Fecundity determines the extinction threshold in a Canadian assemblage of longhorned beetles (Coleoptera: Cerambycidae)

Reproductive rate has been suggested to have a positive effect on the amount of habitat loss a species can tolerate while emigration from habitat patches has been suggested to have both positive and negative effects. Forest fragmentation has been suggested to have negative effects on forest species. We determined the extinction threshold for 12 species of saproxylic (dead wood dependent) longhorned beetles (Coleoptera: Cerambycidae) using trap catch data from Ontario, Canada. We also determined the maximum egg production of each species and whether they were likely to move outside of forest patches. We found a strong negative relationship between reproductive rate and the minimum habitat amount required for species presence. This relationship is obscured if the scale of investigation is not appropriate for the study organism. As well, species caught moving outside forest habitat had lower extinction thresholds than species not caught moving outside forest but this was not significant after accounting for reproductive rate. Fragmentation did not have an effect on the minimum habitat requirements. These relationships can inform predictions of which species will be most affected by habitat loss.