What's polygenic inheritance

[thewax]

What does polygenic inheritance mean (the book's (that I use) definition was very confusing - i.e. what's a continuum, etc.)?

[Darby]

Think about traits that have multiple proteins producing them. Each protein is coded from a different gene, and the trait is the result of not just a pair of allele codes, but a pair for each contributing protein. Your height (ignoring strong environmental factors) would be such a trait; there's not just a single gene for height, but several that work in a complex combination, and you can only send one allele per pair on to each of your kids.

[keenangp]

Hey,

the textbook definition does suck a little bit.. Quantitative traits which vary along a continuum, woo!

Right.. here is an example of a continuum | || ||| |||| ||| || |

Each "gradient" changes a little bit at a time. Just like skin tone. There are no "black people" or "white people", all of our skin tones vary by little bits. Darker to lighter and everything in between, runs along a continuum.

Well if one gene coded for black and one for white, we wouldn't have so many interesting skin colours, instead we have somewhere along the lines of six genes which all contribute to our skin colour.

ex. X codes for white skin and O codes for black skin.

xxoooo <darker individual
xxxooo < tan individual
xxxxoo < lighter individual
xxxxxo < IRISH! (lol) Notice how it varies along a "continuum" changing in gradients.

Because all of these genes add together to determine our skin tone, they are called quantitative. (They quantitate our skin colour so to speak.) So if you see a trait which varies along a continuum, changes are that trait is quantitative, affected by many genes.


Note: Skin colour is also multifactorial, environmental factors play a big role in it's appearance.

[thewax]

Thanks!!!!!!!

[Zach]

Hey, great response. I just stumbled across this forum and am becoming quickly impressed. I am an undergrad at Salt Lake Community College in Utah studying ecology and systematics of various groups of Arachnida (i.e. evolutionary ecology). I am new to phylogenetic theory and other such aspects of our field and feel this forum will be a valuable asset.

thanks!