Population decline
The pinky finger of evolution
Mating
The ring finger of evolution
Mutation
The middle finger of evolution
Immigration
The index finger of evolution
Natural selection
The thumb of evolution that describes the selection of traits that benefit an organism in its environment as it evolves
Variation, overproduction of offspring, differential survival and reproduction, inheritance, and progressive change over generations
The five major components of natural selection
Variation
A component of natural selection stating a population must possess a variety of traits, regardless of their visibility
Meiosis, mutation, and sexual reproduction
Three processes that can lead to a variation within a population
Overproduction of offspring
A component of natural selection stating a population must produce too many offspring for its environment to create a struggle for existence that requires organisms to compete
Differential survival and reproduction
A component of natural selection stating an organism better suited to its environment is more likely to survive and reproduce
Inheritance
A component of natural selection stating an organism that reproduces will pass on its traits to its offspring
Progressive change over generations
A component of natural selection stating a characteristic better suited to an environment will become more common over time as one less suited becomes less common
Adaptation
A characteristic that makes an organism better suited to its environment and way of life by developing over time through natural selection
Silent owl flight
An example of an adaptation
Transitional fossil
A fossil that can link modern-day species with their likely ancestors since the sequence in which fossils appear matches the expected sequence of evolution
Homologous structure
A structure with a similar genetic structure as but different function than another
Humerus and radius
Two examples of homologous structures in the human arm
Analogous structure
A structure with a different genetic structure than but similar function as another
Bird and insect wings
Two examples of analogous structures that enable flight
Vestigial structure
A rudimentary organ or structure that serves no purpose
Coccyx
An example of a vestigial structure in a human:
Divergent evolution
A process where one species diverges into different species after spreading out into different environments that leads to homologous structures from a common ancestor
Convergent evolution
A process where multiple species evolve in the same environment that leads to analogous structures due to the need for similar traits
Sexual selection
A trait that conveys fitness to attract a mate and enables reproduction
