Fertility and Mortality Components for Natural Selection in Goa, India

Natural selection acts to preserve those genotypes that are beneficial among organisms which increase possibilities of survival, procreation and multiplication from generation to generation at the expense of less advantageous ones. Selection is one of the major evolutionary forces that bring about changes in the genetic make-up of a population. This study is to show opportunity for natural selection and variation in selection indices among Kharvi and Ramponkars of Goa, India. To measure this selection, the data from 130 mothers were obtained who belonged to different ethnic groups of Goa. Various index and components were computed using Crow's Index and Johnston and Kensinger's Index. There are a total of 549 pregnancies experienced by 160 mothers during their reproductive lifespan and the successful outcomes (live births) were 536 out of 549 pregnancies. The total selection intensity (I) calculated according to Crow's formula was lower than that calculated according to Johnston and Kensinger's Index. The percentage of fertility component contributed more to the total selection index (I), that is, I_t or I₂, than the mortality component.