This lesson introduces natural selection as a process that changes populations over generations. It also distinguishes natural selection from intentional breeding and explains the basic conditions that allow selection to occur.
Natural selection is the differential survival and reproduction of individuals because of differences in their heritable characteristics. Individuals do not all leave the same number of surviving offspring. When a heritable trait helps its carriers reproduce more successfully in a particular environment, that trait can become more common in later generations.
All flashcards
What is natural selection?
Differential survival and reproduction associated with heritable differences, which can change trait frequencies in populations over generations.
What is biological fitness?
Relative reproductive success: an organism’s contribution to future generations through its offspring.
How does artificial selection differ from natural selection?
Artificial selection involves intentional human breeding choices; natural selection results from environmental effects on survival and reproduction.
What is genetic drift?
Random change in genetic variation, with especially strong effects in small populations.
What is reproductive isolation?
A reduction in gene flow between populations that can contribute to the formation of distinct species.
Quiz questions
Which outcome characterizes directional selection on a trait?Answer: One extreme is favored, shifting the population average toward it.
During industrial pollution in parts of Britain, why did dark peppered moths become more common?Answer: They were better camouflaged on soot-darkened surfaces and reproduced more successfully.
In the simplified r/K selection framework, which pattern is associated with r-selected species?Answer: Producing many offspring, each with a relatively low chance of reaching adulthood.
How can antibiotic use increase the frequency of resistance in a bacterial population?Answer: Resistant bacteria are more likely to survive and reproduce than susceptible bacteria.
What did the modern synthesis integrate?Answer: Darwinian natural selection with Mendelian genetics.
Based on the Wikipedia article Natural selection, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.