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classify organisms
It is important to categorize and classify organisms to be able to group them into similar groupings and to be able to determine evolutionary relationships.
classification level
domain, kingdom, phylum, class, order, family, genus, species
binomial nomenclature
A naming system developed by Carolus Linnaeus that uses the genus and species name of the organism,. Both names are always either italicized or underline, the genus name is always capitalized and the species name is always lowercase.
Enhydra lutris
species name is lutris
dichotomous key
A tool used to identify unknown organisms. The general rules: each step should have only 2 options, the options should be observable or physical traits, language must be such that the user understands the meaning of the descriptions.
species
a group of organisms that can breed to produce fertile offspring. A change in allele frequencies indicates that evolution (change) is occurring within a particular population.
variation
amount of different phenotypes of particular traits present in a population.
variation in population
these differences can be caused by mutations and/or crossing over (gene shuffling) through reproduction.
natural selection
process that favorable heritable traits become more common in successive generations of a population of reproducing organisms and causes unfavorable traits to become less common.
directional selection
The peak of bell shaped curve of phenotypes shifts one way. Affect in a phenotype/genotype of a population in 1 direction away from the average in a particular environment over time.
disruptive selection
population splits into 2 subgroups, each specializing in 2 phenotypes at opposite ends. against individuals at an intermediate type. Pressure of natural selection is strong/long lasting the curve splits into 2. Extreme traits are favored.
stabilizing selection
selection against both extremes results in a bell curve that is more narrow and in same general place. Individuals with moderate/average phenotypes, picks against phenotype extremes.
fossil record
remains of ancient life that can be dated using various methods. Are seen as a record of life on earth and how it has changed. (DTE)
homologous body structures
structures that have different mature forms but develop from the same embryonic tissues. (DTE)
geographic distribution of living species
organisms that are somewhat similar are found dispersed on different continents throughout the world. (DTE)
comparative embryology
early stages of many organisms with backbones looks very similar. (DTE)
genetic comparison
The more closely DNA matches the more closely related the organisms. (DTE) Comparing 2 organisms to determine how related the organisms are. Can be done by looking at the actual sequences of nucleotide or by looking at the sequences of amino acids that make up particular proteins.
allele frequency changes
variation can occur within a population through mutations and gene flow (migration between populations of a species, bring alleles with them into new population). Natural selection can act upon these populations by selecting for individuals with favorable traits becoming less coming (evolution). Another way that evolution can occur is through genetic drift which results in 1 trait becoming more common over another simply because the individuals with the more common trait were able to produce more offspring completely randomly.
speciation
formation of new species. In order to occur, 2 or more populations must become reproductively isolated from each other (populations can no longer reproduce).
behavior isolation
2 populations become reproductively isolated because the individuals have differences in mating rituals.
geographic isolation
2 populations become reproductively isolated by physical separation either through a barrier (ex: mountain) or distance (ex: separated by cascade mt range)
temporal isolation
2 populations breed at different times (ex: 1 population might only breed at night and the other only during the day)
divergent evolution
pattern of evolution in which 2 closely related species become more and more dissimilar over time.
convergent evolution
process by which species that are not closely related independently develop similar traits (ex: evolution of flight in birds and mammals is thought to have happened independently)
coevolution
change in the genetic composition of 1 species (or group) in response to a genetic change in another. (ex: shape of a species of flower changes over time such that the insect that pollinates this flower can no longer get to the flower part to pollinate and get food. So the insect population will change with the flower population)
vestigial trait
homologous characters of organisms which have lost all or most of their original function in a species through evolution. (ex: whales will retain bones that resemble the pelvis and femur or other mammals that still have the ability to walk despite not being able to walk themselves)
differential reproduction
competition among members of a population for valuable resources and some are better able/adapted to their environment that others to survive to reproductive age and pass their genes on.
evolution
changes in a population of organisms, in genetic terms: change in the relative frequency of alleles in a population.
common ancestors
when 2 populations diverge in 2 separate species
taxonomy
practice/science at caterogrizing/assigning
phylogeny
evolutionary relationships among organisms
evolutionary classification
grouping organisms based on evolutionary history
cladistic analysis
identifies/considers only characteristics of organisms that are evolutionary innovations (new characteristics that arise as lineages evolve over time)
derived characters
characteristics in recent parts of lineage but not in older members
cladogram
diagram showing evolutionary relationships among a group of organisms, represents an evolutionary tree
molecular clock
use DNA comparisons to estimate length of time 2 species have evolved independently
fitness
ability to survive/reproduce in its specific environment
adaptation
inherited characteristic that increases an organism
s chance of survival (anatomical, structural, physiological process/function, behavior)
descent with modification
each living species descended with changes from other species over time, all living organisms are related to one another
common descent
all species (living/extinct) were derived from common ancestors (single tree of life)
artifical selection
nature provided the variation, humans selected those variations that they found useful
gene pool
all genes
relative frequency of allele
number of times the allele occurs in a gene pool compared to other alleles for the same gene occurs.
polygenic traits
traits controlled by 2 or more genes
Note 
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