BIOL 111 - PLANTS 1

No, bc does not include all descendants from same ancestor (not including eukaryotes) Yes, same recent common ancestor No, they are a sister not the whole sister group No they evolved from same ancestor not from each other

Monophyletic Group

Sister groups

Two groups that split from common node

Common node

Sharing common node means evolved from common ancestor, not (necessarily) that one group evolved from the other.

A note about taxonomy and human bias

In 1735 Linaeus creates his first classification system for nature with three kingdoms: animals plants and rocks

1969…

Not all organisms are animals or vegetables

This lasted for a long time monera=bacteria Anything that is not a plant or fungi or animal is a protist Algae not discovered yet

2005

Redone with dna evidence

Only looking at eukaryotes (getting rid of monera)

Everything else on the tree is a protist (outdated term for all the eukaryotes we didnt know enough about)

7-11 supergroups

Cryptomycetes are recently discovered as fungi 

• Combined with microsporidianna? are half the fungi species in the world

Archaeplastids (the whole group photosynthesizes) Discorbids Rhizarians Alveolates Stramenopiles Haptista Amoeboaozns (plant parasites lost their ability to) NOT OPISTHOKONS

Branches with photosynthetic organisms

Origin of phoyosynthesis

Invented by cyanobacteria Energy from sun can be captured directly Causes the longest global ice age in earths history Multicellularity occurs after photosynthesis GEO=oxygen pumped into atmosphere very intensely and sudden oxygenation of the earth due to photosynthesis

How did so many eukaryotes get photosynthesis

The capture of photosynthesis: Endosymbiotic origin of chloroplasts hypothesis

• heterotrophic= get nutrients by eating
  Cyanobacteria has 3 membranes, however chloroplasts only have 2

• Engulfs and incorporates into its own structure and metabolism

• Usually eaten gets digested, but in this case, they work together

• Only chloroplasts and mitochondria have 2 membranes the rest have 1

Endosymbiotic origin of chloroplasts evidence

2 walls are the two components of bacterial cell walls extant=still around  Cyanobacteria lives in some cells instead of chloroplast

How did chloroplasts spread to most eukaryote ‘supergroups’?

1. It would be too big of a leap for photosystems to evolve again Or 4:horizontal gene transfer

The capture and spread of photosynthesis

Huge horizontal gene transfer Current best fit explanation

Prokaryotes because they include cyanobacteria and there are so many of them

Phytoplankton

More than half the oxygen on earth produced by phytoplankton 25% being done by bacteria  (50% of the 50% done by phytoplankton)

diatoms=algae in glass houses

• They build shells made of sillica

Brown algae (Phaeophytes)

Macro algae Multicellular (NOT A PLANTbecause there is no vascular system, to get photosynthesis from one end to another) Fucoxanthin works with choloroplasts

80m (kelp) Kelp is a genius that has the fastest growth rate of any seaweed

Famous Phaeophytes: Kelp

Grow up to 2x height of a person a week therefore only takes a few years to fully grow

• This is because they are in a soup of nutrients and most importantly because of they dont have to support their own weight (dont fight against gravity), as it is supported by water

biogenic=its habitat created by other organisms

Kelp forests in ecology

Sea otters eat urchins, urchins eat kelp, when otters were hunted to extinction, urchins boomed and ate all kelp. When sea otters were introduced, they ate urchins,and led to regeneration of kelp

Alternation of Generations and Spores

Only in kelp? diploid=sporophyte(2n) produce spores (n) (2n→n) Gametophyte (n) produce gametes(2n) (n→2n) Spores are haploid

Red Algae pt.1

Different colors penetrate different depths of the ocean Their pigment absorbs blue light so they are doing well in the lowest darkest blue parts of ocean

Red algae pt. 2

Coraline Red algae

Have calcerious deposits in cell walls Corals are acc red algae Evolution of red algae plummeted due to parrot fish, because they try to eat coral, and end up eating the algae→ led to loss of species of red algae.  They poop out sand tho.

Trophic cascade: When the population or behaviour of one organism creates a cascade of changes to the populations/behaviour of other species in the food web/community (different trophic levels) 

• Eg. the sea otters, urchins, and kelp example

Sister taxa/ sister groups

Two groups that share an immediate common ancestor, making them each other’s closest relatives.

Protist

A diverse group of mostly single-celled eukaryotic organisms that are not plants, animals, or fungi.

Plantae

The kingdom comprising of all land plants, algae, and certain photosynthetic organisms.

Archaeplastids

A major group of eukaryotes that includes red algae, green algae, and land plants.

Opisthokonts

A group of eukaryotes that includes animals, fungi, and some protists, characterized by a posterior flagellum.

Chloroplasts

Organelles in plant and algal cells where photosynthesis occurs.

Endosymbiosis

A symbiotic relationship where one organism lives inside the cells of another, often beneficially.

Secondary endosymbiosis

The process by which a eukaryotic cell engulfs another eukaryotic cell that has already undergone primary endosymbiosis.

Thallus

The body of a plant or alga that lacks vascular tissue, roots, stems, and leaves.

Trophic cascade

A series of changes in a food web caused by the addition or removal of a top predator, affecting multiple levels of the ecosystem.

Alternation of generations

A life cycle in plants and some algae that alternates between a multicellular diploid phase (Sporophyte) and a multicellular haploid phase (Gametophyte).

Sporophyte

The diploid, spore-producing phase in the life cycle of plants and some algae.

Gametophyte

The haploid, gamete producing phase in the life cycle of plants and some algae.

How many chloroplasts does one cell have?

Varies from on (in some single-celled algae) to up to 100 in some land plants.

How do chloroplasts get passed on to offspring?

For single celled organisms the answer is relatively easy - chloroplasts replicate within a cell and the cell divides, such that each daughter cell has at least one chloroplast. For sexually reproducing multi-cellular organisms (Like the kelp in that life cycle diagram) the answer is more complicated. At least one gamete must carry a chloroplast, so that it can be inherited by the offspring. It is almost always the female gamete (Egg), which is why we say that the chloroplast genome is maternally inherited (Mitochondria must be inherited the same way).

Do cyanobacteria have chloroplasts?

Nope. Functionally the cyanobacteria is the chloroplast in the eukaryotic cell. Or rather becomes a chloroplast through time.

What’s an example of an extent cyanobacteria living symbiotically within a eukaryote?

Lichens! But there are lots of other examples too.

What did you mean when you said both chloroplast membranes were from the bacteria cell wall?

Cyanobacteria has 2 membranes. Then a third is formed when engulfed, however it is lost to facilitate transfer of materials, so chloroplasts are left with the 2 cell membranes of the cyanobacteria. Other organelles that havent been captured/engulfed only have 1 membrane

Can branches on a phylogeny be both sister groups and monophyletic?

Does timeline on the ‘origin of photosynthesis’ refer to origin of oxygenic photosynthesis or anoxygenic photosynthesis?

Timeline refers to oxygenic photosynthesis. The timeline of photosynthesis evolution is a bit hazy (Thus the half a billion year time window), but current consensus is that anoxygenic photosynthesis evolved first, maybe more than 3 billion years ago.

More details on alternation of generations: Key points re Specifies that have alternation of generations

• Both the n and 2n life stages are multicellular (always)

• The n and 2n life stages can be independent, free living organisms (sometimes)

More details on alternation of generations: Might help to contrast to sexually reproducing eukaryotes that do not have alternation of generations, like humans.

• Only our 2n life stage is multicellular (our haploid life stages are just sperm and eggs, no equivalent to multicellular gametophytes)

• Only our 2n life stage is free living

• Our haploid life stages (sperm and eggs) are not free-living: they don’t survive outside the human 2n body, they never grow via mitosis.

What’s a protist?

Means any Eukaryote that’s not a land plant, fungi, or animal. Most protists are unicellular but some are not just multicellular (eg red algae) but huge (eg kelp).

Viridiplantae

Refers to the group of green plants, including land plants ((like trees and moss

Experimental Evolution

A research method where scientists study how organisms evolve in controlled environments.

Non-vascular Plants

Plants like mosses and liverworts that do not have vascular tissue (xylem and phloem) for transporting water and nutrients.

Bryophytes:

A group of non-vascular plants, including mosses, liverworts, and hornworts, that are simple and lack roots, stems, and leaves.

Flavonoids

Compounds in plants that protect them from UV radiation and pathogens, and are also responsible for many of their colors

Cuticle

A waxy layer on the surface of plants that helps prevent water loss.

Sporopollenin

A tough, protective substance found in the walls of spores and pollen, which protects them from environmental damage.

Gametangia

Structures in plants where gametes (sperm and eggs) are produced.

Liverworts and Hornworts:

Types of bryophytes; liverworts often grow in moist areas, while hornworts are distinguished by their horn-shaped sporophytes.

Viridplantae

Green algae

A- faint pink species of green algae (they produce a red pigment which exists on snow during the winter but you cant see it then during the spring they activate red pigment to protect themselves from UV radiation) since the color is darker than snow, it increases speed of snow melt, leads to warming of alpine environments leads to climate change

Not b because that is saltwater where green algae is not a key factor

PART 1: How will Algae respond to elevated CO2?

The dip each year is summer arriving in the northern hemisphere, since all plants put out their leaves and start breathing again, lowering the atmospheric CO2 levels→potential effect of global plant biomass in affecting atmospheric co2. There's so much  more plants in the northern hemisphere so it has a greater global effect so its not compensated by southern hemisphere

PART 2: How will Algae respond to elevated CO2?

When primary prod increases, they take more cp2 out of atmosphere Plants in co2 higher environments, photosynthesis increase This may compensate for humans causing co2 problems Same genus as snow algae but diff species

PART 3: How will Algae respond to elevated CO2?

They let two lines(high co2 and low) evolve in their respective co2 levels, then let them grow in normal, after 1000 generations

Primary production should increase in a high co2 environment, but it may not increase as much as expected, because once they are exposed to high co2 for a long time, they become less efficient You have to account for evolution (evolve to be less efficient)

800 million years

KNOW THIS

KNOW THIS

STUDY THIS

Green algae biggest success if giving rise to land plants Land plants are monophyletic STUDY THIS!!!

Molecular phylogenies suggest major difficult transitions:

Transition was not easy n/a Suggests it was a difficult evolutionary transition n/a

Why move onto land? (Advantages)

• Huge uncolonized area

• abundant light

• Readily available CO2

• Less herbivory (at the time)

Why is it so hard to move onto land? (Challenges)

• UV radiation

• Dehydration

• Dispersal

• Gravity

• Nutrients

Gravity and nutrients eventually becomes an issue, but initially, they were single celled organisms, therefore did not matter

Key innovation: Better Sunscreen

• Eg. pink green algae

• They stop making chlorophyll in fall and may reabsorb some of them, leading to visibility of the other pigments

Key innovation: Cuticle

Cuticle covers epidermal cells Need gas(CO2), therefore cant have a full cuticle until u can figure out how to still absorb gas

How do plants reproduce on (dry) land?

Desiccation-resistant Spores

Protective, complex reproductive organs

gametangia=where gametes are produced Instead of sperm being released immediately, they are enclosed in this structure Individual plants can produce, female, male or both

Embryos nourished by parental tissues

archegonia=where female eggs produced

• Earliest life stage is now protected and nourished

Extant nonvascular land plants = Bryophytes

• >14 000 species

• Mosses

• Liverworts

• Hornworts

EXCEPTION: Desert moss

Brophytes: Lifestyle

=non-vascular=no complex transport system

Can only absorb nutrients surface level

Cuticle is rudimentary bc they have no other way to absorb

Gametophyte-dominant Life Cycle

• Not the same as kelp

STUDY THIS

• Mossy part of a moss is the gametophyte (n)

Moss: super fragile or toughest plants around?

• Only plant in antarctica

• Only ones to exist in all 7 continents

• Can completely dry out then regenerate

Famous Moss?

-compacts and produces dirt??

- most effective in capturing carbon

- act as quick sand

- people would hide bodies in peat

Do only female gametophytes produce sporophytes?

Once plants with female gametangia produce sporophytes, because the sporophyte comes from the fertilized 2n zygote, and that zygote is held in the female gametangia.

What happens to gametophytes after fertilization?

They just keep on being mosses. The gametophytes can be long-lived and go through multiple rounds of sexual reproduction (ie producing gametes that give rise to sporophytes)

What happens to sporophytes after fertilization?

• They release their spores and then die.

• This is one of the reasons we say that bryophytes have gametophyte-dominant life cycle: the gametophytes are larger and longer than the sporophytes.

What’s the advantage of the gametophyte stage?

This is the stage where sexual reproduction occurs. Sexual reproduction is when genes get shuffled and new genetic combinations arise. It is important for genetic diversity, which in turn is the fuel that natural selection works on. Populations with higher genetic diversity should be better Abe to deal with new environments. That could mean the ability to deal with a change to their current environment to (eg a new disease emerges, the climate changes) or the ability to colonize new environments.

Is forming mycorrhizal partnerships with fungi an advantage to colonizing land?

When did lichens evolve?

Recent evidence suggests they evolved after vascular plants.

How do mosses withstand drying out so well?

How did moss get to Antarctica?

Vascular tissue

Vascular tissue: Specialized plant tissue (xylem and phloem) that transports water, nutrients, and sugars throughout the plant.

Extant

Extant: Refers to species, organisms, or entities that are currently living or still in existence.

Silurian

Silurian: A geologic period approximately 443 to 419 million years ago, significant for the diversification of early life on land and in the oceans.

Prototaxites

Prototaxites: An extinct genus of giant fungi or fungus-like organisms that lived during the Silurian and Devonian periods.

Stoma/Stomata

Stoma/Stomata: Small openings on the surface of leaves and stems that allow gas exchange (CO2 in, O2 and water vapor out) in plants.

Tracheid

Tracheid: A type of elongated cell in the xylem of vascular plants that facilitates the transport of water and minerals.