Surprisingly little population genetic structure in a fungus‐associated beetle despite its exploitation of multiple hosts

Abstract

In heterogeneous environments, landscape features directly affect the structure of genetic variation among populations by functioning as barriers to gene flow. Resource-associated population genetic structure, in which populations that use different resources (e.g., host plants) are genetically distinct, is a well-studied example of how environmental heterogeneity structures populations. However, the pattern that emerges in a given landscape should depend on its particular combination of resources. If resources constitute barriers to gene flow, population differentiation should be lowest in homogeneous landscapes, and highest where resources exist in equal proportions. In this study, we tested whether host community diversity affects population genetic structure in a beetle (Bolitotherus cornutus) that exploits three sympatric host fungi. We collected B. cornutus from plots containing the three host fungi in different proportions and quantified population genetic structure in each plot using a panel of microsatellite loci. We found no relationship between host community diversity and population differentiation in this species; however, we also found no evidence of resource-associated differentiation, suggesting that host fungi are not substantial barriers to gene flow. Moreover, we detected no genetic differentiation among B. cornutus populations separated by several kilometers, even though a previous study demonstrated moderate genetic structure on the scale of a few hundred meters. Although we found no effect of community diversity on population genetic structure in this study, the role of host communities in the structuring of genetic variation in heterogeneous landscapes should be further explored in a species that exhibits resource-associated population genetic structure.

Determinants of Genetic Structure in a Nonequilibrium Metapopulation of the Plant Silene latifolia

“…In such cases Whitlock [8] suggests the use of a hypergeometric sampling correction to account for the sampling error normally assumed by a binomial sampling error. Recently Wood et al [55] describe a more recent analysis of the same focal Bolitotherus cornutus metapopulation, though not exactly the same section as Whitlock [8] . Wood et al [55] report much lower values of F ST values for microsatellite markers, which might be similarly affected by the issues described by Edelaar et al [54] wherein markers showing larger numbers of alleles, e.g.…”

“…Recently Wood et al [55] describe a more recent analysis of the same focal Bolitotherus cornutus metapopulation, though not exactly the same section as Whitlock [8]. Wood et al [55] report much lower values of F ST values for microsatellite markers, which might be similarly affected by the issues described by Edelaar et al [54] wherein markers showing larger numbers of alleles, e.g. microsatellites, will show a general trend towards smaller values of F ST compared to markers that have fewer alleles (allozymes), but also because a multinomial-hypergeometric correction was not included for the estimation of F ST .…”

Social network position experiences more variable selection than weaponry in wild subpopulations of forked fungus beetles

“…Mate guarding typically lasts for several hours and has been demonstrated to be a reliable indicator of insemination success (Conner, 1988(Conner, , 1989. Sufficient migration occurs to maintain genetic homogeneity among subpopulations (Wood, Donald, Formica, & Brodie III, 2013).…”

Forked Fungus Beetle (suggested common name) Bolitotherus cornutus (Panzer) 1794 (Insecta: Coleoptera: Tenebrionidae)

“…The cyclical nature of fungal resource emergence and exploitation by beetles ensures that well-established populations and newly emerging populations co-occur on a landscape scale. The patchy nature of these populations makes this system an excellent model for investigating the effects of local extinction and re-colonization (Whitlock 1991;Wood et al 2013). As a result, the presence of this beetle has been used to infer the effect of habitat fragmentation at different scales (Kehler and Bondrup-Nielsen 1999).…”