Rarity of density dependence or population regulation with lags?

SEVERAL recent reviews of published life tables1–3 concluded that density-dependent regulation is infrequent in insect populations, prompting a vigorous debate among eco legists4–10. Little attention, however, has been directed to one issue: most life-table analyses look only for direct (not-lagged) density dependence. Thus, there is a real danger that populations characterized by delays in regulation will be relegated to a density-independent limbo by an analysis not equipped to recognize such behaviour. I have evaluated the evidence for delayed density dependence in population dynamics of 14 forest insects, and assessed the effect of regulation lags on the likelihood of detecting direct density dependence. Eight cases exhibited clear evidence for delayed density dependence and lag-induced oscillations, but direct density dependence was detected in only one of these. This result suggests that traditional analyses will not, in general, detect density-dependent regulation in populations that are characterized by lags and complex dynamic behaviour.

[1]  T. Royama.  Population Persistence and Density Dependence , 1977 .

[2]  P. Moran.  The Statistical Analsis of the Canadian Lynx cycle. 1. Structure and Prediction. , 1953 .

[3]  P. Stiling.  The Frequency of Density Dependence in Insect Host‐Parasitoid Systems , 1987 .

[4]  G. Varley,et al.  Population Changes in German Forest Pests , 1949 .

[5]  M. Hassell,et al.  Insect Population Ecology: An Analytical Approach , 1974 .

[6]  R. F. Morris.  Single‐Factor Analysis in Population Dynamics , 1959 .

[7]  D. R. Strong,et al.  Density-vague population change. , 1986, Trends in ecology & evolution.

[8]  P. Stiling,et al.  Density-dependent processes and key factors in insect populations , 1988 .

[9]  M. Hassell.  Detecting regulation in patchily distributed animal populations , 1987 .

[10]  A. Berryman.  POPULATION CYCLES OF THE DOUGLAS-FIR TUSSOCK MOTH (LEPIDOPTERA: LYMANTRIIDAE): THE TIME-DELAY HYPOTHESIS , 1978, The Canadian Entomologist.

[11]  T. Prout,et al.  Competition Among Immatures Affects Their Adult Fertility: Population Dynamics , 1985, The American Naturalist.

[12]  Alan A. Berryman,et al.  Dynamics of Forest Insect Populations , 1988, Population Ecology.

[13]  William W. Murdoch,et al.  Aggregation of parasitoids and the detection of density dependence in field populations , 1987 .

[14]  T. Royama,et al.  Fundamental Concepts and Methodology for the Analysis of Animal Population Dynamics, with Particular Reference to Univoltine Species , 1981 .

[15]  P. Rothery,et al.  The Detection of Density-Dependence from a Series of Annual Censuses. , 1987, Ecology.

[16]  M. Brown.  Denstity Dependence in Insect Host‐Parasitoid Systems: A Comment , 1989 .

[17]  George E. P. Box,et al.  Time Series Analysis: Forecasting and Control , 1977 .

[18]  J. P. Dempster,et al.  Spatial heterogeneity, stochasticity and the detection of density dependence in animal populations , 1986 .

[19]  Gwilym M. Jenkins,et al.  Time series analysis, forecasting and control , 1972 .

[20]  J. P. Dempster,et al.  THE NATURAL CONTROL OF POPULATIONS OF BUTTERFLIES AND MOTHS , 1983 .

[21]  M. Hassell.  Insect natural enemies as regulating factors , 1985 .

[22]  C. Walters,et al.  Effects of Measurement Errors on the Assessment of Stock–Recruitment Relationships , 1981 .

[23]  L. Mehrhoff.  The Dynamics of Declining Populations of an Endangered Orchid, Isotoria Medeoloides , 1989 .

[24]  R. F. Morris.  The Value of Historical Data in Population Research, with Particular Reference to Hyphantria cunea Drury , 1964, The Canadian Entomologist.