Which is the major cause of Speciation, Reproductive isolation or Geographical isolation for both asexual and sexual situation? (explain with example if can be)
Answers
Major causes of speciation are :
(i) Geographical isolation of a population caused by various types of barriers (such as mountains, ranges, rivers and sea). The geographical isolation leads to reproductive isolation due to which there is no flow of genes between separated groups of population .
(ii) Genetic drift caused by drastic changes in the frequencies of particular genes by change alone.
(iii) variations caused in individual due to natural selection.
Geographical isolation is the major factor in the speciation of sexually reproducing animals because it interruptes the flow of genes between their isolated populations through the gametes. The geographical isolation however cannot be a major factor in the speciation of a self pollinating plant species because it does not have to look to other plans for its process of reproduction to be carried out. Geographical isolation also cannot be a major factor in the specification of an asexually reproducing organism because it does not require any other organism to carry out reproduction.