envs lecture 2 Flashcards
who talked about evolution pre-darwin
plato and aristotle
what is one of the big questions in evolutionary biology
how to explain variation in nature, within species, etc.
what is concept of eidos
‘form’ or ‘idea’ or ‘essence’
give example of essentialism
horses have an immutable (fixed/unchangeable) properties, but each individual has its imperfections
what is essentialism/pre-darwinian view
variation is accidental imperfection
where does this pre-darwinian view come from
from a perception of creationism; idea that life was created by an all powerful being, all life was perfect
basically what did pre-darwinians think
variation is imperfection
what happened in 18th century w/r to thinking of evolution
profound changes in thinking about nature and history of earth
uniformitarianism
present is the key to the past
who came up w/ uniformitarianism
geologists James Hutton, Charles Lyell
what is catastrophism
sudden violent and short-lived events were responsible for current state of the earth
what did Hutton and Lyell argue
the same geological processes operated in the past as in present, and therefore geological data could be explained by causes that we observe
what contrasts w/ uniformitarianism
catastrophism
describe catastrophism
ties the current state of the earth to sudden violent and short-lived events like volcanism, or events like asteroid impacts
describe reality w/r to uniformitarianism
both ongoing events AND catastrophic events play a role in evolution
georges cuvier
animal anatomist, studied fossils
what was cuvier among the earliest to recognize
fossil forms were likely extinct
why was this idea of fossils forms being extinct a hard concept to grasp
didn’t match the ideas of the day that all organisms were part of the ‘great chain of being’,
great chain of being
scale/ladder of nature created by god
what did jean-baptiste pierre antoine de monet, chevalier de lamarck do
developed theories of phenotypic evolution and speciation
was lamarck correct
nah
define lamarck’s theory of phenotypic evolution
inheritance of acquired characteristics —> traits acquired during the course of an individual’s lifetime were passed on to offspring
example lamarck’s theory
lengthening of giraffe’s necks over lifetime would be passed down, or thickening of blacksmith’s arms
inheritance of acquired characteristics
changes in individuals within a generation passed onto next generation
natural selection
variation among individuals, certain variants more likely to survive and pass traits onto next generation
lamarck’s theory of speciation
species originate by spontaneous generation, have not originated from common ancestors
who was pre-darwin
plato & aristotle, james hutton & charles lyell, georges cuvier, lamarck
when was Darwin
1859
who was darwin
1809-1882, voyage of the beagle, accomplished naturalist
what inspired Darwin
Thomas Malthus’s that argued rate of human pop growth is higher than rate of increase in food supply, leading to famine
what did malthus inspire darwin to think
inspired his ideas about struggle for existence
when did darwin read malthus
1838
describe process of publishing origin of species
after formulating his theory, spent 20 yrs trying to sort out flaws, then finaly published it
when did he publish origin of species
1859
why did he take a long time to publish origin of species
b/c he knew it would be controversial
two major theses of origin of speceis
- descent w/ modification (evolution), 2. causal agent of evolutionary change (natural selection)
describe the process of nat selection as a cause of evolution through generations
early in gen 1: heritable/genetic differences in phenotype
later in gen 1: natural selection acts
generation 2: evolutionary change via natural selection
how are the peppered moths example of nat selection/evolution
variation in phenotype, traits are heritable, etc.
what is the variation in phenotype
melanic and non-melanic peppered moths
describe these phenotypic traits
heritable; have a genetic basis
describe peppered moths
white form; soot from coal burning caused black form to be popular, then white form became popular after coal burning decreased
what is suggested agent of selection w/ peppered moths
predation by birds
descent w/ modification
describes biological evolution
natural selectoin
differential survival or reproductive success of classes of entities that differ in one/more characteristics
criteria for natural selection
differences, that are inherited (must be inherited for evolution by natural selection)
1st component of darwin’s book
evolution
what is evolutoin
characteristics of lineages of organisms change over time
what is 2nd component of darwin’s book
common ddescent
what is common descent
all life could be portrayed as one great family tree (tree of life, a metaphor
was common descent a new or old view of evolution
radically new
what is 3rd component of darwin’s book
gradualism
what is gradualism
proposition that differences b/w radically diff organisms have evolved incrementally, small steps thru intermediate forms
what is 4th component of Darwin
population change
what is population change
thesis that evolution occurs by changes in the PROPORTIONS of individuals within a population that have diff inherited characteristics b/c of differential survival and reproduction (natural selection)
what is 5th component
natural selection
what is natural selection
darwin; changes in proportion of individuals w/ diff characteristics are caused by differences in their ability to survive and reproduce; such changes result in evolution of adaptations
who independently conceived natural selection
Alfred Russell Wallace
was evolution a new theory
no
was common descent a new idea
yeah
was gradualism (slow incremental change) a new idea
yeah
what are adaptations
traits that improve an individual’s chance at survival and reproduction in a given env.
what was the Darwinian view of evolution
variation is adaptive, natural selection acts on that variation
describe pre vs. post darwinian view of variation
before they would see this variation as imperfection; Darwin & Wallace would say the variation is adaptive, natural selection acts on this variation
who was Wallace
british naturalist, traveled the world collecting specimens; came up w/ same idea as darwin: Evolution happens thru natural selection
what did wallace spur darwin to do
publish origin of species
what was wallace called
father of biogeography
wallace’s line
major biogeographic barrier b/w australasia and asia
wallace effect
explanation for speciation via ‘reinforcement’
what is biogeography
subfield of evolutionary biology; field that focuses on geographic distributions of organisms
what’s up w/ Wallace’s line
barrier, noticed that many groups of organisms were only found north or south of the line
basically what is wallace’s line a barrier of
barrier b/w australasia fauna
what’s up w/ wallace effect
natural selection can contribute to reproductive isolation of incipient species (recently derived species) by creating barriers to breeding and geneflow b/w populations and ultimately leading to speciation
was darwin’s theory accepted or controversial
initially very controversial
when was idea of evolution by common descent accepted
1870s
was the cause of evolution accepted
no, debated the idea that nat selection caused evolution
how long after publication of Origin was the idea of nat selection rejected
60 years
what did this rejection of nat selection lead to
rise of mutationist theories
what are mutationist theories
argued that discretely diff organisms arose via mutation, nat selection was not required for origin of new species
what was mutation seen as
an alternative to nat selection
basically sum up idea of evolution and how it was accepted during that time
evolution was a fact at that point, but the theory/explanation wasn’t agreed upon
richard goldschmidt’s idea
‘hopeful monsters’
what was goldschmidt’s idea
sudden drastic changes reorganize the heritable material in an organism ,create new species “hopeful monsters”
what would creation of hopeful monsters lead to
most of this massive genetic change would be deleterious, individuals wouldn’t survive, but some would
what would some individuals surviving lead to
diversification
basically sum up richard’s idea
sudden, drastic changes create new species –> hopeful monsters
another way to describe goldschmidt’s idea
macroevolution through macromutation
was richard’s hopeful monsters idea true
no, didn’t pan out
what was an important cornerstone to Darwin’s theory
heritability
but what was a big gap in his theory
heritability of traits; didn’t know how to explain that
who helped fill in this gap
gregor mendel; did pea experiments, figured out inheritance of phenotypic characters
what was big gap in darwin
we know traits were inherited, but no one knew HOW traits were inherited (DNA, etc.)
evolutionary theory after Darwin
mendelian genetics
what was mendel’s idea
particulate inheritance
when was mendel’s idea published
1865
what were evolutionary theories after Darwin
mendel
when was Mendel’s ideas actually listened to
published in 1865 (around time of origin of species), ignored until modern synthesis
when was modern evolutionary synthesis
1930s and 40s
what was modern evolutionary synthesis
‘revolution’, contributions of geneticists, ecologists, systematists, paleontologists
what did modern synthesis do
combined Darwin’s theory w/ facts of mendelian genetics
chief principle of modern synthesis
adaptive evolution is caused by natural selection on mendelian genetic variation
what is neo darwinism
adaptive evolution is caused by nat selection on mendelian genetic variation
major players of modern synthesis
ronald a. fisher, j.b.s. haldane, sewall wright
what did fisher, haldane, and wright do
developed a mathematical theory of population genetics, showed that mutation & natural selection together cause adaptive evolution
what is mutation in terms of nat selection
mutation isn’t alternative to nat selection, but rather raw material
what did those three create
field of population genetics
what is example of genetic drift
founder effect
what is founder effect
OG population is 50% red 50% green. a subset of them go to an island, forming a founding population. founder effect, radom sampling of OG population leads to diff. proportion of phenotypes % genotypes. now it is 20% red, 80% green.
what does random sampling effect cause
genetic drift
what is random sampling & genetic drift one way of
one way genetic drift causes evolution (AKA change in gene frequencies)
another big player in modern synthesis
Ernst Mayr
3 major contributions of Mayr
biological species concept (BSC), theory of geographic (allopatric speciation), theory of founder effect speciation
what is BSC
species are groups which are reproductively isolated (don’t exchange genes) from other groups
2 ways for a diverging species to become reproductively isolated
premating and postmating isolating mechanism
premating isolating mechanism
phenotypic preference such as preference for similar coloration or specific display
post-mating isolating mechanism
infertility, inviability of hybrid offspring
theory of geographic/allopatric speciation
new species form when populations become geographically isolated, thus can undergo genetic divergence
theory of founder effect speciation
drastic reductions in population size promote speciation (e.g. ‘genetic revolutions’)
4 major causes of evolution within species
mutation, geneflow/migration, nat selection, genetic drift
what happens over long periods of time to these microevolutionary processes
these microevolutionary processes account for origin of new speices and ultimately macroevolution, major evolutionary change
what is mutation
creation of new variants
what is geneflow/migration
movement of genes or variants of genes
what is nat selection
differential reproductive success of phenotypic variants
what is genetic drift
random effects such as founder events leading to sampling of alleles in populations causing changes in gene frequencies over time
1st fundamental principle of evolution/major tenet of modern synthesis
phenotype (observed characteristics) is different from genotype (set of genes in an individual’s DNA)
what is phenotypic difference can be from
partly from genetic differences, partly from direct (within generation) effects of environment
what is 2nd principle
heredity of variation is based on ‘particles’ / genes that retain their identity as they pass thru generations
3rd principle
evolutionary change is a population level process that entails changes in proportions/frequencies of individual organisms w/ diff genotypes
4th principle
genes mutate at a low rate, too low to cause a population to shift from one genotype to another
how do population shifts mainly occur from
random fluctuations (genetic drift) and nonrandom changes (nat selection)
5th principle
even a slight amount of selection can bring about substantial genetic changes; thus selection can account for both slight AND extreme genetic differences
6th principle
mutations can accumulate in populations, thus populations harbor genetic variation
can mutations accumulate in populations
yeah
do populations harbor genetic variation
yeah
7th principle
differences between populations & species are often adaptive (evolved due to natural selection), and are based on differences at several or many genes of small effect (evolution occurs by small steps)
what does adaptive mean
evolved due to natural selection
describe differences b/w populations and species
adaptive
how does evolution occur (big or small steps)
small steps
8th principle
species are characterized by barriers to genetic exchange and interbreeding (reproductive isolation), and usually evolve in geographic isolation
reproductive isolation
barriers to genetic exchange and interbreeding
9th principle
all organisms form a great ‘tree of life’ of phylogeny; all forms of life have descended from a single common ancestor in remote past
example of biology since modern synthesis (1950+)
discovery of DNA
who discovered structure of DNA
watson and crick and rosalind franklin
when did watson and crick discover DNA
1953
what is the biochemical mechanism of inheritance
DNA
molecular evolution
analysis of processes and history of changes in genes
basically what was an important revolution in biology and evo bio
discovery of DNA, ability to unlock its secretes
what is new field in evolutionary biology
molecular evolution
what were leaders of modern synthesis called
adaptationists
what did adaptationists argue
almost all features of organisms were adaptive and evolved via natural selection
what did the molecular evolution ‘revolution’ do
changed this idea
was ernst meyer an adaptationist
yea; was a leader of modern synthesis
what did molecular evolution lead them to realize
not everything is driven by selection
what did Motoo Kimura do
published Neutral Theory of Molecular Evolution
what does natural selection require to act on
requires phenotypic variation to act upon
but what actually happens w/r to genetic changes
many genetic changes don’t actually cause phenotypic change/variation
what was Kimura’s hypothesis
most DNA evolution occurs by genetic drift rather than natural selection
wobble position
mutation at 3rd position won’t change the AA, so won’t change the phenotype
what happens if theres a mutation at wobble position
won’t change the protein, essentially silent change
silent changes
natural selection can’t see these changes, cuz they don’t cause change in phenotype
if there’s a mutation in that site will it change phenotype of organism
no
what does most DNA sequence evolution happen thru
genetic drift (random sampling events) rather than natural selection
does most DNA sequence evolution happen thru natural selection
nah, genetic drift
but how can u compare DNA sequences
compare proportion of synonymous DNA changes that don’t change AAs, to non-synonymous ones that do change AAs
what did this comparison provide a foundation for
foundation for detecting natural selection on DNA sequences
who were important players in the field of sociobiology
william D. hamilton, robert trivers
what was another important piece of post-modern synthesis era
focused on evolution of sociality on behavior
what did evolution of sociality on behavior include
ideas about confusing altruistic behaviors and eusociality and conflict in nature
what did sociobiology focus on
issues like evolution of social behavior
what is confusing altruistic behavior
kin selection; why do individuals help each other, what does that have to do w/ natural selection
what does new age of genomics and phylogenomics lead to
insights into size, organization, structure of genomes from terabytes of data and billions of reads of DNA sequence data
what does this information yield insight into
causes & consequences of evolution, genetic basis of adaptation
what else does data lead to
opportunities for reconstructing robust tree of life to understand evolutionary history
how do we study evolution
we infer evolutionary history and its causes, by making predictions and matching those to observed data
how do we study macroevolution
comparing data (like variation in genes) w/ theoretical models (HW EQ)
what is microevolutionary scale
comparing variation in genes to theoretical models like HW equilibrium
what is macroevolutionary scale
paleontology, comparative biology, phylogenetics
