Biology Mechanisms of Natural Selection Flashcards

Co-evolution between a flower and its specific pollinator is driven by:

Answer: Reciprocal selection pressures between two interacting species

Co-evolution involves reciprocal evolutionary changes in two or more species that interact closely, each acting as a selection pressure on the other.

Antibiotic resistance in bacteria evolving within a single patient's infection is an example of:

Answer: Directional selection acting on existing variation

Antibiotic treatment acts as directional selection, favoring pre-existing resistant bacteria over sensitive ones already present in the population.

Which type of reproductive isolation involves hybrid offspring that are sterile?

Answer: Hybrid sterility

Hybrid sterility is a postzygotic barrier where hybrids survive but cannot reproduce, as seen in mules (horse × donkey crosses).

The concept of punctuated equilibrium proposes that evolution:

Answer: Occurs in bursts of rapid change followed by long periods of stasis

Punctuated equilibrium, proposed by Gould and Eldredge, suggests species remain relatively unchanged for long periods interrupted by rapid evolutionary change.

Frequency-dependent selection occurs when:

Answer: The fitness of a phenotype depends on how common it is in the population

In frequency-dependent selection, a phenotype's fitness increases when rare (negative frequency-dependence) or when common (positive frequency-dependence).

Vestigial structures provide evidence for evolution because they:

Answer: Represent structures that were useful in ancestral species but reduced in descendants

Vestigial structures are reduced or nonfunctional remnants of structures that had functions in ancestral species, reflecting shared evolutionary history.

Which statement correctly describes the relationship between genotype, phenotype, and natural selection?

Answer: Natural selection acts on phenotype; if phenotypic differences are heritable, allele frequencies change

Natural selection acts on phenotypes; when phenotypic variation is heritable (genetically based), differential survival and reproduction shift allele frequencies over generations.