Humans may differ in skin colour and general appearance, yet they all share the same genetic makeup. One explanation for our drastic changes is that they resulted through evolutionary pressure, where the need to be easily recognised pushed us towards having widely different faces.
The preserved remains of extinct animals, plants, or other species that perished millions of years ago are known as fossils. These fossils provide information on numerous extinct organisms as well as clues as to how evolution may have taken place. It is possible to infer an organism’s possible appearance and lifestyle from fossils. More crucially, …
What are fossils? What do they tell us about the process of evolution? Read More »
The wing of a butterfly and the wing of a bat cannot be considered homologous organs as they do not have a common ancestor. Although both structures are useful for flying, they have independently evolved. This is indicated by the difference between the wings of a butterfly and a bat, which are made up of …
Let us take the instance of humans and chimpanzees. Although it was traditionally believed that only humans could smile or burst into laughter, chimpanzees are capable of a wide variety of emotional expression. The orbicularis oculi muscle spontaneously contracts and lifts the cheekbones when the limbic system of the brain is activated, causing wrinkles to …
Geographic isolation cannot be taken into account in the case of asexually reproducing organisms. This is because meiosis does not occur during asexual modes of reproduction.
Geographical isolation often has a minor role in the pollination of plant species because a self-pollinating plant species won’t acquire any new traits. However, some environmental changes may be possible that some environmental changes will lead to certain variations.
Factors that would result in a new species are as follows: (a) Mutation (b) Genetic drift (c) Natural selection (d) Geographical isolation (e) Generative isolation for prolonged periods (f) Environmental factors on the isolated populations (g) Quantum of genetic variant transmissible from one generation to the following generation
The genetic diversity of the species decreases as does the size of the tiger population. This results in a limitation on the variations which will be introduced within the genetic makeup of the tigers. This lack of variation will result in serious implications. For example, if a disease develops among the tiger population, it might …
The acquired trait cannot be inherited by the next generations as the changes do not reflect in the DNA of the germ cells. For example, a muscle builder cannot pass on his skills to his progeny as they are limited to non-reproductive cells only.
A single characteristic may increase a population in any of the following two ways: (a) Natural selection: If a population considers an attribute helpful, it will grow naturally. For example, mosquitoes that are resistant to a certain pesticide will pass on their genes, making their progeny resistant as well. The chemical kills the mosquitoes that …
