9th grade biology evolution vocab
divergent evolution
the accumulation of differences between groups that can lead to the formation of new species
analogous structures
body parts that share common function, but not structure
plication
a fold or corrugation
epoch
a period of time in history or in a person's life
convergent evolution
a process by which evolution produces similar structures and characteristics in distantly related organisms
genetic drift
a random change in allele frequency
orthogenetic
an obsolete biological hypothesis that organisms have an innate tendency to evolve in a unilinear fashion
punctuated equilibrium
an equilibrium that is interrupted by brief periods of more rapid change
phylogenic tree
an evolutionary diagram showing the evolutionary relationships among organisms
adaptation
any heritable characteristic that increases an organism's ability to survive and reproduce in it's environment
gene pool
consists of all the genes, including all the different alleles for each gene, that are present in a population
fitness
describes how well an organism can survive and reproduce in it's environment
genetic equilibrium
if a population is not evolving, allele frequencies in it's gene pool do not change
vestigial structure
inherited from ancestors but have lost much or all of their original function due to different selection pressures acting on the descendant
artificial selection
nature provides the variations, and humans select those they find useful
directional selection
occurs when individuals at one end of the curve have higher fitness than individuals at the middle or at the other end
disruptive selection
occurs when individuals at the outer ends of the curve have higher fitness than individuals near the middle of the curve
reproductive isolation
occurs when organisms stop breeding with original mates and start isolating and breeding with other mates, forming new species
geographic isolation
occurs when two populations are separated by geographic barriers such as rivers, mountains, or bodies of water
gradualism
slow and steady
homologous structures
structures that are shared by related species and have been inherited from a common ancestor
stabilizing selection
takes place when individuals near the center of the curve have higher fitness than individuals at either end
speciation
the formation of a new species
allelic frequency
the number of times an allele occurs in a gene pool, compared to the total number of alleles in that pool for the same gene
fossil
the preserved remains or traces of ancient organisms
adaptive radiation
the process by which a single species or a small group of species evolves over a relatively short time into several different forms that live in different ways
natural selection
the process by which organisms with variations most suited to their local environment survive and leave more offspring
camouflage
the process in which an organism blends into it's environment to prevent danger or predator-ism
evolution
the process of change over time
mimicry
the process of imitating to entertain or ridicule
