Evolution Flashcards
Natural selection
Natural selection is a process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals.
Evolution
def. Evolution is a measure of changes in allele frequencies in a population over successive generations
Broad def. Evolution is defined as descent with modification from a common ancestor.
- Modification: Evolution only occurs when there are CHANGES IN ALLELE FREQUENCY within a population over time
- Descent: Evolution involves passing on these HERITABLE genetic changes to the next generation
- Common ancestor: Present day species are RELATED through a common prehistoric ancestor that have changed and adaptive OVER TIME
Allele frequency
Allele frequency is a measure of chances of finding a particular allele of a gene within the population.
Variation
Variation is differences between individuals of the SAME SPECIES due to presence of different alleles.
Selection pressure
Selection pressure refers to environmental factors, biotic and abiotic, acting upon survival and reproductive success of members of a population.
Gene flow
Gene flow is the transfer of alleles from one POPULATION to another, due to the movement of fertile individuals or their gametes.
Genetic drift
Genetic drift is a change in allele frequency due to chance events - chance because which allele ends up lost from the original gene pool is an indiscriminate, random event.
Founder effect
A few, random individuals from a larger population become pioneers of a newly isolated population and are not likely to carry all the alleles present in the original population.
Bottleneck effect
A catastrophic event leading to a drastic reduction in population resulting in the reduction of allele frequencies and even elimination of alleles in a random nature.
Mutation
A mutation is a random change in an organism’s DNA and are a source of new alleles.
Population
A population is a group of interbreeding individuals belonging to a species and sharing a common geographic area.
Species
(BIOLOGICAL CONCEPT)*** A species is a group of organisms capable of interbreeding and producing fertile, viable offspring and are reproductively isolated from other such groups.
(Genetic Concept) A species is a group of genetically compatible interbreeding organisms in a natural population that is genetically isolated from other such groups.
(Ecological Concept) A species is a group of organisms sharing same ecological niche.
(Morphological Concept) A species is a group of organisms sharing similar body shape and other structural features.
(Phylogenetic Concept) A species is the smallest group of organisms that share a most recent common ancestor and can be distinguished from other such groups.
Niche
Niche refers both to the place an organisms lives and its interactions with the environment i.e. the roles that an organisms plays in its habitat (e.g. predator, prey, primary producer or consumer, decomposer, etc.)
Phylogenetic tree / Phylogeny
A phylogenetic tree is a diagram that depicts lines of evolutionary descent of different species from a common ancestor
Speciation
Speciation is a process by which one or more new species arise from a previously existing species.
