Observed and Potential Range Shifts of Native and Nonnative Species with Climate Change

Downloaded from www.annualreviews.org. Guest (guest) IP: 193.147.173.203 On: Mon, 19 May 2025 09:42:12 ES55_Art02_Bradley ARjats.cls October 7, 2024 17:42 Annual Review of Ecology, Evolution, and Systematics Observed and Potential Range Shifts of Native and Nonnative Species with Climate Change Bethany A. Bradley,1,2 Evelyn M. Beaury,3 Belinda Gallardo,4Inés Ibáñez,5Catherine Jarnevich,6 Toni Lyn Morelli,2,7 Helen R. Sofaer,8 Cascade J.B. Sorte,9and Montserrat Vilà10,11 1Department of Environmental Conservation, University of Massachusetts, Amherst, Massachusetts, USA; email: [email protected] 2Northeast Climate Adaptation Science Center, University of Massachusetts, Amherst, Massachusetts, USA 3Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA 4InstitutoPirenaicodeEcología,ConsejoSuperiordeInvestigacionesCientíficas,Zaragoza,Spain 5School for Environment and Sustainability, University of Michigan, Ann Arbor, Michigan, USA 6Fort Collins Science Center, US Geological Survey, Fort Collins, Colorado, USA 7Northeast Climate Adaptation Science Center, US Geological Survey, Amherst, Massachusetts, USA 8Pacific Island Ecosystems Research Center, US Geological Survey, Hawaii National Park, Hawaii, USA 9Department of Ecology and Evolutionary Biology, University of California, Irvine, California, USA 10Doñana Biological Station, Spanish National Research Council (EBD-CSIC), Sevilla, Spain 11Department of Plant Biology and Ecology, University of Sevilla, Sevilla, Spain Annu. Rev. Ecol. Evol. Syst. 2024. 55:23–40 First published as a Review in Advance on June 17, 2024 The Annual Review of Ecology, Evolution, and Systematics is online at ecolsys.annualreviews.org https://doi.org/10.1146/annurev-ecolsys-102722- 013135 This work is licensed under a Creative Commons Attribution 4.0 International License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. See credit lines of images or other third-party material in this article for license information. Keywords alien species, biological invasion, global environmental change, range shift, species spread rate, species distribution modeling Abstract There is broad concern that the range shifts of global flora and fauna will not keep up with climate change,increasing the likelihood of population declines and extinctions. Many populations of nonnative species already have advantages over native species, including widespread human-aided dispersal and release from natural enemies. But do nonnative species also have an advantage with climate change? Here, we review observed and potential range shifts for native and nonnative species globally. We show that nonnative species are expanding their ranges orders of magnitude faster than native species, reflecting both traits that enable rapid spread and ongoing 23 Downloaded from www.annualreviews.org. Guest (guest) IP: 193.147.173.203 On: Mon, 19 May 2025 09:42:12 ES55_Art02_Bradley ARjats.cls October 7, 2024 17:42 Native species: populations of species within the limits of their historical natural range Nonnative species: species with established populations (i.e., viable self-sustaining populations) outside of their historical range due to either accidental or intentional human transportation and introduction; also termed alien, displaced, exotic, introduced, or nonindigenous Niche: the combination of biotic and abiotic conditions in which a species can maintain a population (i.e., fundamental niche); observations of species typically capture a portion of its niche (i.e., realized niche) because species have not dispersed into all available habitat and some suitable environmental conditions may not exist human-mediatedintroduction.Wefurther showthat nonnative specieshave largepotential ranges and range expansions with climate change,likely due to a combination of widespread introduction and broader climatic tolerances. With faster spread rates and larger potential to persist or expand, nonnative populations have a decided advantage in a changing climate. 1. INTRODUCTION Conservation scientists worry that native flora and fauna will not shift their ranges quickly enough to keep up with rapid climate change (IPCC 2023), leading to large-scale population declines and alterations to the composition and diversity of ecological communities (e.g., Chen et al. 2011, Lenoir & Svenning 2015,Pecl et al.2017). At the same time, invasion scientists worry that nonnative flora and fauna could expand rapidly into new regions (e.g.,Dukes & Mooney 1999,Hellmann et al. 2008), further exacerbating their ecological impacts. This juxtaposition seems to present a conflict. Native species, which inhabit their historical geographic range, are expected to fail to expand while nonnative species,which inhabit a novel geographic range due to human introduction, are expected to succeed. Here, we review the evidence associated with these two expectations to ask: Does climate change create an advantage for nonnative species? For populations to persist with climate change,both native and nonnative species have to adapt in place and/or shift their geographic ranges to maintain their ecological niches (Davis & Shaw 2001, Hutchinson 1957). Climatic tolerance is an important determinant of a species’ niche because most species are limited in some way by temperature or precipitation (e.g., Pearson & Dawson 2003, Whittaker 1970). While species’ ecological niches may change over time due to adaptation (Somero 2010), species ranges are likely to change much more rapidly (e.g., Quintero & Wiens 2013, Willis & MacDonald 2011).With temperatures warming across the planet (IPCC 2023), species ranges are generally projected to shift to higher latitudes (poleward), higher elevations (upward), and/or deeper depths. However, there is large variation among species in terms of whether ranges are projected to expand, remain stable, or contract with climate change (e.g., Warren et al. 2018). Although species ranges have always shifted in response to climate (e.g., Jackson et al. 1997, Willis & MacDonald 2011), current rates of climate change are orders of magnitude faster than those that species have experienced during their evolutionary history (IPCC 2023, Williams et al. 2007). The current velocity of climate change, or the rate of geographic shift required for species to track rising temperatures (Loarie et al. 2009), has been estimated to average 3.25 km/year on land (Dobrowski & Parks 2016) and 2.75 km/year in the ocean (Burrows et al. 2011). Climate velocities are even higher in areas warming at faster rates [e.g., at higher latitudes (Burrows et al. 2011)] and where species need to move around barriers to dispersal [e.g., in patchy habitats or complex topography (Dobrowski & Parks 2016)].Rapid warming will require species to shift their ranges at unprecedented rates to keep up with climate change. Given that all species need to shift their ranges to keep up with climate change, species origin (native versus nonnative) may seem like an arbitrary distinction. However, considering origin is important because it may affect not only the ability of species to keep up with climate change but also their role in an ecosystem. First, nonnative species rarely provide equivalent ecosystem benefits to those provided by native species, generally supporting less diverse ecosystems. For example, nonnative plants host an average of 14 times fewer species of native Lepidoptera than native plants (Tallamy & Shropshire 2009). Similarly, nonnative tree plantations contain few native plants while adjacent native forests contain predominantly native understory plants, including 24 Bradley et al. Downloaded from www.annualreviews.org. Guest (guest) IP: 193.147.173.203 On: Mon, 19 May 2025 09:42:12 ES55_Art02_Bradley ARjats.cls October 7, 2024 17:42 Species range: geographical area of a species occurrence Velocity of climate change: rate of movement along the Earth’s surface required to maintain a constant temperature Dispersal: movement of a species within or beyond its native or nonnative range where it might establish a new population Invasive species: subset of nonnative species that have established populations that are spreading within the introduced range and have a negative impact on biodiversity, local ecosystems, species, or ecosystem services Spread: the movement of a species within or beyond its native or nonnative range and subsequent establishment of a population species of conservation concern (Vu Ho et al. 2023). Indeed, nonnative species are associated with biotic homogenization, where the combination of loss of rare species and addition of the same nonnative species creates an ecological sameness of flora and fauna across landscapes (Petsch et al. 2022). Second, nonnative species have the potential to become invasive. Invasive species are a subset of nonnative species whose populations are spreading within their nonnative range and have detrimental impacts on biodiversity, ecosystems, and ecosystem services (Roy et al. 2023). Over 30% of nonnative vertebrate and invertebrate species and over 20% of nonnative plants may become invasive and ecologically harmful globally (Jeschke & Pyšek 2018, Pfadenhauer & Bradley 2024). Invasive species harm ecosystems by consuming native flora and fauna (e.g., Gallardo et al. 2016); outcompeting native species for resources like nutrients, shelter, and space (e.g., Liebhold et al. 2017); and even altering ecosystem structure and function (Roy et al. 2023). Collectively, invasions lead to declines in native populations and diversity (Bradley et al. 2019) and can drive native species to local extinction (Bellard et al. 2016). These clear differences in the ecological benefits and in the potential for ecological harm between native and nonnative species make it important to consider how species origin interacts with climate change. Moreover, with widespread and increasing introductions of nonnative species into new regions or countries (hereafter, human-mediated introductions) (Seebens et al. 2017), there is reason to believe that nonnative species have an advantage in keeping up with climate change.Many nonnative species are intentionally introduced, for example, via the pet, aquarium, and ornamental plant trades, and become established following accidental escape into natural areas (Lockwood et al. 2019, Padilla & Williams 2004, Reichard & White 2001). Global trade also creates numerous accidental introductions,with nonnative species transported either as contaminants of a commodity or as stowaways in traded goods (Hulme et al. 2008). Human activities not only introduce nonnative species to new areas but also often continue to facilitate dispersal once species are introduced, both intentionally [e.g., in home and urban gardens (Bayón & Vilà 2019, Beaury et al. 2021)] and accidentally [e.g., by ballast water or through marine corridors (Rilov & Galil 2009)]. Although the human-mediated introduction of nonnative species over long distances and outside their native ranges is common, the introduction of native species to expand their historical native range in response to climate change remains relatively rare (e.g.,Breed et al.2018). Instead, human-mediated introduction of native species typically focuses on reintroducing species in areas where they have gone locally extinct, increasing the populations of native species of conservation concern, supporting commercial or recreational stocks, or restoring habitats. Native species that have shifted their ranges outside of their historical native range (e.g., in response to climate change) are termed neonative (Essl et al. 2019), and there is ongoing debate as to whether rangeshifting native species are a cause for concern versus a beneficial phenomenon that should be encouraged (Nackley et al. 2017, Wallingford et al. 2020). Of even greater debate in conservation and management is the idea of assisted migration,or the intentional introduction of native species outside of their native range and into habitats becoming newly suitable due to climate change (McLachlan et al. 2007). For example, only in 2023 did United States’ federal government policy generally allow for the assisted migration of rare and endangered species to enable range shifts of species at risk of extinction in their historical range (USFWS 2023). Although science and management approaches to native and nonnative species differ, the two sets of species are affected by similar climate-driven forces. First, many studies have already observed species shifting their ranges in response to climate change (e.g., Lenoir et al. 2020, Parmesan & Yohe 2003), but rates of spread and ability to keep up may differ between native and nonnative species (Sorte et al. 2010). Second, projections of species’ distributions with climate www.annualreviews.org •Species Range Shifts with Climate Change 25 Downloaded from www.annualreviews.org. Guest (guest) IP: 193.147.173.203 On: Mon, 19 May 2025 09:42:12 ES55_Art02_Bradley ARjats.cls October 7, 2024 17:42 Human-mediated introduction: intentional or unintentional introduction of nonnative species into a new region; there are six principal introduction pathways: release (e.g., game animals), escape (e.g., spread from gardens), contaminant (e.g., insect on nursery plant), stowaway (e.g., larvae in ballast water), corridor (e.g., interconnected waterways), and unaided (i.e., natural dispersal across political borders) Neonative: populations of species that have expanded the limits of their historical natural range in response to human-caused environmental change Assisted migration: the intentional human-mediated movement of a species into habitats anticipated to be suitable due to climate change Range shift: directional change in a species’ geographic distribution, for example, in response to climate change change indicate that the ranges of both groups are likely to shift (e.g., Pearson & Dawson 2003), but the area of potential range expansion and range contraction may also differ between native and nonnative species. Here, we review studies of observed and potential range shifts for native and nonnative species to uncover any differences between the two groups and address whether climate change is likely to create an advantage for nonnative species. 2. OBSERVED MOVEMENT: HOW FAST ARE NATIVE SPECIES SPREADING IN COMPARISON TO NONNATIVE SPECIES? In order to assess how well native versus nonnative species might keep up with climate change, we compiled observations of species spread rates across different taxa and ecosystems. In recent decades,there has been a strong scientific focus on testing whether native species ranges are shifting in response to climate change (e.g., Lenoir et al. 2020, Parmesan & Yohe 2003, Rubenstein et al. 2024). Analyses of whether nonnative species are shifting in response to climate change are less common because many are actively expanding in all directions due to a lack of equilibrium with the environment of their introduced range (Václavík & Meentemeyer 2012).Thus,it is likely that natural dispersal and human-mediated secondary spread, rather than climate change, are the main drivers of existing observations of nonnative species’ movement. Nevertheless, nonnative species spread rates have been measured at two distinct spatial scales. First,at larger spatial scales,human-mediated introductions can be used to estimate spread rate directly associated with humans (Seebens et al. 2021). Although not classically thought of as spread, human-mediated introductions continue to facilitate the secondary spread of nonnative species within their nonnative ranges (e.g., Beaury et al. 2021) and are therefore important to consider. Second, at finer spatial scales, numerous studies have measured the secondary spread of nonnative species following their introduction into a novel geographic range (e.g., Horvitz et al. 2017, Rapoport 2000). These measures of secondary spread typically aim to measure natural dispersal but may include a combination of natural dispersal and human-mediated secondary spread. Wecomparedthree observed ratesofspread:nativespeciesspread,nonnativespecies secondary spread, and human-mediated introductions of nonnative species. We expected that rates of native species spread would be lower than rates of nonnative species secondary spread, which would be lower than rates of human-mediated introductions. For native species, we compiled data on observed range shifts as a measure of native species spread using a database derived from a systematic literature review by Rubenstein et al. (2024) (Supplemental Appendix 1), which is a comprehensive compilation of observational studies of species range shifts in response to current climate change. From this database, we included only studies that examined leading edge spread rates and showed a positive or no change in species range; we excluded those showing a range contraction,as equivalent data for nonnative species are lacking. Where there were multiple observations across studies or locations for a single species, we averaged the spread rates. For nonnative species, we compiled data on rates of secondary spread using previous reviews (Rapoport 2000, Vilà et al. 2021) and literature searches on Web of Science (https:// webofknowledge.com) (Supplemental Appendix 1). Although methods vary by study, rates are typically based on changes in the observed distribution of nonnative species across consecutive surveys or on the maximum observed distance of secondary spread from the initial introduction location after a particular time.If several spread rates were given for the same species at a single location for different periods of time,we recorded the average spread rate.If spread rates were given for multiple locations, within or across studies, we recorded all spread rates and then calculated an average spread rate for each species. 26 Bradley et al. Downloaded from www.annualreviews.org. Guest (guest) IP: 193.147.173.203 On: Mon, 19 May 2025 09:42:12 ES55_Art02_Bradley ARjats.cls October 7, 2024 17:42 Historical range: native geographic area of a species reflecting its environmental limitations, evolutionary history, and dispersal capacity Range expansion: establishment of a species in areas beyond its historical range, e.g., in response to climate change Range contraction: disappearance of a species from part of its historical range, e.g., in response to climate change For human-mediated introductions of nonnative species, we obtained data from Seebens et al. (2021). Using these data, we calculated the average distance between a new record of a nonnative species and each previous record using the Alien Species First Record Database (Seebens et al. 2017). The data are reported at the country scale, and rates are based on average distance divided by time between records. Because the introduction rates change over time (newer records are closer together as a species is introduced to more countries),we selected only species with records in more than 20 regions and averaged the rates by species. In our comparison, we included species in taxonomic classes that had at least two measurements for native spread, nonnative secondary spread, or human-mediated introduction rates, resulting in measurements from 249 native species,242 nonnative spreading species,and 192 nonnative species with human-mediated introductions.Classes included mammals (Mammalia), birds (Aves), ray-finned fishes (Actinopterygii), insects (Insecta), crustaceans (Malacostraca), gastropods (Gastropoda), dicot flowering plants (Magnoliopsida), and monocot flowering plants (Liliopsida). To avoid overrepresenting classes with more species (Supplemental Appendix 1,Supplemental Table 1), we randomly selected a comparable number of species for each of the three groups (nativespread,nonnativespread,and human-mediated introduction)tocalculate average spreadrates. Human-mediated introductions were significantly faster than nonnative spread,and both were significantly faster than native spread (Kruskal–Wallis test, X2=535, degrees of freedom =2, p<0.001) (Figure 1a). The average spread rate (mean ±SD) associated with human-mediated introductions of nonnative species (1,883 ±434 km/year) was more than 50 times faster than nonnative species secondary spread (35 ±67 km/year) and 1,000 times faster than the average rate of native species spread (1.74 ±4.11 km/year). Similarly, the average nonnative species secondary spread rate was over 20 times faster than the average rate of native species spread (Supplemental Appendix 1,Supplemental Table 1). Within taxonomic groups, the biggest differences were found for dicot flowering plants,where spread rates (mean ±SD) for human-mediated introduction (1,911 ±486 km/year) and nonnative Spread rate (km/yr) All taxa Mammals Birds Ray-finned fish Insects Crustaceans Gastropods Dicot plants Monocot plants 0.1 1 10 100 1,000 10,000 a 247 242 192 b 43 38 28 51 17 20 6 16 18 98 96 46 6 4 3 5 6 4 34 45 61 7 10 4 Native spread Nonnative spread Nonnative introduction 3.25 Figure 1 Observed spread rates between native and nonnative species (a) across and (b) within taxonomic classes. The average rates of native species’ spread (blue), nonnative species’ secondary spread within the introduced range (light red), and nonnative species’ spread rates due to human-mediated introduction (nonnative introduction; dark red) across all taxa. Differences in spread rates for the three groups are highly significant across and within taxa (p <0.001) (Supplemental Table 1). Error bars represent the standard deviation. Numbers indicate the sample size (nspecies). The gray dashed line represents the average velocity that terrestrial species need to move to keep up with climate change (3.25 km/year). Note that the data are presented on a log scale. www.annualreviews.org •Species Range Shifts with Climate Change 27 Downloaded from www.annualreviews.org. Guest (guest) IP: 193.147.173.203 On: Mon, 19 May 2025 09:42:12 ES55_Art02_Bradley ARjats.cls October 7, 2024 17:42 Secondary spread: dispersal of a nonnative species after its initial human-mediated introduction; secondary spread could be biological, human-mediated, or both Trait: morphological and functional characteristic of a species including those related to physiology, biomass allocation, growth rate, size, and fitness species secondary spread (15.5 ±23.0 km/year) were 14,000 and 100 times faster, respectively, than that of native species (0.14 ±0.54 km/year) (Figure 1b). Similarly, nonnative ray-finned fish (1,800 and 80 times faster for human-mediated and nonnative spread, respectively) and insects (1,200 and 30 times faster for human-mediated and nonnative spread, respectively) spread at substantially higher rates than their native counterparts (Supplemental Appendix 1,Supplemental Table 1). Although mobile species such as vertebrate and invertebrate animals might be expected to move faster than sessile species (i.e., plants), there were no significant differences (post-hoc Tukey test, p >0.05) (Figure 1b;Supplemental Appendix 1,Supplemental Table 2) with two exceptions: The secondary spread of nonnative ray-finned fish was higher than those of nonnative dicot flowering plants (Tukey test, p =0.02) and birds (Tukey test, p =0.06), and the spread rates of native birds were higher than those of native dicot flowering plants (Tukey test, p =0.04). 3. WHY ARE NONNATIVE SPECIES SPREADING FASTER? Observations of native and nonnative species’ spread rates (Figure 1) clearly illustrate that nonnative species, spreading within their nonnative range at an average rate of 35 km/year, are well poised to keep up with the velocity of climate change (2.75 km/year in the ocean; 3.25 km/year on land). In contrast, many native species, calculated here to be spreading at an average rate of 1.74 km/year, may fall behind. Moreover, our calculated native species spread rate is likely an overestimate given that we focused only on positive measures of expansion at the leading edge to be more comparable to nonnative species spread measurements. A recent paper that included zeroes and negative values calculated the average native species spread rate to be 1.11 km/year (Lenoir et al. 2020). This disconnect between spread rates and the velocity of climate change is particularly acute for native plants,which are moving an order of magnitude slower (0.14 km/year) on average. The faster spread rates of nonnative species may be due to human selection of species with traits that lead to faster dispersal, ecological and evolutionary advantages that species gain in their nonnative range,and/or continued association with and assistance from humans both within and across regions. 3.1. Nonnative Species’ Traits Confer an Advantage Rapid growth rates, prolific reproduction, generalist behavior, and phenotypic plasticity are all common traits among nonnative species that not only contribute to their ability to establish successfullyin a new range (van Kleunen etal.2018a) but alsosupport therapid spreadrates needed to track a changing climate (Simberloff 2000). Population spread is highly dependent on reproductive output (Clark et al. 2001), which contributes to a higher incidence of long-distance dispersal events (Clark et al. 1999) and to faster population growth once established (Capellini et al. 2015). For example, using a meta-analysis, Mason et al. (2008) found that nonnative invasive plants had higher fecundity than cooccurring native species, producing 6.7 times more seeds and increasing their potential for population spread. Likewise, fast population growth and high competitive performance, common among invasive species, contribute to faster nonnative plant spread by increasing the availability of propagules (Ibáñez et al. 2009). Additionally, nonnative animals tend to be less sensitive than their native counterparts to extreme weather events like heat waves, cold spells, storms, and floods, whose frequency is expected to increase under climate change scenarios (IPCC 2023, Gu et al. 2023), and nonnative plants tend to be favored with climate change due to their tendency to respond to temperature rather than daylight cues (Willis et al. 2010). All of these traits may contribute to faster spread rates of nonnative species under climate change. Individual populations of nonnative species may also have higher fitness and greater ability to spread than native populations due to high genetic diversity. Nonnative populations have 28 Bradley et al. Downloaded from www.annualreviews.org. Guest (guest) IP: 193.147.173.203 On: Mon, 19 May 2025 09:42:12 ES55_Art02_Bradley ARjats.cls October 7, 2024 17:42 Enemy release: decrease in the population regulation of introduced nonnative species into a new region by herbivores, parasites, and pathogens, resulting in a rapid increase in their abundance historically been viewed as experiencing genetic bottlenecks that might limit population establishment (for examples, see Hänfling 2007).However, studies from disparate taxa using molecular markers now show that multiple independent introductions from a variety of sources across the native range are typical for nonnative species introduction. This phenomenon leads to substantial genetic variation among nonnative populations, with genes drawn from multiple geographically distinct populations from the native range (e.g., Castagné et al. 2023, Smith et al. 2020). Genetic variation through admixture of multiple population sources might enhance rapid adaptation to new environmental conditions (Kolbe et al. 2007) and aid in population range expansion (Rius & Darling 2014) due to the presence of individuals with traits that support faster spread. Thetransport andintroduction ofnonnative speciesis also likely to selectfor traitsthat support rapid spread and enable population growth (Colautti et al.2006,Theoharides & Dukes 2007).For example, rapid growth rates are a desirable trait in ornamental plants (van Kleunen et al. 2018b), which is the primary pathway of nonnative plant introductions (Reichard & White 2001). Nonnative species might also be better equipped to spread due to fewer predators and herbivores keeping them in check. In the native range, coevolved natural enemies can constrain species’ population growth and subsequent spread (Maron & Vilà 2001),but many studies show that nonnative plants released from above- and belowground herbivores and pathogens invest more resources in growth and reproduction than native plants (Liu & Stiling 2006,Zhao et al.2020).Although studies quantifying how the lack of natural enemies translates to plant population dynamics are scarce, it is plausible that enemy release enables nonnative species to become more abundant and spread faster into new habitats (DeWalt et al. 2004). The bulk of evidence for the population benefits of enemy release has been found in plants,but studies have also demonstrated release from pathogens and parasites and associated demographic advantages in nonnative animals (Torchin & Mitchell 2004), indicating that enemy release could support faster nonnative spread across taxa. 3.2. Nonnative Species’ Introduction Patterns Confer an Advantage In addition to differences in traits that affect spread rates, there are substantial differences in geography between native and nonnative species. Specifically, the availability and accessibility of unoccupied habitat that a species could potentially spread into differ systematically between native and nonnative populations (González-Moreno et al. 2015). For native species, habitat that becomes newly suitable under climate change typically emerges at one edge of the range—poleward or toward higher elevations (Lenoir et al. 2020, Mason et al. 2015) (Figure 2a). Due to suboptimal environmental conditions, native species tend to exhibit diminished reproductive outputs at the edges of their climatic range (e.g., Kawecki 2008), which likely reduces reproductive performance and spread rates. Additionally, directional dispersal in response to climate change may be limited by natural and human-created dispersal barriers (Dobrowski & Parks 2016), slowing or halting native species’ spread rates.In contrast,nonnative species are less likely to have established throughout all available habitat (Bradley et al. 2015, González-Moreno et al. 2015), creating opportunities to spread from multiple introduction points and in multiple directions (Figure 2b). Similarly, unintentional introductions of species such as nonnative invertebrates via contaminant or stowaway pathways can lead to spread from multiple points of introduction (e.g., Jacobi et al. 2012), resulting in high rates of secondary spread. Thus, nonnative species might have higher observed spread rates (Figure 1) because having multiple introduction sites allows them to overcome dispersal barriers. In addition to having fewer limits on spread direction, nonnative species often have an advantage due to close association with humans; indeed, many have been introduced because of their utility to humans. Rather than limiting habitat connectivity, human land uses can create corridors for rapid dispersal of nonnative species (Resasco et al. 2014), while disturbance can www.annualreviews.org •Species Range Shifts with Climate Change 29 Downloaded from www.annualreviews.org. Guest (guest) IP: 193.147.173.203 On: Mon, 19 May 2025 09:42:12 ES55_Art02_Bradley ARjats.cls October 7, 2024 17:42 Potential range: the geographic range suitable for a species under either current or future climate change scenarios Species distribution model (SDM): a geographic representation of a species’ niche created by combining species occurrence data with environmental information –30°–40°–50°–60°–70° a Native species b Nonnative species 0° –10° –20° –30° –30°–40°–50°–60°–70° Occurrence Spread Occurrence Spread Longitude (°) Latitude (°) Figure 2 Occurrences and spread for a hypothetical native and nonnative species with similar numbers of observed occurrences. (a) A native species has already had time to disperse into and fill in its range, resulting in opportunities to spread predominantly at range margins. With climate change, spread directions (blue arrows) are typically poleward. (b) Nonnative species are often introduced into multiple suitable locations by humans (human-mediated introduction; solid black arrows). Secondary spread is due to human-mediated long-distance dispersal within the introduction region (dashed arrows) or natural dispersal (red arrows), which could happen in any direction (and is not only climate driven). These advantages enable faster spread rates for nonnative species. support common nonnative traits of rapid growth and prolific reproduction (Jauni et al. 2015), which would result in rapid spread. Consequently, spread rates of nonnative populations are likely a combination of both natural dispersal and human-mediated secondary spread, with humansdisproportionatelyresponsibleforsecondaryintroductionsthat occur throughlong-distance dispersal events (Figure 2b) (Suarez et al. 2001). For example, nonnative plants are commonly transported across long distances as ornamentals and often introduced into cooler climates at higher latitudes, giving them an advantage with a warming climate (Bradley et al. 2012, Van der Veken et al. 2008). Overall, human-mediated introduction enables the rapid movement of species across thousands of kilometers. For the groups included in our analyses, human-mediated introduction led to spread rates several orders of magnitude higher than native species’ spread rates. Furthermore, the secondary spread of nonnative species (which might still have included some level of human mediation) was much faster than the spread of native species (Figure 1) (Seebens et al. 2021). Human introductions provide an enormous advantage to the ability of nonnative species to keep up with climate change. 4. PROJECTED CHANGES IN SPECIES DISTRIBUTIONS In addition to observations of how quickly species are able to spread, another key component of whether climate change creates an advantage for nonnative species is how much habitat is available for them to spread into. Predictions of potential range often rely on species distribution models (SDMs; also known as ecological niche models), which aim to create a geographic representation of a species’ niche by combining species occurrence data with environmental information (Elith & Leathwick 2009). Because climate is a key driving factor of distributions (Pearson & Dawson 30 Bradley et al. Downloaded from www.annualreviews.org. Guest (guest) IP: 193.147.173.203 On: Mon, 19 May 2025 09:42:12 ES55_Art02_Bradley ARjats.cls October 7, 2024 17:42 2003, Whittaker 1970), particularly across broad regions, many of these models rely on climate predictors. SDMs have often been used to predict range shifts under future climate conditions (e.g., Allen & Bradley 2016, Gallardo et al. 2017, Warren et al. 2018), providing projections of the potential distributions of both native and nonnative species with climate change. To assess whether native and nonnative species differ in their potential ranges, we searched the literature for SDM studies projecting current and future ranges for native and nonnative taxa. Unexpectedly, few studies included both groups, instead focusing on one or the other (e.g., Allen & Bradley 2016, Gallardo et al. 2017, Warren et al. 2018). In order to avoid biased comparisons associated with different modeling approaches, data sources, climate scenarios, and timelines, we focus on data sets from three studies that used the same distribution modeling approach for both native and nonnative taxa to examine the projected effect of climate change on the ranges of North American seed plants (Zhang et al. 2017), European fish (Radinger & García-Berthou 2020), and North American birds (Langham et al. 2015). For each study, we identified taxa as either native or nonnative to the study region and extracted each species’ modeled current range extent, area of habitat gained versus lost, and future range extent. In all three studies, future ranges were predicted for the year 2050 under comparable emissions scenarios resulting in ∼2°C of warming (Supplemental Appendix 2). Our final data set included range sizes for 4,406 native and 681 nonnative plants (Zhang et al. 2017), 458 native and 10 nonnative birds (Langham et al. 2015),and 11 native and 5 nonnative fish (Radinger & García-Berthou 2020). All models assumed that species (both native and nonnative) could shift into all available projected habitats. From these case studies, birds and fish were projected to experience a net expansion with climate change on average, while plants were predicted to experience a net contraction (Figure 3). However, the average magnitude of the respective range expansion or contraction differed by species origin. Nonnative birds were projected to expand more than native birds, as they have a much larger modeled area of habitat gain than of habitat loss. Nonnative plants were projected to contract less than native plants, driven by the larger extent of area gained relative to native plants. Habitat loss and gain were very similar for nonnative and native fish,although nonnative fish were projected to experience smaller gains and smaller losses than native fish.Overall,nonnative species were projected to have more or similar habitat availability with climate change relative to native species, by either gaining more suitable habitat (birds), contracting less (plants), or remaining the same (fish). Across all three taxonomic groups, future potential range size was strongly correlated with current potential range size (Pearson’s correlation coefficient: birds,r=0.95; fish,r=0.75; plants, r=0.90). Accordingly, species with large potential range sizes, regardless of origin, were more likely to have large areas of expansion and contraction with climate change. Although we did not test for differences in potential range sizes between nonnative and native birds and fish because sample sizes were too small, there was a large difference in range size between native and nonnative plants. Nonnative plants had average potential range sizes 120–130% larger than those of native plants (current range ±SD: native plants, 2,973 ±2,694 km2; nonnative plants, 3,586 ±2,727 km2; future range ±SD: native plants, 2,537 ±3,131 km2; nonnative plants, 3,317 ±3,817 km2). 5. WHY MIGHT RANGE EXPANSION BE GREATER FOR NONNATIVE SPECIES? 5.1. Potential Range Changes Suggest an Advantage for Nonnative Species Nonnative species are projected to have larger range expansion and/or smaller range contraction than native species with climate change, leading to a net advantage for nonnative species www.annualreviews.org •Species Range Shifts with Climate Change 31 Downloaded from www.annualreviews.org. Guest (guest) IP: 193.147.173.203 On: Mon, 19 May 2025 09:42:12 ES55_Art02_Bradley ARjats.cls October 7, 2024 17:42 Jacobi WR,Hardin JG,Goodrich BA, Cleaver CM.2012. Retail firewood can transport live tree pests.J. Econ. Entomol. 105(5):1645–58 Jauni M, Gripenberg S, Ramula S. 2015. Non-native plant species benefit from disturbance: a meta-analysis. Oikos 124(2):122–29 Jeschke JM, Pyšek P. 2018. Tens rule. In Invasion Biology: Hypotheses and Evidence, ed. JM Jeschke, T Heger, pp. 124–32. Wallingford, UK: CABI Kawecki TJ. 2008. Adaptation to marginal habitats. Annu. Rev. Ecol. Evol. Syst. 39:321–42 Kolbe JJ,Glor RE,Schettino LR,Lara AC, Larson A,Losos JB.2007.Multiple sources,admixture,and genetic variation in introduced Anolis lizard populations. Conserv. Biol. 21(6):1612–25 Kremen C, Cameron A, Moilanen A, Phillips SJ, Thomas CD, et al. 2008. Aligning conservation priorities across taxa in Madagascar with high-resolution planning tools. Science 320(5873):222–26 Langham GM, Schuetz JG, Distler T, Soykan CU, Wilsey C. 2015. Conservation status of North American birds in the face of future climate change. PLOS ONE 10(9):e0135350 Lenoir J, Bertrand R, Comte L, Bourgeaud L, Hattab T, et al. 2020. Species better track climate warming in the oceans than on land. Nat. Ecol. Evol. 4(8):1044–59 Lenoir J, Svenning J-C. 2015. Climate-related range shifts—a global multidimensional synthesis and new research directions. Ecography 38(1):15–28 Liebhold AM, Brockerhoff EG, Kalisz S, Nuñez MA, Wardle DA, Wingfield MJ. 2017. Biological invasions in forest ecosystems. Biol. Invasions 19(11):3437–58 Liu C,Wolter C,Xian W,Jeschke JM.2020.Most invasive species largely conserve their climatic niche.PNAS 117(38):23643–51 Liu H, Stiling P. 2006. Testing the enemy release hypothesis: a review and meta-analysis. Biol. Invasions. 8(7):1535–45 Loarie SR, Duffy PB, Hamilton H, Asner GP, Field CB, Ackerly DD. 2009. The velocity of climate change. Nature 462(7276):1052–55 Lockwood JL, Welbourne DJ, Romagosa CM, Cassey P, Mandrak NE, et al. 2019. When pets become pests: the role of the exotic pet trade in producing invasive vertebrate animals.Front. Ecol. Environ. 17(6):323–30 Maron JL, Vilà M. 2001. When do herbivores affect plant invasion? Evidence for the natural enemies and biotic resistance hypotheses. Oikos 95(3):361–73 Mason RAB, Cooke J, Moles AT, Leishman MR. 2008. Reproductive output of invasive versus native plants. Global Ecol. Biogeogr. 17(5):633–40 Mason SC, Palmer G, Fox R, Gillings S, Hill JK, et al. 2015. Geographical range margins of many taxonomic groups continue to shift polewards. Biol. J. Linnean Soc. 115(3):586–97 McLachlan JS, Hellmann JJ, Schwartz MW. 2007. A framework for debate of assisted migration in an era of climate change. Conserv. Biol. 21(2):297–302 Nackley LL, West AG, Skowno AL, Bond WJ. 2017. The nebulous ecology of native invasions. Trends Ecol. Evol. 32(11):814–24 Padilla DK, Williams SL. 2004. Beyond ballast water: aquarium and ornamental trades as sources of invasive species in aquatic ecosystems. Front. Ecol. Environ. 2(3):131–38 Parmesan C, Yohe G. 2003. A globally coherent fingerprint of climate change impacts across natural systems. Nature 421(6918):37–42 Pearson RG, Dawson TP. 2003. Predicting the impacts of climate change on the distribution of species: Are bioclimate envelope models useful? Global Ecol. Biogeogr. 12(5):361–71 Pecl GT, Araújo MB, Bell JD, Blanchard J, Bonebrake TC, et al. 2017. Biodiversity redistribution under climate change: impacts on ecosystems and human well-being. Science 355(6332):eaai9214 PetschDK,dosSantos BertoncinAP,OrtegaJCG,ThomazSM.2022.Non-nativespecies drivebiotic homogenization, but it depends on the realm, beta diversity facet and study design: a meta-analytic systematic review. Oikos 2022(6):e08768 Pfadenhauer WG, Bradley BA. 2024. Quantifying vulnerability to plant invasion across global ecosystems. bioRxiv 2024.02.21.581382. https://doi.org/10.1101/2024.02.21.581382 Pfadenhauer WG, Nelson MF, Laginhas BB, Bradley BA. 2023. Remember your roots: Biogeographic properties of plants’ native habitats can inform invasive plant risk assessments. Divers. Distrib. 29(1):4–18 38 Bradley et al. Downloaded from www.annualreviews.org. Guest (guest) IP: 193.147.173.203 On: Mon, 19 May 2025 09:42:12 ES55_Art02_Bradley ARjats.cls October 7, 2024 17:42 Quintero I, Wiens JJ. 2013. Rates of projected climate change dramatically exceed past rates of climatic niche evolution among vertebrate species. Ecol. Lett. 16(8):1095–103 Radinger J,García-Berthou E. 2020.The role of connectivity in the interplay between climate change and the spread of alien fish in a large Mediterranean river. Global Change Biol. 26(11):6383–98 Rapoport EH. 2000. Remarks on the biogeography of land invasions. Rev. Chil. Hist. Nat. 73(2):367–80 Reichard SH, White P. 2001. Horticulture as a pathway of invasive plant introductions in the United States: Most invasive plants have been introduced for horticultural use by nurseries, botanical gardens, and individuals. BioScience 51(2):103–13 Resasco J, Haddad NM, Orrock JL, Shoemaker D, Brudvig LA, et al. 2014. Landscape corridors can increase invasion by an exotic species and reduce diversity of native species. Ecology 95(8):2033–39 Rilov G, Galil B. 2009. Marine bioinvasions in the Mediterranean Sea – history, distribution and ecology. In Biological Invasions in Marine Ecosystems: Ecological, Management, and Geographic Perspectives, ed. G Rilov, JA Crooks, pp. 549–75. Berlin, Heidelberg: Springer Rius M, Darling JA. 2014. How important is intraspecific genetic admixture to the success of colonising populations? Trends Ecol. Evol. 29(4):233–42 Roy HE,Pauchard A,Stoett P,Renard Truong T,Bacher S,et al.2023.IPBES Invasive Alien Species Assessment: Summary for Policymakers. IPBES Secr., Bonn, Germany. https://doi.org/10.5281/zenodo.10127924 Rubenstein MA, Weiskopf SR, Bertrand R, Carter SL, Comte L, et al. 2024. CoRE (Contractions or Range Expansions) Database: Global Database of Species Range Shifts from 1802–2019. US Geological Survey, Reston, VA, updated Mar. 29. https://doi.org/10.5066/P99VP2TW Seebens H, Blackburn TM, Dyer EE, Genovesi P, Hulme PE, et al. 2017. No saturation in the accumulation of alien species worldwide. Nat. Commun. 8(1):14435 Seebens H, Blackburn TM, Hulme PE, van Kleunen M, Liebhold AM, et al. 2021. Around the world in 500 years: inter-regional spread of alien species over recent centuries.Global Ecol. Biogeogr. 30(8):1621–32 Simberloff D. 2000. Global climate change and introduced species in United States forests. Sci. Total Environ. 262(3):253–61 Smith AL, Hodkinson TR, Villellas J, Catford JA, Cserg˝ o AM, et al. 2020. Global gene flow releases invasive plants from environmental constraints on genetic diversity. PNAS 117(8):4218–27 Somero GN. 2010. The physiology of climate change: How potentials for acclimatization and genetic adaptation will determine ‘winners’ and ‘losers.’ J. Exp. Biol. 213(6):912–20 Sorte CJB, Williams SL, Carlton JT. 2010. Marine range shifts and species introductions: comparative spread rates and community impacts. Global Ecol. Biogeogr. 19(3):303–16 Suarez AV, Holway DA, Case TJ.2001. Patterns of spread in biological invasions dominated by long-distance jump dispersal: insights from Argentine ants. PNAS 98(3):1095–100 Tallamy DW, Shropshire KJ. 2009. Ranking lepidopteran use of native versus introduced plants. Conserv. Biol. 23(4):941–47 Theoharides KA,Dukes JS.2007.Plant invasion across space and time: factors affecting nonindigenous species success during four stages of invasion. New Phytologist 176(2):256–73 Torchin ME,Mitchell CE.2004.Parasites,pathogens,and invasions by plants and animals.Front. Ecol. Environ. 2(4):183–90 Twardek WM, Taylor JJ, Rytwinski T, Aitken SN, MacDonald AL, et al. 2023. The application of assisted migration as a climate change adaptation tactic: an evidence map and synthesis.Biol. Conserv. 280:109932 USFWS(US FishWildl.Serv.).2023.Endangered and Threatened Wildlife and Plants; Designation of Experimental Populations. 88 FR 42642, USFWS, Washington, DC. https://www.federalregister.gov/documents/ 2023/07/03/2023-13672/endangered-and-threatened-wildlife-and-plants-designation-of- experimental-populations Václavík T, Meentemeyer RK. 2012. Equilibrium or not? Modelling potential distribution of invasive species in different stages of invasion. Divers. Distrib. 18(1):73–83 Van der Veken S, Hermy M, Vellend M, Knapen A, Verheyen K. 2008. Garden plants get a head start on climate change. Front. Ecol. Environ. 6(4):212–16 van Kleunen M, Bossdorf O, Dawson W. 2018a. The ecology and evolution of alien plants. Annu. Rev. Ecol. Evol. Syst. 49:25–47 www.annualreviews.org •Species Range Shifts with Climate Change 39 Downloaded from www.annualreviews.org. Guest (guest) IP: 193.147.173.203 On: Mon, 19 May 2025 09:42:12 ES55_Art02_Bradley ARjats.cls October 7, 2024 17:42 van Kleunen M, Essl F, Pergl J, Brundu G, Carboni M, et al. 2018b. The changing role of ornamental horticulture in alien plant invasions. Biol. Rev. 93(3):1421–37 Vilà M, Dunn AM, Essl F, Gómez-Díaz E, Hulme PE, et al. 2021. Viewing emerging human infectious epidemics through the lens of invasion biology. BioScience 71(7):722–40 Vilà M, Ibáñez I. 2011. Plant invasions in the landscape. Landscape Ecol. 26(4):461–72 Vu Ho K, Kröel-Dulay G, Tölgyesi C, Bátori Z, Tanács E, et al. 2023. Non-native tree plantations are weak substitutes for near-natural forests regarding plant diversity and ecological value. Forest Ecol. Manag. 531:120789 WallingfordPD,MorelliTL,AllenJM,BeauryEM,BlumenthalDM,etal.2020.Adjusting thelens ofinvasion biology to focus on the impacts of climate-driven range shifts. Nat. Clim. Chang. 10(5):398–405 Warren R, Price J, Graham E, Forstenhaeusler N, VanDerWal J. 2018. The projected effect on insects, vertebrates, and plants of limiting global warming to 1.5°C rather than 2°C. Science 360(6390):791–95 Whittaker RH. 1970. Communities and Ecosystems. London: Macmillan Williams JW, Jackson ST, Kutzbach JE. 2007. Projected distributions of novel and disappearing climates by 2100 AD. PNAS 104(14):5738–42 Willis CG, Ruhfel BR, Primack RB, Miller-Rushing AJ, Losos JB, Davis CC. 2010. Favorable climate change response explains non-native species’ success in Thoreau’s woods. PLOS ONE 5(1):e8878 Willis KJ, MacDonald GM. 2011. Long-term ecological records and their relevance to climate change predictions for a warmer world. Annu. Rev. Ecol. Evol. Syst. 42:267–87 Zerebecki RA, Sorte CJB. 2011. Temperature tolerance and stress proteins as mechanisms of invasive species success. PLOS ONE 6(4):e14806 Zhang J, Nielsen SE, Chen Y, Georges D, Qin Y, et al. 2017. Extinction risk of North American seed plants elevated by climate and land-use change. J. Appl. Ecol. 54(1):303–12 Zhao Y-Z, Liu M-C, Feng Y-L, Wang D, Feng W-W, et al. 2020. Release from below- and aboveground natural enemies contributes to invasion success of a temperate invader. Plant Soil 452(1):19–28 40 Bradley et al.