I am fascinated by the interactions, co-evolution and often co-dependencies among different groups of organisms. Given the complexity of studying such relationships in real time, I employ genomic tools, complimented by ecological approaches. Such methods allow me to elucidate aspects of species’ migration, genetic variation, physiology and behavior in order to answer questions relating to environmental adaptation, speciation, population structure, evolutionary relationships and co-evolution.
The mountain pine beetle can be a significant economic and ecological insect pest during periods of population outbreak. The most recent outbreak in Canada resulted in millions of hectares of lost forest, but also led to a significant range expansion and the establishment of mountain pine beetle in jack pine, a novel host. In order to mitigate the continued expansion of mountain pine beetle it was imperative to understand how the beetles were able to breach a natural barrier and establish on a new host. Using genome-wide single nucleotide polymorphisms obtained from a draft genome I was able to integrate population and landscape genomics to identify key populations. By incorporating outlier loci detection methods, I identified several genes that provided the first glimpses of areas in the mountain pine beetle genome subject to selection pressure that may be conferring an adaptive advantage in novel habitats. These results answered important evolutionary questions and had significant impact by providing insight into how the beetle could expand its range. These findings were highlighted in the editors note for Molecular Biology and Evolution, a live radio presentation on CBC, and a newspaper article (23 April 2014).
Signatures of selection in the mountain pine beetle system
(Keeling et al. 2013, Janes et al. 2014)
Ecology & evolution of native orchids
Building on a foundation of ecology and plant soil interactions, this research incorporated molecular methods with my increasing interest in speciation and hybridization. The applicability of the ecological species concept to closely related members of the subtribe Pterostylidinae was investigated using ordination techniques. These results suggested that the species did not fit the ecological concept. A phylogenetic approach resolved some of the taxonomic confusion and helped to prioritize species for conservation by providing greater insight into the evolutionary relationships among species. However, questions relating to a particular species complex with putative hybrids remained unanswered. Applying population genetic approaches that assess migration and gene flow, I showed that a number of morphologically similar individuals, which had been assigned as different species, were best treated as a single species. These findings were significant in freeing valuable conservation resources for species truly in need.
My interest in evolutionary processes and the role of co-evolution in speciation was broadened when I began integrating concepts from species-specific relationships. Orchids in particular have unique life histories that often cannot be completed without symbiotic mycorrhiza. In addition, many Australasian and European orchids rely on sexual deception for pollination. In the case of mycorrhiza, many orchids have species- or taxon-specific dependencies on mycorrhiza for germination. In this system, being a fungal generalist may have evolutionary advantages over being a fungal specialist (species specific). In the case of sexual deception, orchid species will mimic the attractant pheromones of insect species and the general appearance of a female insect in order to ensure pollination. Again, this system relies on a very specific relationship – any variation within a species may lead to the attraction of a different pollinator, potentially contributing to speciation and/or hybridization events. These are areas of research that I intend to pursue in the future.
(Janes 2006; Janes 2008; Janes & Duretto 2010; Janes et al. 2010a, 2010b, 2010c; Janes et al. 2012)
Studies of mating systems and sex ratios
Despite being one of the most studied bark beetles in North America, few studies had systematically assessed the mating system of mountain pine beetle, and it was unclear whether female beetles were polyandrous. My continued research using genomic data, and the innovative incorporation of parentage software in an insect system, showed that mountain pine beetles are indeed polygamous and that they appear to make use of brood parasitism under epidemic conditions (featured as a Heredity podcast). In addition, the female-biased sex-ratio had been a long-standing area of interest. Several researchers had confirmed the sex skew but little had been elucidated in terms of the environmental or selective pressures resulting in the skew. My colleagues and I addressed these questions by developing a predictive model to characterize sex-ratio and assess environmental influences. The results show that differential larval mortality as a result of difference in tree diameter is the cause of sex skew. These findings contribute to the effective management of these forest insect pests by improving predictive outbreak models that rely on estimates of female numbers and fecundity.
(Janes et al. 2016, James et al. 2016)
Woodland eucalypt diversification
The importance of ancient standing variation and introgressed alleles in recently diverged species is becoming an increasingly popular area of research. Teasing apart the patterns of historical versus contemporary gene flow, and new mutations, is fundamental to our understanding of adaptive and evolutionary processes. For example, the source of raw genetic material for evolution can have significant impacts on the speed and success with which a population can adapt, and on the genomic signatures resulting from selection. Eucalyptus is a species rich genus (>700 species) with numerous species co-occurring and creating hybrid zones. As such, Eucalyptus provides a unique opportunity to study the sources of genetic variation underlying adaptive radiation.
Understanding gene flow between restricted and widespread eucalypts
Hybridisation is a phenomenon increasingly recognized as important in the evolution of plants, animals, and fungi because it can contribute to the origin of new species. However, it can also delay the speciation process and/or erode species integrity, especially in rare and restricted species as the rare species genetic integrity can be 'swamped' by genes from other species through pollen transfer. Several recent studies suggest that continued gene flow between hybrids and pure species (termed ‘introgression’) may play an integral role in species diversification and survivorship, as the process not only facilitates the transfer of adaptive genes into new environments, but also provides greater genetic diversity for selection to act upon. To better understand the relative roles of hybridisation in the historical and ongoing survival of restricted species, more thorough assessments of interspecific gene flow and its mechanisms are required.
This project will investigate the gene flow between restricted and widespread species, focusing on the ecologically important box-ironbark eucalypts, by addressing the following questions:
Hybridisation is considered a threat to rare and restricted species, but how many have evidence of historical and/or contemporary hybridisation in their genomic signatures?
Are restricted species contributing to the adaptability of widespread species that ‘capture’ their genetic variation?
To what extent do different pollinator species facilitate inter-specific gene flow (relative to random expectations)?
(Alwadani et al. 2019)