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

Table 2 Association analysis of species co-occurrence

Latitude	N	An. arabiensis vs. An. gambiae S	An. arabiensis vs. An. gambiae M	An. gambiae M vs. An. gambiae S
>12°30'N	102	+0.13 (-0.07, +0.31)	-0.06 (-0.09, -0.03)*	-0.06 (-0.20, +0.16)*
<12°30'N	203	-0.13 (-0.18, -0.08)	+0.25 (+0.10, +0.39)	-0.15 (-0.20, -0.09)
Total	305	-0.11 (-0.18, -0.02)	+0.27 (+0.14, +0.39)	-0.22 (-0.27, -0.16)

* confidence limits are approximate because some Monte Carlo replications returned indeterminate values of the V coefficient due to the occurrence in the 2 × 2 contingency table of more than one cell with zero values.
Association coefficients V (95% bootstrap confidence limits) assessing the degree of co-occurrence of species pairs across sampled locations, stratified by two latitudinal classes representing regions of contrasting levels of relative abundance of the two molecular forms of An. gambiae s.s. (cf. Figures 1 and 2). N = number of sampled locations (i.e. villages).

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