Ch. 7: Evolution and Adaptation Flashcards
traits are a combination of ____ + ____
genotype + environment
deoxyribonucleic acid (DNA)
molecule of 2 strands of nucleotides in double helix
nucleotides: __ + ___ + ___
sugar + phosphate group + 1 of 4 nitrogenous bases
nitrogenous bases
A (adenine), T (thymine), C (cytosine), G (guanine)
chromosomes
long strands of DNA wound around proteins into compact structure
Genes
regions of DNA that code for proteins for trait
Alleles
different forms of 1 gene
- 1 from each parent: 1 one each gamete (haploid- 1 set of chromosomes)
Polygenic trait
1 trait determined by several genes (several alleles)
- ex: ABO Blood Type
benefit of polygenic traits
allows for wide range of phenotypes
Pleiotropy
1 gene affects multiple traits
Epistasis
expression of 1 gene is controlled by another gene
Heterozygous
2 diff alleles of 1 gene (Bb)
Homozygous
2 identical alleles
Codominant
2 alleles contribute to phenotypes
Recessive
masked by dominant
Gene pool
all alleles from individuals in a population
Random assortment
haploid gametes w/ any combination of alleles from diploid parent
Mutation
random change in sequence of nucleotides in region of DNA (gene or expression of gene)
Recombination
reshuffling of genes when DNA is copied during meiosis and chromosomes exchange genetic material
3 means for genetic variation
random assortment, mutation, recombination
Genetic drift
when genetic variation is lost bc of random variation in mating, mortality, fecundity, and inheritance
Bottleneck effect
reduction of genetic diversity in population bc of large reduction in size
Founder effect
small number of individuals leave large population to colonize new area and bring w/ them only small amount of genetic variation
Selection
certain phenotypes are favored to survive and reproduce over other phenotypes
Stabilizing selection
individuals w/ intermediate phenotypes have higher survival and reproductive success than those w/ extreme phenotypes
Directional selection
individuals w/ one extreme phenotype have higher fitness than avg population
Disruptive selection
individuals w/ either extreme phenotype have higher fitness than individuals with intermediate phenotype
3 types of selection (nonrandom processes)
stabilizing selection, directional selection, disruptive selection
Microevolution
evolution at population level
Artificial selection
humans decide which individuals will breed and the breeding is done w/ preconceived goals for specific traits
Industrial melanism
industrial activities cause habitats to become darker due to pollution, so individuals w/ darker phenotypes are favored
Macroevolution
evolution at higher level of organization (new species)
- levels of: species, genera, families, orders, phyla
Speciation
evolution of new species
Phylogenetic trees
hypothesized patterns in relationship b/w populations, species, genera
Allopatric speciation
evolution of new species through geographic isolation
Sympatric speciation
evolution of new species w/o geographic isolation
Polyploid (polyploidy)
species w/ 3+ sets of chromosomes
- diploid –> tetraploid (3)
- can’t breed w/ original species can cause speciation
- common in plants!
Adaptations
evolutionary change in behavior, physiology and morphology that increases fitness
adaptation takes place only on the ___ level
population
adaptations are produced through
natural selection
forms of adaptations (examples)
- behavior allows better evasion of predators (camouflage, etc.)
- protein that function better at body temp
- anatomical feature allows access to new resources
- producing toxins to decrease competition
crypsis
camouflage
- the ability of an organism to conceal itself especially from a predator by having a color, pattern, and shape that allows it to blend into the surrounding environment
vestigial structures
feature that was an adaptation for ancestors, but have evolved to be nonfunctional for current day organisms bc environment has changed
- ex: appendix
4 requirements for adaptations:
- heritable (genetic)
- functional (usable)
- adaptive (increased fitness)
- current function
natural selection
survival of the fit (fit enough) to survive and successfully reproduce
- does not produce perfect organisms
short-comings of natural selection
- lack of existing genetic variation necessary
- changing 1 feature effects another feature (longer legs = run faster, but break easier)
jury-rigged design
- some species are all women (hermaphrodites)
-constrains possible variations
evolution
change in gene frequency over time to increase fitness (survival and reproduction)
chemical evolution
how inorganic matter (molecules and energy) turned into/formed organic matter (life)
biological evolution
“decent w/ modification”: change in a populations’ genetic make-up through successive generations
- takes time; not an individual basis (population)
- evidence from fossil fuels and DNA
- small scale and large scale
where did N, O, H, C come from at the beginning of earth?
exploding stars created dust (molecules)
Carolus Linnaeus (1707-1778)
- founder of taxonomy and binomial nomenclature
- grouped according to similarities
- ASSIGNS: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
taxonomy / binomial nomenclature:
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
- founder: Carolus Linnaeus
Comte de Buffon (1707-1788)
- “natural history”
- biogeographer
- changes in nature; organisms adapt
Catastrophism
periodic catastrophic events destroy most species in local extinctions, repopulated by migration or new creations
paleontology
the branch of science concerned with fossil animals and plants
Georges Cuvier (1769-1832):
- The father of paleontology
- First to suggest extinction
geology
the science that deals with the earth’s physical structure and substance, its history, and the processes that act on it; earth = old
- James Hutton
- Charles Lyell
Lamarck’s theory of evolution, 1809
Life evolved along w/ evolution of earth (gradual)
- tendancy toward greater complexity and more “perfect” adaptations.
- teleological evolution (evolution with a predetermined purpose!)
Biological evolution
biological evolution involving descent through genetic inheritance
- all life has common ancestors
clade = monophyletic group =
group with 1 common ancestor
True/False: humans evolved from chimpanzees
FALSE
- Humans and chimpanzees share recent common ancestor that was neither chimpanzee nor human
Voyage of the HMS Beagle 1831-1836
- the origin of species
- Galapagos: diff islands had diff species w/ same ecological niche
Charles Darwin:
Proposed that species can change (evolve) over time, via natural selection.
- 1859: published On the Origin of Species by Means of Natural Selection
Natural selection (Darwin definition)
Individuals within a population are phenotypically variable- and those differences can influence how well they acquire resources, (food, shelter, mates, etc.) and therefore can affect their reproductive success.
A.R. Wallace also developed ____
a theory of natural selection at the same time, collaborated with Darwin
mechanisms of evolution in natural selection (3):
- lots of variation in heritable traits = required
- populations overproduce offspring
- survival of the fittest offspring
fossil theory
fossil species do not look like current species –> must be diff –> evolution
- history of extinctions: 5 previous, 1 current
evidence for evolution (11)
- fossil theory / extinctions
- homologies
- anatomy
- comparative anatomy
- developmental biology
- cellular/molecular evidence
- Distribution in Time and Space
- Geographical Evidence
- Evidence by Example
- Ecology
- Experiments
history of extinctions
- 5 previous
- current 1
homologies
Similar characteristics due to relatedness
analogous
same function, different structure
- ex: wing of bird vs wing of bee
homologous
same function, same structure
- ex: wing of bird vs wing of bat
Developmental homologies
structures arise from the same embryonic structures and are morphologically similar
Chronology:
- Relative dating:
- Numerical dating:
- Relative dating- fossils in temporal sequence based on position in rocks
- Numerical dating- relies on decay of radioactive elements (uranium, potassium, rubidium, carbon)
____ links all life on earth to common ancestor
DNA
Geographical Evidence
Distribution of living things; evolution and mvmt of continental plates
artificial selection
evolutionary process in which humans consciously select for or against particular features in organisms
mechanisms of change:
- Mutation
- migration (gene flow)
- genetic drift
- natural selection
coevolution
How different species can affect each other’s evolution
- 2 species evolve together
- ex: mites and parasites evolve w/ their host
- ex: dogs and humans
3 requirements for natural selection (“formula” for natural selection)
- variation
- differential reproduction
- heredity
NEW genes only arise from a ___
mutation
new combinations of genes can arise from ___ in sexual reproduction
sexual crossover
sexual selection
animals choose their mates for a reason (whatever it may be) and that will be passed on to offspring
3 modes of selection
- directional selection
- diversifying selection
- stabilizing selection
sexual dimorphism
distinct difference in size/appearance b/w the sexes of an animal (and difference between sexual organs)
male peacock feathers are there for what reason?
intimidate predators, impress mates (with color/patterns and dances with feathers)
male competition
compete for females (time for mating), compete for food/resources
female choice
which males to mate with, for how long, which male will fertilize her eggs
intrAsexual selection
competition for mates (ex: males fighting/competing for females)
intErsexual selection
mate choice
runaway selection
middle ground for trait is best: less or more decreases fitness
- ex: ideal bird tail length is midlength
- short or long tail decreases fitness
handicap principle
females prefer males with handicaps because they have survived with their handicap so they are very fit
good genes hypothesis
you can see the good genes (phenotype)
what creates variation?
mutation and sexual reproduction
- NOT evolution
Species
group that interbreeds in nature
ring species
counterexample to speciation based solely on interbreeding
chronospecies
different stages in the same evolving lineage that existed at different points in time in the fossil record
Speciation
evolution of new species; lineage-splitting event that produces 2+ separate species
- Causes: geographical isolation, pre-zygotic (before egg is fertilized), post-zygotic (after egg is fertilized), food isolation
a clade is a…
sister group
causes for speciation
geographical isolation, reduction in gene flow, reproductive isolation
peripatric speciation
small population isolated at edge of larger population (special kind of allopatric)
parapatric speciation
continuously distributed population (special kind of sympatric)
3 requirements for evolution
- variation
- isolation (geographic or sexual)
- time
evolution
any change in heritable (physical) traits, anatomy or behaviors within a population across generations
- Gene distribution changes over time
Descent w/ modification
parents have children that behave similarly and differently
- Creates new traits
Common descent
everything came from 1 original species
whales evolved from…
the same origin of bisons and pigs
- they had legs!
homologous structures
organisms share finely detailed structures
- bc of common descent almost all vertebrates have similar bone structure
Pre-zygotic barriers for speciation (3):
Mechanical, Temporal, behavioral
Mechanical barriers for speciation
don’t have lock-and-key fit for sex
Temporal barriers for speciation
breed at diff times
behavioral barriers for speciation
how they attract mates
post-zygotic barriers for speciation (2):
- zygote mortality- fertilized, but zygote immediately dies
- hybrid sterility- horses and donkeys can create mules; mules can’t reproduce at all (sterile offspring)
speciation causes:
- geographical isolation
- pre-zygotic (before egg is fertilized)
- post-zygotic (after egg is fertilized)
- food isolation
Peripatric speciation
evolution of new species when small group breaks off from larger group and forms new species bc of physical barrriers
- one group is much smaller than the other
- founder and bottleneck effect
Parapatric speciation
evolution of new species due to large area and organisms only mate with nearby organisms; slight differences in habitats effect speciation
Gradual evolution
thousands –> millions of years for speciation
Fast evolution
mutations and breeding produce immediately different offspring
4 modes of speciation
allopatric speciation, sympatric speciation, peripatetic speciation, parapatric speciation
plants can use ___ for speciation (easily) that animals can’t use
hybridization
-form of sympatric speciation
2 modes of speciation common in plants
hybridization, polyploidy
genetic equilibrium (and it’s 5 conditions)
- Allele frequencies at a locus are not changing
– Population is not evolving
– Five Conditions: - No mutation
- Random mating
- Gene doesn’t affect survival or reproduction
- Large population
- No immigration/emigration
