Variation and Speciation Flashcards
What is artificial selection?
Organisms with beneficial characteristics are selected by humans and allowed to reproduce, passing on the alleles for these characteristics to their offspring
What is allopatric speciation?
Speciation due to organisms of a species being separated by geographical barriers so that over time members of the two populations become so different that they become unable to interbreed and are to be considered two different species
What is the biological species concept?
The biological species concept is a group of similar organisms that can interbreed and produce fertile offspring
What is a clade?
A monophyletic taxonomic group, that is, a single ancestor and all of its descendants
What is cladistics?
A method of classifying organisms based upon their evolutionary ancestry.
What is continuous variation?
Genetic variation, also called quantitative variation, where there is a wide range of phenotypic variation within the population.
There are no distinct categories. It is controlled by many genes.
What is directional selection?
A type of natural selection in which the allele and genotype frequency within a population changes because there is change to the environment that favours one extreme phenotype.
Leads to evolution
What is discontinuous variation?
Genetic variation where there are distinct phenotypic categories.
Also called qualitative variation. Usually controlled by one gene
What is disrupted selection?
A type of natural selection in which the allele and genotype frequencies change because there is a selection pressure favouring either extreme phenotype.
May lead to speciation
What is environmental resistance?
The combined action of biotic and abiotic factors that limits the growth of a population
Define evolution
The process of gradual change in the inherited traits being passed from one generation to the next within a population.
Leads to a new species
Define a gene pool
Total genetic information possessed by the reproductive members within a population of organisms
What is genetic drift?
The change in allele frequency in a population, as some alleles are passed to the next generation and some disappear.
This causes some phenotypic traits to become rarer of more common
What are the assumptions made with the Hardy-Weinberg Principle?
- No mutation
- No selection
- No immigration
- Mating is random
- Population is large
