18 flashcards · Shared on 19 August 2026 by AtomAI Library
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What is natural selection?
The process by which individuals with heritable advantageous traits tend to leave more offspring
What is natural selection?
The process by which individuals with heritable advantageous traits tend to leave more offspring
Which conditions are necessary for natural selection to produce evolutionary change?
Heritable variation and differences in reproductive success
In evolutionary biology, what does fitness mean?
An organism's contribution of offspring to future generations
Why must a trait be heritable for natural selection to cause evolutionary change?
Only heritable traits can be passed from parents to offspring
What is the ultimate source of new alleles in a population?
Mutation
How does natural selection affect genetic variation?
It acts on existing phenotypic variation and changes allele frequencies
What is an adaptation?
A heritable characteristic that increases fitness in a particular environment
A population initially has a range of body sizes, but individuals with intermediate size leave the most offspring. Which pattern of selection is occurring?
Stabilizing selection
When one extreme phenotype is favored over other phenotypes, what is the likely effect on the population?
The trait distribution shifts toward the favored extreme
What is speciation?
The evolution of new species from existing populations
According to the biological species concept, members of the same species are organisms that normally can do what?
Interbreed and produce fertile offspring
How can reduced gene flow promote speciation?
It allows separated populations to accumulate genetic differences
What is allopatric speciation?
Speciation caused by geographic isolation of populations
Which event could begin allopatric speciation?
A river forms and separates one population into two
What is sympatric speciation?
The formation of species without geographic separation
Which example is a prezygotic reproductive barrier?
Two populations breed during different seasons
Which situation represents a postzygotic reproductive barrier?
A hybrid survives but is unable to reproduce
What is a likely consequence when two populations experience different environments for many generations?
Natural selection may favor different adaptations in each population