Dynamics of experimental populations of native and introduced blowflies (Diptera: Calliphoridae): mathematical modelling and the transition from asymptotic equilibrium to bounded oscillations

The equilibrium dynamics of native and introduced blowflies is modelled using a density-dependent model of population growth that takes into account important features of the life-history in these flies. A theoretical analysis indicates that the product of maximum fecundity and survival is the primary determinant of the dynamics. Cochliomyia macellaria, a blowfly native to the Americas and the introduced Chrysomya megacephala and Chrysomya putoria, differ in their dynamics in that the first species shows a damping oscillatory behavior leading to a one-point equilibrium, whereas in the last two species population numbers show a two-point limit cycle. Simulations showed that variation in fecundity has a marked effect on the dynamics and indicates the possibility of transitions from one-point equilibrium to bounded oscillations and aperiodic behavior. Variation in survival has much less influence on the dynamics.

Análise multivariada da evoluçäo craniana em roedores caviíneos: convergência de trajetórias ontogenéticas / Multivariate analysis of skull svolution in Caviine rodents: convergence of ontogenetic trajectories

O presente trabalho analisa a forma craniana de três gêneros de roedores caviíneos. A análise estatística multivariada mostrou que a semelhança de forma craniana é provavelmente devia à convergência com o tamanho nas trajetórias ontogenéticas, estimada através da análise de regressäo de escores individuais derivados da análise dos componentes principais dos caracteres morfométricos cranianos