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-Map of the Southern Hemisphere showing the locations of all samples used. Further details for each site are provided in table 1. Inset (modified from McLoughlin 2001): approximate alignment of the Gondwanan continental landmasses (NZ 5 New Zealand; AP 5 Antarctic Peninsula; SAm 5 South America) that have formed the basis for vicariant hypotheses.
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Throughout the Southern Hemisphere many terrestrial taxa have circum-Antarctic distributions. This pattern is generally attributed to ongoing dispersal (by wind, water, or migrating birds) or relict Gondwanan distributions. Few of these terrestrial taxa have extant representatives in Antarctica, but such taxa would contribute to our understanding o...
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... climate cooling leading to the glaciation of Antarctica. This is likely to have occurred once the South Tasman Rise had cleared the Oates Land coast of East Antarctica (;32 MYA) and Drake's passage had opened to deep water circulation (;28 MYA) (McLoughlin 2001;Lawver and Gahagan 2003). Although the circum-Antarctic currents (and polar front, see fig. 1) were sufficient to iso- late Antarctica from other continental landmasses, glacia- tion of Antarctica did not reach its maximum extent until around 10 MYA (Miller and Mabin 1998;Roberts et al. 2003), and some species may have survived by shifting in a habitat following climate changes in a similar manner to glacier foreground ...
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... were made between 2001 and 2005 from four continental Antarctic sites (Trans-Antarctic Mountains, Ross Sea Region); in addition, taxonomically related spe- cies were targeted from three islands in close proximity to the Antarctic Peninsula, six subantarctic islands, Tasmania and mainland Australia, New Zealand, and Patagonia ( fig. 1 and table 1). Springtails were extracted from vegetation, soil, and the underside of rocks using a Tullgren funnel, floatation technique, or aspirator and preserved in 95% eth- anol and stored at ÿ20°C. All outgroup individuals were identified by Arne Fjellberg and ingroup individuals by Penelope Greenslade, with vouchers deposited at ...
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... tree (using a proportion of variable sites sensu Lockhart et al. 1994) was similar to the maximum-parsimony (MP) tree (with all sites and also removing third codon posi- tions), but these were not congruent with some groupings in the maximum likelihood (ML) tree (using general time Table 1 Species Examined (with codes), Location (see also fig. 1 reversible [GTR] 1 I 1 C; model chosen using Modeltest) or Bayesian analysis (using a separate model for each codon po- sition, first: F81 1 I; second and third: GTR 1 C)calculated in MrModeltest 2.1 (Nylander 2004) and implemented in MrBayes 3.1 (Ronquist and Huelsenbeck 2003) using four chains of five million generations, sampling ...
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... species; Cryptopygus sp. 2 from New Zealand (CA3), Cryptopygus sp. 3 from Patagonia (CA4), and Cryptopygus sp. 4 from Heard (CA5) and Macquarie Islands (CA2). Surprisingly, in group IV three Cryptopygus spp.-two from Marion Island (Cryptopygus dubius-CD and Cryp- topygus antarcticus travei-CAT) and a single subspecies from the nearby (see fig. 1) I ˆ les Crozet (Cryptopygus ant- arcticus reagens-CAR)-grouped with the Antarctic species Antarctophorus subpolaris (AS) and were sister to a group containing Cryptopygus sp. 5 from mainland Australia (CA6) and Cryptopygus sp. 6 from Tasmania (CA7) (fig. ...
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... our results, C. antarcticus sensu stricto (type locality: Gerlache Straits; Antarctic Peninsula) appears restricted to the Antarctic Peninsula and offshore islands (maritime Antarctica) (1.5%-6.3% divergence) ( fig. 1 and table 2). The level of sequence divergence (12.3%- 17.4%) between populations of C. a. maximus from I ˆ les Kerguelen (CAM1) and Macquarie Island (CAM2) in group I are consistent with levels reported elsewhere for recognized springtail (e.g., .14%; ...
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... is dominated by 90% endemicity, indicating that they are not recent immigrants (Wise 1967). Second, the Antarctic species are geographically partitioned into four distinct biogeographic regions within the Trans-Antarctic Mountains, suggesting long-term glacial barriers have sep- arated these species assemblages that may have evolved in situ ( fig. 1; see also Wise 1967;). This is supported by high levels of sequence divergence (.25%) (table 2) between the Antarctic species and their respective closest phylogenetic neighbor (fig. 2); for exam- ple, A. subpolaris (AS) with C. dubius (CD) coincides to isolation around 21-14 MYA (20-15 MYA to each other); the Antarctic G. terranova ...
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We examined levels of genetic variability within and among populations of three Antarctic springtail species (Arthropoda: Collembola) and tested the hypothesis that genetic divergences occur among glacially-isolated habitats. The study was conducted in southern Victoria Land, Ross Dependency, Antarctica, and samples were collected from locations in...
Citations
... For Antarctic biota, there is a growing body of molecular evidence revealing long-term isolation and persistence of short-range endemic species on the Antarctic continent [7,[58][59][60][61][62][63][64]. For springtails that are a dominant driver for biodiversity patterns across the Antarctic realm [25] (figure 1), data show that these endemic species were likely present in ice-free refuges for at least 15-12 Ma [17,46,58]. ...
... For Antarctic biota, there is a growing body of molecular evidence revealing long-term isolation and persistence of short-range endemic species on the Antarctic continent [7,[58][59][60][61][62][63][64]. For springtails that are a dominant driver for biodiversity patterns across the Antarctic realm [25] (figure 1), data show that these endemic species were likely present in ice-free refuges for at least 15-12 Ma [17,46,58]. Endemism is present in most sectors of the continent [6,7], and this is supported by geological dating indicating long-term icefree conditions at sites (figure 2a; see also electronic 2 royalsocietypublishing.org/journal/rsbl Biol. ...
... 34 Ma; [79][80][81]). More recently, molecular data have revealed that species found on the continent are a suite of unique locally endemic survivors from at least the last 56,58] when ice sheet thickening appears to have reached its maximum [17,46,82]. Together, these data highlight striking (a) Distribution of springtail species shown as coloured dots with ellipses indicating short-range endemic species, overlaid on the land elevational topography of Antarctica (blue = below sea level, green/yellow/brown = above sea level, see key in (b)). ...
The origin of terrestrial biota in Antarctica has been debated since the discovery of springtails on the first historic voyages to the southern continent more than 120 years ago. A plausible explanation for the long-term persistence of life requiring ice-free land on continental Antarctica has, however, remained elusive. The default glacial eradication scenario has dominated because hypotheses to date have failed to provide a mechanism for their widespread survival on the continent, particularly through the Last Glacial Maximum when geological evidence demonstrates that the ice sheet was more extensive than present. Here, we provide support for the alternative nunatak refuge hypothesis-that ice-free terrain with sufficient relief above the ice sheet provided refuges and was a source for terrestrial biota found today. This hypothesis is supported here by an increased understanding from the combination of biological and geological evidence, and we outline a mechanism for these refuges during successive glacial maxima that also provides a source for coastal species. Our cross-disciplinary approach provides future directions to further test this hypothesis that will lead to new insights into the evolution of Antarctic landscapes and how they have shaped the biota through a changing climate.
... Another cluster (blue) seems not to have a predominant topic, but the words that stand out the most are 'strategy' and 'summer' suggesting some attention to life histories around phenological processes under macroclimatic conditions. This cluster could be considered the closest aggregation to our review topic because we also find related terms like 'cold tolerance', 'cold hardiness', ' Cryptopygus antarcticus ' (an Antarctic Collembola superspecies, ( Stevens et al., 2006 )), and 'lethal temperature', among others. On the other hand, a red cluster, highlights the topics 'abundance' and 'richness' as dominant, in turn suggesting the relevance of thermal tolerance limits to account for community level patterns and the geographic distribution of species. ...
Global changes in soil surface temperatures are altering the abundances and distribution ranges of invertebrate species worldwide, including effects on soil microarthropods such as springtails (Collembola), which are vital for maintaining soil health and providing ecosystem services. Studies of thermal tolerance limits in soil invertebrates have the potential to provide information on demographic responses to climate change and guide assessments of possible impacts on the structure and functioning of ecosystems. Here, we review the state of knowledge of thermal tolerance limits in Collembola. Thermal tolerance metrics have diversified over time, which should be taken into account when conducting large-scale comparative studies. A temporal trend shows that the estimation of ‘Critical Thermal Limits’ (CTL) is becoming more common than investigations of ‘Supercooling Point’ (SCP), despite the latter being the most widely used metric. Indeed, most studies (66%) in Collembola have focused on cold tolerance; fewer have assessed heat tolerance. The majority of thermal tolerance data are from temperate and polar regions, with fewer assessments from tropical and subtropical latitudes. While the hemiedaphic life form represents the majority of records at low latitudes, euedaphic and epedaphic groups remain largely unsampled in these regions compared to the situation in temperate and high latitude regions, where sampling records show a more balanced distribution among the different life forms. Most CTL data are obtained during the warmest period of the year, whereas SCP and ‘Lethal Temperature’ (LT) show more variation in terms of the season when the data were collected. We conclude that more attention should be given to understudied zoogeographical regions across the tropics, as well as certain less-studied clades such as the family Neanuridae, to identify the role of thermal tolerance limits in the redistribution of species under changing climates.
... In order to understand the dispersal, over short and long distances, of microarthropods in Victoria Land, molecular studies have been conducted on different springtail species [22,[27][28][29][30][31]. These have identified that the presence of glacial barriers strongly influences species distributions, and that these have likely limited gene flow between restricted and isolated refugia during various glacial maxima [22,28,32]. Analogous biogeographical patterns have been reported for the prostigmatid mite Stereotydeus mollis by Womersley and Strandtmann, 1963, in Victoria Land [33][34][35][36], although with higher genetic divergence, possibly due to higher activity levels and shorter generation time [33,37] and/or to a longer evolutionary history than for the springtails. ...
... For S. belli it is possible that historical events, such as habitat fragmentation due to glacial events, divergence in isolation and subsequent range expansion [32][33][34][78][79][80], are responsible for the patchy distribution of these populations and their genetic isolation. All the S. belli populations were clearly distinct, with KAY and CCI clustered together and separated from both CHA and CJO. ...
... The patterns of diversity observed today in many Antarctic species can be traced back to historic events, such as habitat fragmentation, divergence in isolation and subsequent range expansion, that influenced the distribution of species particularly at local scales [32][33][34]81]. The resulting patterns of genetic variation can be used to infer ecological factors (e.g., effective population size, dispersal capacity), as well as those affecting speciation processes. ...
In the harsh Antarctic terrestrial ecosystems, invertebrates are currently confined to sparse and restricted ice free areas, where they have survived on multi-million-year timescales in refugia. The limited dispersal abilities of these invertebrate species, their specific habitat requirements, and the presence of geographical barriers can drastically reduce gene flow between populations, resulting in high genetic differentiation. On continental Antarctica, mites are one of the most diverse invertebrate groups. Recently, two new species of the free living prostigmatid mite genus Stereotydeus Berlese, 1901 were discovered, bringing the number of Antarctic and sub-Antarctic species of this genus up to 15, of which 7 occur along the coast of Victoria Land and in the Transantarctic Mountains. To examine the biodiversity of Stereotydeus spp., the present study combines phylogenetic, morphological and population genetic data of specimens collected from nine localities in Victoria Land. Genetically distinct intraspecific groups are spatially isolated in northern Victoria Land, while, for other species, the genetic haplogroups more often occur sympatrically in southern Victoria Land. We provide a new distribution map for the Stereotydeus species of Victoria Land, which will assist future decisions in matters of the protection and conservation of the unique Antarctic terrestrial fauna.
... Stevens et al., 2006Stevens et al., , 2007Tilbrook, 1967; but had not been examined further until molecular data from populations previously identified as 'F. grisea' on the Antarctic continent (northern Victoria Land), South Shetland Islands, and further south on the Antarctic Peninsula showed wide divergence in mitochondrial DNA indicating that more than one species was likely .Friesea grisea, with the type locality on South Georgia, has recently been redescribed and, based on morphology, shown to have a distribution restricted to that sub-Antarctic island alone (Greenslade, 2018a). ...
... We targeted the commonly used mtDNA (COI) gene which has successfully delineated between Collembola species (e.g. Carapelli et al., 2020;Stevens & D'Haese, 2014Stevens et al., 2006). PCR products were amplified using the primers LCO1490 (forward) and HCO2198 (reverse) (Folmer et al., 1994) or primers specific to Collembola (Schneider et al., 2011;Schneider & D'Haese, 2013 and references therein) on the thermocycler (Eppendorf Mastercycler® EP gradient) under the following conditions: 94°C for 1 min for initial denaturation, 5 cycles of 94°C for 1 min, annealing at 47°C for 90 s and extension at 72°C for 1 min, followed by 35 cycles at 94°C for 60 s, 90 s at 51°C and 60 s at 72°C, with a final extension of 72°C for 5 min. ...
... Coloured lines visualise historic records of island linkages for species based on morphology (dashed line) and those confirmed by molecular data (solid). Each map utilised historic records (see but have been adapted taking into account molecular data: for (A) current study; (B) see Stevens et al. (2006) Currently, there are 18 continental Antarctic, Antarctic Peninsula and sub-Antarctic Friesea species known (see key). Of these, there are five marine littoral species originally described from sub-Antarctic islands, F. jeanneli, F. multispinosa, F. litoralis, F. voisini and F. tilbrooki. ...
The pan‐Antarctic distributions of several collembolan species have been supported by morphology for over 120 years. However, for most species where molecular data are available, these are now known to belong instead to several species, and most classified as short‐range endemics. One such species, Friesea grisea, had a pan‐Antarctic distribution that has been in question, but until recently, specimens of F. grisea from the type locality on South Georgia have not been included in any molecular appraisal. Here, we compare the molecular identity of specimens of F. grisea, from South Georgia, with other Antarctic and sub‐Antarctic species using the mitochondrial COI gene. A Bayesian phylogenetic analysis for 14 species of Friesea from southern regions, including F. grisea sensu stricto with species previously identified as ‘F. grisea’ (F. antarctica, F. gretae and F. propria) confirms the distinctness of the South Georgian specimens based on molecular data, and these results are confirmed morphologically. The genus Friesea is one of the most speciose genera of Collembola known in the Antarctic region, and we provide an annotated key (dichotomous and interactive versions) to all Friesea species in the sub‐Antarctic and Antarctica. We compare the biogeography of Friesea to other Collembola from the region to highlight our current understanding of species boundaries and island linkages.
... La escasa conectividad terrestre en las latitudes templadas y subpolares del hemisferio sur ha generado una gran variedad de taxa terrestres que presentan distribuciones disjuntas circumantárticas. Este patrón generalmente se atribuye a patrones de dispersión (e.g., viento, agua, aves migratorias, etc.) o a vicarianza asociada a distribuciones gondwánicas relictas (Frenot et al. 2005;Stevens et al. 2006;McGaughran et al. 2010). ...
Los archipiélagos Diego Ramírez y Cabo de Hornos se ubican en el extremo austral de la ecorregión subantártica de Magallanes y hasta ahora su diversidad de insectos y otros invertebrados terrestres ha sido escasamente caracterizada. En este trabajo, presentamos un catastro actualizado de invertebrados, con un foco en la entomofauna
terrestre del archipiélago Diego Ramírez, y exploramos de manera preliminar las afinidades
biogeográficas de este archipiélago austral con el resto de las islas subantárticas presentes al norte de la Corriente Circumpolar Antártica. Encontramos que la isla Gonzalo, en el archipiélago Diego Ramírez, no contiene especies de insectos y otros invertebrados exóticos. La fauna de invertebrados terrestres registrados durante este estudio, incluye
32 taxa, principalmente de la Clase Insecta, los cuales se encuentran distribuidos en diferentes hábitats, siendo las comunidades de Poa flabellata los hábitats más importantes. La comparación de la entomofauna del archipiélago Diego Ramírez con otras islas subantárticas indica una baja similitud total entre la fauna reportada aquí y
el resto de las islas, excepto con las Georgias del Sur. Sin embargo, la biota que los vincula
es de origen gondwánico, lo cual sugiere la existencia de antiguas conexiones biogeográficas vicariantes. Este trabajo es un aporte al desarrollo, fortalecimiento e inauguración de la Red de Monitoreo Ecológico de Largo Plazo Cabo de Hornos (Red LTER Cabo de Hornos). El enfoque particular en las islas Diego Ramírez contribuye directamente a llenar un “punto ciego” en nuestro conocimiento actual en cuanto a los efectos del cambio ambiental global en los ecosistemas subantárticos, generando información esencial para su conservación en el corto, mediano y largo plazo.
... The evolutionary history of Antarctic springtails has been studied in increasing detail using molecular tools over the last two decades [30][31][32][33] and a growing consensus has been obtained for their long-term persistence in Antarctica and survival in local refugia during glacial maxima [34,35]. Present-day populations are the descendants of lineages that colonized suitable environments up to many millions of years ago, subsequently persisting through multiple and intense periods of glaciation [36,37]. ...
... High levels of cryptic diversity have been recognized in various species of springtails [38][39][40] including some occurring in the Antarctic Continent [30]. The three congeneric Friesea species analyzed in this study have genetic interspecific divergence ranges (9% to 17.4%) consistent with values reported for other congeneric springtail species (8% to 22%) [31,[40][41][42] and values of genetic divergence ≤ 2% and ≥ 9% in intraspecific and interspecific comparisons, respectively (i.e., a 7% barcode gap). ...
Springtails and mites are the dominant groups of terrestrial arthropods in Antarctic terrestrial ecosystems. Their Antarctic diversity includes a limited number of species, which are frequently endemic to specific regions within the continent. Advances in molecular techniques, combined with the re-evaluation of morphological characters and the availability of new samples, have recently led to the identification of a number of new springtail species within previously named, but ill-defined, species entities described in the last century. One such species, the neanurid Friesea grisea, originally described from sub-Antarctic South Georgia, was for many years considered to be the only known springtail with a pan-Antarctic distribution. With the recent availability of new morphological and molecular data, it has now been firmly established that the different representatives previously referred to this taxon from the Antarctic Peninsula and Victoria Land (continental Antarctica) should no longer be considered as representing one and the same species, and three clearly distinct taxa have been recognized: F. antarctica, F. gretae and F. propria. In this study, the relationships among these three species are further explored through the sequencing of the complete mtDNA for F. gretae and the use of complete mitogenomic as well as cytochrome c oxidase I data. The data obtained provide further support that distinct species were originally hidden within the same taxon and that, despite the difficulties in obtaining reliable diagnostic morphological characters, F. gretae is genetically differentiated from F. propria (known to be present in different locations in Northern Victoria Land), as well as from F. antarctica (distributed in the Antarctic Peninsula).
... Species closely related to C. antarcticus, i.e., belonging to Cryptopygus sensu Rusek, have also been found in this study in South Africa (see below) but their status remain unsolved because of the taxonomic and molecular complexity of this group (Deharveng, 1981;Stevens et al. 2006;McGaughran et al. 2010 Description. Body size 0.7-0.9 ...
... In fact, they all almost fit to the strict diagnosis of the genus Cryptopygus proposed by Rusek (2002). This complex, often recorded just under the name 'C. antarcticus', is widely distributed in the sub-Antarctic (Deharveng 1981, Stevens et al. 2006 and less in temperate zones of the Southern Hemisphere (South America: Mari Mutt and Bellinger 1990;Australia: Greenslade, 1994;New Zealand: Babenko and Minor 2015), with C. hirsutus extending into Costa Rica. In South Africa, we have also found the forms with clavate tenent hairs on the tibiotarsi and the characteristic 'antarcticuslike' furca and so then belonging to 'C. antarcticus' complex. ...
Species of the genera of the Cryptopygus complex in South Africa are morphologically revised. Five new species of the genus Cryptopygus Willem, 1902 s. s. and one new species of the genus Isotominella Delamare Deboutteville, 1948 are described. Cryptopygus abulbus sp. nov. and C. bulbus sp. nov. have only one chaeta on the anterior side of dens and no chaetae on the anterior side of manubrium, the latter species being characterized by the presence of a bulb at apex of antennae; C. inflatus sp. nov. shows a rare combination of eight ocelli on each side of the head with a tridentate mucro; C. longisensillus sp. nov. has five long s-chaetae on the fifth abdominal segment; C. postantennalis sp. nov. is unique by having a very long and slender postantennal organ with strong inner denticles; Isotominella laterochaeta sp. nov. is the second member of the genus and differs from the type species by many more anterior chaetae on the manubrium and the presence of chaetae on ventral side of metathorax. The genera are discussed and a key to all species of the Cryptopygus complex recorded in South Africa is given. The focus is on the Western Cape Province where the complex is the most diverse and sampling more complete than in other provinces of South Africa.
... The first, second, and third codon positions were partitioned and we applied a relaxed uncorrelated lognormal molecular clock with Yule speciation process and general time reversible plus a gamma site heterogeneity model (GTR+ ⌫). Based on Stevens et al. (2006) and McGaughran et al. (2010), we used an arthropod strict molecular clock conservative calibration of 1.5%-2.3% divergence per million years (0.0115 substitutions/site) as derived from comparisons between geological and molecular data (Brower 1994;Gaunt and Miles 2002;Quek et al. 2004;Papadopoulou et al. 2010;Ho and Lo 2013). ...
... In contrast to our observations of dispersal between distant locations, we also observed an abundance of haplotypes and lineages that were restricted to individual aquifers (i.e., endemic lineages found in BA (lineage 14), CS (lineage 2), LDS (lineage 12), SM (lineage 8), UM (lineage 16)). Collembola are small and known to occupy many specialised niches, and highly structured and re-stricted phylogeographic patterns are not unusual (Endo et al. 2015;Frati et al. 2004;Garrick et al. 2008;Stevens et al. 2006). Local adaptation to favourable pockets of habitat are a common observation in less mobile species. ...
The subterranean islands hypothesis for calcretes of the Yilgarn region in Western Australia applies to many stygobitic (subterranean–aquatic) species that are “trapped” evolutionarily within isolated aquifers due to their aquatic lifestyles. In contrast, little is known about the distribution of terrestrial–subterranean invertebrates associated with the calcretes. We used subterranean Collembola from the Yilgarn calcretes to test the hypothesis that troglobitic species, those inhabiting the subterranean unsaturated (non-aquatic) zone of calcretes, are also restricted in their distribution and represent reciprocally monophyletic and endemic lineages. We used the barcoding fragment of the mtDNA cytochrome c oxidase subunit 1 (COI) gene from 183 individuals to reconstruct the phylogenetic history of the genus Pseudosinella Schäffer (Collembola, Lepidocyrtidae) from 10 calcretes in the Yilgarn. These calcretes represent less than 5% of the total possible calcretes in this region, yet we show that their diversity for subterranean Collembola comprises a minimum of 25 new species. Regionally, multiple levels of diversity exist in Pseudosinella, indicative of a complex evolutionary history for this genus in the Yilgarn. These species have probably been impacted by climatic oscillations, facilitating their dispersal across the landscape. The results represent a small proportion of the undiscovered diversity in Australia’s arid zone.
... The sharp genetic distinction between the three F. antarctica lineages is not striking per se, as recent studies already put forward the hypothesis that F. antarctica may represent a cluster of multiple cryptic species [4,35]. In fact, striking was the previous recognition of the presence over Antarctica of a single "pan-Antarctic" springtail species, especially considering that most of the sampling sites correspond to physically remote geographic regions (Antarctic Peninsula and Victoria Land) and also taking into account the vicariant origin of Antarctic springtails in general [59,60] and their limited dispersal capabilities. This latter characteristic is likely to underlie the differentiation of a third evolutionary lineage in Cape Hallett, the northern-most sampling locality along the Victoria Land coastline, which is separated from all the other sites by the major barrier of the Tucker Glacier ( Figure 1 and Table 1). ...
The invertebrate terrestrial fauna of Antarctica is being investigated with increasing interest to discover how life interacts with the extreme polar environment and how millions of years of evolution have shaped their biodiversity. Classical taxonomic approaches, complemented by molecular tools, are improving our understanding of the systematic relationships of some species, changing the nomenclature of taxa and challenging the taxonomic status of others. The springtail Friesea grisea has previously been described as the only species with a “pan-Antarctic” distribution. However, recent genetic comparisons have pointed to another scenario. The latest morphological study has confined F. grisea to the sub-Antarctic island of South Georgia, from which it was originally described, and resurrected F. antarctica as a congeneric species occurring on the continental mainland. Molecular data demonstrate that populations of this taxon, ostensibly occurring across Maritime and Continental Antarctica, as well as on some offshore islands, are evolutionarily isolated and divergent and cannot be included within a single species. The present study, combining morphological with molecular data, attempts to validate this hypothesis and challenges the taxonomic status of F. antarctica, suggesting that two additional new species, described here as Friesea gretae sp. nov. and Friesea propria sp. nov., are present in Continental Antarctica.
... van Vuuren, Lee, Convey, & Chown, 2018), often indicating allopatric speciation processes (e.g. Allegrucci, Carchini, Convey, & Sbordoni, 2012;Stevens, Greenslade, Hogg, & Sunnucks, 2006). At a finer scale, intra-island population differentiation has been detected for several species, aligning with historical barriers to gene flow such as glaciers and topography (e.g. ...
Human‐mediated transport of species outside their natural range is a rapidly growing threat to biodiversity, particularly for island ecosystems which have evolved in isolation. The genetic structure underpinning island populations will largely determine their response to increased transport and thus help to inform biosecurity management. However, this information is severely lacking for some groups, such as the soil fauna. We therefore analysed the phylogeographic structure of an indigenous and an invasive springtail species (Collembola: Poduromorpha), each distributed across multiple remote sub‐Antarctic islands, where human activity is currently intensifying. For both species, we generated a genome‐wide SNP dataset and additionally analysed all available COI barcodes. Genetic differentiation in the indigenous springtail Tullbergia bisetosa is substantial among (and, to a lesser degree, within) islands, reflecting low dispersal and historic population fragmentation, while COI patterns reveal ancestral signatures of post‐glacial recolonisation. This pronounced geographic structure demonstrates the key role of allopatric divergence in shaping the region's diversity and highlights the vulnerability of indigenous populations to genetic homogenisation via human transport. For the invasive species Hypogastrura viatica, nuclear genetic structure is much less apparent, particularly for islands linked by regular shipping, while diverged COI haplotypes indicate multiple independent introductions to each island. Thus, human transport has likely facilitated this species’ persistence since its initial colonisation, through the ongoing introduction and inter‐island spread of genetic variation. These findings highlight the different evolutionary consequences of human transport for indigenous and invasive soil species. Yet both demonstrate the need for improved intraregional biosecurity among remote island systems, where the policy focus to date has been on external introductions.
