Southward Range Research Articles

Past and future climate effects on population structure and diversity of North Pacific surfgrasses

AbstractAimUnderstanding the impacts of past and future climate change on genetic diversity and structure is a current major research gap. We ask whether past range shifts explain the observed genetic diversity of surfgrass species and if future climate change projections anticipate genetic diversity losses. Our study aims to identify regions of long‐term climate suitability with higher and unique seagrass genetic diversity and predict future impacts of climate change on them.LocationNortheast Pacific.Time PeriodAnalyses considered a timeframe from the Last Glacial Maximum (LGM; 20 kybp) until one Representative Concentration Pathway (RCP) scenario of future climate changes (RCP 8.5; 2100).Major Taxa StudiedTwo seagrass species belonging to the genus Phyllospadix.MethodsWe estimated population genetic diversity and structure using 11 polymorphic microsatellite markers. We predicted the distribution of the species for the present, LGM, and near future (RCP 8.5, no climate mitigation) using Species Distribution Models (SDMs).ResultsSDMs revealed southward range shifts during the LGM and potential poleward expansions in the future. Genetic diversity of Phyllospadix torreyi decreases from north to south, but in Phyllospadix scouleri the trend is variable. Phyllospadix scouleri displays signals of genome admixture at the southernmost and northernmost edges of its distribution.Main ConclusionsThe genetic patterns observed in the present reveal the influence of climate‐driven range shifts in the past and suggest further consequences of climate change in the future, with potential loss of unique gene pools. This study also shows that investigating climate links to present genetic information at multiple timescales can establish a historical context for analyses of the future evolutionary history of populations.

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.

Incidental pinnipeds at high latitudes of the Vestfold Hills, Prydz Bay, East Antarctica

AbstractSpecies distributions are predicted to change with future climate-associated ecosystem changes such that so-called ‘vagrant’ individuals may become established or re-establish in areas currently thought to be beyond their principle ranges. Survey data were collated for occurrences of pinniped (seal) species at very high latitudes of the Vestfold Hills, East Antarctica. Aside from Weddell seals (Leptonychotes weddellii) and southern elephant seals (Mirounga leonina), which aggregate annually at the Vestfold Hills to breed and/or moult, three other pinniped species were observed with the recession of the fast-ice edge. Leopard seal (Hydrurga leptonyx) occurrences increased with an increase in a seasonally abundant prey resource, and crabeater seals (Lobodon carcinophaga) were seen at a time that coincides with their moult period. Occurrences of sub-adult male Antarctic fur seals (Arctocephalus gazella) increase the known southward range for this species and may reflect population increases at source populations in the Kerguelen Plateau area. Although there were no direct sightings of Ross seals (Ommatophoca rossii), their presence close to the Vestfold Hills was detected by underwater passive acoustic monitoring. Sightings of obligate drift-ice species and sub-Antarctic fur seals may change at the Vestfold Hills with climate-mediated changes in sea-ice conditions.

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.

Decoupling pioneering traits from latitudinal patterns in a north American bird experiencing a southward range shift.

Ecogeographic rules describe spatial patterns in biological trait variation and shed light on the drivers of such variation. In animals, a consensus is emerging that 'pioneering' traits may facilitate range shifts via a set of bold, aggressive and stress-resilient traits. Many of these same traits are associated with more northern latitudes, and most range shifts in the northern hemisphere indicate northward movement. As a consequence, it is unclear whether pioneering traits are simply corollaries of existing latitudinal variation, or whether they override other well-trodden latitudinal patterning as a unique ecogeographic rule of phenotypic variation. The tree swallow Tachycineta bicolor is a songbird undergoing a southward range shift in the eastern United States, in direct opposition of the poleward movement seen in most other native species' range shifts. Because this organic range shift countervails the typical direction of movement, this case study provides for unique ecological insights on organisms and their ability to thrive in our changing world. We sampled female birds across seven populations, quantifying behavioural, physiological and morphological traits. We also used GIS and field data to quantify a core set of ecological factors with strong ties to these traits as well as female performance. Females at more southern expansion sites displayed higher maternal aggression, higher baseline corticosterone and more pronounced elevation of corticosterone following a standardized stressor, contrary to otherwise largely conserved latitudinal patterning in these traits. Microhabitat variation explained some quantitative phenotypic variation, but the expansion and historic ranges did not differ in openness, distance to water or breeding density. This countervailing range shift therefore suggests that pioneering traits are not simply corollaries of existing latitudinal variation, but rather, they may override other well-trodden latitudinal patterning as a unique ecogeographic rule of phenotypic variation.

Impacts of Climate Change on Densities of the Urchin Centrostephanus rodgersii Vary among Marine Regions in Eastern Australia

The urchin Centrostephanus rodgersii is expanding its range southward in eastern Australia, which has been associated with negative ecological impacts, including shifts from kelp forests to barrens. However, limited analyses are available that examine the factors influencing its abundance and distribution across the entirety of this range. Here, we utilise data from 13,085 underwater visual census surveys, from 1992 to 2022, to develop an urchin density model for C. rodgersii across its historical and extending geographical range. We apply this model to examine whether C. rodgersii densities are increasing and to project future urchin densities by 2100 under IPCC climate scenario RCP 8.5. Significant increases in C. rodgersii densities were detected in data for the South-east marine region of Australia, which encompasses Tasmania, Victoria, and the far south coast of New South Wales (NSW) over the last 30 years. In the Temperate East marine region (encompassing Queensland and NSW waters to 36.6° S), however, no significant increases in densities were observed. Future projections indicated that further substantial increases in C. rodgersii densities are likely to occur in the South-east marine region and substantial reductions in most of the Temperate East marine region by 2100. Importantly, results indicate that current and future changes to C. rodgersii densities in Australia vary among marine regions. Therefore, the future ecological impacts of urchins on temperate ecosystems, including the formation of barrens, will also vary among regions. Consequently, management actions will need to differ among these regions, with the South-east marine region requiring mitigation of the impacts of increasing C. rodgersii densities, whereas the Temperate East marine region may need actions to preserve declining C. rodgersii populations.

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.

Southward range extension and transboundary movements of reef manta rays Mobula alfredi along the east African coastline.

Opportunistic in-water and aerial surveys in South Africa and the analysis of contributed citizen science data have extended the known range of reef manta rays Mobula alfredi along the eastern coast of Africa by 140 km (to Mdumbi Beach) and verified the first transboundary movements for the species. Additionally, six new long-range dispersal records have provided evidence of connectivity with the M. alfredi population off the Inhambane coastline of Mozambique. Five of these records captured one-way movements, the longest of which was an individual that travelled 505 km from Praia do Tofo to Sodwana Bay with 301 days between sightings. A single individual made a return trip between Závora, Mozambique and Sodwana Bay, South Africa (a total distance of ~870 km). These findings support the Convention on Migratory Species listing for the species, suggesting regional transboundary management units are warranted for this wide-ranging elasmobranch.

First record of Warren's sixgill sawshark Pliotrema warreni (Pristiophoriformes: Pristiophoridae) and the West African catshark Scyliorhinus cervigoni (Carcharhiniformes: Scyliorhinidae) in Namibia, and notes on the habitat of the bull shark Carcharhinus leucas (Carcharhiniformes: Carcharhinidae)

Abstract Warren's sixgill sawshark, Pliotrema warreni, is confirmed for the first time in Namibian waters, from two specimens. One specimen was collected by fisheries observers on a vessel fishing in southern Namibian waters in March 2010. The other was found dead on a beach in central coastal Namibia, in August 2014. The West African catshark, Scyliorhinus cervigoni, is documented for the first time in northern Namibia, from a specimen recorded during surveys of chondrichthyan bycatch on a commercial bottom trawler. This extends the species' range southwards from Angola. Records of bull sharks Carcharhinus leucas are also documented, providing a better understanding of their distribution in Namibia. Several anglers have reported catching bull sharks in the Kunene River (from the riverbank on the Namibian side) and just south of the river mouth, along the Namibian coast.

Range reexpansion after long stasis: Italian otters (Lutra lutra) at their northern edge.

Species range shifts and expansion are subjects of primary research interest in the context of climate warming and biological invasions. Few studies have focused on reexpansion of species that suffered severe declines. Here, we focused on population recovery of Eurasian otters (Lutra lutra) in Italy, first detected in 2003 after a southward range contraction. We modeled the rate of range expansion and occupancy at the northern expanding front (central Italy), to gain insights into the progress of recovery and mechanisms of reexpansion. We performed a field survey in 2021, which redefined the northern limit of distribution further north, in close proximity to the Gran Sasso National Park. Then we analyzed a time series (1985-2021) of distances of northernmost occurrences from the center of the 1985 range. Using segmented regression, we were able to identify a prolonged stasis of the northern range edge and a simultaneous increase in occupancy from 0.151 to 0.4. A breakpoint was estimated in 2006, after which the range expanded northwards at an average rate of 5.48 km/year. From 2006 to 2021, the overall northward shift was about 80 km. Occupancy continued to increase until 2019 and abruptly declined in 2021. These patterns suggest that the reexpansion of the range can be limited by low occupancy at the expanding front. As occupancy increases, long-distance dispersal increases and then range expands. The low occupancy at the current distribution limit of otters may reflect a higher anthropogenic pressure on northern habitats, which could slow down the reexpansion process.

Westward range expansion of the eastern rock lobster (Sagmariasus verreauxi) in Australia

Abstract The eastern rock lobster (Sagmariasus verreauxi) inhabits the east coast of Australia from southern Queensland to the South Australian border including Tasmania, with the highest abundances found in New South Wales. Changes in strength, duration, and intensity of the eastern Australian current have expanded the species range southward but until recently, records of the species in western regions of south-eastern Australia were rare. Here, we report the first ever verified records of S. verreauxi in the northern zone rock lobster fishery of South Australia, which are the most westerly records ever documented in terms of overall distribution for this species. We hypothesise that two westward flowing systems, the offshore Flinders current and the inshore coastal current may be possible mechanisms for larval transport.

Multi-decadal changes in the at-sea distribution and abundance of black-browed and light-mantled sooty albatrosses in the southwest Pacific Ocean

Abstract Many long-term studies have reported changes in seabird abundance and distribution in response to climate change and various anthropogenic activities. However, a greater understanding of how species are responding to change over large spatial and temporal scales are required—particularly at high latitudes such as the Southern Ocean. We examined black-browed Thalassarche melanophris (BBAL) and light-mantled sooty Phoebetria palpebrata albatross (LMSA) observations spanning over 50 years. Both species have a wide-ranging distribution in a rapidly changing Southern Ocean. We used generalized additive models (GAMs) to investigate environmental drivers of their abundance and occurrence. Our results show that climate indices, sea surface temperature and sea surface height are the main drivers influencing the distribution and abundance of both species. The abundance of BBAL southeast of Australia was observed to be decreased substantially whereas no significant change was observed in the abundance of LMSA. Both species demonstrated contrasting distributions along their latitudinal gradient with BBAL showing early stages of a southward range shift. Our analyses suggest that responses to climate change are species-specific. These rare, long-term data have provided an understanding of species’ responses to past changes in the marine environment and can provide critical information for future conservation and management.

The first records of Niphargus hrabei and N. potamophilus in Ukraine and Bulgaria significantly enlarge the ranges of these species

Niphargus comprises hundreds of narrowly-endemic West Palaearctic subterranean taxa. However, a few exceptional species inhabit surface waters and have remarkably large ranges. Herein, based on morphological and molecular analyses, we provide important new records for two of these species. N. potamophilus, previously known from the eastern Azov Sea lowlands, is reported for the first time from Ukraine and Bulgaria from localities adjacent to the Black Sea. These findings expand its range westward by more than 1000 km along the coastline. From Bulgaria, we also report for the first time N. hrabei, a species previously known to occur along the middle and lower Danube lowlands and in isolated populations at the foothills of the Northern Caucasus. Our new record thus extends its range southwards by more than 150 km. Both species contained unique haplotypes at all of the sampled localities. These were, nevertheless, not very divergent from more distant populations, emphasizing their good dispersal ability. Ecologically, the sampling localities were generally characterized by stagnant to low running water, dense vegetation, and muddy substrate. Overall, our results bring important insights, shedding more light on the biogeography and ecology of Niphargus.

Habitat use of the mistle thrush (Turdus viscivorus): the importance of urban areas and permanent crops

The mistle thrush is a species that occurs in old-growth forests, especially coniferous forests, in hilly and mountain areas and avoids warm and dry areas and human settlements. Despite this, in recent decades, the mistle thrush has colonised Apulia, southern Italy's lowlands and coasts, in rural and urban contexts. This study investigates the habitat selection of this species in central Apulia, in both the breeding season and winter, by carrying out 301 point counts and 264 linear transects. Data were collected to build a Species Distribution Model (SDM) for each season with the MaxEnt algorithm and the regional land use map, selecting variables through the Akaike Information Criterion. Overlap in the suitability of both seasons was measured using Schoener's D. A total of 133 observations of mistle thrush were noted during the breeding season and 85 observations during winter. During the breeding season, the mistle thrush selected olive orchards, especially those near vineyards and urban areas, where it could find food and safe places to nest. In this period, however, it was also found in coniferous woodlands. The mistle thrush also used vineyards in winter, whereas it avoided urban areas in this period, possibly due to food scarcity. Non-irrigated arable lands were avoided all year round, whereas natural grasslands were only avoided during the winter. Irrigated arable lands positively affected the species. Furthermore, 60% of habitat characteristics were similar between the breeding and winter seasons. It is unclear what makes the mistle thrush shift its range southward and downslope. However, it is likely due to the general increase in forest cover, a positive rainfall trend in Central Italy during summer, and the absence of competition with similar species in central Apulia.

A new record of Leptobotia pellegrini Fang, 1936 (Teleostei, Cypriniformes, Botiidae) from the Western Nghe An Biosphere Reserve, Vietnam

We report a new record of Leptobotia pellegrini Fang, 1936 from the Western Nghe An Biosphere Reserve, Vietnam, based on 25 specimens collected in the Kien stream (Ca River), Tuong Duong district, Nghe An province. Morphological features of these specimens were confirmed against the description of this species by Fang (1936). Our new data extend the species’ geographic range southward by approximately 650 km from the Gam River (Na Hang, Tuyen Quang province), Vietnam.

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.

The invasive Atlantic blue crab Callinectes sapidus Rathbun, 1896 expands its distributional range southward to Atlantic African shores: first records along the Atlantic coast of Morocco

The invasive Atlantic blue crab Callinectes sapidus Rathbun, 1896 expands its distributional range southward to Atlantic African shores: first records along the Atlantic coast of Morocco

Impacts of climate change on the geographic distribution of African oak tree (Afzelia africana Sm.) in Burkina Faso, West Africa

Afzelia africana Sm – a multipurpose leguminous tree species – is threatened in West Africa – a climate change hotspot region. Yet, although the impacts of land use on this species dynamics have been widely reported, there is a little literature on the impacts of climate change on its spatial distribution. This study aimed to predict the impacts of climate change on the geographic distribution of A. africana in Burkina Faso. A total of 4,066 records of A. africana was compiled from personal fieldwork and vegetation database. Current and future bioclimatic variables were obtained from WorldClim website. For future climatic projections, six global climate models (GCMs) were selected under two emission scenarios (RCP 4.5 & RCP 8.5) and two horizons (2050 & 2070). Presence data and bioclimatic variables were processed in ArcGIS software and used in the algorithm MaxEnt (maximum of entropy) to predict the species distribution. Findings showed that maximum temperature of warmest month and mean temperature of coldest quarter mostly affect the habitat suitability of A. africana. About 25.54% of Burkina Faso land surface was currently suitable for A. africana conservation. Under future climatic projections, all the climate models predict climate-driven habitat loss of the species with a southward range shift. Across the two emission scenarios, the spatial extent of suitable habitats was predicted to decline from 9.43 to 23.99% and from 12.29 to 25% by the horizons 2050 and 2070, respectively. Habitat loss and range shifts predicted in this study underline the high vulnerability of A. africana to future climate change. Reforestation actions and the protection of predicted suitable habitats are recommended to sustain the species conservation.

Rediscovery of the endemic Afrotropical genus Spathioplites (Hymenoptera, Braconidae, Doryctinae) with major range extension records for Spathioplites phreneticus

The endemic, monotypic Afrotropical genus Spathioplites Fischer, 1962 is rediscovered based on new specimens collected in South Africa and Senegal. Spathioplites phreneticus Fischer, 1962 was previously known from the holotype (male) and 12 paratypes (11 males and a female) collected in Chad in 1959. As part of an ongoing long-term insect inventory survey program in Africa new specimens were recently collected in Tswalu Kalahari Game Reserve in South Africa, extending the distribution range southwards by 4900 km. An additional historical specimen from Senegal was discovered in the collections of the Natural History Museum in Paris, extending the range westwards by 4000 km. Possible reasons for the disjunct distribution exhibited by current locality records for this species are discussed. The holotype male and a paratype female, as well as one of the two newly collected South African females were imaged. These photographs, as well as genus and species re-descriptions, are provided. An identification key to the Old World genera in the doryctine tribe Spathiini s. str. is also presented. All images and interactive identification keys are available on www.waspweb.org.