A harem master can only father two dozen offspring at a time because he is at the peak of his fighting ability.
There is a cost to being a harem master.
Stags have less body fat because they are large and powerful.
They are more likely to die of starvation during bad times.
Harem master behavior will only persist in the population if the cost is less than the benefit.
There are two examples of how diversity is maintained.
There are many ways in which diversity can be maintained.
Sexual reproduction recombines all genes due to meiosis and fertilization.
The result of genetic drift may be contrary to adaptation to the environment.
Natural selection causes imperfect adaptation to the environment.
Evolution doesn't start from scratch.
evolution is constrained by the available diversity just as you can only bake a cake with the ingredients available to you.
Birds might benefit from lightweight titanium bones, but they still have the same amount of calcium and other minerals as other reptile's.
You probably follow the same steps as your elders when you mix the ingredients for a cake.
The emergence of novel features is restricted by the processes of development.
The wing of a bird has the same bones as those of other animals.
There are compromises that make imperfections common.
The success of humans is due to their dexterous hands, but the spine is vulnerable to injury because it did not support the body in an erect position in our ancestors.
There is a benefit to evolve that outweighs the cost.
The cost of spine injuries from assuming an erect posture outweighs the benefit of freeing the hands.
Sexual selection has a reproductive benefit, but not an adaptive benefit.
The environment has a role to play in maintaining diversity.
If a population occupies a wide range, it may have several subpopulations designated as subspecies because of recognizable differences.
Subspecies help maintain diversity.
Each subspecies has a different set of alleles.
Gene flow may occur among the populations because they are adjacent to one another.
Interbreeding may keep each subspecies from fully adapting to its environment.
Specific selecting agents Page 292 help maintain diversity in the environment.
Birds can help maintain the frequencies of both light-colored and dark-colored moths, depending on the color of background vegetation.
A search image can cause a predator to pick the most common trait among their prey.
An animal's preference for food can change.
The average beak size of the medium ground finch on the Galapagos Islands depended on the availability of food.
Birds with larger beaks were favored in times of scarcity.
Maintenance of variation among a population's members has survival value for the species.
Heterozygote advantage helps maintain genetic and phenotypic diversity in future generations.
It can be devastating if you have the disease.
Patients can have a wide range of health problems, from low resistance to disease, to severe anemia, physical weakness, and poor circulation.
In these individuals, the red blood cells tend to pile up and block the flow of blood.
Due to an early death or debilitation caused by Malaria, fewer offspring are produced by individuals with this genotype.
Malaria is more common in Africa than in the US.
The red blood cell is turned into a sickle-shaped object by the parasites.
The parasites die when red blood cells lose potassium.
The population has a Heterozygote advantage.
If the protozoan that causes Malaria is present in the environment, it's important to maintain the allele.
In the parts of Africa where Malaria is common, 1 in 5 individuals is a Heterozygous and only 1 in 100 is a Homozygous.
Stabilizing selection is thought to have influenced other alleles.
Cystic fibrosis can lead to lung infections and other problems.
The person has a defect in the plasma membrane protein because of the recessive allele.
The normal version of the normal version of the normal version of the normal version of the normal version of the normal version of the normal version of the normal version of the normal version of the normal version of the normal version of the normal version of the normal version of the normal version of the normal The population had the allele that was maintained because of Heterozygote superiority.