Origin, Evolution, and Distribution of Animals: Insights from Zoological Studies
Explore the origin, evolution, classification, and global distribution of animals, based on detailed zoological research and historical perspectives.
Introduction
Understanding the origin, evolution, and distribution of animals is central to zoological and ecological studies. This topic explains how life might have begun, the processes that shaped animal diversity, and how species spread across the globe. By studying fossil records, theories from renowned biologists, and biogeographic models, we gain a clearer view of our planet’s natural history.
Students, researchers, and nature enthusiasts will find this exploration valuable for grasping fundamental biological concepts. This detailed excerpt dives deep into milestones of evolutionary biology, classification systems, and how various species occupy different ecozones. Read on for an unaltered look into a scholarly thesis that highlights this fascinating journey of life.
Article
Histogenesis of Animals: Origin, Evolution, Classification and Distribution
*“How life originated and evolved on Earth is the biggest scientific process which has remained unsolved till now, but the quest to find out the clear facts has always interested us. Many scientists have tried to explain this in convincing ways.
Until the early 19th century many people believed in the regular spontaneous generation of life from non-living matter. In a letter to Joseph Dalton Hooker on 11 February 1871, Charles Darwin, an English naturalist and geologist, best known for his contributions to evolutionary theory proposed a natural process for the origin of life.
He suggested that the original spark of life may have begun in a “warm little pond, with all sorts of ammonia and phosphoric salts, lights, heat, electricity, etc. A protein compound was then chemically formed ready to undergo still more complex changes”.
No real progress was made until 1924 when Alexander Oparin reasoned that atmospheric oxygen prevented the synthesis of the organic molecules. Organic molecules are the necessary building blocks for the evolution of life. In his “The Origin of Life”, Oparin argued that a “primeval soup” of organic molecules could be created in an oxygen-less atmosphere through the action of sunlight.
Around the same time J.B.S. Haldane also suggested that the Earth’s pre-biotic oceans, which were very different from what oceans are now, would have formed a “hot dilute soup”. In this soup, organic compounds, the building blocks of life, could have formed. This idea was called biopoiesis.*
In the early 19th century Jean-Baptiste Lamarck, proposed his theory of the transmutation of species, the first fully formed theory of evolution.
Charles Robert Darwin established that all species of life have descended over time from common ancestors, and in a joint publication with Alfred Russel Wallace introduced his scientific theory that this branching pattern of evolution resulted from a process that he called natural selection, in which the struggle for existence has a similar effect to the artificial selection involved in selective breeding.
In 1858 Charles Darwin and Alfred Russel Wallace published a new evolutionary theory which was explained in detail in Darwin’s.
Sir Julian Sorell Huxley was a British evolutionary biologist, eugenicist, and internationalist. He was a proponent of natural selection, and a leading figure in the mid-twentieth century modern evolutionary synthesis. Huxley and biologist August Weismann insisted on natural selection as the primary agent in evolution.
Ernst Walter Mayr was born in Germany, but worked as a resident of United States. He was one of the 20th century’s leading evolutionary biologists. He was also a renowned taxonomist, tropical explorer, ornithologist, philosopher of biology, and historian of science. His work contributed to the conceptual revolution that led to the modern evolutionary synthesis of Mendelian genetics, systematics, and Darwinian evolution, and to the development of the biological species concept.
Ernst Mayr approached the problem with a new definition for species. In his book Systematics and the Origin of Species (1942) he wrote that a species is not just a group of morphologically similar individuals, but a group that can breed only among themselves, excluding all others. When populations within a species become isolated by geography, feeding strategy, mate choice, or other means, they may start to differ from other populations through genetic drift and natural selection, and over time may evolve into new species.
Some other Evolutionary biologists whose work and publications are the land marks in this attempt to understand the process of Evolution better are: Avers, C.J., 1974. Evolution. Campbell, B., 1985. Human Evolution. Colbert, E.H., & Morales, M., 1991, Evolution of the Vertebrates:
A History of the Backbones Animals Through Time. Conn, H.W., 1900, The Method of Evolution. Haldane, J.B.S., 1966, The Causes of Evolution. M.W. Strickberger has made profound contributions to our understanding of the evolutionary process. He tried to explain Evolution in the light of Genetics.
Other Indian Authors who have tried to understand Evolutionary Biology and cited the process in their books are P.K. Gupta, 1999, Cytology, Genetics and Evolution, M.P. Arora, 2000, Organic evolution. V.B. Rastogi, 2003, Organic evolution. B.S. Tomar & S.P. Singh, 2000, Evolutionary Biology.
Classification of Animals
In order to simplify the process of naming and classifying different animals G.G. Simpson, in 1961 wrote a book which dealt with principles of animal taxonomy and Ernst Mayr, in 1969 discussed Principles of systematic zoology in his book.
Distribution of Animals
The traditional biogeographic regions were first modeled by Alfred Wallace in The Geographical Distribution of Animals (1876). These were based on the work of Sclater’s terrestrial biogeographic regions.
Some of the recognized work of different Biologists in the field of Zoogeography are P.J. Darlington, 1957, The zoogeography: The geographical distribution of animals. Wilma George, 1962. Animal geography and A.R. Wallace, 1962 The geographical distribution of animals.”
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