Fig. 1.

Representative specimens of a laboratory-reared male (top) and a laboratory-reared female (bottom) blackspotted stickleback (G. wheatlandi). When compared to females, males are smaller, have larger heads, longer median fins, and shorter, deeper caudal peduncles. Scale bar = 5 mm. Twenty-one landmarks were chosen based on Albert et al. (2008): (1) anterior extent of maxilla, (2) anterior extent of orbit, (3) ventral extent of orbit, (4) posterior extent of orbit, (5) posterior extent of supraoccipital, (6) first dorsal spine insertion, (7) second dorsal spine insertion, (8) third dorsal spine insertion, (9) posterior insertion of dorsal fin, (10) posterior extent of caudal peduncle, (11) posterior insertion of anal fin, (12) anterior insertion of anal fin, (13) insertion point of pelvic spine into the pelvic girdle, (14) posterior extent of ectocorocoid, (15) dorsal extent of ectocorocoid, (16) dorsal insertion of pectoral fin, (17) posteriodorsal extent of operculum, (18) ventral extent of operculum, (19) dorsal extent of preopercular, (20) posterioventral extent of preopercular, (21) anterioventral extent of preopercular.