Scale strength as a cost of rapid growth in sunfish

Comparisons among populations have revealed adaptive variation in growth ra te within several species. However, theoretical models suggest that a cost to rapid growth must exist in order to explain why some populations grow sl owly. Based on previous work with development of the: cranial skeleton in p umpkinseed sunfish, we proposed that rapid gros th may compromise the stren gth of all skeletal elements in vertebrates. Using pumpkinseed from six pop ulations known to differ in their intrinsic growth rates, we correlated str ength of scales, in terms of resistance to penetration, with individual gro wth rate. We found a negative correlation that was consistent both within a nd among populations. This trade-off between growth rate and scale strength may have fitness consequences in terms of likelihood of surviving predatio n attempts or swimming efficiency.