The relation between the number of parasites/host and host age: population dynamic causes and maximum likelihood estimation.
We examined dynamical factors that shape the distribution of the number of parasites/host in constant or temporally varying environments, and with or without host-age dependent variation in host susceptibility and parasite mortality. We predict properties of the parasite distribution in the absence of density-dependent factors such as density-dependent mortality of recruitment and parasite-induced host mortality. These properties provide a criterion for the detection of density dependence in temporally variable systems with host-age dependent interactions. We have then introduced methods to estimate and statistically evaluate the effects of host age or size on the distribution of parasites/host. The methods are based on a maximum likelihood protocol for linear and non-linear regression when data are negatively binomially distributed. We have illustrated the use of the theoretical results and statistical methods by re-analysing the data of Halvorsen & Andersen (1984) on cestode infections in Norwegian arctic charr and by analysing new data on nematode infections in Caribbean Anolis lizards.
Pacala
S W
SW
Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs 06268.
Dobson
A P
AP
D000367:Age Factors; D000818:Animals; D004169:Diphyllobothriasis / Q000469:parasitology / Q000662:veterinary; D004170:Diphyllobothrium / Q000254:growth & development; D005260:Female; D005393:Fish Diseases / Q000469:parasitology; D005399:Fishes / Q000469:parasitology; D006790:Host-Parasite Interactions; D008116:Lizards / Q000469:parasitology; D008297:Male; D008954:Models, Biological; D009348:Nematoda / Q000254:growth & development; D009349:Nematode Infections / Q000469:parasitology / Q000662:veterinary; D010271:Parasites / Q000254:growth & development*; D010272:Parasitic Diseases / Q000469:parasitology*