BIO 100 Unit 3

Biological evolution

a change in genetic characteristics of a population of organisms over time. May be caused by genes or environmental factors

Natural selection

process by which traits become more or less common in a population due to consistent effects upon the survival and/or reproduction of their forbearers. Organisms with favorable traits have better survival chances.

Microevolution

changes within a population of a species. easily observed, non-controversial

Macroevolution

results of many microevolutionary changes over a long period of time resulting in a new species. controversial among non-biologists

Theory of Evolution

all present species are descendants of a single common ancestor; all species present are the product of billions of years of accumulated evolutionary changes.

vestigial structure

a structure that is no longer useful to the function of an organism thus representing a function that was once necessary for survival, but became either diminished or nonexistent

cladogram

shows the similarities between animals

phylogenetic tree

shows the evolutionary process of a species

phylogeny

a branching diagram showing relationships between species (or higher taxa) based on their shared common ancestors. Also called phylogenetic trees.

ancestral traits

traits inherited from the common ancestor of a clade (or clade group) and has undergone little change since then.

fitness

relative survival and reproduction of one variant

adaptation

traits that increase individual fitness in an environment

artificial selection

selection imposed by humans

modern synthesis

union of genetics and evolution

diversifying/disruptive selection

both extremes are selected for simultaneously while the intermediate is selected against. most rare type (rock pocket mice on light sandy rock and dark volcanic rock)

stabilizing selection

selection for the average traits. goldie locks - peacock feathers have to be big enough to attract females, but not too big that they make it hard for the peacock to escape predators

directional selection

one extreme trait is greatly favored over the other

linnean classification

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species, Subspecies

Allopatric speciation

a population forms a new species while geographically isolated from its parent population

Sympatric speciation

a small population becomes a new species without geographic separation

Allele

Different forms of a gene. Either the A or the a in the genotype (Aa).

Hardy-Weinberg Theorem equations

p + q = 1
p^2 + 2pq + q^2 = 1

Gene flow

exchanges alleles between two different populations and may result in new alleles being introduced

Genetic drift

the result of chance events (like running over some bugs with your bike)

founder effect

an enabler of genetic drift in which a small subpopulation migrates to an isolated region

bottleneck effect

an enabler of genetic drift in which a population is intact but only a small portion of the individuals are able to pass their alleles to future generations

biological species concept

in this concept, species is, by definition, a group of populations that can interbreed and are reproductively isolated from other groups. its limitations are that it cannot account for fossils, asexual reproduction, or hybrids

morphological species concept

this concept uses measurable differences to define species lines (and uses graphs to show grouping)

behavioral species concept

concept that says members of the same species will share unique behaviors like mating calls

phylogenetic species concept

this concept takes the phylogeny of a species and defines a species as members within the smallest diagnosable unit

endosymbiotic theory

the theory of how prokaryotic bacterial cells became eukaryotic by engulfing smaller bacterial cells which then became organelles and relied on each other for survival