Study Guides (248,610)
Canada (121,635)
BIOL 202 (36)


34 Pages

Biology (Sci)
Course Code
BIOL 202
H E N D R Y...

This preview shows pages 1,2,3,4. Sign up to view the full 34 pages of the document.
BASIC GENETICS SUMMARY Hendry Quantitative genetics - Polygenic: traits influenced by multiple genes - Influenced by environmental conditions - Leads to continuous variation in the trait - Examples o Heights of cadets o Swimming speed of men/women o General cognitive ability (SATs, IQ tests) - Increase # loci = more continuous variation - Environment causes phenotype to vary with genotype (even with one locus) - Variance SS ( ) = = N # Total phenotypic variance = Genetic (AID) + Environmental(ME) - Additive genetic variance o Variance due to additive effects of alleles & genes o Hybrids = intermediates o Resemblance o Hybrid backcrosses to parent forms = phenotypes proportional to the amount of genome in group - Dominance variance o Variance due to dominance effects between alleles o Hybrid = dominant phenotype - Epistatic variance o Due to interactions between different loci o Possible deviation from additive & dominance o Example: Soap berry bug Derived Golden rain tree Smaller beak Ancestral Balloon vine fruit Longer beak Beak type = additive, dominance & epistasis Preference to host site = additive - Maternal o Variance due to phenotype of mom o Important in natural population o Types Genetic Plastic o Example: Mosquito fish weights - Stickleback o Additive genetic effects o Dominance genetic effects Backcross shows: gill rakers = additive & body depth = dominance) Body depth: Length Gill rakers Lake Bigger More Stream Smaller Less - Heritability o Broad sense Proportion of phenotypic variance that has a genetic bases = o Narrow sense Proportion of the phenotypic variance that has additive genetic variance = resemblance between parents & offspring = - Estimating heritability methods o Resemblance between sibs o Resemblance between twins o Slope parent/offspring regressions o Cross-fostering to remove maternal effects (Ex: song sparrow) - Types of selection o Directional Mean shifts Variance changes Evolutionary response (R) = change in mean trait value from one generation to the next Selection differential (S) = difference in mean trait value from before to after selection but before reproduction = o Stabilizing Hybrids = fittest Variance changes Example: increase # galls decrease bugs increase bird attacks o Disruptive Extreme phenotype = fittest Variance changes Example: beak morphs in Galapacos islands - Alternative formulae = = = = , = = - Correlations between traits o Phenotypic correlations Direct selection on 1 indirect selection on 2 Example: arm & leg o Genetic correlations Selection on 1 evolutionary change in 2 Measure not only A but additive genetic covariances between traits + 1 = 1 + 2 - Regression charts o Selection gradients (Survivals & deaths) o V & A basA on parent/offspring relationship o Predictions using = o Measure evolutionary responses o Comparisons between observed & predicted evolutionary response - Gene flow o Draws phenotypes closer together o Even when low = substantial effects on adaptive divergence o Example: stickleback Lake Outlet Inlet Outlet fish phenotypically closer to lake then inlet o Gene flow increases = decrease adaptive divergence Chevrette Genome Composition - Chromosome o Telomere o Kinetochore o Centromere o Sister chromatids o p=short arm o q=long larm - C-value = DNA content of an organism o C-value paradox: no correlation between evolution & genome size increase transposons = increase genome size & repetitive sequences - Classes of eukaryotic DNA sequences Copies/Genome Average bp Where Single copy DNA 1-10 800-1200 Structural genes Moderately 10-100 000 300 rRNA genes repetitive Ribosomal proteins Transposons Highly repetitive > 100 000 Satellite & non-satellite DNAs - Satellite DNA o Prokaryotes = single band for given density on CsCl gradient o Eukaryotes =2 bands (Main band & satellite band (repetiti
More Less
Unlock Document

Only pages 1,2,3,4 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.