Processes in Evolution
What is evolution defined as?
Change in a population’s characteristics over time
Natural selection results in what type of process (adaptive or random)?
Adaptive process
What kind of traits show reduced or no function but indicate common ancestry?
Vestigial traits
True or False: Individuals evolve
False!
A population of beetles varies in color. Birds eat the light-colored ones more. What type of process is this?
Natural selection
What are the two key components of evolution described by Darwin?
Descent with modification and natural selection
What determines which individuals reproduce in a population?
Their traits’ match to the environment
What is a transitional fossil?
A fossil showing intermediate traits between ancestral and modern forms
What’s the difference between acclimation and adaptation?
Acclimation = temporary physiological change
Adaptation = genetic change
If a pesticide kills 90% of insects but 10% survive, what happens to the population over time?
It becomes mostly pesticide-resistant
What is required for evolution to occur in a population?
Heritable variation among individuals
In natural selection, what happens if a trait increases reproductive success?
That trait’s frequency increases in the next generation
What type of homology describes similarities in DNA or amino acid sequences? (Developmental/genetic)
Genetic homology
Does natural selection create new traits when needed?
No, it sorts existing variation; mutations occur by chance
Why do some bacteria evolve antibiotic resistance so quickly?
They have short generation times and high mutation rates
What type of genetic changes provide the raw material for evolution?
Mutations
What does “fitness” mean in evolutionary terms?
Genetic contribution to the next generation (number of offspring that reproduce)
What type of homology is shown by vertebrate embryos having pharyngeal pouches? (Developmental/genetic)
Developmental homology
Why isn’t evolution goal-directed?
There is no predetermined end point; evolution responds to the environment
Why can't populations grow exponentially?
Carrying capacity- only so many organisms can exist in one environment at a time
Why does evolution act on populations rather than individuals?
Because allele frequencies change in populations, not in single organisms
Why did finch beak sizes change during droughts on the Galápagos Islands?
Droughts changed available seed types, favoring different beak sizes over time
What does convergent evolution (homoplasy) tell us about species in similar environments?
Unrelated species can evolve similar adaptations independently
Why can’t evolution produce perfect organisms?
Because of trade-offs and constraints (genetic, historical, environmental)
In a population of birds, larger wings help escape predators but require more energy. What is this called?
A (fitness) trade-off