25: Evolution by Natural Selection Flashcards
Evolution
(1) The theory that all organisms on Earth are related by common ancestry and that they have changed over time, and continue to change, via natural selection and other processes. (2) Any change in the genetic characteristics of a population over time, especially, a change in allele frequencies.
Population
A group of individuals of the same species living in the same geographic area at the same time.
Population Thinking
The ability to analyze trait frequencies, event probabilities, and other attributes of populations of molecules, cells, or organisms.
Descent with modification
The phrase used by Darwin to describe his hypothesis of evolution by natural selection. He meant that species that lived in the past are the ancestors of the species existing today, and that species change through time.
fossil
Any physical trace of an organism that existed in the past. Includes tracks, burrows, fossilized bones, casts, and so on.
fossil record
All of the fossils that have been found anywhere on Earth and that have been formally described in the scientific literature.
extant species
A species that is living today.
Sedimentary rocks
A type of rock formed by gradual accumulation of sediment, particularly sand and mud, as in riverbeds and on the ocean floor. Most fossils are found in sedimentary rocks.
geological time scale
The sequence of eons, eras, and periods used to describe the geologic history of Earth.
extinct species
A species that has died out.
transitional feature
A trait that is intermediate between a condition observed in ancestral (older) species and the condition observed in derived (younger) species.
vestigial trait
A reduced or incompletely developed structure that has no function or reduced function, but is clearly similar to functioning organs or structures in closely related species.
phylogenetic tree
A branching diagram that depicts the evolutionary relationships among species or other taxa.
homology
Similarity among organisms of different species due to their inheritance from a common ancestor. Features that exhibit such similarity (e.g., DNA sequences, proteins, body parts) are said to be homologous. Compare with homoplasy.
genetic homology
Similarity in DNA nucleotide sequences, RNA nucleotide sequences, or amino acid sequences due to inheritance from a common ancestor.
developmental homology
A similarity in embryonic form, or in the fate of embryonic tissues, that is due to inheritance from a common ancestor.
structural homology
Similarities in adult organismal structures (e.g., limbs, shells, flowers) that are due to inheritance from a common ancestor.
morphology
The shape and appearance of an organism’s body and its component parts.
natural selection
The process by which individuals with certain heritable traits tend to produce more surviving offspring that do individuals without those traits, often leading to a change in the genetic makeup of the population. A major mechanism of evolution.
artificial selection
Deliberate manipulation by humans, as in animal and plant breeding, of the genetic composition of a population by allowing only individuals with desirable traits to reproduce.
fitness
The ability of an individual to produce viable offspring relative to others of the same species.
adaptation
Any heritable trait that increases the fitness of an individual with that trait, compared with individuals without that trait, in a particular environment.
tuberculosis
A disease of the lungs caused by infection with the bacterium Mycobacterium tuberculosis.
natural experiment
A situation in which a natural change in conditions enables comparisons of groups, rather than a manipulation of conditions by researchers.
acclimatization
A change in an individual’s phenotype that occurs in response to a change in natural environmental conditions.
acclimation
A change in a study organism’s phenotype that occurs in response to laboratory conditions.
genetic correlation
A type of evolutionary constraint in which selection on one trait causes a change in another trait as well; may occur when the same gene(s) affect both traits.
fitness trade-off
In evolutionary biology, an inescapable compromise between two traits that cannot be optimized simultaneously. Also called trade-off.
