Class Notes (839,626)
Canada (511,431)
Biology (1,309)
BIOL 206 (50)

chap 49.docx

2 Pages

Course Code
BIOL 206
Sidney Eve Matrix

This preview shows 80% of the first page. Sign up to view the full 2 pages of the document.
Sexual Selection influences reproductive success • Sexual selection was Darwin’s explanation for the evolution of apparently useless but conspicuous traits in males of many species, such as bright colors, long tails, horns, antlers, and elaborate courtship displays. • He hypothesized that these traits either improved the ability of their bearers to compete for access to members of the other sex (intrasexual selection) or made them more attractive to the other sex (intersexual selection). • EXPERIMENT: • Hypothesis: having well-developed ornamental traits signals vigor and health • Zebra finch bills are bright red because of carotenoids in their diet. • Carotenoids are antioxidants and part of the immune system. Males in good health will have brighter bills because they need to allocate fewer carotenoids to immune function. • Zebra finch males were fed diets with and without carotenoids. The diet with carotenoids enhanced immune function How Is Genetic Variation Maintained within Populations? • Genetic drift, stabilizing selection, and directional selection all tend to reduce genetic variation within an animal population. • However, most species have considerable genetic variation. • Things that help maintain genetic variation:  sexual reproduction  neutral alleles  frequency-dependent selection  populations in different (varying) environments ___________________________________________________________________________________________________ • Sexual Production Pros & Cons: Pros: • Permits elimination of deleterious mutations • Existing genetic variation is amplified. Cons: • Sexual recombination generates new • Recombination can break up adaptive combinations of alleles on which natural combinations of genes. selection can act. • Reduces rate at which females pass genes to • It expands variation in a trait influenced by offspring. alleles at many loci by creating new genotypes. • Dividing offspring into genders reduces the • Sexual reproduction facilitates repair of overall reproductive rate. damaged DNA. Damage on one chromosome
More Less
Unlock Document

Only 80% of the first page are available for preview. Some parts have been intentionally blurred.

Unlock Document
You're Reading a Preview

Unlock to view full version

Unlock Document

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.