Weak isolation by distance inDiaperis boleti, a fungivorous saproxylic beetle

Andrzej Oleksa,Nadir Erbilgin

doi:10.1093/jis/14.1.109

Abstract

Living in unstable habitats is expected to decrease the intensity of isolation by distance in populations through the need for frequent movements of individuals. Insects associated with fruiting bodies of fungi therefore are supposed to have weak spatial genetic structure of populations compared with those living in more stable habitats. With the use of an amplified fragment length polymorphism technique, this study investigated the isolation by distance, inbreeding, and genetic diversity in Diaperis boleti (L.) (Coleoptera: Tenebrionidae), a fungivorous saproxylic beetle that inhabits sporocarps of Laetiporus sulphureus (Bulliard) Murrill (Polyporales) on trees growing in highly-fragmented agricultural landscapes. Isolation by distance was tested with spatial autocorrelation analysis of kinship (individual-based approach) and correlating matrices of genetic and geographic distances with the Mantel test (population-based approach). These results were compared with the results obtained for saproxylic beetles living in the same landscape but differing in ecological preferences. It was shown that the species dependent on sporocarps of wood-decomposing fungi had higher variability, lower individual inbreeding, and less intensive isolation by distance pattern than saproxylic beetles living in tree hollows. It was also demonstrated that spatial autocorrelation analysis of kinship is a more sensitive approach for detecting fine-scale spatial genetic structure than the Mantel test.

Highlights

The abilities of organisms to disperse among subpopulations and to colonize distant habitat patches are important for metapopulation survival, especially in landscapes subjected to a strong fragmentation (Clobert et al 2004)
Spatial genetic structure in the fungivorous beetle D. boleti is influenced by isolation by distance (IBD)
Because intensive gene flow may be responsible for homogenizing spatial genetic structure, the presence of IBD could be surprising in a species with expected high mobility

Summary

Introduction

The abilities of organisms to disperse among subpopulations and to colonize distant habitat patches are important for metapopulation survival, especially in landscapes subjected to a strong fragmentation (Clobert et al 2004). Theoretical models (e.g., Travis and Dytham 1999) have shown that dispersal strategy of an organism could be related to environmental predictability and habitat longevity. The shortage of data could be attributed to methodological constraints related to dispersal studies in insects. Traditional direct methods, such as mark‒release‒recapture or radio-tracking are applicable for larger species (e.g., Hedin et al 2007, Dubois et al 2010, Drag et al 2011, Chiari et al 2012); for most insects, only indirect, molecular methods are available (for review, see Ranius 2006). Analyses of spatial distribution of genetic diversity in the context of effective gene flow within and among populations should allow for the inference about dispersal in small-bodied insects

Methods

Results

Discussion

Conclusion