Final Exam Flashcards
Don't Fail
Macro-evolution
Major Evolutionary change over a long period of time
Phyletic gradualism
Model of Evolution where most speciation is slow/gradual over time
Punctuated equilibrium
Isolated episodes of rapid speciation between long periods of no change
Genetic variation
Differences in DNA sequences between individuals in a population
Genetic divergence
Process where one species becomes 2
Inbreeding depression
Reduced fitness due to inbreeding
Reproductive isolation
No gene flow, individuals cannot breed, sterile offspring
Pre-zygotic isolation
Mating and fertilization are prevented
Temporal isolation
Species don’t breed at the same time
Behavioral isolation
Different mating behaviors
Ecological / Habitat isolation
Species live in different environments
Mechanical isolation
Sexual organs do not match
Post-zygotic isolation
Mating occurs, but offspring dies or is sterile
Genetic architecture of speciation
- Traits involved in RI are often quantitative
- Many RI genes are under positive selection
- Many RI genes are transcripted
Haldane’s Rule:
If in the offspring of two different animal species one sex is absent, rare, or sterile, that sex is the heterogametic sex.
Geographic Speciation Models (3 models): How geography can block gene flow
- Allopatric Speciation: Geographic ranges do not touch or overlap
- Parapatric Speciation: Ranges touch, but don’t overlap significantly
- Sympatric Speciation: Ranges overlap significantly
Speciation by Polyploids:
New species formed when chromosome number in hybrids doubles, allowing polyploid hybrids to mate with other polyploid hybrids. Reproductively isolated from parent species
Extinct
Species doesn’t exist at all
3 processes of extinction
Large scale extinction event, Loss of diversity, Loss of species diversity
Permian-Triassic Extinction Event
250mya. 95% of marine life and 70% of plant life died. Comet/Asteroid impact
Cretaceous Extinction Event
65mya. 52% of marine life and 18% of land animals went extinct (including the dinosaurs)
Extinction is natural, it occurs at a natural “background” rate of about ______ species per year. We’re now losing species at x1000 that rate.
1-5 species per year
Extirpate
locally extinct, present in other locations
Endemic
Restricted to a certain area for survival
How old are the Primates?
50-55 million years old
When is Human-Chimp divergence?
5 - 7 million years ago
Homo erectus
- 1.8 million - 100,000 years ago.
- Brain = 1000cm^3
- 5.5 feet tall
- Hunter gatherer
- Evidence of shelter/control of fire
- Fully adapted for running endurance
Homo sapiens
- Arose 320,000 - 200,000 years ago
- Arose in Africa, colonized the world.
- Brain = 1300cm^3
- Advanced tools
- Agriculture
Did H. sapiens, Neanderthals, and Denisovans interbreed?
Yes, but less than 5% of Ancient DNA in modern humans.
MRCA
Most Recent Common Ancestor
Where is Human genetic variation the greatest?
Africa
The SRGAP2 gene
Leads to slower Neocortex maturation. Gene duplication during hominid evolution increased brain size and complexity
Speech in human evolution
Voicebox is lower than chimps, resulting in complex communication
Very short body hair in human evolution
- Thought to help keep body and brain cool
2. Reduces body parasites
Why did humans evolve dark skin?
- Dark skin protects against UV
2. Sunburn is teratogen. Sun burns can cause birth defects
Why did humans evolve light skin?
Allows you to make Vitamin D which is vital for health
What is Demography?
The statistical study of human populations
Population
Individuals of the same species
Range
Geographic area inhabited by the population
Meta population
Comprised of distinct population with gene flow
Source population
Supplies new individuals to different populations
A population with a pyramid shape indicates:
Rapid growth
A population with a column shape indicates:
Slow population growth
What is the most common dispersion pattern in animals?
Clumped, for social/protection
Semelparity
Large number of offspring produced at once
Iteroparity
Small number of offspring produced several times
R-selected species
Rapid growth and reproduction
K-selected species
Slow growth and reproduction
Global Fertility rates are also highest in regions were __________ rates are also highest
Infant Morality
What is a Life-Table?
Age-specific summary of the survival of a population
Life Table (Type 1)
High survivors through early and middle ages
Life Table (Type 2)
Constant survivorship through life
Life Table (Type 3)
Low survivorship in early life
Do males and females of the same species have the same survivorship curves?
Yes
Human post-menopausal survival:
Selection favors survival of grand parents that help their children and grand children.
Exponential population growth:
Maximum growth rate under ideal conditions
Logistic population growth:
Population growth is limited by carrying capacity.
Density-Dependent factor on controlling population size
Factors that become more intense as the population increases
Allee Effect
Individuals in a population may have a hard time surviving or reproducing if population size is to small
Density-Independent factors on controlling population size
Factors that affect large or small populations (i.e. Natural Disaster)
