societies. In collectivist cultures such as Japan, self-esteem tends to be flexible, context-sensitive, and influenced by relationships. A Japanese student, for instance, may show restraint in formal settings like school but behave more openly among close friends, reflecting the flexible and dynamic nature of self-concept in such...