student Theophrastus ( - BC) continued his research on the classification of plants, and he was known as the “Father of Botany.” There was a huge gap till 16th century, then the English naturalist John Ray ( – ) wrote several important works through his life. His most important contribution was the establishment of species as the ultimate unit of taxonomy. In he published the Methodus Plantarum Nova , which contained about , plant species, a result of a relatively narrow species concept. His complicated classification was based on many combined characters, as opposed to earlier taxonomists.
John Ray also aimed at publishing a complete system of nature, which included works on mammals, reptiles, birds, fishes and insects. The Swedish biologist Carolus Linnaeus ( - ) father of modern taxonomy and founder of modern systematics developed a scientific system of taxonomy and binomial nomenclature, which is still (with modifications) in use. Aristotle to Linnaeus employed easily observable single to few traits for classification of organisms. With increased knowledge of the several biological domains, many characters were considered for classifying organisms.
This represented the phase of classical taxonomy which was based on overall similarities or affinities derived from morphology, anatomy and embryology of organisms. A modification of this system is the numerical taxonomy, which evolved in the 1950s. This system evaluates the resemblances and differences through statistical methods followed by computer analyses to establish the numerical degree 6KDUNV 5D\)LQQHG ILVK $PSKLELDQV 3ULPDWHV 5RGHQWV UDEELWV &URFRGLOHV %LUGV +DLU $PQLRWLFHJJ )RXUOLPEV %RQ\VNHOHWRQ 9HUWHEUDH (JJVZLWKVKHOOV 5D\ )LQQHG 5RGHQWV Figure . Example of a Cladogram XI Std Biology-Zoology Chapter- placed into the domain Eukarya.
Archaea appears to have more in common with the Eukarya than the Bacteria. Archaea differ from bacteria in cell wall composition and differs from bacteria and eukaryotes in membrane composition and rRNA types. . Domain Archaea This domain includes single celled organisms, the prokaryotes which have the ability to grow in extreme conditions like volcano vents, hot springs and polar ice caps, hence are also called extremophiles.
They are capable of synthesizing their food without sunlight and