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BIO 341 Lecture Topic 1: Course Introduction,
 What are Fungi?

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Corresponding Readings:
  • Moore-Landecker preface, chapter 1
Summary:
Dr. Szaniszlo introduces the course with a brief disclaimer regarding the unique and archaic vocabulary used in the study of fungi.  In the first lecture, he presents the syllabus and runs through the class schedule and policies.  After familiarizing the class with what is to come later in the semester, the professor starts the first lecture topic with the general overview of  the study of fungi (mycology) and begins at the "rock bottom" - with the definition of the word "fungus".

He continues the lecture with a brief discussion of why "fungus" is such a nebulous term; and concludes with the most basic, practical divisions of fungal types.  The first lecture is typically a tiny glimpse at what is to come.

Printed Notes, Main Points:

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What are fungi?

Singular = FUNGUS

Plural = FUNGI

A fungus is ...

Fungi are...

Origin of word fungus

Two schools of thought:

sp(h)ongos - Greek
= sponge-like

fungor - Latin

= to fluorish

Both words probably relate to nature of fungal structures we call mushrooms or toadstools

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Definition of Fungi

Eucaryotic, heterotrophic and absorptive organisms, which have cell walls, typically reproduce asexually and/or sexually by producing spores, and grow either reproductively by budding or nonreproductively by hyphal tip elongation.

Definition excludes:

1. bacteria & blue-green algae (prokaryotes)

2. slime molds

3. true algae & higher plants

4. animals

5. etc.

Definition may include some non-fungi

1. Oomycetes (water molds)

2. etc.

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No perfect definition

1. Fungi historically have represented a very heterogenous grouping of  unrelated or only distantly related organisms.

2. Adaptation of related  or unrelated  fungi or fungal-like organisms to similar ecological niches have led to structural trends that obscured fungal origins (phylogeny*)

* Phylogeny = evolutionary history of genetically related organisms

A. Monophyletic - one origin

B. Polyphyletic - multiple origins

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Trends in evolution that
 tended to obscure fungal nature (phylogeny)

1. Convergent Evolution

unrelated organisms superficially come to look alike

e.g. some fungi and colorless algae

2. Parallel Evolution

members of unrelated groups evolve along similar paths

e.g. some fungi and animals, like slime molds

3. Divergent Evolution

Related organisms come to have very different biology - they took different paths of evolution (adaptation)

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Fungal nutritional types

1. Saprophytes

2. Symbionts

a. mycothallal fungi

e.g. lichens

b. mycorrhizal fungi

- ectomycorrhizal = can be free-living

- endomycorrhizal = obligate symbionts

c. animal-fungal partners

e.g. gut fungi

3. Pathogens

a. majority plant pathogens

b. many animal pathogens

c. relatively few but increasing # of human pathogens

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