1 / 17

Relationship & Inbreeding

Relationship & Inbreeding. Napapan Piyasatian. Outline. What is relationship? How is relationship computed? What is inbreeding? How is inbreeding computed? What is relationship with inbreeding? How is relationship with inbreeding computed?. Relationship .

lily
Télécharger la présentation

Relationship & Inbreeding

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Relationship & Inbreeding Napapan Piyasatian

  2. Outline • What is relationship? • How is relationship computed? • What is inbreeding? • How is inbreeding computed? • What is relationship with inbreeding? • How is relationship with inbreeding computed?

  3. Relationship • Inbreeding occurs when related animals are mated • Outbreeding occurs when less related animals are mated • What is meant by ‘relationship’? • How is it measured?

  4. Relationship • Measures the probable proportion of genes that 2 individuals have in common above the average of the population at some point in time • Probable proportion:element of chance • Above the average of the population:relationship is NOT an absolute measure • At some point in time: increase the relative nature of relationship

  5. Relationship • What would be the relationship between a sire and its offspring? • Proportion of genes that are expected to be in common • Offspring = + http://www.gifshare.com/gif/7851/sperm

  6. Relationship • What is the relationship between humans and chimpanzees? • 97% humans’ DNA = Chimps’ DNA • 99% of all human DNA is the same • Above the average of human populations • Above the average of mammal populations http://animal.discovery.com/mammals/chimpanzee/

  7. Relationship - Are your parents related? • Relative to some point in time • Pick year 0 • Unrelated parents implies unique people in each pedigree • Number of ancestors in a generation • = 2n • 2 parents, 4 grandparents, 8 great-grandparents, etc.

  8. Relationship - Are your parents related? • Number of ancestors in a generation • = 2n • About 66 generations since year 0 (1983/30=66.1) • 266 = 7.4 x 1019 people in each parent’s pedigree in year 0 • Some of the people must be the same

  9. Relationship - Are your parents related? • Relationship from > 5 generations ago • Contribute little to relationship value • Usually the same point in time is the last 5 generations or less • Only 25 = 32 people

  10. Other relationship definition • Relationship measures the expected genetic correlation between the breeding values of animals with this relationship. • This meaning is used in BLUP equations

  11. Types of relationship • Direct relationship – gene passed from one animal to the other • Parent & offspring • Grandparent & offspring • Indirect relationship – common ancestor • Sibs • Cousins

  12. Calculate relationship, RXY • Sewall Wright procedure (1921) • Create an arrow diagram from the block pedigree • Identify all paths that contribute to relationship, including all direct & collateral relationships • Determine all contribution of each path and calculate relationship as the sum of each path’s contribution • Without inbreeding, RXY = sum of all contributions from all paths

  13. Sire Offspring Dam 1. Create an arrow diagram

  14. 2. Identify all paths 1 • Trace path starting at one individual and ending at the other • Always start tracing against the arrows • Arrow can change direction once while tracing the path (collateral relationship) but need not change direction (direct relationship) • Any animal can occur only once in a given path (important to remember this rule when animals are inbred) • Include all paths that contain a new sequence of individuals or one different individual

  15. Path Sire Offspring Sire Offspring Dam 2. Identify all paths 2 Paths for relationship between sire and offspring

  16. Contribution = (½)n (½)1 = ½ Path Sire Offspring 3. Determine contribution of each path

  17. Path Sire Offspring 4. Sum of all contributions • Contribution = (½)n • (½)1 = ½ • RXY= ½

More Related