Note that these percentages were calculated from results using the square root transformation on the data. James (2007) shows that the percentage selection response after square root transformation is a fraction 0.501 of that in actual units. This means that in actual units the response for the period in question was of the order of 65 per cent (an average of 13 per cent per generation). Coupled with the high survival consistently observed in the GIFT strain, the high potential for growth rate makes it a very attractive genetic resource.