Theories of evolution

evolution

The change in the genetic makeup of a population with time.

acquired characteristic

A modification in an organism’s structure or function that is caused by environmental factors during its life.

fitness

The ability to survive and reproduce.

natural selection

A mechanism of evolution that explains how populations can evolve to become better suited to their environments overtime.

speciation

The evolution of new species.

demes

A population of organisms within which the exchange of genes is completely random.

phylogeny

The study of evolutionary lineages of a species or group of species.

convergent evolution

When two species from different ancestors develop similar traits.

parallel evolution

Occurs when a more recent ancestor can be identified, similar to convergent evolution.

divergent evolution

Occurs when species with a shared ancestor develop differing traits due to dissimilarities between their environments.

adaptive radiation

The emergence of a number of lineages from a single ancestorial species.

population

Includes all members of a particular species inhabiting a given location.

gene pool

Is the sum total of all the alleles for any given trait in a population.

gene frequency

The decimal fraction representing the presence of an allele for all members of a population that have this particular gene.

genetic drift

Refers to changes in the composition of the gene pool due to chance.

founder effect

When genetic drift tends to be more pronounced in small populations or new populations.

genetic bottleneck

A large die off event that causes genetic drift.

gene flow

The migration of individuals between populations will result in a loss or gain of genes.

petrification

The process by which minerals replace the cells of an organism.

homologous structures

Have the same basic anatomical features and evolutionary origins.

analogous structures

Have similar functions but may have different evolutionary origins and entirely different pattern of development.

vestigial structure

Structure that is non functional or reduced in function.

intraspecific competition

A competition between individuals of the same species.

autotrophic anaerobes

Chemosynthetic bacteria.

autotrophic aerobes

Green plants and photoplankton

heterotrophic anaerobes

yeasts

heterotrophic aerobes

amoebas, earthworms and humans.