Molecular evidence for a diverse green algal community growing in the hair of sloths and a specific association with Trichophilus welckeri(Chlorophyta, Ulvophyceae)

Abstract

BackgroundSloths are slow-moving arboreal mammals inhabiting tropical rainforests in Central and South America. The six living species of sloths are occasionally reported to display a greenish discoloration of their pelage. Trichophilus welckeri, a green algal species first described more than a century ago, is widely believed to discolor the animals fur and provide the sloth with effective camouflage. However, this phenomenon has not been explored in any detail and there is little evidence to substantiate this widely held opinion.ResultsHere we investigate the genetic diversity of the eukaryotic community present in fur of all six extant species of sloth. Analysis of 71 sloth hair samples yielding 426 partial 18S rRNA gene sequences demonstrates a diverse eukaryotic microbial assemblage. Phylogenetic analysis reveals that sloth fur hosts a number of green algal species and suggests that acquisition of these organisms from the surrounding rainforest plays an important role in the discoloration of sloth fur. However, an alga corresponding to the morphological description of Trichophilus welckeri was found to be frequent and abundant on sloth fur. Phylogenetic analysis demonstrated the retention of this alga on the fur of sloths independent of geographic location.ConclusionsThese results demonstrate a unique diverse microbial eukaryotic community in the fur of sloths from Central and South America. Our analysis streghtens the case for symbiosis between sloths and Trichophilus welckeri.

Chlorella: 125 years of the green survivalist

“…A cryptic diversity of 'green balls' was discovered in manifold aquatic and terrestrial habitats, resulting in the designation of new genera and species [8,9]. New strains with interesting physiological and biochemical features were discovered from exotic habitats, such as salty, acidic, or alkaline waters, leaves of tropical rainforest trees, and the pelt of sloths [9,10]. For a long time, ecologists were unaware of the wide diversity of the spherical green algae, although Chlorella and its relatives belong to the most common aquatic, terrestrial, and aerophytic algae with ubiquitous distribution.…”

Phylogeny and Molecular Evolution of the Green Algae

“…The group is predominantly marine, but several transitions to freshwater or terrestrial habitats have occurred independently (Shimada et al, 2008;Ichihara et al, 2009;Suutari et al, 2010). The orders Ulvales and Ulotrichales have traditionally been distinguished based on life history features: the Ulvales have a life cycle involving isomorphic alternations of multicellular stages, while in the Ulotrichales the diploid, spore-producing stage is a small, thick-walled unicell that is attached to the substrate by a stalk (Codiolum stage) (O'Kelly et al, 2004b).…”

Probing Physical Properties of a DNA‐Protein Complex Using Nanofluidic Channels

“…The landmark article by Woese and Fox (1977) demonstrated that the presence of ribosomal RNA (rRNA) in all living organisms and its high degree of conservation make it an excellent gene for studying species relationships. Since then, rRNA has been a popular choice for phylogenetic inference, ranging from the algae that live on sloth fur (Suutari et al 2010) to 200 metazoan species (Mallatt et al 2010). The biological importance of rRNA (and tRNA) is well established, but recently the significance of other types of noncoding RNA (ncRNA) has been recognized (reviewed in Griffiths-Jones 2007;Mattick 2009).…”