Table 2. Co-expression network centrality and connectivity measures.

A		n	OPTIC TECTUM	n	TELENCEPHALON	t-test p-value
Preference DE genes	Degree average1	57	3.56 (2.83)	12	8.67 (3.64)	0.02*
	Clustering Coefficient2		0.16 (0.72)		0.53 (0.53)	<0.001**
	Neighborhood Connectivity3		7.84 (3.30)		21 (3.66)	<0.001**
Non-preference DE genes	Degree average1	31	6.48 (3.17)	6	3.83 (2.10)	ns
	Clustering Coefficient2		0.24 (0.56)		0.49 (0.70)	ns
	Neighborhood Connectivity3		11.12 (3.5)		8.89 (3.56)	ns
Social affiliation/ female preference genes	Degree average1	10	13.8 (3.7)	3	1.7 (0.4)	0.02*
	Clustering Coefficient2		0.34 (0.6)		0 (0)	<0.01**
	Neighborhood Connectivity3		21.3 (3.7)		2.5 (0.5)	<0.01**

B
Social affiliation/ female preference genes compared to Preference DE genes		OPTIC TECTUM			TELENCEPHALON
	Sample sizes	57/10			12/3
	Degree average1	0.04*			0.02*
	Clustering Coefficient2	<0.01**			<0.001**
	Neighborhood Connectivity3	<0.01**			0.02*

All p-values correspond to t-tests. Sample sizes in B correspond to Preference DE genes/Social affiliation and female preference genes.

¹The number of edges, i.e. other genes, each gene is connected to within the network. Central genes in the network will therefore have high degree values as opposed to more peripheral network genes.

²The ratio of the number of edges between the neighbors of a gene, and the maximum number of edges that could possibly exist between such neighbors (number between 0 and 1). This is a measure of how connected a gene is relative to how connected it could be given the number of neighbors it has. This value will approach 0 for a loosely connected gene and 1 for a fully connected gene in the center of a network

³The average connectivity across all neighbors.