ANSC 305 1st EditionExam # 3 Study Guide Genotype- environment interactionsA. This is when there is a difference in the average performance of animals in two different genetic groups is different in two different environments. i. Different genetic groups- animals in a genetic group (as used in this discussion) have genetic similarities to each other, but are not necessarily all genetically identical to each other.ii. Different environments- used in this discussion, environment involves anything except genetic differences that affect the performance of the animal.B. Examplei. In some cases, the same genotype will have higher performance in both environments. ii. In other cases, one genotype performs better in one environment and the other genotype performs better in the other environment. I. Causes of genotype- environment interactionsA. The genotypes can differ both in their genetic potential for the character of concern and in their adaptation to one or both of the environments. The genetic potential for a character represents the highest performance that animals of this type can achieve in the absence of environmental stress. i. Includes nutritional stress so all of the animals’ nutritional needs/ requirements need to be met in order to achieve its genetic potential.B. The adaptation of the different genotypes to the different environments determines how much of their genetic potentials can be achieved under the stresses of these environments.i. Adaptation refers to attributes of an animal being adapted and not to the process of becoming adapted.II. Transmitting ability and expected progeny differenceA. Transmitting ability (a measure of genotype for a particular quantitatively inherited character) is the average amount that a large number (infinity) of this animal’s progeny would differ from the progeny of an animal with a transmitting ability of zero.B. Expected progeny difference or EPD for a particular character is the average amount thatits progeny are expected (based on the available information) to differ from the progeny of an animal whose EPD is zero for that character.C. Milk EPD-An animal’s milk EPD is its EPD for maternal effects on weaning weight. It is theaverage amount that its daughters’ progeny are expected (based on the available information) to differ in weaning weight from the progeny of the daughters of an animal whose milk EPD is zero, due to maternal effects. D. Total Maternal EPD- An animal’s total maternal EPD is the average amount that its daughters’ progeny are expected (based on the available information) to differ in These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.weaning weight from the progeny of the daughters of an animal whose total maternal EPD is zero (due to maternal and direct effects).i. Total maternal EPD= Milk EPD + ½ Weaning Weight EPDIII. Genetic correlationA. Correlated charactersi. The phenotypic correlation between two characters, X and Y, is a measure of both the degree (low to high) and direction (+ or -) of the correspondence between the phenotypes of the two characters. ii. The genetic correlation between two characters is a measure of both the degree(low to high) and direction (+ or -) of the correspondence between the transmitting abilities of the two characters. B. Causes of genetic correlationi. Pleiotrophy (major effect!)- among the many loci that affect the performance forone character, some (or all) of them may also affect the phenotype of the other character. Three types:1. The two traits may be (at least partially) measures of the same thing 2. The phenotype for one of the traits may affect the phenotypic expression of the other trait (for example, a larger sheep has more surface area than a small one, so, if fleece characteristics (such as staple length, fleece density and percent body cover) are similar, the larger sheep has the potential to produce a heavier fleece.3. The product of a gene (for example, a hormone, a hormone receptor, or an enzyme) may be involved in a biochemical pathway that affects both characters. ii. Linkage- where among the many loci that affect one of the characters, some may be on the same chromosome and close to loci that affect the other character (minor effect).iii. Genotype- environment interactions- where in one environment, animals can meet their nutritional requirements but, in another environment, increased nutritional requirements for one trait may limit the performance of another trait. IV. Cattle Color InheritanceA. Extension locus (E, E+ and e alleles)i. Difference in genotype at this locus result in black vs. red (or red with some black hair) base colorsB. Graying locus (G and g alleles)i. Homozygosity of the g allele causes cattle of the E+_ or ee genotype to be gray. This locus is linked to the spotting and reddening locus.C. Black nose, feet, and tail locus (B and b alleles)i. Presence of the B allele in cattle with a red (or grey) base color causes black nose, feet and tail in homozygotes and some degree of black pigmentation in most heterozygotes; most homozygotes and heterozygotes will have some black hair interspersed among the red (or grey) hair. D. Dilution (Charolais type) locus (D and d alleles)i. Presence of the D allele causes dilution to a lighter shade in heterozygotes and to white in homozygotesE. Dilution (Simmental type) locus (C and c alleles) -- ** will not be asked about**F. Roaning Locus (R and r alleles)i. Presence of the R allele causes roan color in heterozygotes and white color in homozygotesG. Spotting Locus (S, SH, SS, SG, SP and s alleles)i. Presences of these alleles causes various types of white spotting. This locus is linked to the greying and reddening loci.H. Reddening Locus (N and n alleles)i. Presence of the n allele causes cattle of the EE+ genotype to be “reddened” to a lighter color than black (some are reddish or brownish black, but some are red or tan; note that they are born with this lighter color). This locus is linked to the spotting and greying loci. V. Breed ColorsA. Hereford- ee bb dd rr GG SH SHB. Angus- EE bb dd rr GG SSC. Red Angus- ee bb dd rr GG SSD. Charolais- ee bb DD rr GG SSE. Shorthorn- ee bb dd __ GG SS- red, white or roan depending on roaning locusF. Holstein- EE bb dd rr GG ssG. Brahman- E+E+ BB dd rr __