Biological factors contributing to bark and ambrosia beetle species diversification

Abstract

The study of species diversification can identify the processes that shape patterns of species richness across the tree of life. Here, we perform comparative analyses of species diversification using a large dataset of bark beetles. Three examined covariates-permanent inbreeding (sibling mating), fungus farming, and major host type-represent a range of factors that may be important for speciation. We studied the association of these covariates with species diversification while controlling for evolutionary lag on adaptation. All three covariates were significantly associated with diversification, but fungus farming showed conflicting patterns between different analyses. Genera that exhibited interspecific variation in host type had higher rates of species diversification, which may suggest that host switching is a driver of species diversification or that certain host types or forest compositions facilitate colonization and thus allopatric speciation. Because permanent inbreeding is thought to facilitate dispersal, the positive association between permanent inbreeding and diversification rates suggests that dispersal ability may contribute to species richness. Bark beetles are ecologically unique; however, our results indicate that their impressive species diversity is largely driven by mechanisms shown to be important for many organism groups.

Know your farmer: Ancient origins and multiple independent domestications of ambrosia beetle fungal cultivars

“…Additionally, for sparsely sampled clades such as this, it is unlikely the oldest lineages representative of that clade will be sampled, resulting in consistent underestimate for the age of the crown node. This same bias is likely to be true for the estimated ages of the Platypodinae (Jordal, ) and the Scolytinae (Gohli et al., ) though less pronounced as estimates for both were based on more extensive taxon sampling. This bias makes it likely that the actual age of the first fungal cultivars is slightly older than 86 million years making them contemporaries of Tesserocerini, the first farming beetle tribe which arose 96 Ma (Figure , 95% credibility 88.5–103.4) (Jordal, ).…”

“…The timing for the origins of farming behaviour in Scolytine beetles is from Jordal and Cognato () and Gohli et al. (). All known instances of farming in Scolytinae evolved after the radiation of Platypodinae.…”

“…The timing of domestication events in Ophiostomatales are indicated by A, B and C. The origin of farming in Platypodinae (red dotted line) is from Jordal () while the timing for the known origins in Scolytinae (green line and triangles) is from Jordal and Cognato () and Gohli et al. (). Underlined taxa are genomes sequenced in this study, colours indicate farming beetle associate (Platypodinae/Scolytinae); however, many Raffaelea species are promiscuous and associate with more than one beetle.…”

Combining Phylogenetic and Occurrence Information for Risk Assessment of Pest and Pathogen Interactions with Host Plants

“…These 23 species were selected because of their phylogenetic relationship to Xyleborus glabratus, an invasive alien species in North America and vector of the fungus Raffaelea lauricola, which causes Laurel Wilt Disease and is a major agent for tree mortality for species of Lauraceae [10]. In general, these data coincided with recently published information on the phylogenetic relationships of ambrosia beetles [11]. The taxonomy of beetle species to X. glabratus was checked using information validated for GBIF and NCBI with the R package taxize [12].…”

Morphological and Molecular Perspectives on the Phylogeny, Evolution, and Classification of Weevils (Coleoptera: Curculionoidea): Proceedings from the 2016 International Weevil Meeting

“…Comparative analyses of diversification indicated a very rapid adaptive radiation by the permanently inbreeding and fungus-cultivating lineage Xyleborini beginning around 20 Ma: the highest speciation rate for any lineage of Scolytinae. More detailed analyses using the software SLOUCH revealed significant effects of inbreeding and deep host shifts for the diversification of the subfamily [120]. High diversification rates were further emphasized by the likely high levels of cryptic species in some inbreeding lineages, e.g., Hypothenemus eruditus (Westwood) and allied species groups [121].…”