Types of Natural Selection Flashcards

Questions and Answers

What are the three types of natural selection?

Stabilizing (correct)

Directional (correct)

Natural

Disruptive (correct)

Natural selection is a blend of?

Chance and the sorting of alleles

What does natural selection favor?

Some alleles over others so the outcome is not random

How does natural selection affect allele frequencies?

Increases the frequencies of alleles that provide a reproductive advantage Signup and view all the answers

What is relative fitness?

The contribution an individual makes to the gene pool of the next generation relative to the contribution of other individuals Signup and view all the answers

What occurs during directional selection?

Shifts a population's frequency curve for a phenotypic character in one direction Signup and view all the answers

What happens during disruptive selection?

Increases the numbers of extreme types at the expense of intermediate forms Signup and view all the answers

What is stabilizing selection?

Eliminates the number of extremes and favors the more common intermediate forms Signup and view all the answers

What does sexual selection involve?

Individuals with certain inherited characteristics are more likely to obtain mates Signup and view all the answers

What is sexual dimorphism?

A difference between the two sexes in secondary characteristics Signup and view all the answers

Study Notes

Types of Natural Selection

Natural selection includes three main types: disruptive, stabilizing, and directional.
Each type plays a unique role in shaping population dynamics and allele frequencies.

Natural Selection Mechanics

It is a combination of chance events and the sorting of alleles based on adaptive advantages.
Unlike random processes, natural selection consistently favors certain alleles, leading to predictable outcomes.

Effects of Natural Selection

The process increases frequencies of alleles that contribute to reproductive success.
This leads to adaptive evolution, enhancing an organism's fitness in its environment.

Relative Fitness

Relative fitness measures an individual's contribution to the gene pool of the next generation compared to others.
It is a critical factor for understanding natural selection and evolutionary success.

Directional Selection

Directional selection occurs when environmental changes favor one extreme phenotype over others.
This results in a shift in the population's phenotype frequency in the direction of that favored trait.

Disruptive Selection

Disruptive selection promotes individuals at both extremes of a phenotype range.
It reduces the prevalence of intermediate phenotypes, increasing variation within the population.

Stabilizing Selection

Stabilizing selection acts against extreme phenotypes, favoring more common, intermediate forms.
This type reduces overall genetic variation within a population, maintaining a status quo.

Sexual Selection

Sexual selection involves individuals with certain inherited traits having a better chance of attracting mates.
This mechanism drives the evolution of traits that may not necessarily enhance survival but improve mating success.

Sexual Dimorphism

Sexual dimorphism refers to the distinct differences in secondary sexual characteristics between males and females.
These differences can manifest in size, coloration, or other phenotypic traits, often enhancing reproductive success.

Description

Explore the three types of natural selection: disruptive, stabilizing, and directional. Understand how natural selection is influenced by chance and the sorting of alleles, and how it affects allele frequencies. Use these flashcards to reinforce your knowledge on the concepts and mechanisms of natural selection.