Shifting Adaptive Topography in a Two-Stage Life History Model

Adaptive topographies depicting fiitness response to increasing post-reproductive growth potential in a juvenile-adult model in which there is an infinite number of adult age classes. The "stable age" equation is 1 = Bj/l + pjBa/l2 + pjpaBa/l3 + pjpa2Ba/l4 + ... where the B's and p's are respectively effective fecundities and post-breeding survival rates of juveniles and adults. Reproductive effort pairs, (Ej-Ea), are color-coded by exp(l1) according to the visible spectrum with dark red denoting low fitness values and dark violet, high. In all figures, there are two adaptive peaks. For low growth potential, the highest peak corresponds to large reproductive expenditures by juveniles. With increasing growth potential, this peak moves to the left, i.e., optimal juvenile effort declines, and the juvenile reproduction peak is eventually eclipsed by the peak at the left corresponding to no juvenile reproduction. Life history functions, B(Ei) and p(Ei) as follows: Bi(Ei) = bi(3 Ei2 - 2 Ei3); bj = ba = 1.5 p(Ei) = p(1 - Ei); pj = 0.8; pj = 0.9 g(Ei) = 1 + g(1-Ei); gj, ga = [0,50]. Click the image to start/stop the animation.