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

Biological Barriers

prevent two different species from producing viable, fertile offspring

Allopatric Speciation

geographic barriers separate the 2 species

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

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

sympatric speciation

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

Hybrid Zones

where two species meet up to produce mixed ancestry offspring

Prezygotic Barriers

before the zygote (fertilized egg)

Speciation

one species splits into two or more species; generates biodiversity

Reproductive Isolation

individuals are NOT the same species if they can’t successfully reproduce

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