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Introduction. What is Molecular Systematics?. What is Molecular Systematics?.
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What is Molecular Systematics? Molecular systematics is a branch of the traditional field of systematics that utilizes molecular biology techniques. The evolutionary relationships of organisms are studied using their DNA, RNA and protein sequences to establish their systematic positions. They make use of cladistic and phylogenetic methods. - Wikipedia
Molecular systematics: The detection, description, and explanation of molecular biological diversity, both within and among species. - Natural History Collections Website, University of Edinburgh
Evolution of Molecular systematics • Classification has long been practised, as far back as Theophrastus period (c. 370-285 AD). • the classification became more systematic and organized during Linneaus time (1707-1778). • systematic and organized classification is important so that it could be referred and managed easily.
Estimation of organisms on the earth Seed Plants 240,000 Pteridophyte (ferns) 12,000 Bryophyte 23,000 Algae 17,000 Fungi 120,000 Lichen 16,000 Green-blue Algae 500 Bacteria 3,000 Protozoa 30,000 Vertebrate 1,000,000 Invertebrate 50,000 Total ~1,512,000
Linneaus (1758) developed hierarchical system of nomenclature. The system is independent of evolutionary theory. • Evolutionalists (Lamarck 1809, Darwin 1859, Haeckel 1866) co-opted Linneaus system to produce a classification based on phylogenetic relatioships.
The phylogeny and classification of life as proposed by Haeckel (1866)
The word phylogeny does not appear in the index to Julian Huxley’s Evolution: The Modern Synthesis, published in 1942. • Botanist Walter Zimmermaun (1930; 1931; 1934; 1943) and zoologist Willi Hennig (1950; 1966) defined objective methods for reconstructing evolutionary history based on the shared attributes of extant and fossil organisms. • The methods were refined and developed into explicit criteria for estimating phylogeny in 1960s.
The last 40 years have seen major conceptual and operational advances in the estimation of phylogeny. • At about the same time in 1960s, revolution was happening in molecular biology. • Methods for examining the molecular structure of proteins and nucleic acids were soon adopted by evolutionary biologists, and the data available for phylogenetic estimation began to increase exponentially.
Electrophoresis isozymes in 1970s RFLP technique in 1980s based on mitochondrial and kloroplast genomes PCR technique in early of 1990s Improvement of DNA sequencing automation technique in 1990s