12th grade Evolution & Classification

evolution

The gradual change in a species over time OR a population of organisms changing over time

natural selection

mechanism by which individuals that have inherited beneficial adaptations survive and reproduce more on average than do other individuals. One mechanism by which populations change over time or evolve.

variation

the differences within a single species

biological species concept

group of similar organisms capable of interbreeding and producing fertile offspring

speciation

formation of new species

homologous structures

structures that have slightly different functionality forms in different organisms but have a lot of similarities in structure and development ; evidence of common ancestry

behavioral isolation

Form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding

temporal isolation

form of reproductive isolation in which two or more species reproduces at different times

geographic isolation

form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water

disruptive selection

form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle

directional selection

Form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve

stabilizing selection

Natural selection that favors intermediate or "average" variants by acting against extreme phenotypes

Domain Eukarya

Domain of all organisms whose cells have nuclei, including protists, plants, fungi, and animals

Domain Archaea

One of the three domains of life; contains prokaryotic cells that often live in extreme habitats. Are surprisingly similar to eukaryotic cells because they have introns and their DNA wrapped around histone proteins

Domain Eubacteria

unicellular, prokaryotic, suited to pretty much any environment on this planet except for the most extreme ones. Also is killed by antibiotics, lacks introns & histones for DNA to wrap around

selective breeding

the human practice of breeding animals or plants that have certain desired traits- serves as evidence the CHANGE over time (Evolution) is possible

Polyploidy

condition in which an organism has extra sets of chromosomes. These organisms with extra CANNOT reproduce with their diploid relatives and are therefore brand new species (just after 1 generation)

adaptive radiation

An evolutionary pattern in which many species evolve from a single ancestral species. (As seen in Galapagos finches)

Node on a cladogram

On a cladogram, shows the point at which 2 or more species share a common ancestor. The point from which they split into different species through speciation.

outgroup

in a cladogram, the species that is LEAST related to the others shown

clade

evolutionary branch of a cladogram that includes a single ancestor and all its descendants

primitive characteristic

the characteristic found in all members of the cladogram

derived characteristic

Characteristic that appears in recent parts of a lineage, but not in its older members

alelle frequency

The measure of the relative frequency of an allele at a genetic locus in a population; expressed as a proportion or percentage.