Evolution Flashcards
What are the two types of evolution
microevolution and macroevolution
microevolution
the change in allelic frequencies in a gene pool
(crab scenario)
macroevolution
speciation - creation of a new species
Hulton
GEOLOGIST
studied earth and figured out it was older than 6000 years old
also figured out that the earth is changing
Malthus
ECONOMIST
had the idea that rich people will survive because they can afford to live, but poor people can’t (buying food, etc.)
SURVIVAL OF THE FITTEST
Lamarck
NATURALIST
said people can pass down acquired characteristics (which was wrong), but got right that favorable traits accumulate generation through generation
Cuvier
PALIENTOLOGIST (studied fossils)
believed in creationism (not evolution, basically that god created everything) and thought that fossils supported that belief
Lyell
GEOLOGIST
expanded on what Hutton said/discovered
Darwin
NATURALIST
publishes many papers about what he discovers on a boat ride, including “On The Origin Of Species”
(also wrote articles in the same science journal/magazine a Wallace)
Wallace
NATURALIST
published articles in the science journal/magazine, sends Darwin hiss hypothesis of natural selection
Darwins Observations
- members of a population often vary in their inherited traits
- all species can produce more offspring than the environment can support, and many of their offspring fail to survive and reproduce
Darwins inferences
- Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals
- This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations
what are the five assumptions required for the hardy Weinberg law?
- the population mates randomly
- no mutations occur
- no selection occurs (no influence of “fitness”).
- no migration (no gene flow)
- large population size (no genetic drift)
Hardy Weinberg Law
For a given gene A with alleles frequencies p (dominant) and q (recessive) in a parental population
the next generation will be in equilibrium (the gene frequencies p and q will not change over time).
Gene Pool
the combination of all the genes (including alleles) present in a reproducing population or species
Speciation
one species splits into two or more species
OR
when one species changes enough to now be classified as a distinct species
Morphological species concept
if you look alike, your the same species
Ecological species concept
if you occupy the same niche, your the same species
phylogenetic species concept
defines a species as the smallest group of individuals that shares a common ancestor
Molecular Biological Species Concept???
if the DNA is similar enough, then they are the same species
biological species concept
if you can breed and produce FERTILE AND VIABLE offspring then you are the same species
Counterexamples to the biological species concept
doesn’t work for asexually reproducing organisms (because then every organism would be it’s own species)
doesn’t work for fossils
usually doesn’t work for hybrids (mules can’t breed to make another mule)
Hybrid
e.g. a mules (a breed between a DONKEY AND A HORSE MAKE a MULE)
Reproductive isolation
prevents members of different species from. mating with each other
prevents gene flow between species
maintains separate species
Reproductive barriers
serve to isolate the gene pools of species and prevent interbreeding (to make hybrids).
Reproductive barriers can either be…
prezygotic - prevent sperm and egg from ever meeting; zygote is never made
OR
postzygotic - sperm and egg do meet and zygote is created; that. zygote does not grow up to be a fertile offspring
Habitat isolation
PREZYGOTIC BARRIER
if you live in two different places, you can’t mate, and the gene pools will remain separate
(doesn’t have to be geographically far away, could just be land vs water, etc)
Temporal isolation
PREZYGOTIC BARRIER
if you mate at different times, your gene pools will remain separate
(could be different mating seasons over the year, or even different times of day)
Behavioral isolation
PREZYGOTIC BARRIER
If you don’t perform the right mating ritual/behavior (dance, song, etc), you won’t mate, and the gene pools remain separate
Mechanical isolation
PREZYGOTIC BARRIER
Sex organs are not compatible, so you can’t mate (location, shape, etc), and the gene pools remain separate
Gametic isolation
PREZYGOTIC BARRIER
the proteins on the surface of the sperm don’t match up with the proteins on the surface of the egg, so the sperm can’t fertilize the egg (so you can’t mate), and the gene pools remain separate
Reduced hybrid viability
POSTZYGOTIC VIABILITY
the hybrid doesn’t live; the egg is fertilized but it dies before it is born
Reduced hybrid fertility
POSTZYGOTIC VIABILITY
the hybrid lives, but it is infertile (e.g. mule)
Hybrid breakdown
POSTZYGOTIC VIABILITY
The hybrid can reproduce, but the offspring of the hybrid (F2 generation) cannot reproduce
Allopatric speciation
there is a geographical separation between populations of the same species, isolating their gene pools
the isolated populations no longer can reproduce, and the separate gene pools will change (they have their own mutations, food, etc)
they may change enough so that even if you did put them back together, they could no longer mate
Sympatric speciation
a new species arises in the same geographical area (no geographic barrier) as a parent species
some ways this may happen:
- polyploidy
- habitat differentiation
- sexual selection
polyploidy
cells have more than 2 complete sets of chromosomes (more than 2n)
gametes are then formed with more chromosomes than they should have, and can’t mate with cells that have the normal amount
BUT, the gametes can mate with themselves, so they do
in one generation, you go from having a cell with one diploid number, to a cell with a new, higher diploid number (new species, can’t mate with old one)
