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Question
The wing of a bat and the human arm both possess a radius, an ulna and phalanges. Which of the following mechanism is most responsible for this structural similarity?
The wing of a bat and the human arm both possess a radius, an ulna and phalanges. Which of the following mechanism is most responsible for this structural similarity?
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Solution
The correct option is C Divergent evolution
A. Divergent evolution is a process in which same basic organ becomes adapted by specialisation to different functions. For example, wing of a bat and the human arm. Both possess a radius, an ulna and phalanges i.e. their basic structure is same but they perform different functions. Hence, they are homologous organs.B. Adaptive radiation is the development of different functional structures from a common ancestral form. When a group of organisms share a homologous structure which is specialized to perform a variety of functions, it shows adaptive radiation. For example, Darwin's finches of Galapagos islands had common ancestors whose beaks modified according to their feeding habit.C. Directional selection occurs whenever the environment changes in a particular way and therefore, is a selective pressure for species to change in response to the environmental change. For example industrial melanism. Industrial melanism is a phenomenon shown by light coloured peppered moth (Biston betularia typica) and dark coloured moth (Biston betularia carbonaria). It is a evolutionary process in which darker individuals predominate over lighter individuals since the industrial revolution is a result of natural selection.D. Convergent evolution is a process during which organisms with different evolutionary history evolve similar phenotypic adaptations in response to common environmental conditions. Hence, analogous organs are formed which have different basic structure but perform similar functions. For example, insect wings and birds wings.E. Stabilizing selection occurs when the environment does not change. Natural selection has to produce change and if an environment does not change there is no pressure for well adapted species to change. Fossil evidences suggest that many species remain unchanged for long periods of geological time.So, the correct answer is Divergent evolution.
A. Divergent evolution is a process in which same basic organ becomes adapted by specialisation to different functions. For example, wing of a bat and the human arm. Both possess a radius, an ulna and phalanges i.e. their basic structure is same but they perform different functions. Hence, they are homologous organs.
B. Adaptive radiation is the development of different functional structures from a common ancestral form. When a group of organisms share a homologous structure which is specialized to perform a variety of functions, it shows adaptive radiation. For example, Darwin's finches of Galapagos islands had common ancestors whose beaks modified according to their feeding habit.
C. Directional selection occurs whenever the environment changes in a particular way and therefore, is a selective pressure for species to change in response to the environmental change. For example industrial melanism. Industrial melanism is a phenomenon shown by light coloured peppered moth (Biston betularia typica) and dark coloured moth (Biston betularia carbonaria). It is a evolutionary process in which darker individuals predominate over lighter individuals since the industrial revolution is a result of natural selection.
D. Convergent evolution is a process during which organisms with different evolutionary history evolve similar phenotypic adaptations in response to common environmental conditions. Hence, analogous organs are formed which have different basic structure but perform similar functions. For example, insect wings and birds wings.
E. Stabilizing selection occurs when the environment does not change. Natural selection has to produce change and if an environment does not change there is no pressure for well adapted species to change. Fossil evidences suggest that many species remain unchanged for long periods of geological time.
So, the correct answer is Divergent evolution.
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