Table 2. Results from generalized linear model to test for effects of genetic background (line), age, and their interaction on crossover frequency in the two intervals assayed.

Chromosome	Source	df	χ2	Prob > χ2
X	Line	4	46.41	< 0.001
	Maternal age	9	126.10	< 0.001
	Line × maternal age	36	48.80	0.075
3R	Line	3	7.84	0.0495
	Maternal age	2	0.039	0.98
	Line × maternal age	6	4.22	0.65

df, degrees of freedom, χ², chi-square value.