Tag: mechanism of evolution

Natural selection is a process governed by changes in environmental factors, these factors produce stress on the organisms. That compels the organisms to undergo changes, in case the organism undergoes changes suitable to the environment, that is, it is suited to survive in the environment will also pass on those traits to the next generation, until the next change occurs. This is natural selection.

"Nothing in Biology Makes Sense Except in the Light of Evolution" is a 1973 essay by the evolutionary biologist and Russian Orthodox Christian Theodosius Dobzhansky, criticising anti-evolution creationism and espousing theistic evolution.

An adaptation is a genetic change or variation that provides survival advantage to the organism.

Biston betularia is the common peppered moth, which was used to study industrial melanism in Britain. The melanic form and lighter coloured form are identical in all respects except for their body colour. Their frequency of occurrence changed with the industrial revolution in Britain.

In the 20th century conception of evolution being caused by a number of complex and often interacting processes. This is essentially a combination of Darwin's concept of natural selection, Mendel's basic genetics, along with the facts and theories of population genetics and molecular biology. So, this theory explains almost all factors related to organic evolution. Hence, this is the most accepted theory as compared to others.

Sterility of hybrid is never a pre - zygotic isolation mechanism.Hybrid zygotes sometimes develop into adults, such as mules (hybrids

between female horses and male donkeys), but the adults fail to develop

functional gametes and are sterile.

Members of species can interbreed naturally. This definition has some exceptions like animals obtained by interbreeding of animals of two species, this definition does not cover asexually reproducing organisms. However, among the options given best answer is Reproductive Isolation.

If species are geographically isolated and separated for long period of time, they may lose ability to interbreed and produce fertile offsprings. Thus leading to formation of new species

Genetic isolation exists when two populations are so different genetically that they cannot produce fertile offspring (or any offspring at all).
Temporal isolation is genetic isolation achieved due to temporal differences in breeding.
Behavioral

Isolation is a form of reproductive isolation in which two populations

have differences in courtship rituals or other types of behavior that

prevents them from interbreeding

The synthetic theory of evolution is based on gene mutation, gene recombination, natural selection, genetic drift, isolation.(Other factors-migration, hybridisation,chance)

1. Mutation, recombination, natural selection, genetic drift and isolation are involved in natural selection.
2. Mutation is an important source of variation that fulfills gene pool and remains a base to polygenic or multi-factorial inheritance.
3. The process of micro-evolution is governed by natural selection and gene flow is affected by reproductive isolation.
4. Evolution is governed by genetic drift.
5. Micro-evolutionary factors create new species.