Table of contents

1. Introduction to Genetics51m
2. Mendel's Laws of Inheritance3h 37m
3. Extensions to Mendelian Inheritance2h 41m
4. Genetic Mapping and Linkage2h 28m
5. Genetics of Bacteria and Viruses1h 21m
6. Chromosomal Variation1h 48m
7. DNA and Chromosome Structure56m
8. DNA Replication1h 10m
9. Mitosis and Meiosis1h 34m
10. Transcription1h 0m
11. Translation58m
12. Gene Regulation in Prokaryotes1h 19m
13. Gene Regulation in Eukaryotes44m
14. Genetic Control of Development44m
15. Genomes and Genomics1h 50m
16. Transposable Elements47m
17. Mutation, Repair, and Recombination1h 6m
18. Molecular Genetic Tools19m
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
  31m
22. Evolutionary Genetics29m

21. Population Genetics

Allelic Frequency Changes

Genetics

21. Population Genetics

Allelic Frequency Changes

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1:32 minutes

Problem 39b

Textbook Question

New allopolyploid plant species can arise by hybridization between two species. If hybridization occurs between a diploid plant species with 2n = 14 and a second diploid species with 2n = 22, the new allopolyploid would have 36 chromosomes. What type of isolation mechanism is most likely to prevent hybridization between the allopolyploid and the diploid species?

Verified step by step guidance

Step 1: Understand the concept of allopolyploidy. Allopolyploidy occurs when two different species hybridize, and their chromosomes combine to form a new species with a unique chromosome number. In this case, the hybridization involves two diploid species with chromosome numbers 2n = 14 and 2n = 22, resulting in an allopolyploid with 36 chromosomes.

Step 2: Recognize that the new allopolyploid species has a different chromosome number compared to the original diploid species. This difference in chromosome number can lead to reproductive isolation because the chromosomes may not pair correctly during meiosis, preventing viable offspring.

Step 3: Identify the type of isolation mechanism. The most likely mechanism preventing hybridization between the allopolyploid and the diploid species is postzygotic isolation. This occurs when hybrid offspring are inviable or sterile due to mismatched chromosome sets.

Step 4: Consider the role of genetic incompatibility. The inability of the chromosomes from the diploid species to pair correctly with the chromosomes of the allopolyploid during meiosis is a form of genetic incompatibility, which reinforces reproductive isolation.

Step 5: Conclude that the isolation mechanism is primarily postzygotic, as it prevents the formation of fertile hybrids between the allopolyploid and the diploid species, ensuring the genetic distinctiveness of the new allopolyploid species.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Allopolyploidy

Allopolyploidy is a form of polyploidy that occurs when two different species hybridize and the resulting offspring have multiple sets of chromosomes from both parent species. In this case, the new allopolyploid plant species has a chromosome number that is the sum of the two parent species' chromosome counts, leading to increased genetic diversity and potential for adaptation.

Hybridization

Hybridization is the process where two different species interbreed to produce hybrid offspring. This can occur between closely related species and can lead to the formation of new species, such as allopolyploids, which can have unique traits and adaptations. However, hybridization is often limited by various reproductive barriers.

Reproductive Isolation Mechanisms

Reproductive isolation mechanisms are biological features that prevent species from interbreeding and producing viable offspring. These mechanisms can be prezygotic, such as temporal or ecological isolation, or postzygotic, such as hybrid inviability. In the context of the question, these mechanisms are crucial for understanding how the new allopolyploid might be prevented from hybridizing with the original diploid species.

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Textbook Question

New allopolyploid plant species can arise by hybridization between two species. If hybridization occurs between a diploid plant species with 2n = 14 and a second diploid species with 2n = 22, the new allopolyploid would have 36 chromosomes. What pattern of speciation is illustrated by the development of the allopolyploid species?

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Textbook Question

New allopolyploid plant species can arise by hybridization between two species. If hybridization occurs between a diploid plant species with 2n = 14 and a second diploid species with 2n = 22, the new allopolyploid would have 36 chromosomes. Is it likely that sexual reproduction between the allopolyploid species and either of its diploid ancestors would yield fertile progeny? Why or why not?

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