All change in species originates at the same point and progresses through a seri

Question

All change in species originates at the same point and progresses through a series of specific steps in achieving microevolution and macroevolution. Detail these processes in a continuous sequence that includes the following concepts/ ideas: (1) Mutation, (2) Variation, (3) Limiting Environment, (4) Competition and/or predation pressure, (5) Differential reproduction/ selective survival, (6) Directional change in allele frequency, (7) Heritability of traits, (8) Isolation, (9) The effect of time, (10) Evidence that supports the theoretical aspects.

Explanation / Answer

1.

A Mutation occurs when a DNA gene is damaged or changed in such a way as to alter the genetic message carried by that gene.

A Mutagen is an agent of substance that can bring about a permanent alteration to the physical composition of a DNA gene such that the genetic message is changed.

Once the gene has been damaged or changed the mRNA transcribed from that gene will now carry an altered message.

The polypeptide made by translating the altered mRNA will now contain a different sequence of amino acids. The function of the protein made by folding this polypeptide will probably be changed or lost. In this example, the enzyme that is catalyzing the production of flower color pigment has been altered in such a way it no longer catalyzes the production of the red pigment.

No product (red pigment) is produced by the altered protein.

In subtle or very obvious ways, the phenotype of the organism carrying the mutation will be changed. In this case the flower, without the pigment is no longer red.

2.

Variation, in biology, any difference between cells, individual organisms, or groups of organisms of any species caused either by genetic differences (genotypic variation) or by the effect of environmental factors on the expression of the genetic potentials (phenotypic variation). Variation may be shown in physical appearance, metabolism, fertility, mode of reproduction, behaviour, learning and mental ability, and other obvious or measurable characters.

Genotypic variations are caused by differences in number or structure of chromosomes or by differences in the genes carried by the chromosomes. Eye colour, body form, and disease resistance are genotypic variations. Individuals with multiple sets of chromosomes are called polyploid; many common plants have two or more times the normal number of chromosomes, and new species may arise by this type of variation. A variation cannot be identified as genotypic by observation of the organism; breeding experiments must be performed under controlled environmental conditions to determine whether or not the alteration is inheritable.

Environmentally caused variations may result from one factor or the combined effects of several factors, such as climate, food supply, and actions of other organisms. Phenotypic variations also include stages in an organism

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