Exam 1-Evolution Flashcards
What is evolution?
any change in inherited traits (allele frequency, permanent) of a population which occur from 1 gen to next, process acts on population NOT individual
What is the fundamental unit of evolution?
genetic mutations, ex: DNA replication, carcinogens, radiation
What is natural selection?
mechanism of evolution whereby differential survival and reproduction of individuals causes some genetic types to outcompete and replace others; acts on individuals but EFFECTS populations, i.e. better adaptation=live longer=reproduce and pass on traits; the allele is more likely to increase in frequency when it confers higher fitness than the ancestral allele; Traits that promote survival and reproduction become more frequent in populations from one generation to the next.
What is genetic drift?
evolution arising from random changes in genetic composition of a population from 1 gen to next; change in frequencies of alleles in a population resulting from the gene pool to make zygotes and from chance variation in the survival and/or reproductive success of individuals; results in nonadaptive evolution
What is the theory of evolution?
is a core set of ideas centered around the concept that all species related and gradually change over time
What is the case study-Virus evolution of Sars-Cov-2?
spike protein allows cells to be infected, receptor binding site (RBD) is important for gaining access to host cells, sequenced genomes of dif animals that could have transmitted, and 2 dif lineages identified where mutations in RBD occurred, Implication:may be able to control how COVID and other diseases/viruses evolve
What are the 5 postulates of the theory of evolution?
- Populations change over time
- Lineages split generating new species
- Descendants diverge extremely from ancestors
- living species share common ancestor
- Earth is very old
What is common ancestry?
common ancestry requires evolution, all living organisms descended from a common ancestor; evidence for CA and against separate ancestry proves evolution
What is separate ancestry
theory that species do evolve and produce new species but the different types of organisms had separate ancestors, more evidence for common ancestry
What is the evidence for common ancestry? (4)
- Biogeography/Geographic distribution
- “Deep” similarities/homologies:
- Transitional Fossels
- Taxonomy:
What is the evidence for common ancestry?
- Biogeography/Geographic distribution: species (living and fossil) tend to live near closest relative, pattern of similar-looking species living in certain parts of the world (and absent from places they could possibly thrive)
- “Deep” similarities/homologies: some species may not look alike but have very similar structures- similar structures may have different functions, if unconstrained (SA) expect dif structures for dif functions ex: vestigial structures, bad design suggest historical constraints
- Transitional Fossils: fossils found carry a subset of traits of significant living groups, traits gained stepwise (but don’t confuse with growing complexity)
- Taxonomy: trait distribution correlated, groups nested in groups, makes sense statistically
Summary:Abundant data supports CA and evolution
What is a species?
populations (or groups of populations) w/in and among which individuals interbreed and outside of which they do not interbreed
Who is accredited for idea of selection?
Darwin credited with idea of selection but many other key figures, like:
Carol von Linne: organized life into nested hierarchy (taxa), binomial naming system (ex:homo sapiens, genus species)
Lamarck:argues for evolution and observed growing complexity, but some misconceptions though evol had goal, no extinction just change, adaption occurs via inheritance of acquired changes (ex: giraffe stretches its neck to get food, passed on to offspring who have longer necks)
Thomas Mathus: all species have capacity to increase in number and more individuals are born then can survive and breed
Alfred Russel Wallace: observed biogeographic patterns in Indonesian archipelago, organisms on 1 side of line shared many similarities, but when cross that line, organisms collectively are more similar to those in Australia than neighboring islands, CO-CONCEIVED theory of evolution by natural selection
What are the 4 postulates for natural selection?
- Individuals w/in species variable due to mutations creating new alleles (segregation and independent assortment making news combos)
- Individuals pass alleles to offspring
- In every gen, some individuals are more successful at surviving and reproducing than others, more offspring are produced than can survive
- Survival and reproduction of individuals are NOT random, successful individuals are those with alleles
+ allelic combos that best adapt them to their environment
ex:mice with white fur are camouflaged on white sand, brown mice have poor camo, composition of population changes from 1 gen to next
What is Darwinian fitness?
traits that allow organisms to have greater reproductive success will be favored, expected net reproductive success (combining survival and reproduction)
What is the significance of the Darwins Finches experiment?
Experiment: during favorable years, species share food= lacks strong selective pressure on beak size, during drought, small seed plants died=strong selective pressure favoring finches with large beaks, when not in drought mean finch beaks shifted to lower/normal range
What is selective breeding/artificial selection?
where humans select phenotypic traits of interest in organisms
What does artificial selection tell us about natural selection?
lessons from art selection: pop can contain alleles that confer traits favored by humans, tend to increase in frequency or become fixed, new mutations can occur, surprising amount of morphological diversity can arise very quicky
What are the 10 misconceptions about selection?
- Evolution is defined as natural selection occurring over time (evolution in inherited traits, natural selection is an aspect of evolution and fitness)
- Evolution tends to result in more complex organisms over time
- Evolution occurs when the environment changes
- Natural selection generates genetic variation in populations
- Natural selection assumes that beneficial mutations are more common than deleterious mutations
- Natural selection assumes that all mutations are equally likely
- natural selection assumes that mutations arise more often when organisms are porly adapted to their environment
- Selection favors traits that promote speciation
- Selection favors traits that reduce the risk of extinction
- Complex traits in living organisms are there too help the organisms survive or reproduce in their current environement
What is the significance of the “Monkey Trial” 1925?
teacher in Tenessee taught evol which was against the law, found guilty and evol was banned in classrooms however when Cold War began, brought evol back to classroom to compete + produce mathematicians, scientist, etc.
What is speciation/lineage-splitting?
- Geographic isolation
- isolation allows for genetic differentiation given environment + cannot reproduce with other groups
- lineages isolated long enough lose the ability to interbreed or if they do produce offspring sterile, involves cessation of gene flow, allow descendant lineages to evolve independently- to acquire dif traits over time
NOT tied to trait evolution
What are the three big ideas of evolution?
- common ancestry unites all life. diverse living species descend from common ancestors
- Populations evolve, genetic composition of populations change over time
- Natural selection provides direction, adaptations explained by natural selection and other related processes
