Name: Homologous and Analogous Organs
Uploaded: 2019-07-19
Duration: 4 min 30 s
Description: A whale, a human and a bird, may be very different in appearance but share a common ancestry. All 3 had the same ancestors, and the proof of that is homologo...

Question

Define 'Species'. What are the important factors leading to the rise of a new species?

Accepted Answer

Species is the basic unit of taxonomy. A biological species is a group of organisms that can reproduce with one another in nature and produce fertile offspring. Species can also be defined based on a shared evolutionary history and ancestry. Consider what would happen if the bushes the beetles feed on are spread widely over a mountain range. The beetle population becomes very large as a result. But individual beetles feed mostly on a few nearby bushes throughout their lifetime. They do not travel far. So, in this huge population of beetles, there will be sub-populations in neighbourhoods. Since male and female beetles have to meet for reproduction to happen, most reproduction will be within these sub-populations. Of course, an occasional adventurous beetle might go from one site to another. Or a beetle is picked up by a crow from one site and dropped in the other site without being eaten. In either case, the migrant beetle will reproduce with the local population. This will result in the genes of the migrant beetle entering a new population.

This kind of gene flow is bound to happen between populations that are partly, but not completely separated. If, however, between two such sub-populations a large river comes into existence, the two populations will be further isolated. The levels of gene flow between them will decrease even further. Over generations, genetic drift will accumulate different changes in each sub-population. Also, natural selection may also operate differently in these different geographic locations. Thus, for example, in the territory of one sub-population, crows are eliminated by eagles. But this does not happen for the other sub-population, where crow numbers are very high. As a result, the green variation will not be selected at the first site, while it will be strongly selected at the second.

Embibe Experts Solutions for Chapter: Genetics and Heredity, Exercise 1: Jammu and Kashmir Board-2019

Embibe Experts Science Solutions for Exercise - Embibe Experts Solutions for Chapter: Genetics and Heredity, Exercise 1: Jammu and Kashmir Board-2019

Questions from Embibe Experts Solutions for Chapter: Genetics and Heredity, Exercise 1: Jammu and Kashmir Board-2019 with Hints & Solutions

Learn and Prepare for any exam you want !