Biosystematics Lecture Notes PDF

Biosystematics  Contents of Lecture 1 What is Biosystematics? History and development of systematics Importance of biosystematics  Biosystematics Biosystematics is simply known as “the study of biodiversity and its origins”. The word systematics is derived from...

Biosystematics  Contents of Lecture 1 What is Biosystematics? History and development of systematics Importance of biosystematics  Biosystematics Biosystematics is simply known as “the study of biodiversity and its origins”. The word systematics is derived from the Latin word `systema‘, which refers to organisms’ systematic arrangement. Biosystematics (bi-o-sys-tem-at-ics) The analysis of biological criteria that uses the characters and data from many disciplines like morphology, anatomy, cytology, genetics, palynology, embryology, ecology, plant geography, phylogeny, physiology, phytochemistry, and evaluation to assess the taxonomic relationships of organisms or populations, especially within an evolutionary framework.  What is Biosystematics? Scientific study of the biological diversity and its evolutionary history OR Scientific classification of living organisms based on their evolutionary relationships The science of systematic involves putting living organisms into categories based on their evolutionary relationships , for example, how closely related they to each others History and development of systematics People who live close to nature usually have an excellent knowledge of the elements of the local fauna (animals) and flora (plants). Their knowledge, however, is according to their need. Hippocrates (460-377 BC), a Greek physician, who is referred to as the Father of Medicine listed organisms with medicinal value. ❖ Aristotle (384-322 BC) ❖ Greek philosopher who practically invented the science of logic. ❖ Greeks had constant contact with the sea and marine life, ❖ Aristotle seems to have studied it intensively during his stay on the island of Lesbos. ❖ He divided organisms into plants and animals, subdividing organisms by their habitats into land, water, or air dwellers. ❖ Theophrastus (371-287 BC) was the successor (student) to Aristotle in the school of philosophy in Ancient Greek. ❖ He is known as the father of Botany. ❖ Theophrastus distinguished plants based on growth (trees, shrubs, subshrubs, herbs), and color of leaves and fruit. ❖ Aristotle and his student Theophrastus classified organisms without stressing on their medicinal value. Pliny the Elder (23-79 AD), a Roman naturalist, who introduced his system of artificial classification in his book Naturalis Historia, an early encyclopedia in Latin. mentions over 1,000 economic plants with about 2,000 items. ❖ John Ray (1627-1705), an English naturalist. ❖ He distinguished the monocotyledonous plants from the dicotyledonous. ❖ He introduced the term species for the first time for any kind of living things. ❖ described about 18600 plants in three volumes ‘Historia Generalis Plantarum’ between 1686-1704. ❖ He published important works on botany and zoology. His classification of plants in his Historia Plantarum, was an important step towards modern taxonomy. Carolus Linnaeus (1707-1778) the Swedish naturalist of 18th century now known as Father of Taxonomy. His classification was based on similarities and differences and was logical classification In his famous book ‘Species Plantarum’(1753) he described 5,900 species of plants Developed the Binomial System of nomenclature which is the current scientific system of naming the species. (species and genus)  Darwinian period On 1958 British naturalist Charles Darwin argued that classification systems should reflect the history of life – that is species should be related based on their shared ancestry in recent history While organisms in higher taxa diverged from shared ancestor further back in history Importance of biosystematics 1- Provide specimen identification - Indirectly, via keys. - Directly, via expert examination. 2 Maintain Collections - Provide reference for identifications - Voucher specimens (A 'voucher specimen' is any specimen, usually but not always a cadaver (corpse) (‫ )جثة‬, that serves as a basis of study and is retained as a reference.) - Serve as permanent repository (store) for important specimens 3. Understanding biological processes - speciation processes - adaptation to environment 4. Pest management Pest species and their natural enemies must be correctly identified before biological control process. 5. Relevance for epidemiology ❑ the correct identification of the pathogen is essential. In order to find remedies (treatment) for diseases caused by pathogenic organisms. For example, ❑ Taxonomists contributed greatly to the successful control of malaria by providing correct identification of the Anopheline species of mosquitoes which are the vectors (transmitting) of the disease-causing parasite.  6. Documentation of Earth’s biodiversity ▪ Biosystematics is important to identify and document Earth’s biodiversity and organize this information in a form that can be utilized by others. ▪ Biosystematics provides a way of documenting the change in the world’s flora and fauna and can therefore provide supporting evidence for phenomena such as human-caused climate change. 7. Predictive value ▪ Phylogenetic patterns that result from systematic studies have predictive value ▪ One seeks additional taxa that may possess a feature of interest found in a specific taxon ▪ For example, the anti-cancer compound taxol was isolated from a particular species of conifer, the Pacific Yew (Taxus brevifolia). ▪ Where else would we look to find other sources of this compound? The logical place to look would be in taxa that are most closely related to T. brevifolia. 8. Conservation priorities. ▪ Biosystematics provides a basis for biodiversity conservation priorities. ▪ In order to maximize diversity, it makes sense to try to preserve groups from throughout the tree of life, rather than large numbers from one branch. In this way we will tend to preserve a wider array (group) of features that have potential use for humans. 9. Evidence of geological changes ▪ Systematics provides independent evidence for patterns of geological change. ▪ When land masses fragment or experience other fundamental change, the taxa that live on them record this change.