6
$\begingroup$

I have tried to calculate the relatedness for haplodiploid organisms, but cannot understand the calculations behind full sister and full brother.

Haplodiploidy r taken from wikipedia (taken from Wikipedia: haplodiploidy

I have managed to solve the other cases. Since female will have ZZ:

female will share 1/2 of her genes with daughter

female will share 1/2 of her genes with son

female will share 1/2 of her genes with mother

female will share 1/2 of her genes with father

Since male will have only Z:

male will share 1 (100%) of his genes with his daughter

male won't share anything with his son (unfertilized eggs leads to male in haplodiploidy system)

male will share 1(100%) of his genes with his mother

male won't share anything with his father (unfertilized eggs leads to male in haplodiploidy system)

Even though I figured out how others work, I wasn't able to calculate r for fullsister fullbrother? How can it be 3/4,1/4,1/2,1/2?

$\endgroup$
  • 2
    $\begingroup$ Is this a homework question? If so, you should sow us the work you've done so far, including the ones you already figured out. $\endgroup$ – Michael S Taylor Sep 25 '14 at 10:35
  • $\begingroup$ The table is taken from Wikipedia: Haplodiploidy, right? If so, you should include a reference. $\endgroup$ – fileunderwater Sep 25 '14 at 10:46
3
$\begingroup$

This is a relative thing in haplodiploidy system.

r = Mother's side + father's side(in this case)

D--Daughter

S--Son

F-Father

M-Mother

Note:

You can get the below things from the question image itself.(All that you need to do is to read male and female appropriately as son,father,mother,daughter based on the context.So simple!) question image

1.rMD=1/2

2.rMS=1/2

3.rDM=1/2

4.rDF=1/2

5.rFD=1

6.rFS=0

7.rSM=1

8.rSF=0

case 1:

rDD=(rDM*rMD) + (rDF*rFD)

rDD=(1/2*1/2)+(1/2*1)

rDD=3/4 female full sister case 2:

rDS=(rDM*rMS) + (rSF*rFD)

rDS=(1/2*1/2)+0*1

rDS=1/4 female full brother case 3:

rSD=(rSM*rMD) + (rDF*rFS)

rSD=(1*1/2)+(1/2*0)

rSD=1/2 male full sister case 4:

rSS=(rSM*rMS) + (rSF*rFS)

rSS=(1*1/2)+(0*0)

rSS=1/2 male full brother

$\endgroup$
7
$\begingroup$

It is useful to think in terms of the proportion of genetic material that an individual gets from each parent and the amount of this genetic material that will be shared with another individual (on average), and then sum this together i.e. as:

$ relatedness = prop_{mother} * shared_{mother} + prop_{father} * shared_{father} $

A female will share 50% of the genetic material from the mother's side and 100% if the material from the father's side with her full sisters: $0.5*0.5 + 0.5*1 = 0.75$

A female will share 50% of the genetic material from the mother's side and 0% if the material from the father's side with her brother: $0.5*0.5 + 0.5*0 = 0.25$

A male will share 50% of the genetic material from the mother's side with his sister (and doesn't get any from the father's side).

A male will share 50% of the genetic material from the mother's side with his brother (and doesn't get any from the father's side).

Remember also that this only holds if the female has only mated once.

$\endgroup$
  • $\begingroup$ A female will share 50% of the genetic material from the mother's side and 100% if the material from the father's side with her full sisters--then it should be 0.5*0.5+1*1 right? and A female will share 50% of the genetic material from the mother's side and 0% if the material from the father's side with her brother: 0.5∗0.5+0*0 right? $\endgroup$ – ecolover Sep 27 '14 at 18:14
  • $\begingroup$ A female still gets 50% of her genetic material from each parent, so it should be 0.5 in both calculations. The first case you suggest would lead to a relatedness of 1.25, which is clearly impossible. $\endgroup$ – fileunderwater Sep 27 '14 at 23:10
  • $\begingroup$ Yes but are we using 0.5 because 1.25 is impossible? $\endgroup$ – ecolover Sep 30 '14 at 14:00
  • $\begingroup$ No, because 50% (0.5) of the genetic material in a female comes from each parent. $\endgroup$ – fileunderwater Sep 30 '14 at 14:16
  • $\begingroup$ okay relatedness=propmother∗sharedmother+propfather∗sharedfather Does this generalised statement apply in all cases other than haplodiploidy to calculate relatedness? $\endgroup$ – ecolover Oct 1 '14 at 6:27

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.