Ciliate biogeography in Antarctic and Arctic freshwater ecosystems: endemism or global distribution of species?

Abstract

Ciliate diversity was investigated in situ in freshwater ecosystems of the maritime (South Shetland Islands, mainly Livingston Island, 63 degrees S) and continental Antarctic (Victoria Land, 75 degrees S), and the High Arctic (Svalbard, 79 degrees N). In total, 334 species from 117 genera were identified in both polar regions, i.e. 210 spp. (98 genera) in the Arctic, 120 spp. (73 genera) in the maritime and 59 spp. (41 genera) in the continental Antarctic. Forty-four species (13% of all species) were common to both Arctic and Antarctic freshwater bodies and 19 spp. to both Antarctic areas (12% of all species). Many taxa are cosmopolitans but some, e.g. Stentor and Metopus spp., are not, and over 20% of the taxa found in any one of the three areas are new to science. Cluster analysis revealed that species similarity between different biotopes (soil, moss) within a study area was higher than between similar biotopes in different regions. Distinct differences in the species composition of freshwater and terrestrial communities indicate that most limnetic ciliates are not ubiquitously distributed. These observations and the low congruence in species composition between both polar areas, within Antarctica and between high- and temperate-latitude water bodies, respectively, suggest that long-distance dispersal of limnetic ciliates is restricted and that some species have a limited geographical distribution.

Pole-to-Pole Connections: Similarities between Arctic and Antarctic Microbiomes and Their Vulnerability to Environmental Change

“…Finlay and Fenchel (2004) state that the cosmopolitan fraction of organisms in the bacterial size range is usually about 2.5-fold higher than detected in the present study. Cox et al (2016) also found a percentage of ∼35-60% cosmopolitan OTUs in Antarctic fungi and Petz et al (2007) showed that 13% of freshwater ciliate species were shared between the Arctic and the Antarctic. For larger organisms Griffiths et al (2009) suggest a general level of endemism of 50% in Southern Ocean benthos, and even greater levels of endemism (up to possibly 100% at species level) are reported across a range of Antarctic terrestrial biota Pugh and Convey, 2008).…”

Algal biomass and pigments along a latitudinal gradient in Victoria Land lakes, East Antarctica

“…Only limited support was obtained for a systematic decrease in eukaryotic (primarily fungi, algae and protists) diversity with latitude (Lawley et al 2004;Petz et al 2007), that is, when the comparisons were made between maritime and continental Antarctic sites, whereas there was no evidence for a trend of decreasing diversity across the entire range of the maritime Antarctic. Similar findings were also reported for tardigrades and rotifers (Sohlenius & Boströ m 2005) and plants (Peat et al 2007).…”

Characterization of the pheromone gene family of an Antarctic and Arctic protozoan ciliate, Euplotes nobilii

“…In them we find an unique combination of ecological and biological properties. In addition to representing a major microbial component of every aquatic system also in the polar regions [1,2], they are facultative sexual organisms. Their life cycles in fact involve an optional alternation between periods of vegetative growth (mitotic multiplication) associated with availability of energetic resources from the environment, and sexual events associated with famine and other stressing conditions [3].…”