Predicting engineering effects of shelterbuilders

While comparative studies examining the engineering effects of different shelter types (or species of shelter-builders) have yet to be conducted, several features might be expected to be important and deserve consideration when planning experiments involving shelter-builders.

These include the persistence, size, number, and accessibility of shelters, as well as their physical properties. Persistent shelters, or shelter types that are routinely colonized by other shelter-builders (e.g., many leaf ties and rolls) should have greater effects on arthropod communities than shelters that disassemble following abandonment by the primary engineer (Jones et al. 1997). Larger structures may also have greater engineering impacts by permitting secondary occupation by a greater number of arthropods with a wider range of body sizes. For solitary shelter-builders, shelter size is at least partially constrained by the size of the foliage of their host plants. The number of leaf shelters constructed (and abandoned) by an individual arthropod over its life should be positively related to its engineering impacts. Leaf shelters also vary considerably in their accessibility to secondary occupants, with some shelters (e.g., many leaf folds and rolls) being "sealed shut" while others (e.g., many loose leaf webs) are quite open to potential colonists. Finally, shelters providing a high-quality microenvironment that ameliorates the most important climatic threats facing many arthropods in a particular environment are likely to have greater engineering effects than shelters with microenvironments that are little changed from ambient (non-sheltered) habitats or that provide microclimates used by only a small subset of potential colonists.

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