Chapter 8 Flashcards
directional selection (p. 326)
selection that favours an increase or decrease in the value of a trait from the current population average
stabilizing selection (p. 327)
selection against individuals exhibiting traits that deviate from the current population average
disruptive selection (p. 328)
selection that favours two or more variations of a trait that differ from the current population average
sexual selection (p. 328)
differential reproductive success caused by variation in the ability to obtain mates; results in sexual dimorphism, and mating and courtship behaviours
genetic drift (p. 331)
changes to allele frequency as a result of chance; such changes are much more pronounced in small populations
genetic bottleneck (p. 332)
a dramatic, often temporary, reduction in population size, usually resulting in significant genetic drift
founder effect (p. 332)
genetic drift that results when a small number of individuals separate from their original population and establish a new population
Hardy-Weinberg principle (p. 333)
In large populations in which only random chance is at work, allele frequencies are expected to remain constant from generation to generation.
microevolution (p. 336)
changes in gene (allele) frequencies and phenotypic traits within a population and species
speciation (p. 336)
the formation of new species
reproductive isolating mechanism (p. 336)
any behavioural, structural, or biochemical trait that prevents individuals of different species from reproducing successfully together
prezygotic mechanism (p. 336)
a reproductive isolating mechanism that prevents interspecies mating and fertilization (for example, ecological isolation, temporal isolation, and behavioural isolation)
postzygotic mechanism (p. 336)
a reproductive isolating mechanism that prevents maturation and reproduction in offspring from interspecies reproduction
allopatric speciation (p. 337)
the formation of a new species as a result of evolutionary changes following a period of geographic isolation
sympatric speciation (p. 339)
the evolution of populations within the same geographic area into separate species
adaptive radiation (p. 341)
the relatively rapid evolution of a single species into many new species, filling a variety of formerly empty ecological niches
divergent evolution (p. 342)
the large-scale evolution of a group into many different forms
convergent evolution (p. 343)
the evolution of similar traits in distantly related species
coevolution (p. 344)
a process in which one species evolves in response to the evolution of another species
macroevolution (p. 348)
large-scale evolutionary changes including the formation of new species and new taxa
abiogenesis (p. 348)
the origin of life from non-living matter
Cambrian explosion (p. 350)
the rapid evolution of most major animal phyla that took place over approximately 40 million years during the Cambrian period
cladistics (p. 350)
a method of determining evolutionary relationships based on the presence or absence of recently evolved traits
derived trait (p. 350)
a trait that has evolved relatively recently with respect to the species or groups being discussed
