Lecture 2 pt 1 Flashcards
Exam
Plato , Aristotle
believed life forms unchanged since the beginning + species are fixed
Catastrophism
Large-scaled disaster destroy species
explains extinction and differences
Lamarck
“drive to perfection” - proposed mechanism
1) use/disuse
2) inheritance of acquired traits
Uniformitarianism
geological change occurs slowly and gradually
1) natural laws are always constant
3) scientist should explain past with same processes
Darwin
Collected fossils, uniformitarianism , explanis fossils on mountain top
Galapagos island
many endemic species found in one place
Theory of natural selection
“descent with modification” =evolution
operates without ultimate goal
selects organism more fit to survive
artificial selection
humans selecting desired traits _ breeding to emphasize those traits
Direct observation ( evidence for evolution)
variation exists in a population
environment favors one variation over the other nature “selects” those with desirable features
sedimentation
sand/silt is carried by rivers , organisms dies, lower layers are compressed
Fossils
organic components(carbon) replaced with inorganic materials ( rock)
Biogeography
Pangea “supercontinent”, continents drift apart, distribution of species reflects evolutionary and geologic change
Homology
( shared ancestry ) similarity implies a common ancestry followed by adaptation + specialization
Analogy
analogous structure, evolved independently to solve a problem but is not due to shared ancestry
Convergent evolution
Wings for flight , emerged differently in mammals, birds, and insects
Vestigial organs
leftover structures that have little if any function
Microevolution
Small, change in frequency of alleles
Genetic variation in population
existence of 2+ alleles in a population
Gene pool
All alleles for all genes in that species
Hardy Weinberg Rules
No new mutations
pop must be large
pop must be isolated
mating events must be random
random odds of survival
predicts no evolution and is in an equilibrium
Genetic drift
Random fluctuations in allele frequencies in a population
Genetic drift : Bottle neck
Severe random reduction in pop size
decreases overall genetic variation
Genetic drift: Founder effect
Colonization of a new habitat by a few individuals
- smaller colonies unlikely tp represent original genepool
Gene flow
Movement or exchange of alleles between pops
( immigration - emigration)
Genetic drift & gene flow–> natural selection
all of these are examples of evolution but not adaptation which comes from natural selection ,
happens by chance and sorting
Sexual selection
example of natural selection ( has chance)
certain traits make individuals more likely to obtain mates
secondary sexual traits, differences not directly related to reproduction or fitness.
