Genomic analyses indicate resilience of a commercially and culturally important marine gastropod snail to climate change.

Genomic vulnerability analyses are being increasingly used to assess the adaptability of species to climate change and provide an opportunity for proactive management of harvested marine species in changing oceans. Southeastern Australia is a climate change hotspot where many marine species are shifting poleward. The turban snail, Turbo militaris is a commercially and culturally harvested marine gastropod snail from eastern Australia. The species has exhibited a climate-driven poleward range shift over the last two decades presenting an ongoing challenge for sustainable fisheries management. We investigate the impact of future climate change on T. militaris using genotype-by-sequencing to project patterns of gene flow and local adaptation across its range under climate change scenarios. A single admixed, and potentially panmictic, demographic unit was revealed with no evidence of genetic subdivision across the species range. Significant genotype associations with heterogeneous habitat features were observed, including associations with sea surface temperature, ocean currents, and nutrients, indicating possible adaptive genetic differentiation. These findings suggest that standing genetic variation may be available for selection to counter future environmental change, assisted by widespread gene flow, high fecundity and short generation time in this species. We discuss the findings of this study in the content of future fisheries management and conservation.

Climate change threatens unique evolutionary diversity in Australian kelp refugia.

Climate change has driven contemporary decline and loss of kelp forests globally with an accompanying loss of their ecological and economic values. Kelp populations at equatorward-range edges are particularly vulnerable to climate change as these locations are undergoing warming at or beyond thermal tolerance thresholds. Concerningly, these range-edge populations may contain unique adaptive or evolutionary genetic diversity that is vulnerable to warming. We explore haplotype diversity by generating a Templeton-Crandall-Sing (TCS) network analysis of 119 Cytochrome C Oxidase (COI) sequences among four major population groupings for extant and putatively extinct populations only known from herbarium specimens of the dominant Laminarian kelp Ecklonia radiata in the south-western Pacific, a region warming at 2-4 times the global average. Six haplotypes occurred across the region with one being widespread across most populations. Three unique haplotypes were found in a deep-water range-edge population off Moreton Island, Queensland, which likely represents both a contemporary and historic refuge during periods of climatic change. Hindcasting E. radiata cover estimates using extant data, we reveal that this region likely supported the highest kelp cover in eastern Australia during the last glacial maximum. The equatorward range edge, deep-water kelp populations off Moreton Island represent a genetically diverse evolutionary refuge that is currently threatened by warming and requires prompt ex-situ conservation measures.

A Historical Summary of the Distribution and Diet of Australian Sea Hares (Gastropoda: Heterobranchia: Aplysiidae).

Matt J. Nimbs, Richard C. Willan, and Stephen D. A. Smith (2017) Recent studies have highlighted the great diversity of sea hares (Aplysiidae) in central New South Wales, but their distribution elsewhere in Australian waters has not previously been analysed. Despite the fact that they are often very abundant and occur in readily accessible coastal habitats, much of the published literature on Australian sea hares concentrates on their taxonomy. As a result, there is a paucity of information about their biology and ecology. This study, therefore, had the objective of compiling the available information on distribution and diet of aplysiids in continental Australia and its offshore island territories to identify important knowledge gaps and provide focus for future research efforts. Aplysiid diversity is highest in the subtropics on both sides of the Australian continent. Whilst animals in the genus Aplysia have the broadest diets, drawing from the three major algal groups, other aplysiids can be highly specialised, with a diet that is restricted to only one or a few species. Although the diets of some widespread, frequently-observed taxa have been investigated, those for lesser-known, endemic taxa remain unclear and require specific investigation.