Tardigrade diversity: an evaluation of natural and disturbed environments of the province of Salta (Argentina)

Abstract

Argentine tardigrades are relatively unknown and, in many cases, unstudied; in the province of Salta in northwestern Argentina the lone record of tardigrade dates to the 1980s. Here, we evaluate and compare tardigrade diversity in natural habitats (N), urban environments (U) and rural communities (R) of Yungas. This work seeks to verify the existence of a reduction in tardigrade diversity outside their native habitats and if there is a biotic homogenization in the urban communities. Tardigrade community assemblages were compared between habitats using non-metric multidimensional scaling and a multi-response permutation procedure. Beta diversity was analysed in its component parts, species turnover and nesting, using a modified Raup-Crick test. Gamma diversity was divided into alpha and several beta levels. In total, 2080 eutardigrade and heterotardigrade specimens were registered and showed differences in tardigrade assemblages between habitats; the most diverse habitat was R. The beta diversity partition showed a nesting pattern in the U communities, highlighting faunal homogenization, while species turnover was key in the R and N communities. There was species loss from N to U communities, most markedly between R and U; various forces (both stochastic and deterministic) influence the structure of these communities.

Tardigrades in the city: A review of diversity patterns in response to urbanization

“…Only in one study, conducted in Fresno, CA were most of the urban species not found in the adjoining rural areas (Johansson et al, 2011). In all other cases, most of the urban species were also found in the surrounding rural areas (Meininger et al, 1985;Meyer et al, 2013;Rocha et al, 2016;Séméria, 1981Séméria, , 2002. If the tardigrade species found in a city depend on the species already established in the territory around the city, we would expect that closer cities will have more urban species in common than distant cities.…”

“…Tardigrade abundance in a given sample is normally similar in rural and urban sites (Meyer et al, ). In fact, in some cities tardigrade abundance can be higher in urban sites than in rural sites (Rocha et al, ). Therefore, urban environments may not be particularly inhospitable to those tardigrade species that are able to colonize and get established in cities.…”

“…Only identified species are listed, and thus the number of species listed under a city may be lower than the number indicated in Table 1. GP: General Pico, Argentina (de Peluffo et al, 2006); LC: Lake Charles, LA (Meyer et al, 2013); SR: Santa Rosa, Argentina (Peluffo et al, 2007); C: Cincinnati, OH (Meininger et al, 1985); B: Belfast, UK (Roberts & Zimmer, 1990); Z: Zürich, Switzerland (Steiner, 1994); N: Nice, France (Séméria, 1981(Séméria, , 2002; F: Fresno, CA (Johansson et al, 2011); S: Salta, Argentina (Rocha et al, 2016); T: Tokyo, Japan (Utsugi, 1985). Each line connects the number of species in rural and urban sites in the same city investigated to date there is a substantial decline in tardigrade diversity compared to rural sites (Table 1).…”

“…Consequently, tardigrades should a priori be unaffected by urban stressors, and thus species richness should be similar in urban areas and in neighboring rural areas. However, in the studies in which tardigrade diversity has been investigated in both rural and urban sites, the pattern seems to be for the number of species to be lower in urban sites (de Peluffo, Peluffo, Rocha, & Doma, 2006;Johansson, Calloway, Miller, & Linder, 2011;Meyer, Hinton, & Samletzka, 2013;Rocha et al, 2016).…”

“…Tardigrades remain a very understudied group, and this is particularly the case in the context of urban ecology (Rocha et al, ). However, tardigrades can be a very powerful model to investigate the challenges and opportunities encountered by urban colonizers.…”