BioDiveristy Set 14 - FLOWERS AND FUNGI

What was the 4^th Major Evolutionary Transition?

THE DEVELOPMENT OF FLOWERS AND FRUIT

What are angiosperms?

Flowering Plants (around 275,000 species)

“Vessel” Seeds – eggs/ovules are encased in diploid tissue (fruits/flowers)

• Does NOT block fertilization

• Around 150 million years old, likely older

Why do angiosperms spread their seeds through flowers and fruit?

Despite it being a VERY large energy investment, the presence of flowers/fruits increases the likelihood of pollination (major selective pressure)

• Major pollinators are ANIMALS

How are pollinators attracted?

1. REWARD → pollen or nectar

2. ODOR → scent or perfume

3. APPEARANCE → Color, shape, morphological traits

What are anthers?

This structure is found on the tip of a flower’s stamen. This structure produces pollen (male gametophyte)

What are stigmas?

The female reproductive structure of a plant where pollen can germinate

How does pollen germinate within a flower?

Pollen is comprised of a set of grains, each grain has two sperm, when pollen reaches the stigma, a root-like structure grows down the carpel (pistil) à sperm follow it down

• Sperm 1 breaks into the ovary, whilst sperm 2 moves into the ovary and fertilizes the egg → SEED

What is the study of fungi?

Mycology

Fungi have around 1.5 million species

• More similar to animals than plants

What is the term for the individual filaments that make up the entire organism of fungi?

Hyphae

What is the actual fungal organism?

Mycelium, which is comprised of hyphae

What is the structure found below ground for fungi?

This structure is mycelium, the actual organism, absorbing nutrients + water from the soil

What is the structure found above ground for fungi?

This structure is the fruiting body (reproductive structures)

Ex: mushroom – composed of modified hyphae that change form and function to become these reproductive structures on the surface.

What are some characteristics of mycelium?

Start out as spores (can remain dormant), hyphae grow from these spores

• Hyphae have walls known as septa = stability

• Each has a pore in the center → this is where material moves through hyphae

What are some characteristics of the reproductive structures of fungi?

Can be a fruiting body or Sporangia = Both produce spores (diploid)

• These pores spread to the environment, germinating and leading to new mycelium (haploid)

Do fungi have alternation of generations?

YES!! Fungi do have AoG

What is the haploid structure of fungi

It is the gametophytic mycelium

What is the diploid structure of fungi?

It is the Sporophytic Mycelium (fruiting body/reproductive structures)

What are some characteristics of Chytridiomycota (chytrid fungus)

An ancestral group tied to water

1. have mobile spores (sperm and egg) that use flagella for movement

What is the fungus that is causing the Global Amphibian Decline

Caused by chytrid fungi (Batrachochytrium dendronotids)

What are Zygomycota?

Bread/Food molds

What is the special reproductive structure formed by Zygomycota?

Zygosporangium (diploid) - forms when hyphae from two different mycelia meet and fuse

• When fused, they form the spore-producing structure

• Mycelia – have different mating types, not sex (m/f)

What is the additional stage mycelia add to the alternation of generations?

It is the DIKARYON

Haploid mycelium (spore) → two hyphae meet and form zygosporangia, produce DIKARYON (n+n) gametes NOT FUSED → Mature Zygosporangium (gametes fused)

What is the fungi that acts as a symbiont for plants?

GLOMEROMYCOTA (mycorrhiza)

These fungi grow INSIDE ROOT CELLS

• Plants gain nitrogen and phosphorus from fungi

• Fungus receives carbon from exchange

Mutualistic relationship (++)