DP Biology Questionbank
10.3 Gene pools and speciation
Description
Nature of science:
Looking for patterns, trends and discrepancies—patterns of chromosome number in some genera can be explained by speciation due to polyploidy. (3.1)Understandings:
- A gene pool consists of all the genes and their different alleles, present in an interbreeding population.
- Evolution requires that allele frequencies change with time in populations.
- Reproductive isolation of populations can be temporal, behavioural or geographic.
- Speciation due to divergence of isolated populations can be gradual.
- Speciation can occur abruptly.
Applications and skills:
- Application: Identifying examples of directional, stabilizing and disruptive selection.
- Application: Speciation in the genus Allium by polyploidy.
- Skill: Comparison of allele frequencies of geographically isolated populations.
Guidance:
- Punctuated equilibrium implies long periods without appreciable change and short periods of rapid evolution.
Theory of knowledge:
- Punctuated equilibrium was long considered an alternative theory of evolution and a challenge to the long established paradigm of Darwinian gradualism. How do paradigm shifts proceed in science and what factors are involved in their success?
Utilization:
- Many crop species have been created to be polyploid. Polyploidy increases allelic diversity and permits novel phenotypes to be generated. It also leads to hybrid vigour.
Syllabus and cross-curricular links:
Biology
Topic 5.1 Evidence for evolution
Directly related questions
- 16N.2.HL.TZ0.4c: Outline what is required for speciation to occur.
- 16N.2.HL.TZ0.4a: List two causes of variation within a gene pool.
- 16N.1.HL.TZ0.36: Fossil records show that black bears increased in size during the Ice Age and decreased in size...
- 17M.1.SL.TZ1.1: Which structure found in eukaryotes has a single membrane? A. Nucleus B. Lysosome C....
- 17M.1.HL.TZ2.20: The graph shows variations in beak size for the bird Geospiza fortis on an island in the...
- 17M.1.HL.TZ1.36: What can lead to reproductive isolation after just one generation? A. Polyploidy B. Increased...
- 17M.1.HL.TZ2.19: The genetic determination of dogs’ coats can be quite complex, with many different genes acting...
- 17M.2.HL.TZ1.7a: Discuss the role of genes and chromosomes in determining individual and shared character features...
- 17M.2.HL.TZ1.7b: Outline the process of speciation.
- 17M.2.HL.TZ2.7a: Outline how reproductive isolation can occur in an animal population.
- 17M.3.HL.TZ2.1c: Explain the concept of directional selection with respect to this example.
-
20N.2.HL.TZ0.8b:
Describe the changes that occur in gene pools during speciation.
- 17N.1.HL.TZ0.35: How do the concepts of gradualism and punctuated equilibrium differ? A. The timing of...
- 21M.1.HL.TZ2.36: Which cell is a polyploid zygote produced by fusion of one haploid and one diploid gamete?
-
21N.1.HL.TZ1.36:
The graph shows the relationship between mass at birth and the percentage that die shortly after birth for Scottish Blackface lambs.
[Source: Dwyer, C.M., Conington, J., Corbiere, F., Holmoy, I.H., Muri, K., Nowak, R., Rooke, J., Vipond, J. and Gautier,
J.-M., 2016. Invited review: Improving neonatal survival in small ruminants: science into practice. Animal, 10(3),
pp. 449–459.]What type of selection for the lambs is shown in the graph?
A. Disruptive selection, as there is a drop in mortality at intermediate birth masses
B. Stabilizing selection, as lambs with low or high birth mass are less likely to survive
C. Directional selection, as lambs with a high birth mass have high mortality
D. There is no evidence in the graph of selection, as survival frequency is not shown
-
22M.2.HL.TZ2.7c:
Explain how speciation occurs, including the different processes of isolation and selection.
- 22M.1.HL.TZ1.35: What is polyploidy? A. Having an extra set of chromosomes B. Having an extra sex chromosome C....
-
22M.1.HL.TZ2.36:
Three-spined stickleback fish (Gasterosteus aculeatus) vary in the number of armour plates. The graph shows the frequency of individuals with low, partial or complete plating in a three-spined stickleback population living in Kennedy Lake, Vancouver Island, Canada.
[Source: Reprinted from Current Biology, 24, Marchinko, K.B., Matthews, B., Arnegard, M.E., Rogers, S.M. and Schluter, D., Maintenance of a Genetic Polymorphism with Disruptive Natural Selection in Stickleback.
2014. pp.1289–1292 with permission from Elsevier.]Which type of natural selection could result in this pattern of variation in the population?
A. Disruptive
B. Directional
C. Stabilizing
D. Convergent
- 18N.2.HL.TZ0.8c: Research suggests that many living plant species are polyploid. Explain how polyploidy occurs...
- 18M.1.HL.TZ2.21: Which example shows disruptive selection? A. Giraffe necks have become longer over time. B....
-
18M.1.HL.TZ1.36:
What could account for this distribution of height in a population?
[Source: Graph adapted from Six Minutes http://sixminutes.dlugan.com/good-public-speaker-average/]
A. Gene linkage
B. Dominant alleles
C. Independent assortment
D. Multiple genes
- 19M.1.HL.TZ1.35: Natural selection can operate in different ways. What is the effect of disruptive selection? A....
-
19M.1.HL.TZ2.19:
The cheetah (Acinonyx jubatus) is a large cat found in Africa. It has been discovered that organs could be transferred between any two individuals without rejection of the organ.
What is the probable reason for this?
A. Cheetahs have poor reproductive success.
B. Cheetahs have high heterozygosity.
C. Cheetahs have a large gene pool.
D. Cheetahs have a small gene pool.
- 19M.2.HL.TZ1.7b: Explain how natural selection can lead to speciation.
- 19N.1.HL.TZ0.36: A hunter tends to kill the bigger individuals of a population for their meat or for large...
