Unit 6: Evolution Flashcards
Adaptation
inherited characteristic that increases an organism’s chance of survival
Bottleneck Effect
a change in gene frequency following a dramatic reduction in the size of an original population resulting in a loss of genetic diversity
Analogous Structures
body parts in unrelated species that have common functions, but different anatomical structures; are the result of convergent evolution
Directional Selection
a change in gene frequency following a dramatic reduction in the size of an original population resulting in a loss of genetic diversity
Disruptive Selection
form of natural selection that favors individuals at both extremes of the phenotypic range
Evolution
the change in species/populations over time
Fossil
any evidence of past life; provide evidence of evolution
Founder Effect
loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population
Gene Flow
exchange of genes between populations due to the migration of individuals; can be a very important source of genetic variation
Geographical Isolation
a mechanism of evolution in which members of a species become physically separated from each other and over time become different species
Gene Pool
all of the genes present in a single species
Genetic Drift
evolution that occurs due to random change or chance events in small populations
Mutations
a mistake or change in the normal sequence of DNA; can be random/spontaneous OR caused by radiation, tobacco smoke, and chemical exposure
Homologous Structures
anatomical structures in different species that are similar in structure, but have completely different functions; suggest evolution from a common ancestor
Natural Selection
mechanism by which evolution occurs; when the environment favors a trait an organism with that trait is more likely to survive; AKA “survival of the fittest”
Pesticide Resistance
the decreased susceptibility of insects over time to chemicals used to kill them
Phylogenetic Tree/Cladogram
a branching diagram that shows the evolutionary relationships among organisms based on their DNA; shows common ancestry
Primitive
relating to, denoting, or preserving the character of an early stage in the evolutionary or historical development of something.
Speciation
the formation of a new species from an existing species
Stabilizing Selection
natural selection that favors intermediate forms by acting against extreme phenotypes
Vestigial Structure/Organ
A structure/organ that has little or no purpose in a modern day organism, but may have had a purpose in a distant ancestor; examples include: wings of flightless birds, human appendix & coccyx, and hip bones of whales.
The Endosymbiotic Theory
explains how eukaryotic cells evolved from prokaryotic cells
