Question

PRER TEACHING QUESTIONS Microevolution and Macroevolution (Chapters 16 and 17 and Lecture Outline) 1. What is the definition of evolution? Explain this in terms of alloles and gene pools. Describe each of the 4 causes of microevolution. What is the significance of mutations to evolution? Why is natural selection the most well-known" cause? 2. What is the biological species concept? Why is this important for our understanding of speciation? What are some of flaws with this definition? What are the two types of speciation? 3. What are the reproductive isolating mechanisms (both pre-mating and post-mating), and how do they relate to the two types of speciation?

Answer 1

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Evolution:

It is a process of change in the frequency of alleles in a population over a period of time.

Gene pool – consist of all the genes, including all the alleles for each gent that are present in a population.

Cause of Microevolution:

1. Mutation – variations are caused by the mutation in a population. A new mutation constantly appears. A mutation changes amino acid sequence that’s why a change in the protein that causes a change in structure and change in functions. Change in protein can change phenotype and therefore change in fitness.
2. Gene Flow (migration) – when individuals and allele moves in and out of a population. For example, dispersion of pollen by wind and insects, migration of animals. This causes a genetic mixing with the other population. That is the reason gene flow in humans increasing because of transferring alleles.
3. Non-random mating – cause sexual selection.
4. Genetic Drift -- it is the effect of the chance events in a small population

Founder effect of genetic drift

           A new population started with a small population. And it may cause rare traits at high frequency and common traits may get missed.

Bottleneck effect of genetic drift – when a large population is drastically reduced because of a disaster or loss of habitat and the resulting population may not represent accurately original pool.

Significance of mutation to evolution:

A good mutation can cause to further evolution of a species. Bad mutation can cause death to an organism of a species. A neutral mutation doesn’t show any effect on the fitness of an organism of a species. A good mutation is a raw material for evolution because it can make a new organism by changing DNA sequence more fit and that trait will help the organism to survive. And if this mutation is passed off it becomes evolution.

Natural Selection- the main cause

It is a process by which individuals that are better suited to their environment survive and reproduce most successfully; also called survival the fittest.

The environment selects the organism which survives and reproduces it is based on the environment conditions. When an organism selected by the environment it resists certain allele combinations and that causes a change in phenotype. Change in phenotype alters the genotype. Then this genotype starts to accumulate in a population and maintains a favorable genotype. This reduces the genetic diversity that increases the difference in populations
Selection pressures against certain allele combinations. Act on the phenotype, alter the genotype. Accumulates and maintains favorable genotypes in a population. Reduces genetic diversity, increases differences in populations.