Chapter 32.3, Problem 7SAQ

Summary Introduction

To enlist and describe:

The key innovations in the evolutionary history of fungi that allowed them to move from water to land.

Introduction:

Fungi are eukaryotic organisms belonging to the domain Eukarya. Fungi include eukaryotic multicellular organisms. Yeast is the only fungus that is unicellular. Fungi also include molds and mushrooms. They are heterotrophic and saprophytic. They feed on dead and decaying organic matter.

Explanation of Solution

Fungi have accumulated many evolutionary features over the course of time. The innovations that led fungi to move from water to land include the following:

1. 1. Chitin cell walls.
2. 2. Hyphae.
3. 3. Regularly placed septa within the hyphae.
4. 4. Multicellular fruiting bodies.
5. 5. Dikaryotic stage.

The ancient fungi were motile (flagellated) and single-celled that lived in water. However, the current fungi are much complex and involve dikaryotic cells. In the earlier forms of fungi, there was no heterokaryotic stage. Plasmogamy is followed quickly by karyogamy. The elongation of time between plasmaogamy and karyogamy has also led to the evolution of fungi. Development of hyphae has allowed fungi to search and obtain food from new food resources on land. Thus, these features enabled fungi to move from water to land.

Conclusion

The evolutionary features that helped fungi to move from water to land include chitin cell walls, hyphae, dikaryotic stage, multicellular fruiting bodies, and septa in between hyphae.