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Published on: March 10, 2021
Local population size in a flightless insect: importance of patch structure-dependent mortality
1Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, California 93106-9610, USA. hjyoo@purdue.edu
Ecology
|April 11, 2006
Summary
Population models reveal that spatial factors, not just dispersal, significantly influence western tussock moth distribution. Local mortality rates, particularly crawler and pupal parasitism, are key drivers of moth abundance in different habitat patches.
Area of Science:
- Ecology
- Population Dynamics
- Spatial Ecology
Background:
- Understanding population distribution in heterogeneous environments is crucial.
- Demographic rates and dispersal are key factors influencing species distribution.
- The western tussock moth (Orgyia vetusta) distribution is influenced by patch characteristics.
Purpose of the Study:
- To explore the relative importance of demographic rates and dispersal in shaping western tussock moth distribution.
- To investigate how spatial heterogeneity affects population dynamics.
- To identify key mortality factors driving moth abundance patterns.
Main Methods:
- Utilized stage-structured population models to analyze demographic rates and dispersal.
- Conducted spatial surveys to assess moth distribution.
- Developed single-patch and spatially explicit simulation models to test hypotheses.
Main Results:
- Moth distribution was not well explained by passive larval dispersal alone.
- Moth populations were higher on smaller and more isolated patches.
- Crawler mortality increased with patch size and was density-dependent, favoring smaller patches.
- Pupal parasitism by a chalcid wasp varied spatially and could explain higher abundances on isolated patches.
Conclusions:
- Habitat spatial structure simultaneously affects multiple population processes.
- Spatial variation in pupal parasitism significantly impacts moth distribution among patches.
- Even low attack rates on critical life stages can dominate population distribution patterns.
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