Making the most of phylogeny - OPUS - Universität Würzburg

The phylum Tardigrada Part I. Introduction
time of one year. Suzuki (2008) reported a low frequency of males in the culture of
M. tardigradum.
The eggs are colourless or brown and the diameter ranges from 70–110 µm
(Kinchin 1994). Suzuki (2003) found that the most rapidly developing animal laid
eggs 12 days after hatching.
Hypsibius dujardini
Hypsibius dujardini is an obligatory parthenogenetic species (Ammermann 1967).
H. dujardini can be cryopreserved and cultured continuously for long time. The
genome size of about 78 Mbp (Gregory et al. 2007) is one of the smallest genomes
of animals (Gabriel et al. 2007). This is about three-quarters of C. elegans and less
than half the size of the D. melanogaster genome. The generation time is about
14 days at room temperature, the embryos have a stereotyped cleavage pattern
with asymmetric cell divisions, nuclear migrations, and cell migrations occurring in
reproducible patterns.
The rate of protein evolution in H. dujardini is similar to the rate in D. melanogaster
and, thus similar to most other known genomes in metazoans (Gabriel et al. 2007).
Only sparse molecular data are available, but Bavan et al. (2009) described a purinergic
receptor expressed in H. dujardini and Gabriel and Goldstein (2007) examined
the expression of Pax3/7 during embryogenesis.
Richtersius coronifer
Richtersius coronifer, formerly Adorybiotus or Macrobiotus, is a large tardigrade with
body sizes up to 1 mm (Kinchin 1994). R. coronifer is a bryophilic (moss-living)
tardigrade, which can be found all over the world mainly in alpine and arctic
environments up to 5600 m (Ramløv and Westh 2001).
R. coronifer can survive severe dehydration for years (Ramløv and Westh 2001)
and is capable of tolerating temperatures down to −196 ◦ C independent from the
actual state (tun or normal living) (Ramløv and Westh 1992; Westh and Ramløv
1991). The disaccharide trehalose is accumulated up to approximately 2.3 % dry
weight during desiccation (Westh and Ramløv 1991).
Genus Paramacrobiotus
Recently the genus Paramacrobiotus was erected within the family of Macrobiotidae
using morphological characters and gene sequences. Within the genus several
cryptic species from different places around the world could be found, which can
not be clearly separated by morphological or common molecular markers alone
(Guidetti et al. 2009). This cryptic species have been already used for biochemical
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