TABLE 1

Sexual isolation between pure D. yakuba (ST strain) and D. santomea (STO.4 strain)

Pairings
FemaleMale% matedMean CL (SE)
D. yakubaD. yakuba85.615.28 (1.07)
D. yakubaD. santomea47.822.23 (1.53)
D. santomeaD. yakuba14.414.38 (2.26)
D. santomeaD. santomea71.110.32 (0.93)
BC santomeaD. yakubaNA14.97 (0.49)
D. santomeaBC yakubaNA18.70 (0.50)
  • Ninety pairs of flies were watched for 45 min for each of the four pairings of pure species. Females from the backcross to D. santomea were observed until 50% had mated and males from the backcross to D. yakuba were observed for 45 min, when ∼50% had mated. Each pair was observed individually. We recorded whether or not mating occurred during that period, and, if so, the mean copulation latency (CL) of the matings. Mean copulation latencies and their standard errors (SE) are given in minutes.