Ecology of inshore notothenioid fish from the Danco Coast,Antarctic Peninsula

A total of 1,103 inshore notothenioid fish were caught by means of trammel-nets in 4 sites surrounding Cierva Point (Moss Island 1; Moss Island 2; Sterneck Island; Leopardo Island), Danco Coast, West Antarctic Peninsula, during February and March 2000. The families Nototheniidae, Channichthyidae and Bathydraconidae were represented in the samples, Notothenia coriiceps being the dominant fish of the area. Gobionotothen gibberifrons and Trematomus newnesi followed in importance. In general, the fish sampled agreed in terms of number and mass with those of the South Shetland Islands area, except for a marked higher occurrence of G. gibberifrons in the Danco Coast. This supports the hypothesis that the commercial fishery around the South Shetland Islands at the end of the 1970s was responsible for the decrease in the inshore population of G. gibberifrons in that area during the last 17 years. Information on morphometry, reproduction and diet of the fish species caught is provided.     

Geothermal bryophyte habitats in the South Sandwich Islands,maritime Antarctic

Question: How does geothermal activity influence terrestrial plant colonization, species composition and community development in the Antarctic? Location: South Sandwich Islands, maritime Antarctic. Methods: Bryophytes were documented during a biological survey of the archipelago in January and February 1997. Particular attention was given to sites under current or recent influence of geothermal activity. Temperature profiles obtained across defined areas of activity on several islands were linked with the presence of specific bryophytes. Results: Greatest bryophyte richness was associated with geothermally influenced ground. Of 35 moss and nine liverwort species recorded, only four mosses were never associated with heated ground, while eight of the liverworts and 50% of the mosses were found only on actively or recently heated ground. Some species occur in unheated sites elsewhere in the maritime Antarctic, but were absent from such habitats on the South Sandwich Islands. Several species occurred in distinct zones around fumaroles. Maximum temperatures recorded within the upper 0.5 cm of the vegetation surface were 40 ‐ 47 °C, with only Campylopus introflexus tolerating such temperatures. Maximum temperatures 2.5 or 5 cm below the vegetation surface of this moss reached 75 °C. Other bryophytes regularly present in zoned vegetation included the mosses Dicranella hookeri, Sanionia georgico‐uncinata, Pohlia nutans and Notoligotrichum trichodon, and the liverworts Cryptochila grandiflora and Marchantia berteroana. Surface temperatures of 25 ‐ 35 °C and subsurface temperatures of 50 ‐ 60 °C were recorded in these species. Conclusions: These exceptional plant communities illustrate the transport of viable propagules into the Antarctic. Individually ephemeral in nature, the longer term existence of geothermal habitats on islands along the Scotia Arc may have provided refugia during periods of glacial expansion, facilitating subsequent recolonization of Antarctic terrestrial habitats.     

Faunal Comparison of Ants among Cheongsando and Other Islands of South Sea in Korea

ABSTRACT This paper attempts to reveal the biogeographic characteristics of ant fauna of the islands among Korean South Sea, using quantitative analyses. The data treated in this paper are those from Cheongsando Is. and 10 other islands in South Sea which have been well investigated. The faunal similarity is examined using the Nomura-Simpson's Coefficient (NSC). Futhermore, the obtained NSC value matrix is examined by a cluster analysis using UPGMA method. The number of species which has been recorded in the 11 islands are 91 species belonging to 34 genera under 4 subfamilies. Among the above 11 islands, Jejudo Is., which is the largest, has the highest number of species, 67 spp., while Geogeumdo Is. has the lowest, 21 spp. Cheongsando Is. which has directly been investigated by authors has 30 species. The NSC- values between the 11 localities investigated range from 0.522 (Wando Is. to Saryangdo Is.) to 1.000 (Namhaedo Is. to Geojedo Is.). The comparative NSC value of Cheongsando Is. and 10 islands range from 0.522 (to Saryangdo Is.) to 0.833 (to Jejudo Is). The cluster analysis using a similarity index (NSC) showed that the islands of these areas could be grouped into 3, a level of 32%. The similarity of Soando Is. and Geomundo Is. were the closest, 63%, while Soando Is. and Namhaedo Is. were the remotest, 32%. The similarity of Jindo Is. and Cheongsando Is, was 63%, while that of Namhaedo Is. and Cheongsando Is. was 32%.     

Shallow benthic fauna communities of South Georgia Island

Benthic communities in several fjords and sheltered bays of the north coast of South Georgia Island were examined using SCUBA and shore sampling in November 2004. It is one of the most northerly islands within the Polar Front and its well studied, terrestrial biota is described as sub Antarctic. The intertidal and subtidal zones and their fauna are, by comparison, little known. We describe the composition of the substratum and benthic communities of sites in several northern bays, including an exceptional community in the extremely sheltered Moraine Fjord with a 2 m sill at its entrance. In this, like those in some other fjordic systems, some taxa occur shallower than elsewhere, and in this instance, get large and are probably old. Elsewhere, we found the coastal fauna was fairly similar to Antarctic shallow communities in the southern Scotia Arc and Peninsula region. Of the taxa we found, we identified 53 to genus and 41 to species. Most of these were typical Antarctic shallow benthic taxa. Certain flatworms, nemerteans, bivalve and gastropod molluscs, amphipod and isopod crustaceans, asteroid echinoderms and stalked ascidians were very abundant, but some normally common Antarctic higher taxa and species were notably absent or rare.     

Government targets for protected area management: will threatened butterflies benefit?

The UK Government has set targets for biodiversity conservation in England based on several indicators, including the status of protected areas [e.g. Sites of Special Scientific Interest (SSSIs)]. Specifically, the Government aims to achieve favourable condition [defined by Common Standards Monitoring (CSM)] on 95% by area of SSSIs by 2010. SSSIs are important for threatened butterflies and management to achieve favourable condition will play a key role in determining future population levels of these high-profile insects. Because only notified features of SSSIs are considered within CSM, we investigated the level of notification for three threatened butterflies. We found that these species were notified at only 15–33% of SSSIs where they occurred; though most site managers did manage for them under broader site conservation objectives. We investigated the relationship between SSSI condition status and population trend for eight butterfly species of conservation concern to assess the benefit to butterflies of sites attaining favourable condition status. The majority (80%) of population trends on SSSIs in favourable condition were positive, suggesting an overall beneficial impact of SSSI management. However, four of the eight species maintained lower populations at favourable condition SSSIs than at sites in one of the unfavourable condition categories. We suggest that current condition assessment based chiefly on notified vegetation communities lacks the sensitivity to identify the complex habitat conditions for these (mosaic) species. As butterflies are good indictors for a wide range of invertebrates, many species requiring fine-scale habitat heterogeneity may be at risk from the Government’s target.     

Turnover and trends in butterfly communities on two British tidal islands: stochastic influences and deterministic factors

Aim Community trends were investigated for two small islands and two local mainland butterfly communities within the UK over a period of 20–30 years. Location Hilbre Island off the Wirral Peninsula at 53.33° N, 3.10° W; Lindisfarne, an island off the Northumberland coast at 56.41° N, 1.48° W; Leighton Moss at 54.08° N, 2.26° W; Wyre Forest at 52.23° N, 2.14° W, UK. Methods Butterfly species data were collected on Hilbre and two mainland sites (Leighton Moss and Wyre Forest) from 1983 to 2006, and on Lindisfarne from 1977 to 2006, as part of the National Habitat Survey, the UK Butterfly Monitoring Scheme and ‘Butterflies for the New Millennium Atlas’ recording. Matrices of associations (Sokal and Michener’s matching coefficient S_SM; resemblance coefficient) were computed between years and subject to non‐metric multidimensional scaling (NMDS) and Mantel tests. The pattern of extinctions and colonizations at sites were examined, their heterogeneity tested by applying a Friedman test to fractional incidences for the same years. Regression analysis (multiple regression and logit regression) was used to relate butterfly numbers and incidences to climate variables, time and previous records. Results Significant community trends based on population counts and species’ incidences were found for all four sites. There was a significant climatic signal for Hilbre; although this was not apparent for the remaining sites, significant associations occurred between records for a number of species and climatic variables at all sites. Substantial turnover of species on the islands was inversely related to numbers of records for species but not to their conspicuousness to recorders. Main conclusions We argue that time trends are widespread in butterfly communities, even for relatively short periods; they are largely generated by stochastic influences rather than by more substantive factors such as climate change. Potential biases in surveying and recording history are shown to be unlikely. A clear climate signal was found only for the small Hilbre Island, for which there was also evidence for the significant influence of colonization capability of individual source species. We conclude that for many species, small islands will be sinks or pseudosinks and their ‘populations’ vulnerable to small changes in source–sink dynamics.     

The terrestrial arthropod fauna of the Byers Peninsula,Livingston Island,South Shetland Islands

We report the first detailed study of the terrestrial invertebrate fauna of the Byers Peninsula SSSI, Livingston Island, South Shetland Islands. Fourteen micro-arthropod taxa (10 Acari, four Collembola) and two Diptera are recorded, including the first record of the mite Edwardzetes dentifer from the maritime Antarctic. The first record of the midge Belgica antarctica from neighbouring Snow Island is also given. Population composition and density were described in samples from a wide range of terrestrial and freshwater habitats. There was no strong relationship between habitat and microarthropod species occurrence, although comparison of completely vegetated and more stony sites revealed greater population densities at the vegetated sites, and different species proportions at each. Some individual samples contained a wide range of species with none achieving numerical dominance, whilst others from superficially similar sites were dominated by one species. Dipterans were limited to a small number of lakes, streams and seepage areas, where they were sometimes abundant. Population density data and species occurrence are compared with previously published studies from the maritime Antarctic and elsewhere.     

Algal communities of a geothermally heated lagoon on Deception Island (South Shetland Islands)

Kroner Lake, located at Deception Island (Maritime Antarctica), is a unique geothermally heated lagoon in Antarctica. It is declared as special site of scientific interest (SSSI) by Scientific Committee for Antarctic Research (SCAR) for its high biodiversity. A sharp environmental heterogeneity is registered in this lagoon, due to its connection to the sea in its southern margin, and to the input of warm freshwater in the northern one (because of hot springs). This study analyses the biodiversity and abundance of the algal communities (phytoplankton and benthic assemblages) and their relationship with environmental factors. In particular, strong spatial differences of both temperature and conductivity were recorded. The biological studies revealed that the phytoplankton (nanoplankton and microplankton) was dominated by marine diatom species, while the pico-sized fraction was composed by Cyanobacteria Synechococcus-like cells. The epipelon was mainly represented by chain and tubicolous diatoms, among which, Melosira nummuloides was one of the most abundant species. Filamentous Cyanobacteria were also frequently recorded in the algal mats. Kroner Lake is subject to a strong marine influence. Phytoplankton is absolutely dominated by marine diatoms. Spatial variations in temperature and conductivity recorded in the lagoon influence the distribution of the aquatic communities. The greater abundance of pico-sized cells coincided with the warmest site of the water body. Regarding the benthic community, the contribution of freshwater and brackish species is comparatively more important than for the phytoplankton, although the high contribution of marine-derived algae was also evident.     

Ecophysiology of Antarctic vascular plants

Most of the ice and snow-free land in the Antarctic summer is found along the Antarctic Peninsula and adjacent islands and coastal areas of the continent. This is the area where most of the Antarctic vegetation is found. Mean air temperature tends to be above zero during the summer in parts of the Maritime Antarctic. The most commonly found photosynthetic organisms in the Maritime Antarctic and continental edge are lichens (around 380 species) and bryophytes (130 species). Only two vascular plants, Deschampsia antarctica Desv. and Colobanthus quitensis (Kunth) Bartl., have been able to colonize some of the coastal areas. This low species diversity, compared with the Arctic, may be due to permanent low temperature and isolation from continental sources of propagules. The existence of these plants in such a permanent harsh environment makes them of particular interest for the study of adaptations to cold environments and mechanisms of cold resistance in plants. Among these adaptations are high freezing resistance, high resistance to light stress and high photosynthetic capacity at low temperature. In this paper, the ecophysiology of the two vascular plants is reviewed, including habitat characteristics, photosynthetic properties, cold resistance, and biochemical adaptations to cold.     

Regional genetic diversity patterns in Antarctic hairgrass (Deschampsia antarctica Desv.)

Aim  To determine patterns in diversity of a major Antarctic plant species, including relationships of Antarctic populations with those outside the Antarctic zone.
Location  Antarctic Peninsula, Maritime Antarctica, sub-Antarctic islands, Falkland Islands and South America.
Methods  Amplified fragment length polymorphisms (AFLPs) and chloroplast sequences were used to study patterns of genetic diversity in Antarctic hairgrass ( Deschampsia antarctica Desv.) and the genetic relationships between populations over its distribution range. Thirty-eight populations were sampled from a large part of the distribution of D. antarctica , and additionally, herbarium specimens were included for areas from which we could not obtain fresh samples.
Results  A gradient in AFLP diversity was observed going from the Falklands southwards into the Antarctic. This gradient in diversity was also observed within the Antarctic Peninsula: diversity was lower further south. Diversity in the chloroplast genome of D. antarctica was low. Only three chloroplast haplotypes were found, each with a strong regional distribution.
Main conclusions  The phylogenetic construction of AFLP marker frequencies in meta-populations of D. antarctica supports a stepping-stone model of colonization, whereby gene flow mainly occurs between neighbouring populations. It is concluded that long-distance gene flow is very limited in D. antarctica . A very low diversity was found in the sub-Antarctic islands in the Indian Ocean, indicating that these populations have experienced a recent evolutionary bottleneck.     

The influence of landscape,climate and history on spatial genetic patterns in keystone plants (Azorella) on sub‐Antarctic islands

The distribution of genetic variation in species is governed by factors that act differently across spatial scales. To tease apart the contribution of different processes, especially at intermediate spatial scales, it is useful to study simple ecosystems such as those on sub‐Antarctic oceanic islands. In this study, we characterize spatial genetic patterns of two keystone plant species, Azorella selago on sub‐Antarctic Marion Island and Azorella macquariensis on sub‐Antarctic Macquarie Island. Although both islands experience a similar climate and have a similar vegetation structure, they differ significantly in topography and geological history. We genotyped six microsatellites for 1,149 individuals from 123 sites across Marion Island and 372 individuals from 42 sites across Macquarie Island. We tested for spatial patterns in genetic diversity, including correlation with elevation and vegetation type, and clines in different directional bearings. We also examined genetic differentiation within islands, isolation‐by‐distance with and without accounting for direction, and signals of demographic change. Marion Island was found to have a distinct northwest–southeast divide, with lower genetic diversity and more sites with a signal of population expansion in the northwest. We attribute this to asymmetric seed dispersal by the dominant northwesterly winds, and to population persistence in a southwestern refugium during the Last Glacial Maximum. No apparent spatial pattern, but greater genetic diversity and differentiation between sites, was found on Macquarie Island, which may be due to the narrow length of the island in the direction of the dominant winds and longer population persistence permitted by the lack of extensive glaciation on the island. Together, our results clearly illustrate the implications of island shape and geography, and the importance of direction‐dependent drivers, in shaping spatial genetic structure.     

A revision of the Haplocheira group of genera (Amphipoda: Aoridae)

The Southern hemisphere aorid amphipod genera Haplocheira Haswell and Kuphocheira Barnard are revised and Anonychocheirus gen. nov. is described from Antarctica. A key is provided to distinguish the three genera and six species currently known. Material attributed to H. barbimana (Thomson, 1879) from Antarctica, South Georgia, Australia, lies de Kerguelen, New Zealand and Auckland Is. has been re-examined. The Antarctic material proves to be separate on the basis of antennal peduncle proportions, shape of lateral cephalic angle and shape and setation of peraeopod bases. Stebbing's species plumosa is re-established for this entity. Haplocheira robusta Barnard is synonymized with H. barbimana and three subspecies are described, viz. H.b. barbimana (Thomson) from New Zealand and Auckland Is., H.b. typica Haswell from Australia and lies de Kerguelen (shallow water) and H.b. robusta Barnard from Magellanic South America and the Falkland islands. Haplocheira balssi Schellenberg remains a separate species. Kuphocheira setimanus Barnard is re-assessed and K. emancipata sp. nov. described from Antarctica. The new genus Anonychocheirus is presently known only from the type species A. richardsoni sp. nov. described herein.     

Five new species of Culicoides (Diptera: Ceratopogonidae) of the Nansei Islands.

Five new species of Culicoides of the Nansei Islands are described: C. sasai sp.n. from Amami-oshima Is., C. toshiokai sp.n. from Ishigaki Is., C. iriomotensis sp.n. from Iriomote Is., C. flavipunctatus sp.n. from Yonaguni Is., and C. yaeyamaensis sp.n. from the latter three islands. C. toshiokai sp.n. and C. iriomotensis sp.n. are tree-hole breeders, such as C. dendrophilus Amosova, which is common in similar habitats extending from Okinawa to Honshu.     

On Udvardy's Insulantarctica province: a test from the weevils (Coleoptera: Curculionoidea)

'The scattered islands of the southern, cold ocean have clear affinities with one another . . . They are the basis for my Insulantarctica province.'
Udvardy, 1987, p. 190
Analyses of the distributional patterns of weevils (Coleoptera: Curculionoidea) from several Subantarctic islands, namely, Campbell, Auckland, Snares, Antipodes, Chatham, Falklands, Tierra del Fuego, Tristan da Cunha, Inaccessible, Nightingale, Gough, Marion, Prince Edward, Crozet, Kerguelen, and Heard, as well as South America and New Zealand, were carried out in order to determine their historical relationships, and to test the validity of Udvardy's (1987 ) Insulantarctica province. Three parsimony analyses of endemicity (PAE) considering (a) only species, (b) only supraspecific taxa, and (c) species and supraspecific taxa together, were undertaken. The following four groups emerged from the analyses: (1) New Zealand with the Snares, Auckland, Campbell, and Chatham Is., where New Zealand is the sister area to the Chatham Is., and the Auckland Is. are the sister area to Campbell I.; (2) South America with the Falkland Is. and Tierra del Fuego, where South America and Tierra del Fuego together are the sister area to the Falkland Is.; (3) Tristan da Cunha-Gough group, with the islands following the sequence Gough, Tristan da Cunha, Inaccessible, and Nightingale Is.; and (4) Kerguelen, Heard, Crozet, Marion, and Prince Edward Is., with Kerguelen and Heard Is. being sister areas, and Marion and Prince Edward Is. together being the sister area to the Crozet Is. It is concluded that the weevil fauna does not support the existence of an Insulantarctica province; the similarities among the different Subantarctic islands are due more to similar environmental conditions rather than to a common history.     

Aerobiology and colonization in Antarctica — the BIOTAS Programme

Little is known about the aerial transport of microbes, plants and animals into and between Antarctic terrestrial and freshwater habitats. Isolation by the circumpolar Southern Ocean restricts propagules to three main groups: 1) those capable of prolonged survival in the air, 2) those carried by animal vectors, especially Man, and 3) those of marine origin. Diverse ice-free areas available for colonization include: isolated islands with receding ice sheets (e.g., Signy Island), maritime geothermal areas (e.g., Deception Island), and high altitude gcothermal areas on continental volcanoes (e.g., Mt. Erebus). Propagule abundance and diversity are low in Antarctica. Chance affects colonization success because the potential and viability of a propagule must match a favourable habitat for settlement, with adequate time for establishment before conditions become unfavourable.

Aerobiological studies of the whole Antarctic region require international co-operation. The Scientific Committee on Antarctic Research (SCAR) Biological Investigations of Terrestrial Antarctic Systems (BIOTAS) research network has identified aerobiology as a major component of its International Research Programme.

Aerobiology will be ground-, ship- and aircraft-based. To meet the requirements of an intrinsically sparse, diverse Antarctic aerobiota, the British Antarctic Survey is developing a new particle sampler for remote field use.     

Are island plant communities more invaded than their mainland counterparts?

Questions: Are island vegetation communities more invaded than their mainland counterparts? Is this pattern consistent among community types? Location: The coastal provinces of Catalonia and the para‐oceanic Balearic Islands, both in NE Spain. These islands were connected to the continent more than 5.35 million years ago and are now located <200 km from the coast. Methods: We compiled a database of almost 3000 phytosociological relevés from the Balearic Islands and Catalonia and compared the level of invasion by alien plants in island versus mainland communities. Twenty distinct plant community types were compared between island and mainland counterparts. Results: The percentage of plots with alien species, number, percentage and cover percentage of alien species per plot was greater in Catalonia than in the Balearic Islands in most communities. Overall, across communities, more alien species were found in the mainland (53) compared to the islands (only nine). Despite these differences, patterns of the level of invasion in communities were highly consistent between the islands and mainland. The most invaded communities were ruderal and riparian. Main conclusion: Our results indicate that para‐oceanic island communities such as the Balearic Islands are less invaded than their mainland counterparts. This difference reflects a smaller regional alien species pool in the Balearic Islands than in the adjacent mainland, probably due to differences in landscape heterogeneity and propagule pressure.     

Effects of site and species characteristics on nested patterns of species composition in sedge meadows

Biotas of both geographical islands and habitat islands are often nested subsets of the biotas of successively more species-rich islands within the same system. The life history characteristics of a species may determine how that species contributes to the general pattern of species nestedness. Here, I investigate the floras of 56 sedge meadow wetlands in northern Illinois (USA) in order to characterize the degree of nestedness in these communities, determine which individual plant species contribute to the nested pattern, and investigate species characteristics that might be related to nonrandom patterns of distribution in individual plant species. The entire assemblage of species at all sedge meadows was significantly nested. Species richness and area were significantly correlated, and the nested pattern was closely related to site area, suggesting that species drop out of the assemblage in a predictable order as site area decreases. Some individual species exhibited nonrandom distributions across the sites, occurring more often in large, species-rich sites. Large sites were more likely than smaller sites to contain conservative species, i.e., those typical of pristine natural habitat, whereas nonconservative species were distributed more randomly among sites. Nested patterns of distribution of conservative species with respect to site area may result from their high probability of extinction on small sites or from a tendency for required habitats to co-occur on the same large sites. This revised version was published online in June 2006 with corrections to the Cover Date.     

Endolithic microbial composition in Helliwell Hills,a newly investigated Mars-like area in Antarctica

The diversity and composition of Antarctic cryptoendolithic microbial communities in the Mars-analogue site of Helliwell Hills (Northern Victoria Land, Continental Antarctica) are investigated, for the first time, applying both culture-dependent and high-throughput sequencing approaches. The study includes all the domains of the tree of life: Eukaryotes, Bacteria and Archaea to give a complete overview of biodiversity and community structure. Furthermore, to explore the geographic distribution of endoliths throughout the Victoria Land (Continental Antarctica), we compared the fungal and bacterial community composition and structure of endolithically colonized rocks, collected in >30 sites in 10 years of Italian Antarctic Expeditions. Compared with the fungi and other eukaryotes, the prokaryotic communities were richer in species, more diverse and highly heterogeneous. Despite the diverse community compositions, shared populations were found and were dominant in all sites. Local diversification was observed and included prokaryotes as members of Alphaproteobacteria and Crenarchaeota (Archaea), the last detected for the first time in these cryptoendolithic communities. Few eukaryotes, namely lichen-forming fungal species as Lecidella grenii, were detected in Helliwell Hills only. These findings suggest that geographic distance and isolation in these remote areas may promote the establishment of peculiar locally diversified microorganisms.     

Multi‐scale patterns of moss and lichen richness on the Antarctic Peninsula

Mosses and lichens are the dominant macrophytes of the Antarctic terrestrial ecosystem. Using occurrence data from existing databases and additional published records, we analyzed patterns of moss and lichen species diversity on the Antarctic Peninsula at both a regional scale (1°latitudinal bands) and a local scale (52 and 56 individual snow‐ and ice‐free coastal areas for mosses and lichens, respectively) to test hypothesized relationships between species diversity and environmental factors, and to identify locations whose diversity may be particularly poorly represented by existing collections and online databases. We found significant heterogeneity in sampling frequency, number of records collected, and number of species found among analysis units at the two spatial scales, and estimated species richness using projected species accumulation curves to account for potential biases stemming from sample heterogeneity. Our estimates of moss and lichen richness for the entire Antarctic Peninsula region were within 20% of the total number of known species. Area, latitude, spatial isolation, mean summer temperature, and penguin colony size were considered as potential covariates of estimated species richness. Moss richness was correlated with isolation and latitude at the local scale, while lichen richness was correlated with summer mean temperature and, for 17 sites where penguins where present with <20 000 breeding pairs, penguin colony size. At the regional scale, moss richness was correlated with temperature and latitude. Lichen richness, by contrast, was not significantly correlated with any of the variables considered at the regional scale. With the exception of temperature, which explained 91% of the variation in regional moss diversity, explained variance was very low. Our results show that patterns of moss and lichen biodiversity are highly scale‐dependent and largely unexplained by the biogeographic variables found important in other systems.     

Evidence for geographic isolation and signs of endemism within a protistan morphospecies

The possible existence of endemism among microorganisms resulting from and preserved by geographic isolation is one of the most controversial topics in microbial ecology. We isolated 31 strains of "Spumella-like" flagellates from remote sampling sites from all continents, including Antarctica. These and another 23 isolates from a former study were characterized morphologically and by small-subunit rRNA gene sequence analysis and tested for the maximum temperature tolerance. Only a minority of the Spumella morpho- and phylotypes from the geographically isolated Antarctic continent follow the worldwide trend of a linear correlation between ambient (air) temperature during strain isolation and heat tolerance of the isolates. A high percentage of the Antarctic isolates, but none of the isolates from locations on all other continents, were obligate psychrophilic, although some of the latter were isolated at low ambient temperatures. The drastic deviation of Antarctic representatives of Spumella from the global trend of temperature adaptation of this morphospecies provides strong evidence for geographic transport restriction of a microorganism; i.e., Antarctic protistan communities are less influenced by transport of protists to and from the Antarctic continent than by local adaptation, a subtle form of endemism.