Mean kinship is one of the most commonly used genetic tools in the management of captive populations. Why? Well, because its effective and pretty simple to apply. Its also powerful and can be employed to solve several of the larger problems facing captive populations, such as inbreeding, over representation of certain individuals, and founder effects. Remember from week 1 that often the goal of genetic management is to retain at least 90% of the initial genetic diversity for 200 years. How do you do this? Essentially, you do reverse natural selection. That is, if any individual or gene starts getting over represented in the gene pool, you select against it. Kind of like in high school when there was that one kid who wanted to answer all of the questions and the teacher just kind of stopped calling on him. This is the scientific way of doing that for genetic management.
To start, the kinship of a single individual is calculated with the below formula
**see first attached file**
In this formula, n is the number of individuals in individual is pedigree history, and FA describes the relationship of the founding population. (Note, Frankham uses Kij in his example because hes calculating from a pedigree and not genetic data). Thus, Fi is a quantification of inbreeding within individual i. Now thats useful right? But wouldnt it also be useful if we could calculate not just how useful that one individual is, but also to be able to calculate how useful their offspring are and how useful that individual is to the whole population? Well, we can!
Next, mean kinship is calculated using the kinship coefficient between a pair of potential parents
***see second attached file***
where Fi and Fj are the inbreeding coefficients calculated from the pedigree for individuals i and j, since the inbreeding coefficient in any individual is the sum of the inbreeding coefficients of the parents. Using fij, the mean kinship of individual i is equal to the average inbreeding of individual i to the population and is calculated by the following formula
**see third attached file**
where N is the number of individuals in the population (Ballou and Lacy 1995).
Each individual can then be ranked. This method called ranked mean kinship, is a useful way of calculating who the most important (genetically) individuals in your population are and how useful any one breeding pair might be.
The lower the mean kinship value the better. This should make intuitive sense to you, because overall you want to avoid breeding animals that are closely related if you want to avoid inbreeding.
Now its your turn. Please submit your answers in Canvas.
Create a spreadsheet and use a random number generator to create Fi values for 20 individuals. Clearly, all values should be between 0 and 1. For our purposes, assume these values are Fij so that you can easily calculate mki (which is what is used in the table below)
Create a ranked mean kinship table similar to the example below (an actual table from the SSP for Kirks dik-dik, yes, they are super cute). In general terms, describe what the table means and how you would use it in managing a captive population.
Now calculate your population MK (average mean kinship for the population), which is just the average of all of your individual mean kinship values
Describe what this tells you in your own words.
Are there any individuals you wouldnt breed this generation? Do you think that will change in the future? Why or why not.
Ordered Mean Kinship EXAMPLE
Note: These lists are current to January 2020 and values are subject to change with any birth, death, import, export, inclusion, exclusion, or changes in pedigree or pedigree assumptions. Animals with unknown pedigree are signified with a U next to the studbook ID
