title: Molecular evidence for a diverse green algal community growing in the hair of sloths and a specific association with Trichophilus welckeri (Chlorophyta, Ulvophyceae).
abstract: BACKGROUND
  Sloths 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.
  
  
  RESULTS
  Here 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.
  
  
  CONCLUSIONS
  These 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.
authors.affiliation: Department of Environmental Sciences, P,O,Box 65, FIN-00014, University of Helsinki, Helsinki, Finland.
authors.forename: Milla
authors.initials: M
authors.lastname: Suutari
authors.forename: Markus
authors.initials: M
authors.lastname: Majaneva
authors.forename: David P
authors.initials: DP
authors.lastname: Fewer
authors.forename: Bryson
authors.initials: B
authors.lastname: Voirin
authors.forename: Annette
authors.initials: A
authors.lastname: Aiello
authors.forename: Thomas
authors.initials: T
authors.lastname: Friedl
authors.forename: Adriano G
authors.initials: AG
authors.lastname: Chiarello
authors.forename: Jaanika
authors.initials: J
authors.lastname: Blomster
mesh_terms: D000818:Animals; D002489:Central America; D000460:Chlorophyta / Q000235:genetics*; D048028:DNA, Algal / Q000235:genetics; D005843:Geography; D006197:Hair; D010802:Phylogeny; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012896:Sloths; D013020:South America
chemical_list: D048028:DNA, Algal; D012337:RNA, Ribosomal, 18S