An ab Neurospora was crossed with an a + b + form. After meiosis, 1000 asci were dissected and produced the data listed in the table below. What is the linkage arrangement of these loci?

Spore Number	1	2	3	4	5	6	7
1	ab	ab+	ab	ab	ab+	a+b+	ab
2	ab	ab+	ab	ab	ab+	a+b+	ab
3	a+b+	a+b	ab+	a+b	ab+	a+b+	ab
4	a+b+	a+b	ab+	a+b	ab+	a+b+	ab
5	a+b	a+b	a+b+	a+b+	a+b	ab	a+b+
6	a+b	a+b	a+b+	a+b+	a+b	ab	a+b+
7	ab+	ab+	a+b	ab+	a+b	ab	a+b+
8	ab+	ab+	a+b	ab+	a+b	ab	a+b+
	70	32	225	25	10	315	323