28 Nov 2002

Einar Mjølhus "Some examples of dynamics and bifurcations in biological populations with age structure".

In the early 1990s we (that is Arild Wikan, at Harstad College, and myself) made some investigations into the dynamics of time-discrete models of biological populations with age structure. This resulted in Arild's doctoral dissertation. The original idea was to investigate the effect of "fine-structuring" a model, similar to comparing fluid and kinetic models in plasma physics, which was my experience. 

However, it turned out that the field was rich, and also, in fact fairly unexplored. I shall show a few examples of what we found, confining main attention to two of them: 

1. A pronounced 4-periodicity in a large range of models; 
2. A surprising kind of synchronization in another rather general class of models. 

The latter may have relevance to phenomena observed in certain insect populations, e. g., the so-called "magi-cicada", or 17-years-cikada.