bio 1

Scientific theory

A broad, well tested explanation with predictive value (leads to many accurate predictions)- like gravity

Evolution

The change in organisms throughout earths history; change in a populations genetic composition over generations

Is evolution just a theory

No it’s a scientific theory, backed by a lot of evidence

Do individuals evolve

No populations do

Can an organism evolve within its lifetime

No

Does evolution explain the origin of life

No; only describes how existing populations of living things change and diversify over time. For biological evolution to occur, life must already exist

Did organisms evolve on purpose

No, would suggest a goal oriented process; cannot influence the evolution of its own structures in response to the environment

Are species always evolving into higher or better beings

No, they just adapt to changes in the environment

Does evolution create new life forms by dramatic mutations

No, it occurs generation to generation and is passed to offspring; DNA cannot produce new structures in its lifetime

Is evolution a completely random process

No; The presence of certain genes/traits allows the population to adapt and survive and reproduce

Aristotle and evolution

Viewed species as unchanging/fixed based on an increasing ladder of complexity (scale naturae)

Age of reason

Pre Darwin; the rise of scientific inquiry and the use of reason; emphasis on observation, experimentation, and challenging established doctrines

Linnaeus

Created an orderly classification system, grouping species into increasingly general categories, father of taxonomy, invented binomial naming

Binomial naming

Made by Linnaeus, 2 parts: genus (homo) and species (sapien) all italicized

James Hutton

Geologist, gradualism theory: earths geological features (canyon, valley, etc) are a result of gradual mechanisms, slow continuous processes

Charles Lyell

Father of modern geology; expanded huttons ideas by introducing uniformitarianism ; wrote principles of geology; earth is extremely old

Uniformitarianism

By Charles Lyell; same geologic processes in past as today, same rate as today

Lamarck

Linked evolution to adaptation via changes in environment; extinct species have been replaced by descendants with new features; first to propose a mechanism for evolution: use it or lose it; also believed in inheritance of acquired characteristics (wrong)- if you lose an arm your child will lose an arm

2 main ideas of Darwin’s theory

descent with modification and natural selection

descent with modification

Darwins theory; species that live today are descended from ancestral species that were different from the present day species

natural selection

Darwins theory; survival of the fittest; reproduction of individuals with favorable genetic traits that survive environmental change- leads to evolutionary change; heritable variation exists in most species, more offspring are produced than can survive so there is competition for resources

does evolution lead to perfection

no, mutations are random and it often takes many to lead to a new trait which can help or harm or neither; evolution is change in organisms over time

direct observation

evidence of evolution; observe then infer; soapberry bugs get beak length that matches depth of balloon vine fruit

fossil record

evidence of evolution; whales are mammals and their ancestors lived on land- shows transition of adaptive form over time

homologous structures: divergence

evidence of evolution; forms related by common ancestry (like human, dog, bird, whale arms); similarity in layout and construction but the functions are different; indicate that a species is diverging from its ancestors

developmental homology

type of homologous structure; fish and human embryo are very similar, meaning we share a common ancestor

vestigial structures

evidence for evolution; remnants of ancestral (homologous) structures with no present adaptive function (wisdom teeth, tailbone, etc); blind cave salamanders have eyes but dont use them bc they descended from species that could see

analogous structures

structures with similar functions but different ancestors; sometimes misleads us when trying to trace back to common ancestor

convergence

evidence for evolution; unrelated species have similar adaptations under similar environmental conditions ; torpedo shape for swimming- live in same environment so develop similar adaptations; results in analogous structures; wings in birds vs insects

biogeography

distribution of species which corresponds to geographic history; South America is nearest mainland to Galapagos- marine iguana in Galapagos ocean and tree dwelling in South America; they are most similar bc marine evolved from tree dwelling

molecular biology

evidence of evolution; closely related organisms have similar DNA; genetic code is universal, so all of us come from a common ancestor

species

basic unit of biological classification; group of organisms that can interbreed and produce viable, fertile offspring

morphological species

same species based on what they look like; white oak in Tennessee vs texas look alike

biological species

set of populations whose members potential interbreed in nature to produce fertile offspring and do not successfully interbreed with other groups; share the same gene pool and there is gene flow

ecological species

set of organisms adapted to a specific set of resources; morphologically similar, diff species based on utilization of food source; bacteria

gene pool

sum of all alleles in the population

gene flow

movement of genetic material

what if there is no gene flow between two populations

they are different species

how are different species reproductively isolated from other species (biological species concept)

via natural biological barriers: prezygotic and posyzygotic

pre zygotic biological barriers

prevents fertilization (meshing egg and sperm together); 5 types: temporal, habitat, behavioral, gametic, mechanical

post zygotic biological barriers

reproduction happens and causes egg and sperm hybrid but there is a barrier formed after; 3 types: reduced hybrid viability, reduced hybrid sterility, hybrid breakdown

habitat (ecological) isolation

pre zygotic barrier; never meet bc they live in diff habitats

temporal isolation

pre zygotic barrier; can live in same area but breed at diff times of the year

behavioral isolation

pre zygotic barrier; have diff mating rituals/calls/dances; presence or absence of certain behavior prevents mating (like bird sounds)

mechanical isolation

pre zygotic barrier; incompatibility of the sexual organs

gametic isolation

pre zygotic barrier; when gametes cannot fuse together due to difference in gamete cells (wrong pollen on a flower)

gametic isolation

pre zygotic barrier; sperm of one species may not be able to fertilize eggs of another species; proteins on sperm will only bind to specific receptors on the covering of the egg in order to fertilize

reduced hybrid viability

post zygotic barriers; embryo fails to develop or is weak and dies

reduced hybrid fertility

post zygotic barriers; hybrid survives but is sterile or almost so; horse (64) and donkey (62) mate but chromosomes dont pair up properly during meiosis so offspring becomes infertile

hybrid breakdown

post zygotic barriers; 1st generation offspring are viable and fertile but when they mate with each other offspring is feeble or sterile; so 1st get hybrids are good but 2nd gen isnt

biological species cannot apply to fossil species why

reproductive information doesn’t fossilize

biological species cannot apply to asexual species why

no use of zygotes or hybrids

microevolution

how new species form; changes over time in allele frequencies in a population; any change in population allelic or genotypic frequency over time; evolution on smallest scale

how do new species form

micro and macro evolution

macroevolution

the processes that gave rise to new species and higher taxonomic groups with widely divergent characters

speciation

formation of new species; may occur with or without geographic separation; 2 types: allopatric and sympatric

population

group of individuals of the same species that live in same area and interbreed and produce fertile offspring

allopatric speciation

geographic isolation (w barrier); can happen 3 ways: dispersal, vicariance, adaptive radiation

dispersal

allopatric speciation; few members of species become isolated geographically for a long period of time and changes in each group over time leads to divergence; adapts to new environment and evolution occurs via natural selection

vicariance

allopatric speciation; natural situation arises to physically divide the organisms (mountain, river, etc)

hybrid zones in allopatric speciation

area where 2 closely related species interact and interbreed; 3 types: reinforcement, fusion, stability

reinforcement

hybrid zone; due to natural selection, hybrids are less fit than the purebreds, reinforcing the pre zygotic barriers; species continue to diverge until hybridization can no longer occur; A on top of V

fusion

hybrid zone; reproductive barriers weaken until the 2 species merge to become 1; diamond

stability

hybrid zone; barriers remain the same but fit hybrids continue to be produced; rectangle

Dodds experiment

allopatric speciation; flies raised on starch vs maltose; mated them; showed that there was a diet-developed mating preference

adaptive radiation

allopatric speciation; many adaptations evolve from a single point of origin, causing the species to radiate into new ones; from one founder species of bird, multiple others evolved, each with its own distinctive characteristics (beak shape changes relative to what it eats)

sympatric speciation

creation of new species; occurs in same geographical area; based on mating behavior (fish under different light causes interbreeding) and habitat differentiation (2 populations isolated by use of different resources, lay their eggs on certain fruit and mate there); 2 types of chromosomal errors during cell division: aneuploidy and polyploidy

aneuploidy

sympatric speciation; gametes have too many or too few chromosomes due to nondisjunction (chromosomes fail to separate) during meiosis; will have 2n+1 or 2n-1 chromosomes

polyploidy

sympatric speciation; cell or organisms has extra set or sets of chromosomes; results from error in meiosis; 2 types: autopolyploidy and allopolyploidy

autopolyploid

type of polyploidy; sympatric speciation; individual that has more than 2 chromosome sets that are all derived from a single species; chromosomes divide by cell doesn't , so go from 2n to 4n cell

alloploidy

type of polyploidy; sympatric speciation; 2 species mate to produce viable offspring; takes 2 matings to major viable fertile offspring

punctuated equilibrium

rates of speciation; species exhibit a large change in a relatively short period of time followed by long periods of freezing/stasis; remains unchanged for a long time

gradual speciation

species diverge gradually through time with small steps; multiple diff stages in time

without _____ evolution by natural selection cannot happen

genetic variation

phenotypic variation

mostly genetic; the difference in observable traits—such as size, color, or behavior—among individuals in a species; environment can influence expression, creating non-heritable variation; larvae fed on oak flowers and looks like them while larvae fed on oak leaves looks like twigs

genes and inheritance of genes leads to different types of

variation; 2 types: discrete genetic and continuous

discrete genetic variation

2 or more alleles at a single gene locus; a trait is one thing or another, no mixing

continuous variation

phenotypes produced by combined effects of 2 or more genes; controlled by multiple genes and environmental factors

sexual recombination

produces genetic diversity among offspring; crossovers, independent assortment, random fertilization

new alleles arise from

mutations in DNA; only mutations in germ cells that make gametes are passed down; point mutation or chromosomal alterations

does most DNA variability affect phenotype

no; no new allele bc protein translation/gene expression is not affected; non coding sequence is removed via splicing

harmful alleles

most are like this but they may be “hidden” in heterozygotes (Pp) but will pass it on; if environment changes they may become adaptive

neutral alleles

doesn’t provide any advantage or disadvantage; new phenotype doesn’t affect likelihood of leaving offspring; if environment changes they may become adaptive

population genetics

study of what changes allele frequencies in populations through time

genotypic frequency

% of each genotype (AA, Aa, aa) in the population

allelic frequency

% of each allele in the population (A, a)

hardy-weinberg equilibrium

describes a non-evolving population under ideal conditions (so evolution isnt necessary); if a large population reproduces randomly then the genetic frequencies dont change in the next generation (stay in eq); lets us detect microevolution- if the actual ratios dont equal the expected HW ratios then the population is evolving

hardy Weinberg conditions (all must be true)

no mutations, mating is random, no natural selection (equal survival), very large population size, no gene flow in or out

KNOW HOW TO DO P2+2PQ+Q2 EQUATION

p

frequency of dominant allele

q

frequency of recessive allele

p2+2pq+q2 = 1 ; p+q = 1

p2 = frequency of homozygous dom genotype CRCR ; 2pq = frequency of heterozygous genotype CRCW ; q2 = frequency of homozygous recessive genotype

mechanisms of microevolution

natural selection, genetic drift, gene flow

natural selection and microevolution

acts non-randomly on phenotypes- favors individuals with certain characteristics/traits; changes allelic and genotypic frequencies of populations non randomly; always leads to adaptation of population to current environment; flies carrying resistance to DDT

genetic drift and microevolution

genetic frequency changes due to random events; 2 types: founder and bottleneck effect; often occurs in small populations; can cause random changes in allele frequency, reduces genetic diversity, causes allele fixation

fixed allele

allele that is the only option that exists for that gene in a population (always homozygous for all members) all have brown coat BB and no white

founder effect

part of genetic drift; a few individuals become isolated from a larger population and start their own new population; less diverse founder population, causing more genetic drift and some adaptive alleles are lost; can cause maladaptive allele frequency increased (high rate of inherited blindness on an island)

bottleneck effect

part of genetic drift; an event drastically cuts population size due to sudden change in environment (flood, fire, etc); by chance, certain alleles are overrepresented by certain survivors and some are lost

gene flow and microevolution

alleles move in/out of the population; includes migration of adults, dispersal of gametes, seeds, larvae (western vs eastern deer population); adds genetic diversity, reduces differences between populations

relative fitness

contribution an individual makes to a gene pool of the next generation relative to the contribution of the other individuals; best reproductive success; brown Beatles leave more offspringg due to color so they have a higher fitness relative to the green onesdif