Evolution of Populations
What Darwin
didn’t know


how _____________________________
how ______________________________
Biology
1930’s

Mendel’s work ________________________________
 ____________________________________
Watson & Crick
 showed ___________________________________
________________________________

Genetic
Variation


Source of
genetic
variation
Evolution in
genetic terms
many genes have ____________________________
 individual can be ________________________________
mutation: ____________________
 ____________
 caused by _________________________
 may or may not __________________________

sexual reproduction: ____________________________
 ___________________________________ during meiosis
 _______________________ during meiosis

studied in __________________
 population: group of ______________________________
__________________
 gene pool: _____________________________________
 ___________________________________ in population
 ____________________________ in gene pool
 expressed as _____
 e.g. Person A is RR: _______________________

_____________________________________________
Natural selection 
leads to ________________________________________
 _____________________________
Single gene trait 
controlled _______________________________
 ___________________________________


Polygenic trait
e.g. _____________________________________ present
 red form _____________________________
 black form __________________________________
_____________________________________________

controlled by ________________________________________
 _____________________ genotypes and phenotypes
 ________________ of phenotypes

_______________________________ affected in 3 ways:
 directional selection:
 individuals at _____________________________
 e.g. bird beaks: __________________________
birds with larger beaks ____________________
__________________________
 stabilizing selection:
 individuals ____________________________
 e.g. ____________________________

 disruptive selection:
 individuals ______________________________
 e.g. bird beaks: ___________________________
 birds with ________________________
_______________________.
 curve splits into ________________________
 ______________________
Genetic Drift

small populations: ___________________________________.
Founder effect

small groups of individuals _____________________________
 ___________________________ than parent population
 ________________________ new population frequencies.
 given enough time: ______________________.
How does evolutionary change operate??
What are the conditions where there is no evolution??
Hardy-Weinberg principle:
If a population is in genetic equilibrium it means - allele frequencies don’t change = no
evolution
conditions
* to maintain equilibrium from generation to generation there are 5
conditions for no evolution :
1. mating must be random – all members of pop have equal opportunity to produce
offspring
(doesn’t happen – males compete, females are picky)
2. populaiton must be large - >10,000 or more so genetic drift doesn’t happen
(not all populations are that large)
3. no movement into or out of the population – no mixing of gene pool from the bunnies
down the
meadow
(animals do migrate – maybe the clover is sweeter down the
meadow)
4. no mutations – if gene mutations happen will = new alleles in the population
(mutations (errors) can happen any time)
5. no natural selection – all genotypes must survive and reproduce equally (no
advantages)
(there is variety in every population = advantages)
in some populations these conditions are met
if conditions not met = genetic equilibrium dirstrupted =change in allele frequencies =
evolution
Formation of Species
Speciation

formation of _________________.
Species

group of organisms that:
 ________________________ offspring.
 shares a ______________.
How do new species form?
groups of organisms __________________________ that they:
 can _________________.
 _________________ a gene pool.
Reproductive
isolation

Behavioral
isolation

2 species ________________________________________
rituals
 e.g. ______________
Geographic
isolation

2 species ___________________________________ separated
 e.g. _______________________, etc.

2 species _______________________________________ at
different times
 e.g. ______________________ at different times
Temporal
isolation
Patterns of Evolution
Extinction

extinction is a ______________________ on earth
 _______________________ that ever lived are extinct
 natural selection: ______________________________
 species that _______________________ don’t
survive
 natural disasters
 ____________________
Adaptive
radiation

_____________evolves into many _______________
 ancient ______________________________ species
 ancient ______________________________ species
Convergent
evolution

___________________ evolve with similar _________________
 ___________________________
 _______ (fish)
 __________ (bird)
 __________(mammal)
 ________ (mammal)
Coevolution

__________________________________________________
 ________________________
 ________________________
Punctuated
equilibrium

________________ in earth’s history where ______________ in
species occurs (________________)
________________ with _______________ in species (evolution)
