Biology 2 Exam 1

Evolution- Descent with modification; change in the genetic composition (allele frequency) in a population (not an individual level) over time (generations)

Adaptations- inherited characteristics of an organism that enhances its survival and reproduction in a specific environment

Heritable Trait- trait that can be passed on to offspring

Homologous Structures- similar structures due to common ancestors; related structures with different functions

Analagous features- similar structures with the same function that are not due to common ancestry

Convergent Evolution - independent evolution of similar features; when similar features with similar functions evolved separately, not related

Transitional Fossils - fossils that have features of both ancestors and descendants, connects changes in evolution

Tiktaalik - fossil that connects sea and land animals

Endemic Species- species that are found only in one specific place; typically found on islands

Biogeography - the scientific study of the past and present geographic distributions of species

Acquired Trait - trait developed by use during individual's life (giraffe's muscular neck from stretching for leaves

Natural Selection - a process by which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits

Artificial Selection - the selective breeding of domesticated plants and animals to encourage the occurrence of desirable traits (dog breeding)

Vestigial Structures - a feature of an organism that is a historical remnant of a structure that served a function in the organism's ancestors

Microevolution - change in allege frequency in a population over generations

Macroevolution - how we got all genetic diversity in life; broad pattern of evolution over long time spans

Population - individuals of the same species that are living in the same area (breeding group)

Allele - different versions/forms of a gene

Gene - segment of DNA that codes for a protein

Frequency - how common/uncommon an allele is in a population

Phenotype - physical appearance; what natural selection acts on

Genotype - genetic makeup of an organism (alleles organism has)

Discrete characters - either/or traits

Quantitative Characters - vary along continuum

Cline - gradual change in a character along a geographic axis

Point Mutation - single base change; results can be silent, missense, or frameshift, rarely beneficial

Hardy-Weinberg Equilibrium - population not evolving; no change in allele or genotype frequency

Fitness - an individual's contribution to the gene pool of the next generation; reproductive success

Founder Effect - a smaller group getting isolated and starting a new population, genetic diversity decreases because smaller population

Bottleneck Effect - natural disaster causes population to shrink and lose genetic variation (rare alleles are lost)

Gene Flow - Migration

Nonrandom Mating - Sexual Selection; individuals with certain inherited characteristics are more likely than others to obtain mates and reproduce

Sexual Dimorphism - differences between the secondary sexual characteristics of male and female of same species

Mutation - Change in DNA; ultimate source of new alleles

Gene Variability - genetic variation at whole-gene level

Nucleotide Variability - genetic variation at molecular level of DNA

Allele Frequency - how often the allele appears in the population (sum of all allele frequencies must equal one)

Gene Pool - aggregate of all copies of every type of allele at all loci in every individual in a population; aggregate of alleles for just one or a few loci in population

Directional Selection - conditions favor individual exhibiting one extreme of phenotypic range

Disruptive Selection - conditions favor individuals at both phenotypic extremes instead of intermediates

Stabilizing Selection - conditions favor intermediate variants; maintains phenotypic status quo

Biological Species Concept - a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring

Speciation 1 - species splits into two or more species; generates biodiversity Reproductive Isolation - individuals are NOT the same species if they can't successfully reproduce

Biological Barriers - prevent two different species from producing viable, fertile offspring

Allopatric Speciation - geographic barriers separate the 2 species

Sympatric Speciation - NO geographic barrier, so must have other mechanisms; examples: polyploidy, habitat differentiation, sexual selection

Polyploidy - organism has an extra set of chromosomes; a problem in meiosis; common in plants

Habitat Differentiation - a subpopulation exploits a habitat/resource not used by parent population

Hybrid Zones - where two species meet up to produce mixed ancestry offspring Prezygotic Barriers - before the zygote (fertilized egg)

Postzygotic Barriers - after the zygote forms

Punctuated Pattern - sudden change in species over a few generations; burst of rapid change and then a long period of stasis

Gradual Pattern - slow change of species over generations

Spatial Barrier - habitat isolation, separation by mountains, flies on wrong fruit

Temporal Barrier - timing, reproduce at different times (days, seasons, years)

Behavioral Barriers - different courtship rituals (attraction)

Mechanical Barriers - morphological/structural difference (can't mate)

Gametic Barriers - sperm can't get to egg (incompatible biochemistry)

Reduced Hybrid Viability - development is impaired

Reduced Hybrid Fertility - sterile; can't reproduce, infertile (horse x mule)

Hybrid Breakdown - viable hybrid, first generation is fertile, but not future ones

Ribosymes - RNA with catalytic properties

Fossils - remains/traces of organisms from the past

Strata - layers of rocks formed from sand and mud that settle to bottom of wet areas

Relative Dating - which fossils came before/after others

Radiometric Dating - can determine absolute ages of fossil (provides year)

Endosymbiosis - hypothesis that proposes that mitochondria and chloroplasts were formerly small prokaryotes living within larger host cells

Endosymbiont - smaller cell living in a host cell

Cambrian Explosion - burst of evolutionary change; sudden appearance of fossils resembling present-day animal phyla in the Cambrian period; major diversification of animals

taxonomy - our method of naming and classifying organisms

phylogeny - evolutionary history of a species or group of species

sister taxa - organisms that share a common ancestor that is not shared by any other group

clade - a group which includes an ancestral species and ALL its descendants

shared ancestral character - originated in ancestor

shared derived character - evolutionary novelty unique to a clade

maximum parsimony - simplest explanation that is consistent with the data

bracketing - predict by parsimony that features shared by 2 closely related groups were present in common ancestor and all descendants