section of DNA that codes for a protein
number of times an allele occurs in a population, compared to another allele; reported as a percent
slight physical, behavioral, or biochemical differences in individuals in a population
slight differences in genes of individuals in a population. the sources of it are mutations and gene shuffling.
all the alleles in a population
one form of a gene
change in a species/population over time. In genetic terms its the change in the relative frequency of alleles in a species/population over time.
change in DNA's base sequence. the causes are replication errors, radiation, and chemicals. The outcomes of these may or may not affect traits, and if it does the affects may be helpful, harmful, or harmless to the organism's fitness
changes the combination of alleles and sometimes the phenotype but not the relative frequency of alleles in a population. It Occurs during Gamete formation and fertilization
2 or 3 possible phenotypes. Uses a Bar graph usually depending on the allele frequency. Examples: Widow's peak and PTC tasting.
Poly Genic Traits
There are many possible phenotype combinations and the graph has a normal distribution (Bell Curve). Examples: Skin color and Birth Weight.
This states that if allele frequencies are not changing in a population, the population will not evolve and it is said to be in genetic equilibrium as long as several conditions are met:
1. Random mating
2. Large Population
3. No gene flow between populations
4. No Mutations
5. No Natural Selection
condition in which the frequency of alleles in a population remains the same over generations
preference for mates with variations similar to their self (color, size, etc)
A form of natural selection in which individuals with certain inherited characteristics are more likely than other individuals to obtain mates.
most individuals in a population are most likely to breed with nearby mates
only some males get to mate
a chance event changes the population's allele frequency.
population size decreases quickly, usually from natural disaster. Only some individual's genes get passed on which leads to less genetic variability and greater chance of extinction.
(a type of bottleneck) a few individuals from a population establish an isolated new population; their allele frequency is different from the original populations allele frequency.
also known as gene flow between populations; carries alleles between populations of new species
Genetic change occurs in populations not individuals
adaptations/characteristics which make an individual good at "winning" competitions and surviving in its enviroment
when one extreme variation of a trait is fitter than the other extreme or the average. the result is that the average variation shifts towards fitter extreme over several generations
the average variation of the trait is fitter, and the two extremes are not fit, due to two opposing forces. the result: narrower curve; average frequency increases and the average extreme decreases
the average trait is less fit than the extremes and both extremes are equally fit due to the enviroment providing different resources. The result is the single curve becoming 2 curves for 2 distinct phenotypes.
formation of a new species. A species must have a group of individuals that do or can interbreed and produce fertile offspring. Species also have a common anscestor.
genetice differences have become so great that they no longer interbreed and/or are unable to produce fertile offspring
courtship/mating rituals differ too greatly
physical barrier prevents contact
different breeding seasons
physically, mating is impossible
sperm and egg cannot fuse
can't pass on genes
a group of organisms which look similar, interbreed in nature, and produce fertile offspring.
preserved remains of ancient organisms
slight differences among individuals in a population
humans choose which animals/plants will reproduce, based on their favorite traits. The point is ti get more individuals in the population with the desired variations
organisme resembles another organism
organism "blends into" a nonliving object
also called Aposematic Coloration; organism is brightly colored to be conspicuous to predators