Evolution – BSI SIR

NCERT-Convergent Evolution of Mammal—Diagram Explained-NEW EDITION

Evolution, free, NCERT LINE BY LINE / Prof. Siddharth Sanghvi

Adaptive Evolution in Nature: The Fascinating Case of Darwin’s Finches and Australian Marsupials An in-depth look into how two distinct ecosystems, the Galápagos Islands and Australia, shaped the evolution of species through adaptation. Evolutionary Concepts Convergent Evolution Unrelated species evolve similar traits due to similar environmental pressures. Example: Placental mammals & Australian marsupials. Divergent Evolution […]

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NCERT-Convergent Evolution of Mammal—Diagram Explained

Evolution, NCERT LINE BY LINE / Prof. Siddharth Sanghvi

Convergent Evolution of Mammals Convergent Evolution, Divergent Evolution, and Adaptive Radiation Convergent Evolution Convergent evolution occurs when unrelated species evolve similar traits due to similar environmental pressures. This phenomenon is evident in placental mammals and Australian marsupials. Divergent Evolution Divergent evolution occurs when a common ancestor evolves into distinct species due to different environmental conditions.

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NCERT- Evolution Diagram Dinosaur -A family tree of dinosaurs and their living modern day counterpart organisms like crocodiles and birds

Evolution, NCERT LINE BY LINE / Prof. Siddharth Sanghvi

Evolutionary Lineage of Archosauria Category Description Examples Archosauria (Common Ancestor) Archosaurs, a group of reptiles from the early Triassic (~250 million years ago), are the common ancestor of crocodilians, pterosaurs, and dinosaurs. None Branches Crocodylomorpha (Crocodilians) Crocodiles and their relatives diverged early (~230 million years ago). Evolved independently but retained traits of their ancient archosaur

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Five factors are known to affect Hardy-Weinberg equilibrium. These are gene migration or gene flow, genetic drift, mutation, genetic recombination and natural selection. When migration of a section of population to another place and population occurs, gene frequencieschange in the original as well as in the new population. New genes/alleles are added to the new population and these are lost from the old population.There would be a gene flow if this gene migration, happens multiple times.If the same change occurs by chance, it is called genetic drift. Sometimesthe change in allele frequency is so different in the new sample of populationthat they become a different species. The original drifted population becomes founders and the effect is called founder effect.

Evolution, NCERT LINE BY LINE / Prof. Siddharth Sanghvi

MECHANISMS OF EVOLUTION Although the term “evolution” is often used synonymously with “natural selection,” they are actually referring to different concepts. Evolution is an observable phenomenon in which gene frequencies change over time, but it does not explain why a population is undergoing evolution. This is where natural selection—and other mechanisms—come into play. They explain

Five factors are known to affect Hardy-Weinberg equilibrium. These are gene migration or gene flow, genetic drift, mutation, genetic recombination and natural selection. When migration of a section of population to another place and population occurs, gene frequencieschange in the original as well as in the new population. New genes/alleles are added to the new population and these are lost from the old population.There would be a gene flow if this gene migration, happens multiple times.If the same change occurs by chance, it is called genetic drift. Sometimesthe change in allele frequency is so different in the new sample of populationthat they become a different species. The original drifted population becomes founders and the effect is called founder effect. Read More »