Question

Immediate cause of variations of:
A. Mutations
B. Environmental changes
C. Recombinations
D. Inbreeding

Answer 1

Hint: Variation is defined as difference between cells, individual organisms, or groups of organisms of any species caused either by genetic differences or by the effect of environmental factors on the expression of the genetic potentials
For example: Human beings having different colored eyes and dogs are having different lengths of tails.

Complete answer:
Genetic variation or human genetic variation or genetic diversity is the difference within the species.
Variation is defined as the difference among the individuals of the same species.
There are mainly two types of variation.
1. Somatic variation
2. Germinal variation
There are three sources of variation:
1. Mutation
2. Recombination
3. Immigration of genes.
However, recombination by itself does not produce variation unless alleles are segregating already at different loci otherwise there is nothing to recombine.
Recombination is the exchange of DNA segments between homologous chromosomes.
This shuffling of genes brought about by genetic recombination produces increased genetic variation.
During fertilization, gametes coming from parents combine to form a zygote.
Because of recombination and independent assortment in meiosis, each gamete that comes from both the parents contains a different set of DNA.
Though mutation is the ultimate cause of variations but it takes time to appear as variation at the population level.
Mutation is a change in DNA sequence.
It results from DNA copying mistakes which are made during the process of cell division, exposure to ionizing radiation and exposure to chemicals called mutagens.
Environment changes can cause physiological stress that is expressed by a reduction in growth or performance.
Inbreeding: By inbreeding, individuals are further decreasing genetic variation by increasing homozygosity in the genomes of their offspring.

So, the correct option is option C. Recombination.

Note: Variation leads to the evolution.
Evolution: The process by which different kinds of living organisms are believed to have developed from earlier forms during the history of the earth.
Three type of evolution is:
1. Divergent Evolution
2. Convergent Evolution
3. Parallel Evolution