Range Expansion Of Species Research Articles

Range Expansion of Ixodes scapularis and Borrelia burgdorferi in Ontario, Canada, from 2017 to 2019.

Range expansion of the vector tick species, Ixodes scapularis, has been detected in Ontario over the last two decades. This has led to elevated risk of exposure to Borrelia burgdorferi, the bacterium that causes Lyme disease. Previous research using passive surveillance data suggests that I. scapularis populations establish before the establishment of B. burgdorferi transmission cycles, with a delay of ∼5 years. The objectives of this research were to examine spatial and temporal patterns of I. scapularis and its pathogens from 2017 to 2019 in southwestern, eastern, and central Ontario, and to explore patterns of B. burgdorferi invasion. Over the 3-year study period, drag sampling was conducted at 48 sites across Ontario. I. scapularis ticks were tested for B. burgdorferi, Borrelia miyamotoi, Anaplasma phagocytophilum, and Babesia species, including Babesia microti and Babesia odocoilei, and Powassan virus. I. scapularis was detected at 30 sites overall, 22 of which had no history of previous tick detection. B. burgdorferi was detected at nine sites, eight of which tested positive for the first time during this study and five of which had B. burgdorferi detected concurrently with initial tick detection. Tick and pathogen hotspots were identified in eastern Ontario in 2017 and 2018, respectively. These findings provide additional evidence on the range expansion and population establishment of I. scapularis in Ontario and help generate hypotheses on the invasion of B. burgdorferi in Ontario. Ongoing public health surveillance is critical to monitor changes in I. scapularis and its pathogens in Ontario.

Seawater warming favours the northward range expansion of Lessepsian species in the Mediterranean Sea: the cephalaspidean Lamprohaminoea ovalis

AbstractMonitoring the spread of non-indigenous species is fundamental to study global warming effects on marine biodiversity. A valuable tool is represented by the continuous updating of the geographic range expansion of non-indigenous species. Lamprohaminoea ovalis is a Lessepsian mollusc initially recorded in the Mediterranean Sea in 2001. This paper reports its range expansion over the last 20 years related to water warming. The first record of Lamprohaminoea ovalis from the Ligurian Sea (NW Mediterranean) is also reported. Two individuals (about 10 mm length) were observed on a sub-vertical rocky bottom at 26 m depth displaying potential trailing behaviour. This recent finding extends the currently known distributional range of Lamprohaminoea ovalis, representing the northernmost occurrence of this non-indigenous species in the western Mediterranean Sea.

Species range size shapes distance‐decay in community similarity

AbstractAim(i) To assess the dependence between the form of the decrease in biological similarity with distance (distance‐decay) and species range size and (ii) to introduce the use of a sigmoidal model, the Gompertz function, as a flexible alternative able to fit distance‐decay models under a wide variety of species range sizes.LocationApplicable worldwide.MethodsWe computed distance‐decay curves from simulated communities to assess how the species range sizes shape the functional form of distance‐decay patterns (i.e. negative exponential, power‐law or sigmoidal [Gompertz] relationships). Simulations were performed using different sample sizes and species detection probabilities. We also used distribution data of South American mammals to explore the relationship between species range size and the distance‐decay form in an empirical dataset.ResultsOur simulations showed that the power‐law is the best supported model when range sizes tend to be small. An increase in range sizes leads to a negative exponential relationship, taking the shape of a sigmoidal (Gompertz) relationship with the largest range size values. Similar results have been found in the distance‐decay pattern of South American mammals. Remarkably, the Gompertz function fits the data reasonably well in all scenarios.Main conclusionsThe functional form of distance‐decay patterns depends on a key biogeographical attribute: species range size. This dependence makes it an interesting tool to detect biodiversity threats associated with species range expansion, such as the biotic homogenization of faunas. The Gompertz function is the mathematical model that best accommodates different frequency distributions of species range size and, thus, allows cross‐taxa comparison of this biogeographical and ecological pattern.

Modeling the effect of climate change on the distribution of threatened medicinal orchid Satyrium nepalense D. Don in India.

It is vital to understand the distribution area of a threatened plant species for its better conservation and management planning. Satyrium nepalense (family: Orchidaceae) is a threatened terrestrial orchid species with valuable medicinal and nutritional properties. The survival of S. nepalense in wild conditions has been challenged by increasing global surface temperature. Hence, understanding the impact of climate change on its potential distribution is crucial to conserve and restore this species. In present study, Maxent species distribution modeling algorithm was used to simulate the current distribution of S. nepalense in India and predict the possible range shift in projected future climate scenarios. A set of 19 bioclimatic variables from WorldClim database were used to predict the potential suitable habitats in current climatic condition and four Representative Concentration Pathway (RCP 2.6, 4.5, 6.0, and 8.5) scenarios by integrating five General Circulation Models (GCMs) for future distribution modeling of species for the years 2050 and 2070. Furthermore, change analysis was performed to identify the suitable habitat in current and future climate for delineating range expansion (gain), contraction (loss), and stable (no change) habitats of species. The Maxent model predicted that ~ 2.38% of the geographical area in India is presently climatically suitable for S. nepalense. The key bioclimatic variables affecting the distribution of studied species were the mean temperature of warmest quarter, mean temperature of wettest quarter, precipitation of warmest quarter, and temperature seasonality. Under future climate change scenarios, the total suitable habitat of S. nepalense will increase slightly in the Himalayan region and likely to migrate towards northward, but in the Western Ghats region, the suitable areas will be lost severely. The net habitat loss under four RCP scenarios was estimated from 26 to 39% for the year 2050, which could further increase from 47 to 60% by the year 2070. The finding of the predictive Maxent modeling approach indicates that warming climates could significantly affect the potential habitats of S. nepalense and hence suitable conservation measures need to be taken to protect this threatened orchid species in wild conditions.

The relative role of plasticity and demographic history in Capsella bursa-pastoris: a common garden experiment in Asia and Europe.

The colonization success of a species depends on the interplay between its phenotypic plasticity, adaptive potential and demographic history. Assessing their relative contributions during the different phases of a species range expansion is challenging, and requires large-scale experiments. Here, we investigated the relative contributions of plasticity, performance and demographic history to the worldwide expansion of the shepherd’s purse, Capsella bursa-pastoris. We installed two large common gardens of the shepherd’s purse, a young, self-fertilizing, allopolyploid weed with a worldwide distribution. One common garden was located in Europe, the other in Asia. We used accessions from three distinct genetic clusters (Middle East, Europe and Asia) that reflect the demographic history of the species. Several life-history traits were measured. To explain the phenotypic variation between and within genetic clusters, we analysed the effects of (i) the genetic clusters, (ii) the phenotypic plasticity and its association to fitness and (iii) the distance in terms of bioclimatic variables between the sampling site of an accession and the common garden, i.e. the environmental distance. Our experiment showed that (i) the performance of C. bursa-pastoris is closely related to its high phenotypic plasticity; (ii) within a common garden, genetic cluster was a main determinant of phenotypic differences; and (iii) at the scale of the experiment, the effect of environmental distance to the common garden could not be distinguished from that of genetic clusters. Phenotypic plasticity and demographic history both play important role at different stages of range expansion. The success of the worldwide expansion of C. bursa-pastoris was undoubtedly influenced by its strong phenotypic plasticity.

AEDES PERTINAX AND CULEX INTERROGATOR: TWO MOSQUITO SPECIES NEW TO LEE COUNTY, FLORIDA

Recent introductions of mosquito species new to Florida, and range expansions of other species throughout the state, have many mosquito control personnel on alert for discovery of new species in their area. Adult mosquito specimens collected in traps are a common method of detecting new species, but larval surveillance can be important as well. Larval surveillance in Lee County, Florida has increased over the past two years, and samples collected in the 2021 summer season revealed first-time records of two species new to the county: Aedes pertinax and Culex interrogator. Morphological and genetic methods were used to identify these two species new to the county. These species may have been present in Lee County in years past, but without these larval samples, they might have continued to go undetected due to their similar appearance to more commonly-occurring species.

A Note on Thaparocleidus caecus (Mizelle & Kritsky, 1969) (Monogenea: Dactylogyridae) Detected with Morphological and Molecular Tools in Pangasianodon hypophthalmus (Sauvage, 1878) Imported into Turkey

Thaparocleidus caecus (Mizelle & Kritsky, 1969) Lim, 1996 (Dactylogyridae) was reported for the first time from iridescent shark-catfish (Pangasianodon hypophthalmus, Sauvage, 1878) imported into Turkey via the aquarium fish trade. T. caecus were found on the gills of the examined fish with a prevalence of 28%. Identification, based on morphological characteristics for T. caecus, was confirmed by rRNA sequencing, evidencing the transfer of T. caecus to different countries. Our results emphasize that the ornamental fish trade poses a range expansion of un-documented parasite species. 

Phylogenetic inference of where species spread or split across barriers

SignificanceGeography molds how species evolve in space. Strong geographical barriers to movement, for instance, both inhibit dispersal between regions and allow isolated populations to diverge as new species. Weak barriers, by contrast, permit species range expansion and persistence. These factors present a conundrum: How strong must a barrier be before between-region speciation outpaces dispersal? We designed a phylogenetic model of dispersal, extinction, and speciation that allows regional features to influence rates of biogeographic change and applied it to the neotropical radiation of Anolis lizards. Separation by water induces a threefold steeper barrier to movement than equivalent distances over land. Our model will help biologists detect relationships between evolutionary processes and the spatial contexts in which they operate.

Abiotic Factors Influence Thermal Conditions Determining Site Occupancy of Plestiodon fasciatus at High-Latitude Range Limits

Climate change has historically resulted in the expansion, contraction, and shift of species ranges. High-latitude range limits in areas where no physical barrier prevents dispersal are of particular interest in light of species range contraction or expansion because they represent limits that may inhibit occupancy. MacArthur proposed that abiotic factors have a greater influence on species distribution approaching high-latitude range limits. We examined aspects of environmental structure that influence distribution of Common Five-lined Skinks (Plestiodon fasciatus) and are expressed in that species' population dynamics. Eight sites in the southern Shield region of Ontario, Canada were surveyed during the active season for P. fasciatus. We collected data on the canopy cover, slope angle, slope aspect, substrate, cover type, and temperature at sites where P. fasciatus was observed (microsites) and compared these data to the general site conditions (macrosite). We assessed population size using capture–mark–recapture methods and compared population age structure at eight sites to detect if there was a correlation between the characteristics of the macrosites, population size, and age structure. Abiotic factors were the primary limiting factors affecting distribution at high-latitude range limits of the species. Spatial ecology at the individual scale was influenced by sites with suitable thermal conditions. Our results confirm the importance of microsites with suitable thermal profiles as key habitat for ectothermic vertebrates at high latitudes. The influence of temperature as a limiting abiotic factor is expressed in population density of P. fasciatus. Conservation and restoration of high-latitude populations of ectothermic vertebrates should focus on ensuring thermal requirements of the species are met before other factors are addressed, as temperature is likely the single most significant limiting factor at high-latitude range limits.

Resource partitioning may limit interspecific competition among Arctic fish species during early life

Arctic cod (Boreogadus saida) strongly dominates the ichthyoplankton assemblages of High Arctic seas, hence competition with other native species seldom has been studied. Yet, interspecific competition could negatively impact the survival of early life stages of fishes in Arctic areas where higher diversity prevails. We surveyed the ichthyoplankton community of the Greenland Sea, in August–September 2017. Gadids (mostly Arctic cod, with a low number of ice cod Arctogadus glacialis) and non-gadids (bigeye sculpin Triglops nybelini and gelatinous snailfish Liparis fabricii) co-dominated age-0 fish assemblages. Here, we document their diet, prey selectivity, horizontal and vertical distributions as well as that of their prey to assess resource partitioning and the potential for interspecific competition. All fish species occupied the top 30 m of the water column, but Arctic cod occurred in highest abundances over the continental slope, whereas other species distributed almost exclusively over the continental shelf. A particle track analysis suggests that Arctic cod larvae could have hatched in the open waters of the Northeast Water Polynya, drifted with the East Greenland Current, and benefited from the high secondary production associated with these oceanographic features. The diet of gadids did not overlap significantly with the diet of non-gadids, but strong selectivity for Pseudocalanus spp. and Calanus spp. copepodites among the larvae suggests potential competition for these key prey items, although limited by size partitioning of the prey. We thus conclude that interspecific competition among early life stages of Arctic fishes is limited for now. However, changing conditions and the northward range expansion of boreal species following climate change could increase competition and, in turn, negatively affect the recruitment of Arctic ichthyoplankton.

Long distance dispersal of monk parakeets

Invasive species threaten biodiversity all around the world and for this reason, identifying the causes and mitigating their effects is a priority in conservation biology. One of the most important factors when dealing with invasive species is dispersal, because the distribution of dispersal distances among members of a population can greatly affect the rate of spread of these invasive populations. Long distance dispersal events have a disproportionately large influence on dispersal kernel estimations, but because of restricted spatial sampling scales they are difficult to detect. Here we use an extensive database of 3,114 monk parakeets ringed in Barcelona city since 2002 as part of an extensive control program across Catalonia where 3,460 birds have been captured since 2013. Our aim was to describe these long–distance movements of monk parakeets. We recorded dispersal distances of over 10 km for a total of eight individuals. Long–distance dispersions were in all directions and both males and females were involved. While some individuals moved in their first year, others delayed dispersal several years. Given that long–distance dispersal events can have a large influence on the rate of range expansion of invasive species this information can be of great utility when modeling the dispersal and spread of the species.

Fitness‐related traits are maximized in recently introduced, slow‐growing populations of a global invasive clam

AbstractMany species are shifting their ranges and being forced to rapidly respond to novel stressful environmental conditions. Colonizing individuals experience strong selective forces that favor the expression of life history traits notably affecting dispersal and reproductive rates in newly invaded habitats. Limited information is currently available on trait variation within the invasive range despite being critical for understanding ecological and evolutionary factors that drive the process of range expansion of invasive species. Here we evaluated life history shifts in the widely introduced Asian clam Corbicula cf. C. fluminea within its invaded range. Through an exhaustive literature search, we obtained data for 17 invasive populations of this clam from different ecosystems worldwide. We tested the relationship between population and individual parameters relevant to the process of range expansion. Our main results are that recently introduced populations of clams were characterized by (a) low density and low rate of population increase, (b) earlier reproduction in slow‐growing populations of clams, and (c) no effect of density on population increase. All populations of the Asian clam analyzed in this study, which are fixed for one genotype (the lineage called Form A/R), experienced different selective environments in the introduced range. These findings support the perspective that adaptive phenotypic plasticity favored the expression of traits that maximize fitness in recently established populations, which faced stronger r‐selective forces relative to long‐established ones. We discuss the role of plasticity in facilitating rapid adaptation and in increasing the likelihood of populations to overcome difficulties associated with low densities and low population increase in newly invaded areas.

Citizen Science Helps in Tracking the Range Expansions of Non-Indigenous and Neo-Native Species in Greece and Cyprus (Eastern Mediterranean Sea)

Raising knowledge of the dispersal of non-indigenous species (NIS) in new geographic areas is a matter of major concern, as alien species may outcompete the native biota through competition, predation, and hybridization. In the Mediterranean Sea, where biological invasions constitute a serious threat, the combined use of citizen science and social networks amplified the results obtained via traditional research activities, often recording species that would otherwise presumably have passed unnoticed. We hereby report unpublished data for five NIS (the annelid Branchiomma luctuosum, the shrimp Saron marmoratus and the fishes Lutjanus argentimaculatus, Oxyurichthys petersii, and specimens of the group of Abudefduf saxatilis/vaigiensis/troschelii) and one neo-native species (Seriola fasciata) in Greece and Cyprus (eastern Mediterranean Sea), the majority of which were obtained via a focused citizen-science project and constitute new records at a country level. We also revise and update their known distribution in the invaded area, thus contributing to the study of large-scale and well-defined distributional patterns of alien species spreading in the Mediterranean Sea.

A Computer Vision-Based Approach for Tick Identification Using Deep Learning Models.

Simple SummaryTicks are ectoparasites of humans, livestock, and wild animals and, as such, they are a nuisance, as well as vectors for disease transmission. Since the risk of tick-borne disease varies with the tick species, tick identification is vitally important in assessing threats. Standard taxonomic approaches are time-consuming and require skilled microscopy. Computer vision may provide a tenable solution to this problem. The emerging field of computer vision has many practical applications already, such as medical image analyses, facial recognition, and object detection. This tool may also help with the identification of ticks. To train a computer vision model, a substantial number of images are required. In the present study, tick images were obtained from a tick passive surveillance program that receives ticks from public individuals, partnering agencies, or veterinary clinics. We developed a computer vision method to identify common tick species and our results indicate that this tool could provide accurate, affordable, and real-time solutions for discriminating tick species. It provides an alternative to the present tick identification strategies.A wide range of pathogens, such as bacteria, viruses, and parasites can be transmitted by ticks and can cause diseases, such as Lyme disease, anaplasmosis, or Rocky Mountain spotted fever. Landscape and climate changes are driving the geographic range expansion of important tick species. The morphological identification of ticks is critical for the assessment of disease risk; however, this process is time-consuming, costly, and requires qualified taxonomic specialists. To address this issue, we constructed a tick identification tool that can differentiate the most encountered human-biting ticks, Amblyomma americanum, Dermacentor variabilis, and Ixodes scapularis, by implementing artificial intelligence methods with deep learning algorithms. Many convolutional neural network (CNN) models (such as VGG, ResNet, or Inception) have been used for image recognition purposes but it is still a very limited application in the use of tick identification. Here, we describe the modified CNN-based models which were trained using a large-scale molecularly verified dataset to identify tick species. The best CNN model achieved a 99.5% accuracy on the test set. These results demonstrate that a computer vision system is a potential alternative tool to help in prescreening ticks for identification, an earlier diagnosis of disease risk, and, as such, could be a valuable resource for health professionals.

Range expansion of tropical shallow-water marine molluscs in the NE Atlantic during the last interglacial (MIS 5e): Causes, consequences and utility of ecostratigraphic indicators for the Macaronesian archipelagos

Controlled by ecological and physical factors, marine species distribution may vary due to global climatic changes that result from range expansion or contraction (the latter caused by local disappearances, i.e., extirpations). Spanning from 13° to 39°N, the Macaronesian region encompasses five archipelagos located within warm-temperate to tropical climatic zones and influenced by a surface water current regime that favours a N–S range expansion of marine species. The extensive and well-preserved Macaronesian fossil record makes these islands excellent candidates for evolutionary studies. It documents a northward range expansion of tropical species with a Cabo Verdean-Mauritanian-Senegalese biogeographic provenance during the Last Interglacial (LIG). For the first time, a thorough revision and update of marine molluscs’ checklist from the Macaronesian archipelagos for the LIG is presented. On this basis, we hypothesize that the range expansion occurred during the last phase of glacial Termination 2 and was enhanced by ephemeral sea surface currents that created windows of opportunity for the long-distance dispersal of marine species along sweepstake routes. During these short intervals of time, numerous tropical and subtropical species expanded their geographic range northwards, towards what today are subtropical and temperate archipelagos. Simultaneously, however, a smaller number of northern species expanded their ranges southward, some reaching Cabo Verde. This work yields a set of 24 mollusc “ecostratigraphic indicators” (10 bivalve and 14 gastropod species) that are important to identify fossiliferous deposits from the Last Interglacial epoch in Macaronesian archipelagos. Longitudinal range expansions from West African shores to the Cabo Verde archipelago and the Canary Islands were also detected. These are related to coeval weaker upwelling systems which now constitute effective barriers for the exchange of species/individuals between continental and insular shores (e.g., Senegal/Cabo Verde; Morocco/Canaries). Finally, an ecological filter-effect also existed, which we associate with the increasingly longer distances to cover, as many of the most typical representatives of the warm water fauna with Cabo Verde/Senegalese affinities failed to reach the northern Azores and Madeira archipelagos.

Photosynthetic capacity of co-occurring kelp species revealed by in situ measurements

Accurate estimates of productivity of marine macrophytes are crucial to predict the consequences of invasive species expansions and climate-related range shifts on coastal ecosystem functioning and carbon cycling. We examined the potential impacts of climate-driven shifts in the relative abundances of foundation species within a temperate reef system on net primary productivity. Specifically, we estimated productivity rates of 3 co-occurring kelp species (Laminaria hyperborea, L. ochroleuca and Undaria pinnatifida) in contrasting regions of their ranges (centre, leading-edge and invasive, respectively) via in situ photorespirometry methods in Brittany, France. Lamina tissues of cold-temperate L. hyperborea and warm-temperate L. ochroleuca had similar rates of net productivity. The stipes of L. hyperborea, however, displayed much higher rates of productivity and respiration than L. ochroleuca, likely due to the dense macroalgal epiphytes colonising their surface. Our results suggest that replacement of L. hyperborea by L. ochroleuca in the NE Atlantic due to increased dominance or further range expansion of this warm-temperate species might lead to reduced net rates of productivity as a result of increased lamina respiration and reduced photosynthetic capacity of stipes. The invasive kelp U. pinnatifida had high rates of net productivity at saturating light levels (294 µmol O2 g-1 dry weight h-1), 3 times higher than any kelp species ever incubated in situ, helping to explain its high success as an invader. We show that shifts in the distributions and relative abundances of seemingly similar foundation species may lead to subsequent changes in net metabolic balance.

First records of three new lizard species and a range expansion of a fourth lizard species introduced to Aruba

First records of three new lizard species and a range expansion of a fourth lizard species introduced to Aruba

A missing cog in the wheel: an Allee effects perspective in biological invasion paradigm.

Environmental stochasticity and invasive species demographical factors are considered to be fundamental aspects of species invasion. Population size, density, and intraspecific competition are the important determinants of species range expansion. Allee effects, interesting density-dependent phenomena, act as 'mechanism of population regulation' during species expansion. The study intends to understand the trend of published researches and identify research gaps pertaining to biological invasions and Allee effects with the help of bibliometric analysis. Content and citation analysis using key words 'Allee effects' AND 'biological invasion' was conducted on research articles published over a period of two and a half decades from Scopus database for global and Indian context. Understanding of Allee effects dynamics in context of biological invasion is limited, especially in India. Integrating the emerging trends pertaining to Allee effects in the biological invasion framework will strengthen the understanding on species range expansion. It is emphasized that Allee effects can emerge as an important tool to manage invasive species range expansion.

The genetic drivers for the successful invasive potential of a generalist bird, the House crow

What kind of genetic structure helps the rapid range expansion of the invasive species is fundamental to understand spread of invasion. The House crow (Corvus splendens), an ecological generalist, having a large native and introduced distribution range, is a good study model to investigate the genetic structure and adaptations underpinning the evolutionary potential for successful biological invasion. Thirteen mainland and one island native population from the Indian subcontinent were studied using four nuclear introns and mitochondrial genome to determine the phylogeographic structure and demographic history. A large, panmictic long-term expanding native population dating from the last glacial period (~ 30,000 ya) was inferred leading to great genetic diversity across the whole native range. The thirteen mitochondrial encoded proteins, directly involved in the energy supplying pathway, could underlie metabolic adaptations during range expansion under diverse climate conditions. Therefore, to investigate the molecular selection on these genes in native and introduced ranges, five previously studied introduced populations from Southeast Asia and Africa were included. The native populations originating from hot arid and humid tropical areas exhibited the signatures of positive selection on four codons located in three genes (ND5, Cytb and COX2), suggesting these may have evolved under environmental stresses in those regions. Our findings demonstrated the native range population as the reservoir of the species’ genetic diversity, mitogenomic patterns of the introduced populations related to native range of species and no varaints could be associated with climate in introduced range. Thus,inferred that the pre-adapted standing genetic variations evolved during dispersion over the native range are the predominant source of the high evolutionary potential and contribute to the successful invasion history. These findings will help to predict the future introduced range of the House crow.

Population genomics indicates micro‐refuges and riverine barriers for a southern South American grassland nightshade

AbstractAimPleistocene climate oscillations influenced the species distribution and genetic diversity in grasslands, and such climatic changes promoted expansion and contraction cycles, leading to fragmentation and isolation of evolutionary lineages in refuges. This study aimed to infer the evolutionary processes that most influenced the genetic diversity of a South American nightshade Petunia inhabiting subtropical grasslands under the Pleistocene influence.LocationPampa and Chaco.TaxonThe widely distributed herb Petunia axillaris subsp. parodii (Solanaceae).MethodsWe obtained high‐density genome coverage throughout the geographical distribution of Petunia axillaris subsp. parodii. We estimated the genetic diversity and structure to evaluate population differentiation and applied a model‐based demographic analysis to investigate the scenarios that could have influenced the species' evolutionary history. We evaluated the association between neutral and outlier polymorphisms with environmental variables to distinguish the influence of the geographical distance and environmental differences between populations.ResultsThere are three evolutionary lineages in P. axillaris subsp. parodii. The origin and differentiation of these lineages were related to the Pleistocene refuges and rivers acting as barriers to gene flow. We also identified 496 outlier loci related to adaptation to environmental conditions.Main conclusionThe Pleistocene climate changes drove lineage diversification isolated in micro‐refugia. Rivers and changes in their courses may have also acted on the population divergence, serving as barriers to gene flow or even as corridors for species range expansion. These findings contribute to the knowledge of the evolutionary processes that influenced the lineage diversification of South American subtropical grassland species.