Fitness
An organisms ability to adapt to an enviornment and reproduce successfully.
Evolution
Changes in populations of organisms over time.
Natural Selection
Organisms best suited to their environment reproduce more successfully than other organisms.
Vestigial Structures
Structure that had a purpose in an ancestor but no longer serves a useful function to the modern organism
Ex: Human tailbone and appendix, snakes pelvic bones
Genetic Drift
The phenomenon by which allele frequencies in a population change as a result of random events, or chance.
Gene Flow
The process of genes moving from one population to another.
Speciation
The process of species formation.
Gradual Speciation
The smooth and gradual change from one species to another.
Punctuated Equilibrium
The sudden shift in form that results in very different species.
Adaptive Radiation
When many new species form from a single ancestor.
Geographic Isolation
The physical separation of members of a population.
Pre-Zygotic Isolation
Occurs before fertilization
Ex: Incorrect mating behavior, differences in mating times, differences in morphology
Post- Zygotic Isolation
Occurs after fertilization
Ex: offspring may not develop completely, offspring may be sterile and unable to reproduce
Phylogeny
The evolutionary history of a species or a group of related species.
Systematics
Classifying organisms and their evolutionary relationships based on fossils, morphology, genes, and molecular evidence.
Taxonomy
The science of classifying organisms based on similarities and differences.
Phylogenetic Tree
A family tree that shows the evolutionary relationships among groups of organisms.
Cladogram
Patterns of shared characteristics can be depicted in a diagram.