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EVOLUTION

IMPORTANT TERMS:

Abiogenesis: Origin of life from non-living materials.

·         Asteroiods: Minor planets ranging a diameter from 1.5 km to 450km.

·         Adaptive Radiation ( Divergent Evolution): Formation of different structures from acommon ancestral form eg. homologous organs.

·         Allopatric Speciation: Origin of new species in geographically isolated populations.

·         Artificial Selection: Process by which man chooses the traits, he wants to perpetuate.

·         Biogeny: Origin of first life.

·         Biopolesis: Origin of life.

·         Chemogeny: Origin and development of different types of organic molecules.

·         Comets: Small masses of solid particles in universe held loosely together.

·         Cognogeny: Development of different forms of life.

·         Conacervates: Large colloidal cell-like aggregates of complex organic compounds which are supposed to have appeared during the origin of life.

·         Convergent Evolution: Formation of similar traits by unrelated groups of organisms

·          eg .analogous organs.

·         Demes: Refers to genetically isolated populations.

·         Eobiont: Cell-like structure capable of self duplication.

·         Gene Pool: Refers to sum total of all the different kinds of genes (alleles) in a population.

·         Homoplastic Organs: Analogous organs having similar external appearance.

·         Inbreeding: Mating between two closely related individuals.

·         Mass Extinction: Large scale extinction of organisms over relatively short span of time.

·         Nebula: Condensed mass of dust and gas.

·         Natural Selection: Selection of the best adapted individuals by nature.

·         Organic Evolution: Natural process by which newer forms of organisms arise from pre-existing ones through modifications. (or) Descent with modification (Darwin, 1859).

·         Out Breeding: Mating of two unrelated individuals.

·         Palaeogenesis: Occurrence of ancestral traits in the embryo.

·         Palaeontology: Study of fossils or study of remains and impressions of past organisms found in the rocks of different ages.

·         Parallel Evolution: Independent formation of similar traits by related groups of organisms.

·         Progressive Evolution: Formation of more complex and specialized structures from simpler ones.

·         Retrogressive Evolution: Development of simpler and less elaborate forms from complex ones.

·         Speciation: Refers to origin of new species.

·         Sympatric Speciation: Origin of new species in a population occupying the same geographical area.

·         Tectology: Study of functional anatomy of the organisms.

·         Universe (Cosmos): The entire material world that can be seen or detected with certain instruments like telescope. It is considered limitless and includes all stars, planets,satellite,etc.

ADDITIONAL INFORMATION:

·         Anthropology: Study of origin and development of humans in all their physical, social and cultural relationships.

·         Anthropobiology: Study of the biological relationship of the human race.

·         Coenozoic era is also called Age of Mammals, Birds, Fishes, Insects and Angiosperms.

·         Cosmology: Study of universe, its nature, origin and history.

·         Exobiology: Study of possible life outside the earth.

·         Evolutionary Biology: The branch of biology that involves the study of living systems as they change through time.

·         Hyalobates hoolock (the gibbon) is the only ape, found in India (forests of Assam).

·         Most primitive ape is Gibbon.

·         Most developed ape is Gorilla.

·         Life presumably originated in the ancient ocean in Precambrian era.

·         Progenote: It is considered that is was an early single celled common ancestor of archaebacteria, eubacteria and eukaryotes. It indicate that there is no present day bacterial type which can be regarded as an ancestor of eukaryotes.

·         Ordovician Period is also called ‘Age of Giant Molluscs’.

·         Mesozoic era is also called “Age of Reptiles”.

·         Living Fossils: A living fossil is a living animal or plant of ancestral origin with many primitive characters. A living fossil has been living as such from the time of origin without many changes. Examples.(i) Peripatus, Limulus (arthropoda)  (ii) Neopilina (molluse) (iii) Latimeria (bony fish) (iv) Sphenodon (reptile)  (v) Egg laying mammals (vi) Cycas, Ginkgo (gymnosperms).

·         Allen’s Law states that in animals that live in very cold climates, the extremities such as ears, tails etc; become progressively smaller.

·         Bergman’s Law states that the warm blooded animals become larger in the northern and colder parts of their range.

·         Cope’s Law states that there is a tendency for animals to, increase in size during the long course of evolution.

·         Dollo’s Law (Dollo, 1893) states that evolution is irreversible.

·         Gause’s Law (Gause, 1934) or Principle of Competitive Exclusion (Hardin, 1960) states that two species having the same ecological requirements cannot continue to occupy indefinitely the same habitat.

·         Gloger’s Rule states that among warm blooded animals those living in warm and moist climates develop more melanin pigment (darker than the animals in cold, dry climates), whereas formation in dry, hot climates have more yellow and red pigment.

·         Jordan’s Rules states that fishes inhabiting water of low temperature tend to have more vertebrae than those of warmer waters. It has been observed that cold water forms of many species are frequently larger than the individuals from warmer waters.

Darwin’s Theories: Main theories proposed by Charles Darwin are (i) Theory of Natral Selection (ii) Theory of Sexual Selection (iii) Theory of Artificial Selection and (iv) Theory of Pangenesis.

Mr. A. KINGSLIN M.Sc, BEd, Phd,(doing)
Post Graduate Teacher in Botany
St. Mary Goretty Hr. Sec School, Manalikarai 
Kanyakumari district





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