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There was variation in neck length in a population of Galapagos tortoises - NSC Life Sciences - Question 4 - 2018 - Paper 2
Question 4
There was variation in neck length in a population of Galapagos tortoises. The original population from the mainland was separated onto two islands with different en... show full transcript
Worked Solution & Example Answer:There was variation in neck length in a population of Galapagos tortoises - NSC Life Sciences - Question 4 - 2018 - Paper 2
Step 1
Describe how mutations lead to variation within a population
Answer
Mutations are changes in the DNA sequence, which can occur in several forms such as point mutations, insertions, deletions, or duplications. These mutations can change the structure or function of proteins, leading to the creation of new alleles. As a result, mutations introduce genetic diversity into a population, which is essential for natural selection.
Moreover, the emergence of new phenotypes due to mutations can provide the adaptive traits necessary for survival in varying environmental conditions, contributing to the overall variation within a population.
Step 2
Describe how meiosis leads to variation within a population
Answer
Meiosis is a type of cell division that reduces the chromosome number by half, resulting in the formation of gametes. During prophase I of meiosis, homologous chromosomes undergo crossing over, which allows for the exchange of genetic material between maternal and paternal chromosomes. This results in new combinations of alleles.
Furthermore, through random assortment during metaphase I and the independent segregation of chromosomes, the gametes produced are all genetically unique. When fertilization occurs, these variations combine, significantly contributing to the genetic diversity of the population.
Step 3
Describe the role of variation in the speciation of the tortoises
Answer
The role of variation in speciation is crucial. In the case of the Galapagos tortoises, the original population experienced geographical isolation as they became separated onto different islands. This isolation eliminated gene flow between the two populations, allowing them to evolve independently.
Over generations, the tortoises adapted to their specific environments, resulting in significant variation in neck length and other phenotypic traits. If reproductive barriers developed, such as differences in mating behavior or timing, the populations could eventually become distinct species, indicating the formation of new species through adaptive radiation.