Biology Reference
In-Depth Information
Table 9.1 Estimates of known and potential number of species in the major
protist groups
Group
Known
Potential
Amoebozoa
4110
22,600
Opisthokonta (excluding animals)
407,370
2,500,000
10
6
Rhizaria
ca. 11,900
2.5
>
Archaeplastida (excluding plants)
ca. 20,300
220,000
10
6
Chromalveolata
ca. 216,553
2
>
Excavata
ca. 2300
3200
From Table 1 of
Adl et al. (2007)
.
unicellular, colonial, filamentous or parenchymatous organization, which
lack vegetative tissue differentiation except for reproduction (
Adl et al.,
2007
). Protists can be free living or parasitic and are widely distributed on
land and water. Molecular barcoding using SSU rRNA gene sequences
has been used to reveal an extensive genetic diversity of protists in a wide
range of ecosystems (
Bik et al., 2012; Del Campo & Ruiz-Trillo, 2013;
Lopez-Garcia, Rodriguez-Valera, Pedros-Alio, & Moreira, 2001; Moon-
van der Staay, DeWachter, &Vaulot, 2001; Pawlowski et al., 2011
), includ-
ing lineages only known by their genetic signatures (orphan environmental
sequences), found everywhere. Furthermore, the rate of discovery of new
species remains high.
Table 9.1
provides estimates of known and potential
number of species based on unknown DNA sequences found in environ-
mental samples (
Adl et al., 2007
). The recent update of protist classification
(
Adl et al., 2012
) recognizes the grouping of Opishokonta and Amoebozoa
into the Unikonta (
Roger & Simpson, 2009
) and the SAR clade,
encompassing the Stramenopiles, Alveolata and Rhizaria (
Burki et al.,
2007
). Some 145 groups or genera incertae sedis remain with uncertain affil-
iation within protists (
Adl et al., 2012
).
3. GLOBIN NOMENCLATURE
Table 9.2
summarizes a recently proposed comprehensive nomencla-
ture for all globins, including eukaryotes, based on the bacterial globin fam-
ilies (
Vinogradov et al., 2013
). Over the last decade, Burmester, Hankeln
and their collaborators have discovered several new globins in vertebrate
genomes (
Burmester et al., 2004
), including the ubiquitous neuroglobins
