BIOEE 1780 Evolutionary Biology & Diversity - Biodiversity 3 (Plants)

Synapomorphy for Plants

Primary Chloroplasts: Chloroplasts were derived from ancestral cyanobacteria

Glaucophytes

unicellular algae species that undergoes asexual reproduction; retained peptidoglycan in cell wall; sister to Red Algae & Green Plants

Major Groups of Plants (3)

1) Glaucophytes (Sister to Red Algae + Green Plants)

2) Red Algae (Sister to Green Plants)

3) Green Plants

Red Algae

almost all multicellular algae that's red; sister to Green Plants, both having synapomorphy of the loss of peptidoglycan in the cell wall

Major Groups of Green Plants (2)

1) Green Algae

2) Land Plants

Synapomorphies for Green Plants (2)

1) Chlorophyll b - photosynthetic pigment which broadened light absorption range

2) Starch Storage

Synapomorphies for Land Plants (2) & Importance

1) Cuticle - waxy, hydrophobic coating of epidermis in order to mitigate water loss

2) Retention of Embryo - young plant has embryo within protective structure of maternal tissues

Important Evolutions for plants to be able to live on land (cuticle mitigates water loss & protective structure of embryo prevents desiccation)

Alternation of Generations Life Cycle Steps (5)

1) Diploid Sporophytes produces & releases spores (Meiosis)

2) Spores germinate and divide, developing into haploid gametophyte (Mitosis)

3) Gametophyte produces and releases haploid gametes (Mitosis)

4) Gametes fuses into Zygote (Fertilization)

5) Zygote develops into diploid sporophyte (Mitosis)

Difference in Alternation of Generation between Non-vascular & Vascular Land Plants

Non-Vascular Plants: Gametophyte is Dominant Generation (Sporophyte is smaller & dependent on gametophyte)

Vascular Plants: Sporophyte is Dominant Generation (Gametophyte is smaller & dependent on sporophyte)

Major Nonvascular Plant Groups (3)

1) Liverworts - leaf-like gametophytes; doesn't have stomata, lie close to ground to avoid water loss

2) Mosses - appears a thick mats of gametophytes with small sporophytes protruding up; despite not having vascular system, transports water via hydroid cell (small channel)

3) Hornworts - sporophytes lack stalk, allowing for indefinite cell division

All are sister to each other & Vascular Plants

Vascular System

collection of specialized tissues in some plants that transports mineral nutrients up from the roots (xylem) and brings sugars down from the leaves (phloem)

Haploid vs Diploid

one set of chromosomes vs two sets of chromosomes

Main Groups of Vascular Plants (3)

1) Lycophytes - bear microphylls (synapomorphy: simple leave structures with single vein); Sister to Ferns & Seed Plants

2) Ferns - alongside Seed Plants, bear megaphylls (leaves with branching veins)

3) Seed Plants

Main Groups of Seed Plants (2)

1) Gymnosperms - don't grow flowers & fruits, having naked seeds that aren't protected by ovaries (ovaries include fruits)

2) Angiosperms - flowering plants; flower acts as sexual structure, leading to enclosed seed

Structure of Angiosperms (4)

1) Stamen - tube structure that bears anther at top

2) Anther - site of production of pollen grain (found also in gymnosperms), which either form pollen tubes or male gametophytes (sperm)

3) Ovary - site of production of megaspores, which develop into female gametophyte (egg)

4) Pollen Tubes - deliver sperm into ovary to fertilize egg

Double Fertilization

2 sperms engage in fertilization within angiosperms:

One fertilizes egg to produce diploid zygote;

Another fuses with two nuclei to form triploid endosperm - which provides nutrients to zygote

Both are part of seed structure

Examples of Gymnosperms (4)

1) Cycads - palmlike plants

2) Ginkgos

3) Gnetophytes

4) Conifers - cones act as reproductive structure

All Subgroups of Plants

Plants -> Green Plants -> Land Plants -> Vascular Plants -> Seed Plants