Choiseul and Santa Ysabel are separated by about 50 miles of water (see Fig. 17) but have three subspecies in common (_Pteropus rayneri grandis_, _Dobsonia inermis minimus_, and _Nyctimene albiventer minor_.) Choiseul is about 50 miles from Kolombangara and about 35 miles from Vella Lavella, but shares no subspecies with these smaller islands although some species are shared (Tables 5 and 6). From these data one can conclude that exchange of genes between populations on Choiseul and populations on Santa Ysabel is frequent but for some reason exchange of genes between populations on Vella Lavella and Choiseul and Kolombangara and Choiseul is infrequent. A series of small islands (Rob Roy, Wagina, and the Arnavon Islands, not named on the maps) connect Choiseul and Santa Ysabel in stepping-stone fashion (see Fig. 17). Possibly these small islands enhance movement of megachiropterans between Choiseul and Santa Ysabel. TABLE 6. A Summary of Distribution of Polytypic Species of Megachiropteran Bats in the Solomon Islands. Only Islands Well Known Faunistically Are Listed. Column headings: A: Bougainville I: Vella Lavella B: Choiseul J: Kolombangara C: Santa Ysabel K: Russell D: Ndai L: Guadalcanal E: Malaita M: San Cristobal F: Florida N: Ugi G: Fauro O: Rennell H: Shortland P: Ontong Java ===================+==+==+==+==+==+==+==+==+==+==+==+==+==+==+==+== SUBSPECIES | A| B| C| D| E| F| G| H| I| J| K| L| M| N| O| P -------------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-- P. atrata atrata | X| X| | | | | | | | | | | | | | P. atrata anceps | | | X| | | | | | | | | X| | | | Pt. a. solomonis | | | | | | | | | X| | X| X| | | | Pt. a. colonus | | | | | | | | X| | | | | | | | Pt. a. grandis | | | | X| | | | | | | | | | | | Pt. r. rayneri | | | | | X| | | | | | | X| | | | Pt. r. grandis | X| X| X| | | | | | | | | | | | | Pt. r. rubianus | | | | | | | | | | X| | | | | | Pt. r. lavellanus | | | | | | | | | X| | | | | | | Pt. r. monoensis | | | | | | | | | | | | | | | | X Pt. r. cognatus | | | | | | | | | | | | | X| X| | Pt. r. rennelli | | | | | | | | | | | | | | | X| D. i. inermis | X| | | | X| X| X| X| X| | | X| X| X| X| D. i. minimus | | X| X| | | | | | | | | | | | | N. a. bougainville | X| | | | | | | | | X| | X| | | | N. a. minor | | X| X| | | | X| | | | | | | | | +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-- Totals | 4| 4| 4| 1| 2| 1| 2| 2| 3| 2| 1| 5| 2| 2| 2| 1 -------------------+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--