Southward Range Expansion Research Articles

Field monitoring and genetic diversity of the large copper butterfly <i>Lycaena dispar</i> (Lepidoptera: Lycaenidae)

The large copper butterfly Lycaena dispar (Haworth, 1803) (Lepidoptera: Lycaenidae), which is found across Europe and Asia, has been categorized as a near-threatened species (NT) in South Korea from 2012 mainly due to limited distribution. The species has been infrequently observed outside its traditional range in the northwestern region, but no nationwide survey has yet been conducted. In addition, the population genetic data of L. dispar, which is informative to evaluate its vulnerability, remains unknown. In this study, we visited 36 sites spread across all South Korean provinces to verify the distributional range of the species. Mitochondrial cytochrome oxidase subunit I (COI) was also partially sequenced for 53 individuals from nine sites. We observed L. dispar at 15 sites in six provinces, including the two previously known provinces, indicating a southward range expansion. The in-field monitoring and genetic data collectively suggested that L. dispar does not have a limited distribution nor is it isolated, indicating that it should be reclassified as less vulnerable. Our study demonstrates that the combination of field and genetic data can provide a more reliable assessment of the stability of a species.

Rapid southward range expansion of the Fairy Gerygone – a consequence of climate change?

Until the 1920s, the Australian range of the Fairy Gerygone Gerygone palpebrosa was thought to extend south from Cape York to Cardwell (18.3°S), Queensland. However, by 1981 the species was known to occur as far south as Tin Can Bay (25.9°S), and, by 1990, the Sunshine Coast (26.6°S). Sightings of individuals in the Brisbane region (27.5°S), 170 km south of Tin Can Bay, during 2011 and 2012 prompted a review of the southern range limits of the species, and consideration of causes for its southward range expansion. I collated records south of the 26°S parallel using three databases (eBird, WildNet and Atlas of Living Australia), then selected 30 sites that represented their spatial and temporal extent, noting their elevation, distance to the nearest coastline or watercourse, and vegetation according to the Regional Ecosystem classification. Sightings in the Brisbane region have been mostly along rivers or creeks emptying into Moreton Bay, suggesting that dispersal occurs southward along the coast, then inland via watercourses. Rather than being gradual, range expansion in this species has been characterised by ‘leaps’ of 45–59 km at intervals of 6–16 years. Since the early 1970s, at least five other tropical bird species have expanded their range southwards to Coastal Central Queensland. The most likely explanation for such range expansions is birds exploiting ‘new’ areas with suitable thermal regimes that have become available due to global warming. In the Fairy Gerygone, this process may be facilitated by (1) this species’ partiality for forest edge and riparian habitats, and (2) reduced competition with other gerygone species due to differences in preferred habitats and bill morphology.

Hybridization of Atlantic puffins in the Arctic coincides with 20th-century climate change.

The Arctic is experiencing the fastest rates of global warming, leading to shifts in the distribution of its biota and increasing the potential for hybridization. However, genomic evidence of recent hybridization events in the Arctic remains unexpectedly rare. Here, we use whole-genome sequencing of contemporary and 122-year-old historical specimens to investigate the origin of an Arctic hybrid population of Atlantic puffins (Fratercula arctica) on Bjørnøya, Norway. We show that the hybridization between the High Arctic, large-bodied subspecies F. a. naumanni and the temperate, smaller-sized subspecies F. a. arctica began as recently as six generations ago due to an unexpected southward range expansion of F. a. naumanni. Moreover, we find a significant temporal loss of genetic diversity across Arctic and temperate puffin populations. Our observations provide compelling genomic evidence of the impacts of recent distributional shifts and loss of diversity in Arctic communities during the 20th century.

Plasticity and associated epigenetic mechanisms play a role in thermal evolution during range expansion.

Due to global change, many species are shifting their distribution and are thereby confronted with novel thermal conditions at the moving range edges. Especially during the initial phases of exposure to a new environment, it has been hypothesized that plasticity and associated epigenetic mechanisms enable species to cope with environmental change. We tested this idea by capitalizing on the well-documented southward range expansion of the damselfly Ischnura elegans from France into Spain where the species invaded warmer regions in the 1950s in eastern Spain (old edge region) and in the 2010s in central Spain (new edge region). Using a common garden experiment at rearing temperatures matching the ancestral and invaded thermal regimes, we tested for evolutionary changes in (thermal plasticity in) larval life history and heat tolerance in these expansion zones. Through the use of de- and hypermethylating agents, we tested whether epigenetic mechanisms play a role in enabling heat tolerance during expansion. We used the phenotype of the native sister species in Spain, I. graellsii, as proxy for the locally adapted phenotype. New edge populations converged toward the phenotype of the native species through plastic thermal responses in life history and heat tolerance while old edge populations (partly) constitutively evolved a faster life history and higher heat tolerance than the core populations, thereby matching the native species. Only the heat tolerance of new edge populations increased significantly when exposed to the hypermethylating agent. This suggests that the DNA methylation machinery is more amenable to perturbation at the new edge and shows it is able to play a role in achieving a higher heat tolerance. Our results show that both (evolved) plasticity as well as associated epigenetic mechanisms are initially important when facing new thermal regimes but that their importance diminishes with time.

Status, trends, and equilibrium abundance estimates of the translocated sea otter population in Washington State

AbstractSea otters (Enhydra lutris kenyoni) historically occurred in Washington State, USA, until their local extinction in the early 1900s as a result of the maritime fur trade. Following their extirpation, 59 sea otters were translocated from Amchitka Island, Alaska, USA, to the coast of Washington, with 29 released at Point Grenville in 1969 and 30 released at La Push in 1970. The Washington Department of Fish and Wildlife has outlined 2 main objectives for sea otter recovery: a target population level and a target geographic distribution. Recovery criteria are based on estimates of population abundance, equilibrium abundance (K), and geographic distribution; therefore, estimates of these parameters have important management implications. We compiled available survey data for sea otters in Washington State since their translocation (1977–2019) and fit a Bayesian state‐space model to estimate past and current abundance, and equilibrium abundance at multiple spatial scales. We then used forward projections of population dynamics to explore potential scenarios of range recolonization and as the basis of a sensitivity analysis to evaluate the relative influence of movement behavior, frontal wave speed, intrinsic growth, and equilibrium density on future population recovery potential. Our model improves upon previous analyses of sea otter population dynamics in Washington by partitioning and quantifying sources of estimation error to estimate population dynamics, by providing robust estimates ofK, and by simulating long‐term population growth and range expansion under a range of realistic parameter values. Our model resulted in predictions of population abundance that closely matched observed counts. At the range‐wide scale, the population size in our model increased from an average of 21 independent sea otters (95% CI = 13–29) in 1977 to 2,336 independent sea otters (95% CI = 1,467–3,359) in 2019. The average estimated annual growth rate was 12.42% and varied at a sub‐regional scale from 6.42–14.92%. The overall estimated meanKdensity of sea otters in Washington was 1.71 ± 0.90 (SD) independent sea otters/km2of habitat (1.96 ± 1.04 sea otters/km2, including pups), and estimated densities within the current range correspond on average to 87% of mean sub‐regional equilibrium values (range = 66–111%). The projected value ofKfor all of Washington was 5,287 independent sea otters (95% CI = 2,488–8,086) and 6,080 sea otters including pups (95% CI = 2,861–9,300), assuming a similar range of equilibrium densities in currently un‐occupied habitats. Sensitivity analysis of simulations of sea otter population growth and range expansion suggested that meanKdensity estimates in currently occupied sub‐regions had the largest impact on predicted future population growth (r2 = 0.52), followed by the rate of southward range expansion (r2 = 0.26) and the meanKdensity estimate of currently unoccupied sub‐regions to the south of the current range (r2 = 0.04). Our estimates of abundance and sensitivity analysis of simulations of future population abundance and geographic range help determine population status in relation to population recovery targets and identify the most influential parameters affecting future population growth and range expansion for sea otters in Washington State.

Мишоподібні гризуни та землерийки в Харківській області (Україна):видовий склад, поширення, стан популяцій

Since 1957, zoologists of the Kharkiv Sanitary and Epidemiological Station have been conducting annual monitoring of small mammals in Kharkiv Oblast. To assess the current state of populations of mouse-like rodents and shrews, we analysed a dataset for the period from 2000 to 2018. The small mammal fauna was studied at 117 sites in 27 districts (raions) of Kharkiv Oblast. Various types of oak forests, dry and floodplain meadows, riparian vegetation, steppe areas, forest stripes, gardens, fields, and haystacks were examined. Four species of insectivores and 16 species of mouse-like rodents were identified. The dominant and widespread species in the region are Sylvaemus uralensis, Apodemus agrarius, Sorex araneus, Microtus levis, Myodes glareolus, and Sylvaemus tauricus. Some species are less common and in some areas of the region have not yet been identified, including Sorex minutus, Sylvaemus sylvaticus, Crocidura suaveolens, Micromys minutus, Cricetulus migratorius, and Microtus oeconomus. The least common species with single records include Neomys fodiens, Mus spicilegus, Lagurus lagurus, Terricola subterraneus, Dryomys nitedula, and Arvicola amphibius. Indigenous species of the region include seven species, another seven species are those that increased their number and range, three species have recently appeared in the region due to dispersal from adjacent territories, while, on the contrary, the abundance and range of three species have declines. Microtus oeconomus is characterised by a current southward range expansion. Myodes glareolus, which was mentioned in the last century north of our region, is now widely distributed throughout the region and further south. Lagurus lagurus is an invasive species with periodic population outbreaks in the region and currently is rarely recorded.

Morphological and molecular identification of the invasive freshwater snail Physa acuta (Gastropoda: Physidae) into Llanquihue Lake, Chilean Patagonia.

The sewage snail Physa acuta, native to North America, is an effective invasive species around the world. In Chile, it was first reported in 2014 in the north central area of the country. So far, the species has not been recorded in southern Chile. Sampling performed in 2015 in three localities from Llanquihue Lake, Chilean Patagonia, only provided native freshwater snails. However, new collections performed in February 2018 in the same three sites were successful for physid specimens suggesting a biological invasion entailing a large southward range expansion of these snails. Here we performed morphological, microstructural and phylogenetic analyses to investigate whether the new samples belong to Physa acuta. The shell morphology, male copulatory complex and radula microstructure of the new material agree with those of the sewage snail. The molecular phylogenetic analyses using the cytochrome c oxidase subunit 1 (COI) gene confirmed morphological identification. We suggest to take prompt measures to prevent the expansion of Physa acuta in Llanquihue Lake or nearby aquatic ecosystems.

Rapid southward and upward range expansion of a tropical songbird, the Thrush-like Wren (Campylorhynchus turdinus), in South America: a consequence of habitat or climate change?

The Thrush-like Wren (Campylorhynchus turdinus) is a polytypic, non-migratory, cooperatively breeding species of bird widely distributed in central South America. In recent decades it has expanded its range by approximately 24%, based on a published map of its distribution in the mid-1980s and recent reports submitted to eBird up through March 2017. The northwestern subspecies, C. t. hypostictus, dramatically expanded its elevation range upward from approximately 1200 m to 4200 m a.s.l. in the Peruvian Andes. During 1977–2015 the southwestern subspecies, C. t. unicolor, dramatically expanded the southern border of its range from central Brazil and northern Paraguay (approximately 22°06’S) southward into northeastern Argentina and throughout Paraguay to 29°40’S in southeastern Brazil, extending its range east-southeast approximately 934 km at a rate of 24.6 km/yr, and latitudinally southward 838 km at a rate of 22.1 km/yr. It also expanded its range westward into the relatively dry Chaco of western Paraguay and north-central Argentina. Midwinter records near the southern border of its range in northeastern Argentina suggest it is non-migratory. Because of its affinity for disturbed habitats, its range expansion has been attributed to deforestation, but its range expansion is also consistent with the prediction that organisms are extending their geographic distribution toward higher latitudes and elevations as a consequence of climate change.

Public engagement offers insights on the Eurasian red squirrel distribution

After centuries of absence, the Eurasian red squirrel (Sciurus vulgaris) is recolonizing and expanding throughout Portugal. We implemented an online community-based project, which enabled us to obtain unprecedented records on the Eurasian red squirrel distribution, not only allowing us to map its current extent area but also to reconstruct its southward range expansion during the past years in Portugal. Possible origins of dispersion are forested areas in the northwestern and eastern Spanish borders and sites of reintroductions in Lisbon, Porto, and Coimbra. This well-established public engagement platform sets a successful example of integrated efforts between society and academy in gathering data on species distribution.

Effects of temperature, salinity and composition of the dinoflagellate assemblage on the growth of Gambierdiscus carpenteri isolated from the Great Barrier Reef

Increases in reported incidence of ciguatera fish poisoning (hereafter ciguatera) have been linked to warmer sea temperatures that are known to trigger coral bleaching events. The drivers that trigger blooms of ciguatera-causing dinoflagellates on the Great Barrier Reef (GBR) are poorly understood. This study investigated the effects of increased temperatures and lowered salinities, often associated with environmental disturbance events, on the population growth of two strains of the potentially ciguatera-causing dinoflagellate, Gambierdiscus carpenteri (NQAIF116 and NQAIF380). Both strains were isolated from the central GBR with NQAIF116 being an inshore strain and NQAIF380 an isolate from a stable environment of a large coral reef aquarium exhibit in ReefHQ, Townsville, Australia. Species of Gambierdiscus are often found as part of a mixed assemblage of benthic toxic dinoflagellates on macroalgal substrates. The effect of assemblage structure of dinoflagellates on the growth of Gambierdiscus populations has, however, not been explored. The study, therefore investigated the growth of G. carpenteri within mixed assemblages of benthic dinoflagellates. Population growth was monitored over a period of 28days under three salinities (16, 26 and 36) and three temperature (24, 28 and 34°C) conditions in a fully crossed experimental design. Temperature and salinity had a significant effect on population growth. Strain NQAIF380 exhibited significantly higher growth at 28°C compared to strain NQAIF116, which had highest growth at 24°C. When strain NQAIF116 was co-cultured with the benthic dinoflagellates, Prorocentrum lima and Ostreopsis sp., inhibitory effects on population growth were observed at a salinity of 36. In contrast, growth stimulation of G. carpenteri (strain NQAIF116) was observed at a salinity of 26 and particularly at 16 when co-cultured with Ostreopsis-dominated assemblages. Range expansion of ciguatera-causing dinoflagellates could lead to higher frequency of reported ciguatera illness in populated temperate Australian regions, outside the tropical range of the GBR. Therefore, the findings on salinity and temperature tolerance of two strains of G. carpenteri indicates potential adaptability to different local environmental conditions. These are baseline data for future investigations into the potential southward range expansion of ciguatera-causing dinoflagellates originating from the GBR.

Islands within an island: Population genetic structure of the endemic Sardinian newt, Euproctus platycephalus.

The identification of historic and contemporary barriers to dispersal is central to the conservation of endangered amphibians, but may be hindered by their complex life history and elusive nature. The complementary information generated by mitochondrial (mtDNA) and microsatellite markers generates a valuable tool in elucidating population structure and the impact of habitat fragmentation. We applied this approach to the study of an endangered montane newt, Euproctus platycephalus. Endemic to the Mediterranean island of Sardinia, it is threatened by anthropogenic activity, disease, and climate change. We have demonstrated a clear hierarchy of structure across genetically divergent and spatially distinct subpopulations. Divergence between three main mountain regions dominated genetic partitioning with both markers. Mitochondrial phylogeography revealed a deep division dating to ca. 1 million years ago (Mya), isolating the northern region, and further differentiation between the central and southern regions ca. 0.5 Mya, suggesting an association with Pleistocene severe glacial oscillations. Our findings are consistent with a model of southward range expansion during glacial periods, with postglacial range retraction to montane habitat and subsequent genetic isolation. Microsatellite markers revealed further strong population structure, demonstrating significant divergence within the central region, and partial differentiation within the south. The northern population showed reduced genetic diversity. Discordance between mitochondrial and microsatellite markers at this scale indicated a further complexity of population structure, in keeping with male‐biased dispersal and female philopatry. Our study underscores the need to elucidate cryptic population structure in the ecology and conservation strategies for endangered island‐restricted amphibians, especially in the context of disease and climate change.

Influence of past and future climate changes on the distribution of three Southeast Asian murine rodents

AbstractAimWe tested the influence of Pleistocene climatic fluctuations and the potential effect of future climate change on Southeast Asian small mammal distributions using two forest‐dwelling (Leopoldamys herberti and Leopoldamys sabanus) and one karst (Leopoldamys neilli) endemic rodent species as models.LocationSoutheast Asia.MethodsWe used presence–absence data of genetically identified individuals, bioclimatic variables and species distribution modelling techniques to predict potential distributions of the three studied species under current, past [Last Interglacial (LIG) and Last Glacial Maximum (LGM)] and future conditions. We applied a variety of modelling techniques and then used consensus techniques to draw up robust maps of potential distribution ranges at all stages.ResultsAccording to our models, these three Leopoldamys species did not experience significant range contraction during the LGM. Our models revealed substantial range contraction during the LIG for L. herberti in northern Indochina, while its distribution expanded in southern Indochina. Evidence of a southward range expansion during that period was also obtained for L. neilli, whereas L. sabanus remained widely distributed in insular Southeast Asia but experienced a range contraction on the Thai‐Malay Peninsula. The two future climate change scenarios used predicted that large climatically suitable areas would still be available in the future for the three species.Main conclusionsOur model predictions contradict the well‐established hypothesis that Southeast Asian forest‐dwelling species were confined to small refugia during the LGM. Moreover, our results suggest that some Southeast Asian taxa may have been distributed in their refugial state during the LIG rather than the LGM. This could be because of vegetation changes that may have occurred at that time as a result of the increased seasonality observed during the LIG. These Pleistocene refugia may have been localized in northern Indochina but our study also revealed that southern Indochina could provide major potential refugia.

Limited pollen flow and high selfing rates toward geographic range limit in an Atlantic forest bromeliad

Bromeliaceae is a Neotropical family that evolved ecological key innovations in association with extensive adaptive radiation. Its species present a variety of different mating system strategies varying within and among species, within genera and subfamilies. Also, species with a wide geographical range can display large variation in mating system, reproductive success and genetic diversity. Here we combined data from hand pollinations and genetic analysis to assess outcomes of contemporary gene flow and mating system variation at the range edge of Vriesea gigantea. Results from pollen germination rates showed that this species is cryptically self-incompatible. Hand-pollination experiments and genetic analysis of progeny arrays revealed that V. gigantea has a mixed mating system, with high selfing rates (s=0.612), and high inbreeding coefficient (F=0.372). Inbreeding in V. gigantea at southern edge of its distribution range was caused by high levels of selfing rather than by mating among relatives. Moreover, strong pollen pool genetic structure was observed (Φ’FT=0.671), with an increase from north to south. The parameters observed help us to understand historical and ecological conditions under which V. gigantea has experienced moderate to high levels of selfing in the face of reduced pollen flow from central to peripheral populations due to recent southward range expansion.

Climate-induced range shifts of the American jackknife clam Ensis directus in Europe

Mapping the future potential distribution of alien species has become an issue of great concern. Ecological niche models are increasingly used to forecast the spatial range of introduced species in the context of climate warming. Here, we studied the potential spread of the American jackknife clam Ensis directus into European waters. E. directus, a marine bivalve native to the American coasts, was observed in Europe for the first time in the German Bight at the end of the 1970s. Afterwards, the clam quickly colonized the surrounding waters of the North Sea. Although many studies focused on its biology, ecology and colonization, the extent to which E. directus may invade European and Nordic seas remained poorly known. In this study, we used two ecological niche models (ENMs), calibrated on the native area of the mollusk, to evaluate the potential distributional range of the bivalve over European seas. Under current environmental conditions, E. directus should continue to progress towards the southern coasts of France and may also invade new areas in the Adriatic Sea. Projections for the end of the century suggest that the probability of occurrence of E. directus increases from Denmark to France with both ENMs. The Tunisian coasts may also become a new suitable area for the mollusk but the results of the two ENMs differ for this region. Therefore, contrary to what is often observed, a southward range expansion of E. directus is probable, especially as climate will get warmer.

Integrative taxonomy of a poorly known Sahelian rodent, Gerbillus nancillus (Muridae, Gerbillinae)

Aridification processes that affected the Sahelian area of West Africa during the last decades have induced significant changes in plant and animal communities of this region. In rodents, the genus Gerbillus characteristic of North African and Asian arid habitats has been affected by this climatic and environmental trends. Several species of this genus showed a southward range expansion in recent years into the Sahelian bioclimatic zone. Recent sampling in several localities of West Africa (Mali, Niger and Senegal) enabled us to collect numerous specimens of small gerbils. An integrative study of these samples using molecular, morphological and cytogenetical methods revealed that many of them were attributable to Gerbillus nancillus, a secretive and poorly known species. Gerbillus nancillus appears characterized by a well differentiated karyotype with 2n=56 chromosomes, and to represent a unique genetic lineage within this genus. Body and skull measurements of G. nancillus were compared with those of the morphologically similar Gerbillus henleyi, which provided diagnostic clues between them. These new data significantly expand the distribution area of G. nancillus, which now ranges from Sudan in the East to Senegal in the West. G. nancillus is here reported from numerous new localities in Niger and Mali, and for the first time in Senegal, which raises questions about the origin of its presence and the colonization routes it followed to get there. We also show that G. henleyi and G. nancillus are sympatric and apparently often syntopic in the sub-Saharan part of the distribution of G. henleyi.

Ecological coassociations influence species' responses to past climatic change: an example from a Sonoran Desert bark beetle

Ecologically interacting species may have phylogeographical histories that are shaped both by features of their abiotic landscape and by biotic constraints imposed by their coassociation. The Baja California peninsula provides an excellent opportunity to examine the influence of abiotic vs. biotic factors on patterns of diversity in plant-insect species.This is because past climatic and geological changes impacted the genetic structure of plants quite differently to that of codistributed free-living animals (e.g. herpetofauna and small mammals). Thus, 'plant-like' patterns should be discernible in host-specific insect herbivores. Here, we investigate the population history of a monophagous bark beetle, Araptus attenuatus, and consider drivers of phylogeographical patterns in the light of previous work on its host plant, Euphorbia lomelii. Using a combination of phylogenetic, coalescent-simulation-based and exploratory analyses of mitochondrial DNA sequences and nuclear genotypic data, we found that the evolutionary history of A. attenuatus exhibits similarities to its host plant that are attributable to both biotic and abiotic processes. Southward range expansion and recent colonization of continental Sonora from the Baja peninsula appear to be unique to this taxon pair and probably reflect influences of the host plant. On the other hand, abiotic factors with landscape level influences on a diverse suite of codistributed arid-adapted taxa, such as Plio- and Pleistocene-aged marine incursions in the region, also left genetic signatures in beetle and host plant populations. Superimposed on these similarities, bark beetle-specific patterns and processes were also evident: our data revealed two secondarily sympatric,reproductively isolated genetic lineages, as well as a previously unrecognized mid peninsular warm desert refuge. Taken together, this work illustrates that the evolutionary history of species-specific insect herbivores may represent a mosaic of influences,including—but not limited to—those imposed by the host plant.

Climate-Driven Range Extension of Amphistegina (Protista, Foraminiferida): Models of Current and Predicted Future Ranges

Species-range expansions are a predicted and realized consequence of global climate change. Climate warming and the poleward widening of the tropical belt have induced range shifts in a variety of marine and terrestrial species. Range expansions may have broad implications on native biota and ecosystem functioning as shifting species may perturb recipient communities. Larger symbiont-bearing foraminifera constitute ubiquitous and prominent components of shallow water ecosystems, and range shifts of these important protists are likely to trigger changes in ecosystem functioning. We have used historical and newly acquired occurrence records to compute current range shifts of Amphistegina spp., a larger symbiont-bearing foraminifera, along the eastern coastline of Africa and compare them to analogous range shifts currently observed in the Mediterranean Sea. The study provides new evidence that amphisteginid foraminifera are rapidly progressing southwestward, closely approaching Port Edward (South Africa) at 31°S. To project future species distributions, we applied a species distribution model (SDM) based on ecological niche constraints of current distribution ranges. Our model indicates that further warming is likely to cause a continued range extension, and predicts dispersal along nearly the entire southeastern coast of Africa. The average rates of amphisteginid range shift were computed between 8 and 2.7 km year−1, and are projected to lead to a total southward range expansion of 267 km, or 2.4° latitude, in the year 2100. Our results corroborate findings from the fossil record that some larger symbiont-bearing foraminifera cope well with rising water temperatures and are beneficiaries of global climate change.

Canals as Vectors for Fish Movement: Potential Southward Range Expansion ofLepisosteus osseusL. (Longnose Gar) in South Florida

Abstract Lepisosteus osseus (Longnose Gar) is a large-bodied predator, whose Florida distribution remains unclear at the southern edge of its range. We reviewed available literature and museum voucher specimens to provide a more accurate range description, and we discuss recent collections in south Florida. Longnose Gar has not been previously reported in natural habitats south of Lake Okeechobee. Instead, records south of the lake are from canals, and most are recent (since 2000), including our own southernmost 2011 record. No records from Everglades natural habitats have been collected. Previous studies have shown native range expansions in anthropogenically disturbed landscapes. We suggest that the Longnose Gar is expanding its range southward in Florida using canals as dispersal vectors and/or suitable habitat.

沖縄における侵入害虫ミツユビナミハダニの分布拡大ならびに本種沖縄個体群に対する各種農薬の殺虫効果

To determine the current status of the southward range expansion of Tetranychus evansi, a recent invader of Japan, we surveyed occurrence of this species on solanaceous plants throughout Okinawa, a southwestern part of Japan. T. evansi was first detected on Okinawa Island where this species has not been found until 2009, suggesting recent range expansion. The occurrence of T. evansi on a commercially-grown eggplant in Japan was first confirmed, alerting us to the further expansion of damage by this pest. Besides the crop plants, T. evansi was frequently found on a weed, Solanum americanum, which is considered a major source plant. When the acaricidal effect of 22 agrochemicals on T. evansi was examined under laboratory conditions, all the tested chemicals except four spiracle-blocking insecticides were highly effective.

Range expansion induces variation in a behavioural trait in an ant–plant mutualism

Climate oscillations produce dramatic changes in species distribution, even in the tropics. The ant–plant Leonardoxa africana africana hosts and feeds the ant Petalomyrmex phylax, which provides protection against herbivores in return. Both partners of this symbiosis present a recent southward range expansion. To test whether the higher investment in sexuals (and thus lower investment in protective workers) previously documented on the colonization front is compensated by a more effective protective behaviour, we compared ant behavioural investment in plant defence between two populations, one in the core of the range and one on the colonization front. We induced ant patrolling activity by artificially damaging leaflets and measured this activity by counting patrolling ants and calculating the increase relative to constitutive patrolling activity measured on control (undamaged) leaflets. Contrary to our expectation, ant behavioural investment in plant defence was lower on the colonization front. Thus, production of fewer workers is not compensated by more protective behaviour of each. Instead, both traits contribute to a phenotype that is less mutualistic as a whole. By favouring increased allocation to dispersal, range expansion can shape ant behavioural traits and potentially the outcome of mutualism.