unit 7 apbio vocab flashcards

test 4/10

lamarck vs. darwin’s theories of evolution

lamarck: organisms adapted to their environments by ACQUIRING traits in their lifetime; then passed these traits down to their offspring (use and disuse idea)

darwin: organisms are BORN with variations in traits - some being more favorable to their environmental conditions - & all organisms diverged from a common ancestor

natural selection

individuals that have certain traits tend to survive & reproduce at higher rates than individuals without those traits because of those traits

4 main principles of natural selection

1. variation

2. high population growth

3. inheritance

4. survival of the fittest

variation

refers to differences in physical traits among individuals in a population; key variation source is errors in meiosis

inheritance

characteristics can be passed down from parent to offspring

high population growth

organisms overproducing offspring, leading to competition of resources and therefore leads to survival of the fittest

survival of the fittest

individuals with traits that give them an advantage in their environment are more likely to survive; over time, these traits become more common

mutation

change in DNA sequence that can lead to new traits and variations; happen spontaneously and unavoidably

“use and disuse” idea

individuals lose characteristics they do not require, or use, and develop characteristics that are useful according to their environment, which can affect evolution

artificial selection

humans modified species by selecting and breeding organisms with desired traits

examples of artificial selection

crops, livestock, pets - breeding these organisms, but only the ones with desired traits (i.e. certain color, size, or yield in plants)

data to document evolution - direct observation

changes in noticeable characteristics

data to document evolution - homology

similarity of different species resulting from a common ancestor

data to document evolution - fossil record

document patterns of evolution; descent from ancestors and the traits of those ancestors; shown through transitional fossils (these show intermediary traits)

data to document evolution - biogeography

geographic distribution of a species; endemic species are found nowhere else in the world but in 1 location; fossils distributed in patterns that reflect continents being connected (pangea)

vestigial structures

leftover structures of little importance to organisms - from ancestors and evolution

pseudogenes

genes that have lost function due to evolutionary changes

convergent evolution

independent evolution of different lineages creating similar features due to adapting to similar environments or ecological niches; “analogous”

homologous structures

similar STRUCTURE, different FUNCTION - shown in different species that share a common ancestor; divergent evolution

analogous structures

different STRUCTURE, similar FUNCTION - shown in different species that do NOT share a common ancestor and evolved to have similar function by chance; convergent evolution

microevolution

changes in allele frequencies over time within a population

neutral variation

differences in DNA that don’t provide an advantage or disadvantage

5 conditions for hardy weinberg equilibrium

large population, no mutation, random mating, no natural selection, no gene flow; only theoretical - no species on earth is in hardy-weinberg equilibrium

genetic drift

chance events causing allele frequencies to fluctuate unpredictably; bottleneck event and founder’s event

bottleneck event

sudden environmental change drastically reducing a population; ex. any type of natural disaster

founder’s effect

few individuals become isolated from a larger population and establish new & different gene population

gene flow

transfer of alleles in or out of a population due to fertile individuals or their gametes

3 types of natural selection

directional, stabilizing, disruptive

directional selection

conditions favor one extreme of a phenotypic range

stabilizing selection

conditions favor the mean of a phenotypic range

disruptive selection

conditions favor both ends/extremes of a phenotypic range

sexual selection

individuals with certain characteristics are more likely to obtain mates

intrasexual selection

two organisms of the same species compete with each other to mate with the opposite sex

intersexual selection

individuals of one sex select mates from the opposite sex based on specific traits

types of random events that cause evolution

mutations, genetic drift, migration/gene flow

types of nonrandom events that cause evolution

natural selection, artificial selection, sexual selection

hardy weinberg equations

p + q = 1, p² + 2pq + q² = 1; p is dominant ALLELE frequency, q is recessive ALLELE frequency; p² is homozygous dominant individual GENOTYPE frequency, 2pq is heterozygous GENOTYPE frequency, q² is homozygous recessive GENOTYPE frequency

speciation

formation of a new species - resulting in the diversity of life forms; 2 modes - allopatric and sympatric

allopatric speciation

physical barrier separates/divides a small group from the main population - now geographically isolated, preventing gene flow; allele frequencies change, mutations arise

sympatric speciation

new species evolves while still inhabiting the same geographical region, usually due to exploitation of a new food source or habitat or behavior

reproductive isolation

cause of allopatric speciation; 2 types of barriers - prezygotic and postzygotic

prezygotic reproductive barriers; 3 types

prevent attempts to mate or mating completion, or hinders fertilization post-mating

5 types of prezygotic reproductive barriers

habitat, temporal, behavioral, mechanical, genetic

habitat isolation

species live in different areas or occupy different habitats within the same area

temporal isolation

species breed at different times of the day, year, or season and therefore can’t mix

behavioral isolation

unique behavioral patterns & courtship rituals separate species because they only attract certain mates

mechanical isolation

reproductive anatomy/morphology of one species doesn’t fit with the other

genetic/gametic isolation

proteins on the surface of gametes do not allow for the egg and the sperm to fuse

postzygotic barriers

prevent a hybrid zygote from developing into a viable, fertile adult - developmental errors in/out of the womb & may cause infertility; 3 types

3 types of postzygotic barriers

reduced hybrid viability, reduced hybrid fertility, hybrid breakdown

reduced hybrid viability

genes of different parent species may interact in ways that impair the hybrid’s development or survival

reduced hybrid fertility

a hybrid can develop into a healthy adult but is sterile

hybrid breakdown

hybrid of 1st generation may be fertile, but if they try to mate, their offspring is sterile

what are rates of evolution & speciation influenced by

climate, resources, competition, predation, environmental changes/catastrophic events

punctuated equilibrium

species experience long periods of stability interrupted by brief episodes of significant change, leading to speciation

gradualism

evolution occurs slowly and steadily over a long period, leading to gradual changes in species - happens when environment remains stable

morphological species concept

distinguishes species by body shape and other structural features

ecological species concept

distinguishes species based on their ecological niche - living & nonliving interactions

phylogenetic species concept

distinguishes species as smallest group of individuals that share a common ancestor

2 hypotheses on how life formed on earth

abiotic synthesis & extraterrestrial origin

abiotic synthesis hypothesis

early earth’s components could’ve been synthesized organic molecules due to free energy

extraterrestrial origin hypothesis

organic molecules were transported to Earth via comets or meteorites

rna world hypothesis

proposed RNA could’ve been the earliest genetic material - explaining pre-cellular life

heterotroph hypothesis

first life forms were simple organic molecule-eating organisms & evolved from that

endosymbiosis

some of the organelles in eukaryotic cells were once prokaryotic microbes

miller-urey experiments

revealed simple inorganic molecules could combine to form the organic building blocks required for life as we know it; amino acids

adaptive radiation

the diversification of a group of organisms into forms filling different ecological niches - occured after mass extinction events in earth’s history

cladogram - line

descent from an ancestor

cladogram - branch point

common ancestor

outgroup

a lineage that is least closely related to the rest of the organisms

monophyletic group

most recent common ancestor and all of its descendants

paraphyletic group

most recent common ancestor and only some of its descendants, not all

polyphyletic group

doesn’t include most recent common ancestor but includes descendants

sister taxa

groups of organisms that share an immediate common ancestor

basal taxon

lineage that diverges early in the lineage of a group