Читать книгу Algorithms in Bioinformatics - Paul A. Gagniuc - Страница 29

How many species really? Unfortunately, life is not as diverse as previously believed [74, 75]. For more than 250 years, our species has cataloged all the other land and water species at our disposal, and continue to do so. Based on this census, the tree of life contains a total of 1.43 million known species, from which almost 1.42 million are eukaryotes and 12k species are prokaryotes (Table 1.1 and Figure 1.1) [74]. Most of the time, real census ruins the “feng shui” of predictions. In total, even the most enthusiastic predictions forecast between 8 million and 11 million species in existence [74, 76, 77].

However, under the heavy umbrella of uncertainty, predictions and census rarely match when it comes to the total number of species on earth. Among the cataloged species for the tree of life, animal species constitute 78% and plant species represent 15%. Out of a total of 1.4 million species, about 1.2 million species live on land and 19k live in the aquatic environment (Table 1.1).

Table 1.1 The total number of known species.

Source: Refs. [74, 283].

Kingdoms	Land	Water	Total
Eukaryotes
Animals	953k	171k	1125k
Fungi	43k	1k	44k
Plants	216k	9k	224k
Protists	21k	13k	34k
Prokaryotes
Bacteria	10k	1k	11k
Archaea	1k	0k	1k
Total	1244k	194k	1439k

The table shows the total number of known species on earth. The data are divided into two major categories on rows, namely prokaryotes and eukaryotes; and two major categories on columns two and three, namely the environment. Note that 1k means 1000 species.