Lecture 17- Zygos

Lecture 17: Zygomycetes

Introduction to Zygomycetes

  • Zygomycetes are a class of fungi characterized by their unique reproductive structures and life cycles.

T-shirt Competition

  • Announcing a T-shirt design competition for 2024, with submissions due by November 20.

    • Contact for submission: tyjames@umich.edu

  • Encouragement for students to start thinking about their research and reach out for discussions.

Fungal Diversity and Classification

Overview of Key Groups

  • Mucoromycota

    • Includes Glomeromycotina (arbuscular mycorrhizae), Mortierellomycotina (soil-dwelling chitin lovers), and Mucoromycotina (pin molds).

  • Zoopagomycota

    • Comprises Entomophthoromycotina (insect pathogens), Kickxellomycotina (dung and gut symbionts), and Zoopagomycotina (predators).

Characteristics of Zygomycetes

  1. Reproduction

    • Sexual reproduction results in a zygospore, the only diploid stage.

    • Asexual reproduction occurs via sporangia or conidia.

  2. Morphology

    • Mostly coenocytic (multinucleate with no septa).

    • Very few sporocarps, primarily microscopic forms.

Life Cycle of Rhizopus

  • Details the steps of the life cycle:

    1. Sporangium with spores (n).

    2. Gametangia: Fusion leads to zygosporangium (2n).

    3. Meiosis during germination.

    4. Maturation of mycelium and production of new spores.

Fungal Succession and Community Dynamics

Key Concepts in Fungal Ecology

  1. Overview of how fungal communities are structured similarly to plant and animal communities.

  2. The dynamics of fungal succession:

    • Change over time in species structure in an ecological community.

    • Influenced by disturbances like logging, fire, or pollution.

  3. Factors Affecting Fungal Diversity

    • Sequencing depth and its relation to observed species diversity.

    • Environmental factors such as pH, temperature, and nutrient availability.

Migration and Colonization Principles

  • Discusses traditional notions of microbial dispersal:

    • “Everything is everywhere; the environment selects.” - Lourens Baas Becking

  • Examines if fungal communities follow similar principles as macroorganisms regarding migration and colonization.

Case Studies in Fungal Ecology

  1. Functional diversity and the importance of species in ecological communities:

    • Fungi specialize on different hosts, e.g., Trichaptum species.

  2. Deterministic assembly vs historical contingency affect community structure.

  3. Importance of phylogenetic diversity for ecosystem function, particularly in arbuscular mycorrhizal fungi.

Environmental Influences on Fungal Communities

  1. Latitudinal Diversity Gradients

    • Diversity peaks in tropical regions and declines towards the poles.

    • Factors include total productivity, biome age, and climate stability.

  2. Soil Community Dynamics

    • Evidence from global soil samples identifying over 80,000 species.

Various Zygomycete Classes

  • Glomeromycotina: Form mycorrhizal relationships with many plant species.

  • Mortierellomycotina: Chitin-digesting fungi found in soil.

  • Mucoromycotina: Fast-growing molds associated with various fermentation processes.

  • Zoopagomycota and Kickxellomycotina: Predatory and insect-associated fungi.

Summary of Ecological Roles and Traits

  • Focus on competition, nutrient acquisition, and the relationships within ecosystems may set the foundation for understanding future research directions in mycology.