adaptation
inherited characteristic that increases an organism's chance of survival
artificial selection
selection by humans for breeding of useful traits from the natural variation among different organisms
balancing selection
Natural selection that maintains stable frequencies of two or more phenotypic forms in a population (balanced polymorphism)
biogeography
the study of the past and present distribution of species
Bottleneck effect
Genetic drift resulting from a drastic reduction in population size
differential
Selection that causes a shift in allele frequency such that one more more alleles become more common over time
directional selection
occurs when natural selection favors one of the extreme variations of a trait
disruptive selection
natural selection that favors individuals with either extreme of a trait
evolution
the gradual change in a species over time
evolutionary fitness
The contribution an individual makes to the gene pool of the next generation, relative to the contribution of other members of the population
evolutionary tree
a diagram that reflects evolutionary relationships among groups of organisms
extinction
disappearance of a species from all parts of its geographical range
fitness (differential reprod. success)
offspring that survive to reproduce themselves
fossil record
chronological collection of life's remains in sedimentary rock layers
Founder effect
Random change in the gene pool that occurs from a small starting colony size for a population
Gene flow
The gain or loss of alleles from a population by the movement of individuals into our out of a population
Gene Pool
All the genes (alleles) in a population at a given time
Genetic Drift
A change in the gene pool of a population due to chance
Hardy Weinberg Equilibrium(HWE)
a 'null model' of no evolution within a population, i.e. allele frequencies remain constant through generations
homologous structures
similar structures that related species have inherited from a common ancestor
homology
similarity in characteristics resulting from a shared ancestry
Microevolution
evolution resulting from small specific genetic changes that can lead to a new subspecies / a change in a population's gene pool over successive generations; evolutionary changes in species over comparably brief periods of time
Modern Synthesis
A comprehensive theory of evolution that incorporates genetics and includes most of Darwin's ideas, focusing on populations as the fundamental units of evolution
Mutation
A change in the nucleotide sequence of DNA; the ultimate source of genetic diversity
natural selection
The process by which individuals that are better adapted to their environment are more likely to survive and reproduce than other members of the same species
paleontologist
scientist who studies fossils
Population
A group of interacting individuals belonging to one species and living in the same geographic area (that therefore can potentially interbreed)
Population Genetics
The study of genetic changes in populations; the science of microevolutionary changes in populations
sexual dimorphism
marked differences between the sexes in secondary sexual characteristics, which are not directly associated with reproduction
Sexual selection
Change in the gene pool due to behavior that causes preferential mating with one or more genotypes / results from differences in traits affecting access to mates
stabilizing selection
intermediate forms are favored and extreme forms are eliminated/ Selection that maintains generally unchanging allele frequencies over time
strata
layers of sedimentary rock
vestigial organs
organs that serve no useful purpose for the organism; these suggest that sometime in the past they were useful
The Fossil Record
shows that organism have appeared in a historical sequence, and many fossils link ancestral species with those living today (Evidence of Evolution)
Biogeography
observations of the geographical distribution of species when closely related species tend to be found in the same geographical region (Evidence of Evolution)
comparative anatomy
Homologous structures among species and vestigial organs provide evidence of evolutionary history. (Evidence of Evolution), the study of the structures of different organisms. Looking at homologous parts: parts that have similar structure provide evidence
Comparative embryology
closely related species often have similar stages in their embryonic development (Evidence of Evolution)
molecular biology
all species share a common genetic code, suggesting that all forms of life are related through branching evolution from the earliest organisms. Comparisons of DNA and proteins provide evidence of evolutionary relationships.(Evidence of Evolution)
Darwin's theory of natural selection
Individuals best suited for a particular environment are more likely to survive and reproduce than less fit individuals
Natural selection in action
can be observed in the evolution of pesticide -resistent insects, drug-resistant microbes and horned lizards among many other organisms
Hardy-Weinberg formula
p^2 + 2pq = q^2 = 1
population genetics and health science
Hardy-Weinberg formula can be used to estimate the frequency of a harmful allele, which is useful information for public heath programs dealing with genetic diseases
homology
similarity in characteristics resulting from a shared ancestry
vestigial organs
organs that serve no useful purpose for the organism; these suggest that sometime in the past they were useful
Lamarck
French naturalist who proposed that evolution resulted from the inheritance of acquired characteristics. , He thought that use or disuse of a particular body part could cause it to grow or shrink � just like using your arms a lot might cause the muscles t
Charles Darwin
british biologist who introduced the ideas of natural selection and evolution; argued that specific behaviors evolved because they led to advantages in survival or reproduction
evolutionary adaptation
An accumulation of inherited characteristics that enhance organisms' ability to survive and reproduce in specific environments
gradualism
the idea that large changes on Earth can result from the accumulation of small changes over a very long time.
p
in Hardy-Weinberg represents the frequency of the dominant allele
q
in Hardy-Weinberg represents the frequency of the recessive allele
p^2
in Hardy-Weinberg represents frequency of homozygous dominants
q^2
in Hardy-Weinberg represents frequency of homozygous recessives
2pq
in Hardy-Weinberg represents frequency of heterozygotes
bottleneck effect
changes in the gene pool caused by a rapid reduction in population size. Reduces genetic variability
founder effect
Genetic drift that occurs when a few individuals become isolated from a larger population, with the result that the new population's gene pool is not reflective of the original population.
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
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