Suppose an analyzer created a purebred strain of these smart mice and started breeding them with other mice to map the gene responsible for the phenotype. After a few generations, she narrowed the locus down to a 10Mb region on Chromosome 4. In order to create a finer map, Ashley picked 10 SNPs from this region. She genotyped 100 smart mice for each of these SNPs. The results are given in the table below. First column is the ID number of the SNP. Second column shows you which nucleotides are possible for that SNP location. Columns 3 and 4 show how many of the smart mice have either genotype. Assume all genotypes are homozygous:

SNP #	Possible genotypes	Smart mice (Total: 100)
1	A or G	A: 20	G: 80
2	T or C	T: 49	C: 51
3	A or T	A: 11	T: 89
4	C or G	C: 67	G: 23
5	A or C	A: 0	C: 100
6	T or C	T: 52	C: 48
7	A or G	A: 95	G: 5
8	T or C	T: 55	C: 45
9	A or T	A: 40	T: 60
10	A or G	A: 15	G: 85

Which SNPs are linked to the gene you are trying to find? Which ones are not? What test do you need to apply to prove this statistically?

Organize the linked SNPs from furthest to closest to the gene of interest.

After narrowing down the location of the gene to a manageable portion of the chromosome, what does Ashley need to do to exactly prove which gene is making the mice smarter and how?