Chapter 20: Evolution Flashcards
What is Lamarkian Evolution?
- An organism can pass on characteristics acquired during its lifetime to their offspring
- Organisms were driven to more complex forms
What is Darwinian Evolution?
- Those most adapted to exploiting resources are most likely to survive
- Natural Selection
What is natural selection? How does it account for the variability seen in populations today?
Natural Selection: Changes in allele frequency based on the survival and reproduction of others
- depends on variation and competition
- Mutations and sexual reproduction increase genetic variation in a population
What are the 3 different patterns of natural selection?
Stabilizing Selection:
- selects against the extremes (bell graph gets more narrow)
Directional Selection:
- selects against one of the extremes (bell graph shifts one direction)
Disruptive Selection:
- selects against the mean (peak of bell graph turns into a valley)
What is the Hardy-Weinberg equation? How do you do it?
p^2+2pq+q^2=1
p=frequency of dominant allele
q=frequency of recessive allele
- Allele and genotype frequencies will remain constant
What are the 5 necessary conditions for Hardy-Weinberg to be accurate?
- There can be no differences in the survival and reproductive success of individuals.
- Populations must not be added to or subtracted from by migration.
- There can be no mutation.
- The population must be sufficiently large to prevent sampling errors.
- Individuals must mate at random.
Is hardy-Weinberg ever really accurate in real life populations?
No
How are blood groups determined? How are antigens important during this process?
Blood types are determined by the presence or absence of certain antigens. Since some antigens can trigger a patient’s immune system to attack the transfused blood, safe blood transfusions depend on careful blood typing and cross-matching.
What is the Rh factor and why is it important?
RH is a protein found on the red blood cells (Rh positive you have it, Rh negative you don’t)
- very important for pregnant mothers because it’s used to indicate whether the blood of two different people is compatible when mixed – such as blood of a mother and her baby at birth.
Which antigen is present in each blood type? Which antibodies are present in each blood type?
Group A
- A Antigen
- Anti-B Antibodies
Group B
- B Antigen
- Anti-A Antibodies
Group AB
- AB Antigen
- No Antibodies
Group O
- No Antigen
- Anti-A & Anti-B Antibodies
Define Species
Group of individuals that can exchange genetic material through interbreeding, or share alleles through reproduction
Define Gene Pool
All the alleles present in all the individuals in a species
Define Populations
Same species in the same geographical area
Define Fitness
ABILITY TO REPRODUCE: A measure of the extent to which an individual’s genotype is represented in the next generation
Define Artificial Selection
A form of directional selection; successful genotypes are selected by the breeder, not through competition
Define Sexual Selection
Phenotypes that increase the individual’s access to reproductive opportunities, but not necessarily increase their survivability
Define Genetic Drift. When is Genetic Drift a huge factor?
The change in the frequency of an existing gene variant in a population due to random sampling of organisms (variation in the genome)
HUGE FACTOR when a population is sharply reduced in size by a natural disaster (bottleneck effect) or when a small group splits off from the main population to found a colony (founder effect)
Define Geographic Isolation
A population of organisms is unable to transfer genetic information with those of the same species because of location
Define Speciation
Caused by geographic isolation; occurs when the two populations are unable to produce viable, fertile offspring
What are Essential and Fixed Genes?
Essential Genes: genes that are indispensable to support cellular life
Fixed Genes: when their frequency has reached 100% in the population
