Melinda L. Moir

Current Constraints and Future Directions in Estimating Coextinction

Coextinction is a poorly quantified phenomenon, but results of recent modeling suggest high losses to global biodiversity through the loss of dependent species when hosts go extinct. There are critical gaps in coextinction theory, and we outline these in a framework to direct future research toward more accurate estimates of coextinction rates. Specifically, the most critical priorities include acquisition of more accurate host data, including the threat status of host species; acquisition of data on the use of hosts by dependent species across a wide array of localities, habitats, and breadth of both hosts and dependents; development of models that incorporate correlates of nonrandom host and dependent extinctions, such as phylogeny and traits that increase extinction-proneness; and determination of whether dependents are being lost before their hosts and adjusting models accordingly. Without synergistic development of better empirical data and more realistic models to estimate the number of cothreatened species and coextinction rates, the contribution of coextinction to global declines in biodiversity will remain unknown and unmanaged.

Resource allocation for efficient environmental management

Environmental managers must decide how to invest available resources. Researchers have previously determined how to allocate conservation resources among regions, design nature reserves, allocate funding to species conservation programs, design biodiversity surveys and monitoring programs, manage species and invest in greenhouse gas mitigation schemes. However, these issues have not been addressed with a unified theory. Furthermore, uncertainty is prevalent in environmental management, and needs to be considered to manage risks. We present a theory for optimal environmental management, synthesizing previous approaches to the topic and incorporating uncertainty. We show that the theory solves a diverse range of important problems of resource allocation, including distributing conservation resources among the worlds biodiversity hotspots; surveillance to detect the highly pathogenic avian influenza H5N1 virus in Thailand; and choosing survey methods for the insect order Hemiptera. Environmental management decisions are similar to decisions about financial investments, with trade-offs between risk and reward.

Considering Extinction of Dependent Species during Translocation, Ex Situ Conservation, and Assisted Migration of Threatened Hosts

Translocation, introduction, reintroduction, and assisted migrations are species conservation strategies that are attracting increasing attention, especially in the face of climate change. However, preventing the extinction of the suite of dependent species whose host species are threatened is seldom considered, and the effects on dependent species of moving threatened hosts are unclear. There is no published guidance on how to decide whether to move species, given this uncertainty. We examined the dependent-host system of 4 disparate taxonomic groups: insects on the feather-leaf banksia (Banksia brownii), montane banksia (B. montana), and Stirling Range beard heath (Leucopogon gnaphalioides); parasites of wild cats; mites and ticks on Duvaucels gecko (Hoplodactylus duvaucelii) and tuatara (Sphenodon punctatus); and internal coccidian parasites of Cirl Bunting (Emberiza cirlus) and Hihi (Notiomystis cincta). We used these case studies to demonstrate a simple process for use in species- and community-level assessments of efforts to conserve dependents with their hosts. The insects dependent on Stirling Range beard heath and parasites on tigers (Panthera tigris) appeared to represent assemblages that would not be conserved by ex situ host conservation. In contrast, for the cases of dependent species we examined involving a single dependent species (internal parasites of birds and the mite Geckobia naultina on Duvaucels gecko), ex situ conservation of the host species would also conserve the dependent species. However, moving dependent species with their hosts may be insufficient to maintain viable populations of the dependent species, and additional conservation strategies such as supplementing populations may be needed.

Refining sampling protocols for inventorying invertebrate biodiversity: influence of drift-fence length and pitfall trap diameter on spiders

Abstract The limited resources available to inventory biodiversity and conduct ecological monitoring requires efficient protocols for sampling with pitfall traps. Here we consider adding different length drift-fences to pitfall traps on spiders. Four different fencing treatments (no fence, or fence lengths of 2, 4 and 6 m) were evaluated in combination with three trap diameters (4.3, 7.0 and 11.1 cm). Three-way ANOVAs revealed no significant interaction effects between any combinations of fencing treatments, trap size or the spatial positioning of transects within the study site along which traps were arranged. Post-hoc tests showed fences significantly increased the abundance of individuals and richness of spider families, and species collected. Traps with 6 m fences were significantly higher in all of these variables than traps with 2 m fences. ANOSIMs revealed taxonomic composition differed significantly between fenced and unfenced traps at familial, and specific ranks. Among fenced traps, taxonomic composition was influenced primarily by trap diameter rather than fence length. ANOSIMs showed significant differences in taxonomic composition between each trap diameter for fenced traps. An optimal combination of fencing treatment and trap diameter was determined by constructing smoothed species accumulation curves for increasing numbers of traps. Four criteria were considered: equivalent numbers of traps, standardized cumulative trap circumference, standardized cumulative fence length (fenced traps only) and standardized cumulative handling time. For the same number of traps, 11.1 cm traps with 4 and 6 m fences collected the most species. At a standardized trap circumference, long fences were best, with all trap sizes catching similar numbers of species. When fence length was standardized, 11.1 cm traps with 2 or 4 m fences collected the most species. At a standardized handling time all traps caught very similar numbers of species, although most 11.1 cm diameter traps collected more species than other trap sizes and those with 4 m fences were most efficient. Given the similar performance of fenced and unfenced traps for standardized handling time, we outline reasons why unfenced traps may be best.

Identifying and managing threatened invertebrates through assessment of coextinction risk.

Invertebrates with specific host species may have a high probability of extinction when their hosts have a high probability of extinction. Some of these invertebrates are more likely to go extinct than their hosts, and under some circumstances, specific actions to conserve the host may be detrimental to the invertebrate. A critical constraint to identifying such invertebrates is uncertainty about their level of host specificity. We used two host-breadth models that explicitly incorporated uncertainty in the host specificity of an invertebrate species. We devised a decision protocol to identify actions that may increase the probability of persistence of a given dependent species. The protocol included estimates from the host-breadth models and decision nodes to identify cothreatened species. We applied the models and protocol to data on 1055 insects (186 species) associated with 2 threatened (as designated by the Australian Government) plant species and 19 plant species that are not threatened to determine whether any insect herbivores have the potential to become extinct if the plant becomes extinct. According to the host-breadth models, 18 species of insect had high host specificity to the threatened plant species. From these 18 insects, the decision protocol highlighted 6 species that had a high probability of extinction if their hosts were to become extinct (3% of all insects examined). The models and decision protocol have added objectivity and rigor to the process of deciding which dependent invertebrates require conservation action, particularly when dealing with largely unknown and speciose faunas.

Further evidence of the coextinction threat for jumping plant-lice: three new Acizzia (Psyllidae) and Trioza (Triozidae) from Western Australia

Three new species of jumping plant-lice (Psylloidea) are described from Western Australia. Acizzia hughesae sp.n. occurs on Acacia veronica Maslin (Fabaceae: Mimosoideae), A. mccarthyi sp.n. on an undescribed species of Grevillea (Proteaceae) identified by the Western Australian State Government as in need of conservation action (Grevillea sp. ‘Stirling Range’) and Trioza barrettae sp.n. from the critically endangered Banksia brownii (Proteaceae). These new species of jumping plant-lice are considered rare, and at risk of extinction, or coextinction, as they are recorded from plant species with highly restricted distributions in the south-west of Western Australia. Indeed, the Western Australian State Government recently classified two of the three new jumping plant-lice species as threatened.

Which host-dependent insects are most prone to coextinction under changed climates?

Coextinction (loss of dependent species with their host or partner species) presents a threat to untold numbers of organisms. Climate change may act synergistically to accelerate rates of coextinction. In this review, we present the first synthesis of the available literature and propose a novel schematic diagram that can be used when assessing the potential risk climate change represents for dependent species. We highlight traits that may increase the susceptibility of insect species to coextinction induced by climate change, suggest the most influential host characteristics, and identify regions where climate change may have the greatest impact on dependent species. The aim of this review was to provide a platform for future research, directing efforts toward taxa and habitats at greatest risk of species loss through coextinction accelerated by climate change.

Strategic national approach for improving the conservation management of insects and allied invertebrates in Australia: Conservation strategy for Australian insects

Despite progress in recent decades, the conservation management of insects and allied invertebrates in Australia is challenging and remains a formidable task against a background of poor taxonomic and biological knowledge, limited resources (funds and scientific expertise) and a relatively low level of community engagement, education and awareness. In this review, we propose a new, strategic national approach for the conservation of insects and allied invertebrates in Australia to complement and build on existing actions and increase awareness with the general public and government. A review of all species listed under relevant State and Territory Acts, national legislation (EPBC Act) and on international lists (IUCN Red List) indicated that of the 285 species currently listed under these conservation schedules, 10 (3%) are considered extinct, 204 (72%) threatened (Critically Endangered, Endangered or Vulnerable) and 71 (25%) are classified as other (Threatened, Near Threatened, Rare or Least Concern). Comparison of the geographic ranges of listed species in relation to bioregions (IBRA regions) shows a striking discordance in spatial representation across the Australian landscape, reflecting an ad hoc approach to threatened species conservation and the concentration of invertebrate biologists in urban centres of temperate coastal Australia. There is a positive relationship between the number of threatened species and extent of protection according to the National Reserve System within each IBRA region, exemplifying the anomaly in spatial representativeness of listed species. To overcome these shortfalls, we propose a novel educational, regional approach based on selecting, for each of the 89 IBRA regions, a relatively small set of ‘flagship taxa’ (threatened species and/or ‘iconic’ species of high scientific/social value), which are then promoted and/or nominated for listing by the scientific community. Such species could be adopted by local community groups whereby a community‐based regional approach would ensure spatial representativeness of insect conservation across the entire Australian continent. This novel approach may ultimately provide a better strategy for the conservation management of habitats and threatened ecological communities, reducing extinction risk of threatened species and addressing key threatening processes. Members of the Australian entomological community are strongly encouraged to nominate candidate taxa as flagship species for wider promotion and/or listing nationally under the EPBC Act.

Translocation strategies for multiple species depend on interspecific interaction type

Conservation translocations, anthropogenic movements of species to prevent their extinction, have increased substantially over the last few decades. Although multiple species are frequently moved to the same location, current translocation guidelines consider species in isolation. This practice ignores important interspecific interactions and thereby risks translocation failure. We model three different two-species systems to illustrate the inherent complexity of multispecies translocations and to assess the influence of different interaction types (consumer-resource, mutualism, and competition) on translocation strategies. We focus on how these different interaction types influence the optimal founder population sizes for successful translocations and the order in which the species are moved (simultaneous or sequential). Further, we assess the effect of interaction strength in simultaneous translocations and the time delay between translocations when moving two species sequentially. Our results show that translocation decisions need to reflect the type of interaction. While all translocations of interacting species require a minimum founder population size, which is demarked by an extinction boundary, consumer-resource translocations also have a maximum founder population limit. Above the minimum founder size, increasing the number of translocated individuals leads to a substantial increase in the extinction boundary of competitors and consumers, but not of mutualists. Competitive and consumer-resource systems benefit from sequential translocations, but the order of translocations does not change the outcomes for mutualistic interaction partners noticeably. Interspecific interactions are important processes that shape population dynamics and should therefore be incorporated into the quantitative planning of multispecies translocations. Our findings apply whenever interacting species are moved, for example, in reintroductions, conservation introductions, biological control, or ecosystem restoration.

Assessing the success of mine restoration using Hemiptera as indicators

Understanding trends in assemblage composition of key invertebrate groups can provide important insight into the ‘condition’ of, or changes in, the environment. Species density, abundance and composition of Hemiptera (true bugs) were assessed in jarrah (Eucalyptus marginata) forest and a chronosequence of restored bauxite mine pits near Boddington, Western Australia, in order to evaluate how restoration was progressing. A significant difference was uncovered for hemipteran species density between the youngest restored treatment and forest. In contrast, hemipteran composition was distinct between the forest and all restored treatments. Hemipteran composition was associated with the presence of the plant species Conostylis setigera and Trichocline spathulata, and plant structure between 160–180 cm and 260–280, plus soil pH. Restoration was successful in returning Hemiptera with respect to species density, but restoration was yet to attain a similar composition of Hemiptera to that of unmined forest, despite some of the restored sites being almost 20 years old. These results are similar to those of other studies that have assessed the response of Hemiptera to disturbance, and highlight the need to wait for considerable periods in order to achieve restoration goals. This study also confirms the utility of Hemiptera as bioindicators of environmental ‘condition’ and change.