7 Mechanisms and Evidence of Evolution Free Online FlashCards

What is biological evolution?

Evolution is change in the heritable characteristics of populations across generations.

How does natural selection change a population?

Natural selection occurs when inherited variants affect survival or reproduction, causing some individuals to leave more offspring and those variants to become more common over generations.

What is an adaptation?

An adaptation is an inherited trait that improves reproductive success in a particular environment and has become common through evolutionary processes.

Who evolves, and what mechanisms besides selection can change populations?

Populations evolve over generations; individuals do not evolve during their lifetimes. Mutation, genetic drift, and gene flow can also change populations.

What is speciation?

Speciation is the formation of new species from existing populations, commonly as populations diverge and reproductive isolation develops.

What does a branching evolutionary tree represent?

Common ancestry means species descend from shared ancestral populations. Evolutionary trees branch as lineages split; closely related species share a more recent common ancestor.

What can the fossil record reveal about evolution?

Fossils document extinct organisms and change through time in a time-ordered record; some show combinations of traits that help reveal transitions between groups.

Why can antibiotic resistance spread in a bacterial population?

Antibiotics select for bacteria with inherited resistance variants; they do not create those specific variants because bacteria need them.

How can populations become isolated during speciation?

Populations may become isolated geographically, such as by a river or mountain range, or without a physical barrier through differences in habitat, behavior, or mating time.

What can reproductive barriers prevent?

Reproductive barriers can prevent populations from mating, fertilizing eggs, or producing fertile offspring.

What is the evolutionary relationship between humans and chimpanzees?

Humans did not descend from modern chimpanzees. They are separate lineages that share an extinct common ancestor.

How does comparative anatomy support common ancestry?

Related organisms can share underlying anatomical structures despite using them for different functions. Similar forelimb bone arrangements in vertebrates support common ancestry.