Class Notes (834,722)
Canada (508,693)
BIOC16H3 (11)
Lecture 8

BIOC16 Lecture 8.pdf

7 Pages
129 Views
Unlock Document

Department
Biological Sciences
Course
BIOC16H3
Professor
Mark Fitzpatrick
Semester
Winter

Description
BIOC16 Lecture 8 Correlations among traits When you notice that the larger individuals have lighter fur than the smaller individuals so why are these two traits correlated?! - to now we've been dealing with single phenotypic traits! - method to understand genetics and evolution of a group of traits simultaneously! Beetle! ! Weight ! Elytra! ! Flight wings Elytra length Why or how are traits correlated?! - pleiotropic effects: one locus affects more than one trait! Eg: morning glory ( ipomoea purpurea) Simmons and Bucher 1996! ! W- floral pigments! 50% dead! WW -dark! Ww - light! 50% dead ! ww - white! 61% dead W locus has pleiotropic effects on floral color and toxicity! ! 1) pleiotropy! 2) linkage! ! Consider 2 genes A and B - each has 2 alleles A1A2 and B1B2! ! p1 f(A1). q (B1)! p2 f(A2) q(B2)! When the random association isn't observed we call it linkage disequilibrium! - physical linkage! - but physical linkage isn't essential! ! Recombination! -mixing of maternal and paternal genes into new combinations in offsprings! Two instances: 1) meiosis- prophase 1- chromosomes pairing up! - crossing over! 2) random probability that the maternal or paternal chromosomes of each homologous pair line up on either side of metaphase plate.! ! If two loci are unlinked (ie. different chromosomes) the probability of recombination between them is 0.5 ( highest amount of recombination and this number decreases as things become more linked)! If these loci are sufficiently close together ( same chromosome, same arm of chromosome)... They are linked. The probability of recombination between them is now proportional to the physical distance between them. No crossing over - Far apart or on right next to each different chromosomes other ( or same gene) Rate determining how fast a population in linkage disequilibrium (LD) reaches linkage equilibrium (LE) What causes LD?! 1) selection for particular combinations of alleles! 2) mixture of 2 populations with different allele frequencies! 3) random genetic drift! ! Eg: heterostyly in English Primrose ( primula vulgaris)! ! Two genes Gg - style length - shank is dominant! Aa - anther position - high is dominant! ! Morphs! "Pin" - long style and anthers ! are well below stigma! Stigma! Style! ! Anthers ! "Thrum"- short style, stigma is ! midway, anthers high! ! ! ! Homostyle Genes for style length and anther position are in LD! - selection against selfing Quantitative Trait Locus Mapping Case study - lab working on mice and they are interested in longevity - how do you find genes for longevity - you can use knock out however your mutations will result in drastic changes. Looking for subtle evolutionary changes you take a different approach.! ! First step is to ask - does there appear to be variability in the trait of interest? So you see that there is
More Less

Related notes for BIOC16H3

Log In


OR

Join OneClass

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

Sign up

Join to view


OR

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.


Submit