BIO153H5 Lecture Notes - Lecture 10: Secondary Sex Characteristic, Genetic Drift, Disruptive Selection

52 views2 pages
15 Dec 2016
School
Department
Course
Professor
Gene Flow
Transfer of alleles from movement of fertile individuals/ gametes
Reduced genetic differences between populations
2 populations can become one with common gene pool
Reduces fitness in offspring whos parents were well adapted to either environmental conditions
Transfer of alleles can help adapt to local conditions
23.4- Natural Selection
Evolution caused by chance, favouring alleles
Outcome is not random
Relative Fitness
Contribution of individuals genes compared to others
Acts more on phenotype
Directional Selection= favours one extreme (environmental change, , migration)
Disruptive selection= favours both extremes
Stabilizing selection= favours very middle, reduces variation, where extremes can be dangerous
Natural Selection: Adaptive Evolution
Increases frequency of alleles that enhance survival/ reproduction
Match to environment increases
Continuous, environment changes
Genetic drift/ gene flow increase frequency of alleles (adv OR disadv)
Sexual Selection
Certain characteristics are more likely to mate
Sexual dimorphism= difference between 2 sexes in secondary sexual characteristics (colour)
Intrasexual selection= same sex, male vs. male
Intersexual selection= females choice of mate
o Characteristics can make then more in danger of predator, if gain outweighs risk, female
preference increases b/c increase of reproductive success
o Look for good gees
Preservation of Genetic Variation
Neutral variation= diff in DNA sequence that have no selective adv/ disadv
Diploidy
Recessive alleles less favourable from dominant
2 sets of chromosomes (somatic cells)
Balancing Selection
When natural selection has 2 or more forms
Heterozygote advantage= maintains 2+ alleles at locus
o Genotype
o Hetero has higher fitness than homo dominant/ recessive, due to locus, overdominance
o Heterozygotes for sickle cell allele protected against malaria, favours over homo
find more resources at oneclass.com
find more resources at oneclass.com
Unlock document

This preview shows half of the first page of the document.
Unlock all 2 pages and 3 million more documents.

Already have an account? Log in

Document Summary

Transfer of alleles from movement of fertile individuals/ gametes. 2 populations can become one with common gene pool. Reduces fitness in offspring whos parents were well adapted to either environmental conditions. Transfer of alleles can help adapt to local conditions. Contribution of individuals genes compared to others. Directional selection= favours one extreme (environmental change, , migration) Stabilizing selection= favours very middle, reduces variation, where extremes can be dangerous. Increases frequency of alleles that enhance survival/ reproduction. Genetic drift/ gene flow increase frequency of alleles (adv or disadv) Certain characteristics are more likely to mate. Sexual dimorphism= difference between 2 sexes in secondary sexual characteristics (colour) Intersexual selection= females choice of mate: characteristics can make then more in danger of predator, if gain outweighs risk, female preference increases b/c increase of reproductive success, look for (cid:858)good ge(cid:374)es(cid:859) Neutral variation= diff in dna sequence that have no selective adv/ disadv. When natural selection has 2 or more forms.

Get access

Grade+
$40 USD/m
Billed monthly
Grade+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
10 Verified Answers
Class+
$30 USD/m
Billed monthly
Class+
Homework Help
Study Guides
Textbook Solutions
Class Notes
Textbook Notes
Booster Class
7 Verified Answers

Related textbook solutions

Related Documents

Related Questions