Living at the edge: biogeographic patterns of habitat segregation conform to speciation by niche expansion in Anopheles gambiae

Table 6 Measures of ecological niche breadth and overlap

Species pair	Niche Breadth^†		Niche Overlap (L)^§		Directional Overlap Z_x(y)*
	DA	SL	DA	SL	DA	SL
(1) An. arabiensis	0.23	0.53	3.76	1.10	18.2	4.86
(2) An. gambiae M	0.27				17.7	5.65
(1) An. gambiae S	0.34	0.49	3.03	0.52	15.4	2.69
(2) An. arabiensis	0.27				14.7	3.55
(1) An. gambiae M	0.42	0.35	2.26	0.37	11.5	2.50
(2) An. gambiae S	0.40				10.7	1.63

† Levins' standardized niche breadth index B*; Eq. (28) in [64]
§ Lloyd's interspecies patchiness index I; Eq. (12) in [64]
* Loyd's asymmetric interspecific crowding index Z_x(y); Eq. (14) in [64]
Indices of ecological niche breadth, and overlap calculated either over the first discriminant axis segregating Species 1 from Species 2 of a pair (under columns "DA"), or across the sampled locations (under columns "SL"). The first approach provides measures of ecological segregation along the fundamental environmental envelope that discriminate most among the taxa (cf. additional file 7, and Table 5), whereas the second approach provides estimates of the realized degree of segregation between locations. We use the more general notation given by Hurlbert [64] of indices accounting for differences in availability of different resource states. The notation for the particular case of equally abundant resource states is provided as a footnote in the table.

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