Test One Flashcards
What is a norm of reaction?
A norm of reaction is the pattern of phenotypic expression of a single genotype across a range of environments.
It demonstrates how environmental factors can influence the phenotype of an organism.
What are the three conditions necessary for natural selection to occur?
- Variation in traits
- Inheritance of traits
- Differential survival and reproduction
Each condition is crucial for evolution by natural selection as they ensure that advantageous traits can be passed on to future generations.
Define the term fitness as it is used by evolutionary biologists.
Fitness refers to an organism’s ability to survive and reproduce in its environment.
It is often measured by the number of offspring an organism produces.
What trade-off led to differences in guppy life history between high- and low-predation sites?
The trade-off involved between reproductive output and offspring survival rates.
In high-predation environments, guppies tend to have fewer but larger offspring that are more likely to survive.
Explain how the experiment with replicate lines of E. coli revealed limits to how predictable evolution by natural selection is.
The experiment showed that even under identical conditions, different lines of E. coli evolved in unpredictable ways.
This suggests that random mutations and historical contingencies play a significant role in evolutionary outcomes.
Explain why a lack of variation can constrain evolution by natural selection.
A lack of variation limits the potential for natural selection to favor advantageous traits.
Without variation, there are fewer traits for selection to act upon, reducing the adaptability of a population.
Give an example of an evolutionary arms race.
An example of an evolutionary arms race is the relationship between predators and prey, such as cheetahs and gazelles.
Cheetahs evolve faster speeds to catch gazelles, while gazelles evolve better agility to escape.
What are the 6 constraints of natural selection
- Adaptation is proportional to variation.
2.selection is subject to itself - Selection is affected by gene flow
- Selection is limited by physics
- The environment is constantly a moving target
- Selection lack foresight
What are the three conditions necessary for evolution by natural selection?
Variation, differential reproductive success, and inheritance.
True or False: Natural selection acts directly on genotypes.
False
What does evolution by natural selection change?
The characteristics of a population.
How is the fitness of a trait defined?
The expected reproductive success of an individual with that trait relative to others.
What is an adaptation?
An inherited trait that makes an organism more fit in its environment due to natural selection.
What is an exaptation?
A trait that serves one purpose now but served a different function in the past.
Fill in the blank: The process of natural selection operates on _______ in the material world.
Physical structure
True or False: Natural selection can anticipate future changes.
False
What is artificial selection?
Humans selecting which individuals reproduce based on beneficial traits.
What is asexual reproduction?
The production of offspring from unfertilized gametes.
What is sexual reproduction?
The joining of genetic material from two parents to produce offspring.
What is the ‘two-fold cost of sex’?
A cost associated with sexual reproduction.
What are the advantages of sexual reproduction?
- More efficient at purging deleterious mutations
- Leads to more variable offspring
What is sexual selection?
A special case of natural selection involving mate choice or competition.
What is intersexual selection?
Individuals of one sex choose individuals of the other sex as mates.
What is intrasexual selection?
Members of one sex compete for mating access to the other sex.
The 5 main evolutionary models of female mate choice
- Direct benefits
- Good genes
3.runaway selection - Sensory bias
- Genetic compatibility model
