Rethinking the native range concept

Taming the terminological tempest in invasion science

Standardised terminology in science is important for clarity of interpretation and communication. In invasion science - a dynamic and rapidly evolving discipline - the proliferation of technical terminology has lacked a standardised framework for its development. The result is a convoluted and inconsistent usage of terminology, with various discrepancies in descriptions of damage and interventions. A standardised framework is therefore needed for a clear, universally applicable, and consistent terminology to promote more effective communication across researchers, stakeholders, and policymakers. Inconsistencies in terminology stem from the exponential increase in scientific publications on the patterns and processes of biological invasions authored by experts from various disciplines and countries since the 1990s, as well as publications by legislators and policymakers focusing on practical applications, regulations, and management of resources. Aligning and standardising terminology across stakeholders remains a challenge in invasion science. Here, we review and evaluate the multiple terms used in invasion science (e.g. 'non-native', 'alien', 'invasive' or 'invader', 'exotic', 'non-indigenous', 'naturalised', 'pest') to propose a more simplified and standardised terminology. The streamlined framework we propose and translate into 28 other languages is based on the terms (i) 'non-native', denoting species transported beyond their natural biogeographic range, (ii) 'established non-native', i.e. those non-native species that have established self-sustaining populations in their new location(s) in the wild, and (iii) 'invasive non-native' - populations of established non-native species that have recently spread or are spreading rapidly in their invaded range actively or passively with or without human mediation. We also highlight the importance of conceptualising 'spread' for classifying invasiveness and 'impact' for management. Finally, we propose a protocol for classifying populations based on (i) dispersal mechanism, (ii) species origin, (iii) population status, and (iv) impact. Collectively and without introducing new terminology, the framework that we present aims to facilitate effective communication and collaboration in invasion science and management of non-native species.

Savviness of prey to introduced predators

The prey naivety hypothesis posits that prey are vulnerable to introduced predators because many generations in slow gradual coevolution are needed for appropriate avoidance responses to develop. It predicts that prey will be more responsive to native than introduced predators and less responsive to introduced predators that differ substantially from native predators and from those newly established. To test these predictions, we conducted a global meta-analysis of studies that measured the wariness responses of small mammals to the scent of sympatric mammalian mesopredators. We identified 26 studies that met our selection criteria. These studies comprised 134 experiments reporting on the responses of 36 small mammal species to the scent of six introduced mesopredators and 12 native mesopredators. For each introduced mesopredator, we measured their phylogenetic and functional distance to local native mesopredators and the number of years sympatric with their prey. We used predator and prey body mass as a measure of predation risk. Globally, small mammals were similarly wary of the scent of native and introduced mesopredators; phylogenetic and functional distance between introduced mesopredators and closest native mesopredators had no effect on wariness; and wariness was unrelated to the number of prey generations, or years, since first contact with introduced mesopredators. Small mammal wariness was associated with predator-prey body mass ratio, regardless of the nativity. The one thing animals do not seem to recognize is whether their predators are native.

Logical fallacies persist in invasion biology and blaming the messengers will not improve accountability in this field: a response to Frank et al

We analyze the "Logical fallacies and reasonable debates in invasion biology: a response to Guiaşu and Tindale" article by Frank et al., and also discuss this work in the context of recent intense debates in invasion biology, and reactions by leading invasion biologists to critics of aspects of their field. While we acknowledge the attempt by Frank et al., at least in the second half of their paper, to take into account more diverse points of view about non-native species and their complex roles in ecosystems, we also find the accusations of misrepresenting invasion biology, for instance by "cherry-picking" and "constructing 'straw people'", directed at the Guiaşu and Tindale study to be unwarranted. Despite the sometimes harsh responses by leading invasion biologists to critics of their field, we believe that persistent and fundamental problems remain in invasion biology, and we discuss some of these problems in this article. Failing to recognize these problems, and simply dismissing or minimizing legitimate criticisms, will not advance the cause, or enhance the general appeal, of invasion biology and will prevent meaningful progress in understanding the multiple contributions non-native species can bring to various ecosystems worldwide. We recommend taking a more open-minded and pragmatic approach towards non-native species and the novel ecosystems they are an integral part of.

A National Catalogue of Viruses Associated with Indigenous Species Reveals High-Throughput Sequencing as a Driver of Indigenous Virus Discovery

Viruses are important constituents of ecosystems, with the capacity to alter host phenotype and performance. However, virus discovery cued by disease symptoms overlooks latent or beneficial viruses, which are best detected using targeted virus detection or discovered by non-targeted methods, e.g., high-throughput sequencing (HTS). To date, in 64 publications, 701 viruses have been described associated with indigenous species of Aotearoa New Zealand. Viruses were identified in indigenous birds (189 viruses), bats (13 viruses), starfish (4 viruses), insects (280 viruses), and plants (126 viruses). HTS gave rise to a 21.9-fold increase in virus discovery rate over the targeted methods, and 72.7-fold over symptom-based methods. The average number of viruses reported per publication has also increased proportionally over time. The use of HTS has driven the described national virome recently by 549 new-to-science viruses; all are indigenous. This report represents the first catalogue of viruses associated with indigenous species of a country. We provide evidence that the application of HTS to samples of Aotearoa New Zealand's unique fauna and flora has driven indigenous virus discovery, a key step in the process to understand the role of viruses in the biological diversity and ecology of the land, sea, and air environments of a country.

Native-alien populations—an apparent oxymoron that requires specific conservation attention

Many countries define nativity at a country-level—taxa are categorised as either alien species or native species. However, there are often substantial within-country biogeographical barriers and so a taxon can be native and alien to different parts of the same country. Here, we use the term ‘native-alien populations’ as a short-hand for populations that result from the human-mediated dispersal of individuals of a species beyond a biogeographical barrier to a point beyond that species’ native range, but that is still within the same political entity as parts of the species’ native range. Based on these criteria, we consider native-alien populations to be biological invasions. However, we argue that, in comparison to other alien populations, native-alien populations: 1) are likely to be closer geographically to their native range; 2) are likely to be phylogenetically and ecologically more similar to native species in their introduced range; and 3) options to control their introduction or manage them will likely be more limited. We argue this means native-alien populations tend to differ from other alien populations in the likelihood of invasion, the types of impacts they have, and in how they can be most effectively managed. We also argue that native-alien populations are similarly a distinct phenomenon from native populations that are increasing in abundance or range extent. And note that native-alien populations are expected to be particularly common in large, ecologically diverse countries with disjunct biomes and ecoregions. Reporting, monitoring, regulating and managing native-alien populations will, we believe, become an increasingly important component of managing global change.

Dynamic species interactions associated with the range-shifting marine gastropod Mexacanthina lugubris

Globally, species are undergoing range shifts in response to climate change. However, the potential impacts of climate-driven range shifts are not well understood. In southern California, the predatory whelk Mexacanthina lugubris has undergone a northward range shift of more than 100 km in the past four decades. We traced the history of the whelk’s range shift and assessed potential effects using an integrated approach, consisting of field surveys, as well as feeding and thermotolerance experiments. We found that at sites where Mexacanthina and native species co-occurred, native whelks distributions peaked lower in the intertidal. In laboratory experiments, we found that the presence of Mexacanthina led to reduced growth in native whelks (Acanthinucella spirata). Additionally, the range-shifting whelk was able to tolerate higher temperatures than common native species (A. spirata and Nucella emarginata), suggesting further impacts as a result of climate warming. Many species are likely to undergo range shifts as a coping mechanism for changing climatic conditions. However, communities are unlikely to shift as a whole due to species-specific responses. By studying the impacts of range-shifting species, like Mexacanthina, we can better understand how climate change will alter existing community structure and composition.

Ten bridges on the road to recovering Canada’s endangered species

Wildlife is declining around the world. Many developed nations have enacted legislation on endangered species protection and provide funding for wildlife recovery. Protecting endangered species is also supported by the public and judiciary. Yet, despite what appear as enabling conditions, wild species continue to decline. Our paper explores pathways to endangered species recovery by analyzing the barriers that have been identified in Canada, the United States, and Australia. We summarize these findings based on Canada’s Species at Risk Conservation Cycle (assessment, protection, recovery planning, implementation, and monitoring and evaluation) and then identify 10 “bridges” that could help overcome these barriers and bend our current trajectory of wildlife loss to recovery. These bridges include ecosystem approaches to recovery, building capacity for community co-governance, linking wildlife recovery to ecosystem services, and improving our storytelling about the loss and recovery of wildlife. The focus of our conclusions is the Canadian setting, but our findings can be applied in other national and subnational settings to reverse the decline of wildlife and halt extinction.

An Analysis of US State Regulated Weed Lists: A Discordance between Biology and Policy

Weedy and invasive plants threaten our food supply, native biodiversity, and the structure and function of ecosystems. The number and impact of these damaging plants are expected to continue to grow with ongoing global change. Some of the most common policy tools to help mitigate this threat are regulatory weed lists, which limit the importation and movement of listed plant species, but there has never been a comprehensive analysis of plants regulated in the United States. We analyzed US state regulatory lists (e.g., noxious, invasive, prohibited) to evaluate their composition, patterns of listing, congruities with weed distributions, and limitations. In total, 46 states maintain regulatory weed lists that include 3210 total listings of 1249 unique species; 48% of them are introduced, 40% are native, and 12% are not yet found in the United States. Overall, the listed species are not a good reflection of the weeds in each state, and listing appears largely reactive, regulating species after they become widespread. We highlight patterns and incongruities among lists and discuss their implications, especially the large number of regulated species native to the United States.

When all life counts in conservation

Conservation science involves the collection and analysis of data. These scientific practices emerge from values that shape who and what is counted. Currently, conservation data are filtered through a value system that considers native life the only appropriate subject of conservation concern. We examined how trends in species richness, distribution, and threats change when all wildlife count by adding so-called non-native and feral populations to the International Union for Conservation of Nature Red List and local species richness assessments. We focused on vertebrate populations with founding members taken into and out of Australia by humans (i.e., migrants). We identified 87 immigrant and 47 emigrant vertebrate species. Formal conservation accounts underestimated global ranges by an average of 30% for immigrants and 7% for emigrants; immigrations surpassed extinctions in Australia by 52 species; migrants were disproportionately threatened (33% of immigrants and 29% of emigrants were threatened or decreasing in their native ranges); and incorporating migrant populations into risk assessments reduced global threat statuses for 15 of 18 species. Australian policies defined most immigrants as pests (76%), and conservation was the most commonly stated motivation for targeting these species in killing programs (37% of immigrants). Inclusive biodiversity data open space for dialogue on the ethical and empirical assumptions underlying conservation science.

Fact and value in invasion biology

Some invasion biologists contend their science has reached a consensus on 4 facts: cost estimates of the effects of nonindigenous species provided in papers by Pimentel et al. are credible; invasive species generally, not just predators, pose significant extinction threats; characteristic biological differences distinguish novel from native species, ecosystems, communities, and processes; and ontological dualism, which distinguishes between natural and anthropogenic processes and influences, plays a useful role in biological inquiry. I contend there is no convincing empirical evidence for any of these propositions. Leading invasion biologists cite their agreement about these propositions as evidence for them and impugn the motives of critics who believe consensus should be based on evidence not the other way around.