Looks can be deceiving: speciation dynamics of co‐distributedAngophora(Myrtaceae) species in a varying landscape

Abstract

Understanding the mechanisms underlying species divergence remains a central goal in evolutionary biology. Landscape genetics can be a powerful tool for examining evolutionary processes. We used genome‐wide scans to genotype samples from populations of eight Angophora species. Angophora is a small genus within the eucalypts comprising common and rare species in a heterogeneous landscape, making it an appropriate group to study speciation. We found A. hispida was highly differentiated from the other species. Two subspecies of A. costata (subsp. costata and subsp. euryphylla) formed a group, while the third (subsp. leiocarpa, which is only distinguished by its smooth fruits and provenance) was supported as a distinct pseudocryptic species. Other species that are morphologically distinct could not be genetically differentiated (e.g., A. floribunda and A. subvelutina). Distribution and genetic differentiation within Angophora were strongly influenced by temperature and humidity, as well as biogeographic barriers, particularly rivers and higher elevation regions. While extensive introgression was found between many populations of some species (e.g., A. bakeri and A. floribunda), others only hybridized at certain locations. Overall, our findings suggest multiple mechanisms drove evolutionary diversification in Angophora and highlight how genome‐wide analyses of related species in a diverse landscape can provide insights into speciation.

Phylogenetic Reconstruction of the Rainforest Lineage Fontainea Heckel (Euphorbiaceae) Based on Chloroplast DNA Sequences and Reduced-Representation SNP Markers

“…It is possible our analyses identified accessions within the southern subclade at an early stage of divergence, which may signal a genetic cline or adaptation to the diverse environments within the region sampled for these species. Patterns of genetic differentiation that contributed to species differentiation driven by climatic and abiotic differences have been highlighted in a number of plant species and assemblages along eastern Australia [58][59][60]. This unresolved genetic signal may be improved by further sampling across the species range as well as further surveying for new populations, together with the investigation of the influence of environmental factors to better define how this species is positioned within the phylogeny of the genus.…”

Tracking habitat or testing its suitability? Similar distributional patterns can hide very different histories of persistence versus nonequilibrium dynamics

“…Our findings highlight how invading tree species can undergo an expansion phase into novel, previously untested habitat during which they might need to rely on adaptive plasticity (Rutherford et al. 2018, 2021). However, some of the newly occupied areas might be yet to experience those exceptional selective filtering events that will define the true boundaries of the species’ long‐term distribution (Sharma et al.…”

Editorial: Global Changes and Plant Invasions

“…Transcriptomics in combination with growth experiments are increasingly being used to identify the genes involved in abiotic and biotic interactions of invasive plants (e.g., Manoharan et al, 2019;Zhang et al, 2021). Examining alien species at the population level in both the native and invasive ranges (Bossdorf et al, 2005) and incorporating genomics (e.g., Rutherford et al, 2021) could advance our understanding of the mechanisms underlying plant response to global changes. Assessing the impacts of environmental changes on invasions during each invasion stage is important (Catford et al, 2020), as well as long-term experiments (Corli et al).…”