430 



S. F. MacLean, Jr. 



Weight 



a. Growth rate functions relating growth 

 rate to body weight for a subarctic (gj and 

 an arctic (gi) invertebrate. 



log of 

 Weight 



Time 



b. Growth curves resulting from growth rate 

 functions g, and gz. Different development 

 periods A, and U) are required to reach the 

 size fWJ necessary for pupation. 



log of N 

 Number 



of 

 Survivors 



Time 



c. Survivorship curve showing the number of 

 adults (Nt and Nj^ produced after develop- 

 ment periods t, and tz. Slower growth (gz) 

 leads to a longer development time (U) and 

 fewer individuals (N2) surviving to become 

 reproducing adults. 



FIGURE 11-5. Effect of growth rate on sur- 

 vivorship. 



ate arctic coastal tundra (MacLean 1975b, MacLean and Hodkinson 

 1980). 



In Diptera, larval development continues until some point {W„) is 

 reached. At this time, there is a complete change (pupation) from a grow- 

 ing larva to a reproducing adult. The onset of sexual maturity in Enchy- 



I 



