The cause and importance of variation and diversity in organisms
Variation and diversity are both defined as differences between different organisms whether
physiologically, genetically or behaviourally. Variation plays a large role in organisms today,
providing diversity within phenotypes and genotypes through alleles. By having diversity and
variation between alleles, it enables organisms to be suited to their environments and selection
pressures that they can endure, through which they are able to survive and reproduce. Variation has
opened up many pathways in biology to discovering and understanding why animals of different
species act in different ways and how this suits that species.
Initially, to understand variation and diversity, we must understand what causes it. Variation can be
caused by either genetic or environmental factors. Genetically, it can occur through mutations,
meiosis, or random fertilisation of gametes. Random fertilisation produces new combination of
alleles as which gamete fuses with which at fertilisation is a random process, adding to the variety of
offspring produced. Regarding mutations, there can be sudden changes to genes and chromosomes,
whether that is through the substitution of bases in the nucleotide base sequence or the deletion of
a base from the base sequence which would results in a frame shift to the base sequence, altering
the amino sequence and in turn synthesising a different polypeptide chain. There can be mutations
to the chromosomes, either mutations to the whole sets of chromosomes or to the number of
individual chromosomes. This can cause for non-disjunction to occur, where some of the
chromosomes fail to divide during meiosis leaving a gamete with one more or one fewer
chromosome. In meiosis, variation arises through independent segregation of chromosomes, which
is the idea that the chromosome pairs line up the equator at random so whichever combination
paternal and maternal chromosome goes to the daughter cells is by chance. This means that each
daughter cell would contain different chromosomes from division 1, increasing the diversity
between them. Variation can also arise through crossing over in prophase 1 as the chromatids can
become twisted, building up tension and breaking the bonds in sections of chromatid so that these
broken portions may re-join with the other chromatid. This would result in new combinations of
maternal and paternal alleles being produced, increasing the variation between gametes produced.
Environmentally, variation can occur when a selection pressure affects the way the organism’s genes
are expressed. Variation occurs as different climatic conditions, such as soil conditions, pH or food
availability require certain alleles from organisms in order for them to survive and reproduce. This
highlights the multiple pathways from which variation can arise from.
One importance of variation is its role in natural selection. By having variation in alleles between
different individuals of a species, it increases the chance that within the species there are alleles
which provide an advantage to the individual and enable it to survive in its environment and
reproduce to pass down these alleles. The process of natural selection briefly consists of there being
individuals with mutations to their genes in the population, creating new alleles. These alleles
provide an advantage to the individual which is conveyed when they experience a selection pressure
as they can survive this pressure due to their allele. This enables them to reproduce, passing this
allele down to their offspring which increases its allelic frequency. Those without these alleles were
not able to survive as they weren’t suited to the environment. Variation in alleles gives the chance
for alleles that provide more advantage to individuals to arise and increase in frequency. The
mutations in alleles have allowed for evolution to occur, with the most known example being
humans who have developed from apes due to mutations in alleles which enabled us to be more
adapted to our environment and develop in our anatomy and behaviour. Another example would be
the peppered moth, which used to have a light colour to enable it to camouflage against its
background. However, when the Industrial Revolution occurred, the walls and trees became black
due to the soot, so alleles which coded for darker forms of the peppered moth arose and increased
in allele frequency as they were more suited to their environment and were able to survive as they
Variation and diversity are both defined as differences between different organisms whether
physiologically, genetically or behaviourally. Variation plays a large role in organisms today,
providing diversity within phenotypes and genotypes through alleles. By having diversity and
variation between alleles, it enables organisms to be suited to their environments and selection
pressures that they can endure, through which they are able to survive and reproduce. Variation has
opened up many pathways in biology to discovering and understanding why animals of different
species act in different ways and how this suits that species.
Initially, to understand variation and diversity, we must understand what causes it. Variation can be
caused by either genetic or environmental factors. Genetically, it can occur through mutations,
meiosis, or random fertilisation of gametes. Random fertilisation produces new combination of
alleles as which gamete fuses with which at fertilisation is a random process, adding to the variety of
offspring produced. Regarding mutations, there can be sudden changes to genes and chromosomes,
whether that is through the substitution of bases in the nucleotide base sequence or the deletion of
a base from the base sequence which would results in a frame shift to the base sequence, altering
the amino sequence and in turn synthesising a different polypeptide chain. There can be mutations
to the chromosomes, either mutations to the whole sets of chromosomes or to the number of
individual chromosomes. This can cause for non-disjunction to occur, where some of the
chromosomes fail to divide during meiosis leaving a gamete with one more or one fewer
chromosome. In meiosis, variation arises through independent segregation of chromosomes, which
is the idea that the chromosome pairs line up the equator at random so whichever combination
paternal and maternal chromosome goes to the daughter cells is by chance. This means that each
daughter cell would contain different chromosomes from division 1, increasing the diversity
between them. Variation can also arise through crossing over in prophase 1 as the chromatids can
become twisted, building up tension and breaking the bonds in sections of chromatid so that these
broken portions may re-join with the other chromatid. This would result in new combinations of
maternal and paternal alleles being produced, increasing the variation between gametes produced.
Environmentally, variation can occur when a selection pressure affects the way the organism’s genes
are expressed. Variation occurs as different climatic conditions, such as soil conditions, pH or food
availability require certain alleles from organisms in order for them to survive and reproduce. This
highlights the multiple pathways from which variation can arise from.
One importance of variation is its role in natural selection. By having variation in alleles between
different individuals of a species, it increases the chance that within the species there are alleles
which provide an advantage to the individual and enable it to survive in its environment and
reproduce to pass down these alleles. The process of natural selection briefly consists of there being
individuals with mutations to their genes in the population, creating new alleles. These alleles
provide an advantage to the individual which is conveyed when they experience a selection pressure
as they can survive this pressure due to their allele. This enables them to reproduce, passing this
allele down to their offspring which increases its allelic frequency. Those without these alleles were
not able to survive as they weren’t suited to the environment. Variation in alleles gives the chance
for alleles that provide more advantage to individuals to arise and increase in frequency. The
mutations in alleles have allowed for evolution to occur, with the most known example being
humans who have developed from apes due to mutations in alleles which enabled us to be more
adapted to our environment and develop in our anatomy and behaviour. Another example would be
the peppered moth, which used to have a light colour to enable it to camouflage against its
background. However, when the Industrial Revolution occurred, the walls and trees became black
due to the soot, so alleles which coded for darker forms of the peppered moth arose and increased
in allele frequency as they were more suited to their environment and were able to survive as they
