Midterm 2 Flashcards
what does the protist fossil record show
Oldest fossil protist 1.2 bya, red alga
Protists display numerous evolutionary adaptations resulting in widely different organisms
There are also recent radiations (aka bursts of new species and groups)
what are the four stages of eukaryote evolution from prokaryotes
Four stages:
- loss of prokaryote cell walls and replaced with new types of cell wall
- Elaboration of internal membrane systems e.g nuclear envelope
- Development of intracellular trafficking system for molecules
- endosymbiosis leading to phtosynthetic cyanobacteria becoming chloroplast and alpha-protobacteria becoming mitochondria
what is endosymbiosis
Endosymbiosis:
evidence: chloroplast and mitochondria share features with prokaryotes
- circular DNA not in a nucleus
- some very similar enzymes
- similar ribosomes
Chloroplasts have been derived just once
the engulfment of a prokaryote = primary endosymbiosis
some marine protists acquired photosynthesis from absorbing a eukaryotic cell
either red algal or green algal cell, both of which have their own nucleus
how do protists get their nutrition
- Autotrophs
- like algae consume light
- Heterotrophs
- ingestive heterotrophs consume particles and cells
- Absorptive heterotrophs absorb molecules
what is basic protist phylogeny
I. Supergroup Excavata
- Diplomonads
II. Supergroup SAR
- Stramenopiles
i.Diatoms
ii. Brown algae
iii. Oomycetes
- Alveolates
i.Dinoflagellates
ii.Apicomplexans
III. Supergroup Unikonta
- Amoebozoans
IV. Supergroup Archaeplastida
- Rhodophyta
- Chlorophyta
what are some ways protists drive selection
Heterotrophic protists eat other organisms like other protists. They can also be parasites weakening another species’ fitness
They are massive drivers of selection, responsible for killing off species
describe supergroup Excavate
Supergroup Excavata
- Asymmetric in shape, have a feeding furrow on one sideDiplomonds:
- lack chloroplasts and a cell walls
- don’t use ATP or mitochondria
- have mitosomes and hydrogenosomes that are smaller
- anaerobic use iron-sulphur chemistry
- Ex Giardia:
- infects hikers who drink in mountain streams
how is the SAR clade grouped
Supergroup SAR Clade (Stramenopiles, Alveolates, and Rhizarians)
- united on the basis of whole-genome sequencing. very diverse, very controversial
what are Diatoms like
- Diatoms
- have glass cell walls made of amorphous silica dioxide
- Glass is made of thermodynamically unstable stuff. Sorta solid, sorta liquid.
- silica dioxide shells take less energy to produce, so diatoms have more energy for growth making them the fastest growing protists
- 2-500 um in size
- the binary fission that diatoms undergo leaves one daughter cell smaller than the parent due to the way their cell walls work. To overcome the progressive restriction this causes the zygote enters another form called an auxospore which is large and has silica bands instead of a full cell
- so sex resets the size
What are brown algae like
- Brown Algae
- largest seaweeds
- multicellular
- BC is a kelp hotspot with over 30 species
- bullwhip kelp aka mermaid’s bladder, ribbon kelp, bladder wrack, or Ihqyaama
what is primary endosymbiosis
Far in the past one cell (probably a bacteria) entered into the cell of another organism (probably an Archean)
The bacteria was an aerobic organism who uses oxygen to make energy. The exterior organism didn’t digest the smaller one and found its energy production useful.
The smaller organism over time became the mitochondria in Eukaryotes.
A similar process occurred with an organism like a cyanobacterium becoming a chloroplast.
what does Endosymbiosis show, and what are some results
Endosymbiosis shows that when opportunity presents itself in nature then a series of random events usually leads to an organism or population using it.
Mitochondria and chloroplast have two membranes
Endosymbiosis led to changes in the atmosphere and allowed Eukaryotes to grow bigger cells and eventually became multicellular
Mitochondrial DNA is inherited from the mother.
what is secondary endosymbiosis
- sometimes an organism that arose from endosymbiosis can be absorbed by another cell
- ex Red alga was absorbed to make dinoflagellates, Apicomplexcans, and Stramenopiles
- and green alga was absorbed 2 different times to make the line of Euglenids and the line of Chlorarachniophytes
what is the record for number of genomes in one cell
Cryptomonas gyropyronoidosa
- Cell nucleus
- Mitochondria - PE
- Red Alga nucleus - SE
- Chloroplast in the red alga
- Grellia numerosa bacteria
- Megaira polyxenophila bacteria
- Mankyphage virus in the M. polyxenophila
what are hotspots
- places where a great deal of evolution is occuring
- high # of species
- 44% of plants
- 35% of animal diversity
Ex New Caledonia
- plants - ex 14 species of Aravcarie (conifers)
- Animal - ex Blue Kagou (endemic bird)
Endemic = one found in one place
When a species line the blue kagou goes extinct all its parasite species go extinct
Hotspots cover 3% of earth’s surface but hold 50% of plant species
how do hotspots lead to discovery and extinction
~4000 species of plants and fungi are discovered a year
hotspots are major sources of discovery byt they are also threatened by human activity.
how is diatom reproduction scuffed
In diatoms their glass outer shell is made of a big and a small side. when they divide the new shell forms inside the old one. meaning one division has to be smaller.
the progressive restriction of the glass shell is overcome periodically after fertilization when the zygote enters another form called an auxospore. which is a larger cell with silica bands not the normal shell.
what are Oomycetes
Oomycetes or water molds are fungus like protists. They used to be classified within Fungi, but differ significantly.
The vegetative body of this protist is made up of hyphae or filaments that grow in water as well as in soil and decomposing organisms, and even sometimes within living organisms.
what is the 1st type of spore oomycetes have
Spore type no. 1 is a product of vegetative reproduction.
Hyphae produce a zoosporangium that produces zoospores which have 2 flagellae each and are able to move. They eventually turn into cysts which are a resting or dormant stage that lies in the soil till conditions improve.
what is the second type of spore protists have
if conditions are right, the hyphae can also produce either oogonia, which produce female nuclei, or antheridia, which produce sperm nuclei.
When the hyphae meet and fuse, fertilization of male and female nuclei occurs, resulting in zygotes, also known as oospores. Oospores can also lie dormant,
Oomyctes can be pathogenic, Phytophthora infestans caused potato blight in 19th century Ireland.
what are alveolate
Have membrane bound sacs, alveoli under the plasma membrane
dinoflagellates
apicomplexans
what are Dinoflagellates
- highly variable
- some autotrophic
- some heterotrophic
- others mixotrophic
- typically 2 flagellae
- Endosymbiosis with chloroplasts thought to have occurred after the original evolution of dinoflagellates
- have cellulose cell wall plates called thecae just under the plasma membrane within the cytoplasm
- Cause red tides aka Harmful Algal Blooms (HABs) that kill due to toxins produced by dinoflagellates like Gonyaulax catanella that can be concentrated in shellfish.
what are apicomplexans
- named after an “apical complex” or organelles in their sporozoites
- heterotrophic, but were once mixotrophic
- vestigial chloroplas called an apicoplast
- Plasmodium is one of these that causes malaria, complex life cycle that requires two hosts.
what are in Supergroup Unikonta
Amoebozoans
Mycetozoans
what are Amoebozoans
- group contains Amoebozoans and Opisthokonts
- putting Amoebozoans with Opisthokonts destroyed protist phylogeny
what are Mycetozoans
- this is another group that superficially resemble fungi. Once included in fungi
- have plasmodium (not the malaria thing) diploid phase, aka a coenocute a single cell with hundreds of nuclei
- then grow a sporangium which releases haploid spores, a fruiting body that is multicellular
what is Supergroup Archaeplastida
- descended from a secondary endosymbiotic event with a cyanobacterium
- includes red and green algae, and embryophytes (land plants)
what are Rhodophytes
Rhodophyta
- red algae, red pigment phycoerythrin, red masks the green of chlorophyll. No stage has flagellae
- Alternation of generations, most are heteromorphic. Large sporophyte and small gametophyte. Numerous species that are morphologically identical or isomorphic.
what are chlorophyta
Chlorophyta
- green Algae
- Led to plants
- have important chemical like carotenoids, chlorophyll a and b in common with plants
- Some scientists have suggested a new kingdom called Viridaeplantae (including green algae and plants)
- Very diverse, 3 life cycles (haplontic, diplontic, and haplo-diplontic)
What are Oomycetes
used to be classified with fungi, now we know they are different
Oomycetes have two flagellae, cellulose cell walls, and a diploid hyphal nuclei
Fungi had no flagella, chitin cell walls, and a haploid hyphal nuclei
Oomycetes are very hard to control because they have two types of tough dormant spores
Phytophtora ramorum
- killing tanoaks along the west coast
- attakcs and kills 150 species in 37 genera
- federally quarantines
What are apicomplexans
- apicomplexans
- major human parasite
- named after apical complex of organelles in the sporozoite
- plasmodium = cause of malaria
what are Mycetozoa
Mycetozoa
- includes Amoebozoans and Opisthokonts
- Grouping these 2 groups together cause problems for phylogeney
- slime molds (awesome)
Who was KDB
- Kathelyn drew baker discovered that the conchocelis stage of Pyropia was not a different species (conchocleis rosea) but a part of pyropia’s life cycle, one that live on oysters
- Her discovery saved the japanese seaweed industry
how was Pyropia used in Canada
Pyropia was eaten on both coasts of canada
- on the east it was eaten by the Acadians (french Canadians) who served it in soups with a special bread.
- called goeman in french
- eaten on the west coast by the Kwakwaka’wake first nations
- called tagas
- amy deveaux a Uvic student was doing a thesis on the use of Pyropia but these first nations
- the only person who know the information was the chief Adam Dick, since his parents had hid him from residential schooling.
- Pyropia was eaten hot or pressed into cakes or chips
- many taboos associated with handling, harvesting, eating
How did Evolution affect culture
Evolution as an idea spelled the end of the world as we once knew it
It disrupted all religious creation myths that were deeply embedded in culture.
And its all the fault of 5 british scientists
what was James Hutton idea
His idea = uniformitarianism, makes the assumption that natural processes in the universe are the same everywhere and throughout time
His theory of slow processes overturned the dominant idea that most of what we saw was due to short-lived catastrophic events.
who was James Hutton
James Hutton (1726-1797)
a well educated scot who put forward the idea that previous animals and plants were found in ancient sediments laid fown by the sea came from fossils that he uncovered as he was clearing parts of his farm.
In scotland modern layers of sediment lay on top of old red sandstone from the devonian, which is on top of older layers from the Silurian.
who was Charles Lyell
Charles Lyell (1797-1875)
Thought up the geological principle of actualism i.e. geological actions today are the same as those in the past
principle behind paleoecology, the study of ancient extinct ecosystems.
Hutton and Lyell reset the age of the earth from thousands of years old to millions of years.
who was Mary Anning
Mary Anning (1799-1847)
greatest fossil collector of her age
discovered the first complete icthyosaur at age 12
first intact pleiosaur at 25
and Dimorphodon Macryonx at 29
her dog died :(
selled sea shells by the seashore
her friend painted the first aquarium view piece of paleoart to support her living
who discovered evolution
Charles Darwin (1809-1882) and Alfred Russel Wallace (1823-1913)
both independently thought up the theory of evolution.
1858
summarize the history of evolution as an idea
- Hutton and Lyell discovered deep time in geology
- Anning collected, cleaned, and sold fossils from the past
- Victorians were excited by and open to the prospect of fossil discoveries and, became inclined to consider alternative explanations of the origins and evolution of life.
- Although the interpretation of geological evidence was presented as common sense, the theories and ideas began to develop, such as evolution, challenged traditional beliefs.
where did plants come from
Plants = Ebryophytes
which are descended from algae
what unifies plants
Plants are unified by four features
- production of gametes from gametangia
- eggs from archegonia
- sperm from antheridia
- multicellular embryos
- spores with walls
- growth by apical meristems
the last three are features adapted to life on land
how can mosses survive water loss
Mosses are able to lose much of their water
They can do this because mosses are poikilohydric (they lose water freely)
to avoid desiccation, they trap external water
they also have a physiological trick - mosses and moss piglets insert sugars into their membranes and, turn their membranes into an oxygen-excluding glass.
Many moss species can resurrect from complete desiccation.
what are mosses
the first group to branch off of the plant family tree, before early vascular plants
The moss gametophyte is fastened to substrate by small hairs called rhizoids that absorb nutrients. Not specifically for water absorption, as the name little root (rhizoid) implies. All parts of the gametophyte absorb water
what happened to Mary Anning in the 20th century
Mary Anning during the 20th century was largely pushed to the side of the story of evolution.
Then Evie Swine as a 10 year old helped bring her back to popularity. (around 7 years ago)
What is Poikilohydry
> Poikilohydry = lack of ability to maintain and or regulate water content to achieve homeostasis of cells and tissues connected with quick equilibration of cell/tissue water content to that of the environment
Means that they don’t self regulate water content and use the environment.
Will dry out in dehydrated times, then refill when it rains.
what happens if you slice up moss
Mosses can survive being fragmented into many pieces and recover as multiple new mosses.
how do mosses survive desiccation
Mosses lose water freely but trap external water to avoid desiccation.
if they do desicate, they:
- insert sugars into membranes, turning them to oxygen excluding glass
- specialized proteins protect the DNA from stresses
Moss and water bears (moss piglets) (tardigrades) can recover from complete dessication.
how are tardigrades adapted to extreme conditions
- go dormant for up to 30 years
- can survive vaccums
- resist high temperatures (100ºC)
- resist low temperatures (1k)
- resist radiation (UV)
- can survive desiccation due to carbs and proteins in membranes
how are steppe moss adapted to extreme conditions
- go dormant
- resist high temperatures
- survive a vaccum
- resist low temperatures
- resist radiation
- insert proteins and carbs
- hairs catch water
what are some fun facts about mosses
- can eat rocks
- oldest moss, chorisodontium aciphyllum (~5000 years old)
- can survive 1500 years being frozen
- can enter non-metabolic state and extend life indefinitely = cryptobiosis
how do dioecious mosses reproduce
mosses have 2 generations:
- a larger gametophyte
- a smaller sporophyte (which is attached to the gametophyte)
two-thirds of moss species are dioecious, having separate male and female plants.
Male plants are short, because the water is at soil surface. Females are also short so the sperm can reach them.
Sperm can only swim around a meter.
how can moss reproduce if the distance between them is too large
If the distance between two mosses is too big for the sperm, they have a few options:
- they grow closer to each other
- they shoot the sperm towards the female moss
- Mites and springtails carry the sperm
- floods
why did moss numbers drop from 25,000 species to 15,000
Mosses are collected and stored in herbaria, these collections were particularly biased towards localized naming.
so “splitters”, people who tend to think local discoveries are new species, would catagories them as such.
“lumpers” would come along as eliminate species by finding they were the same species as other mosses found further away. extending the original species’ range.
DNA investigations reveal close to 40% of moss species were mistakes, bringing their number to 15,000 from 25,000
populations of the same species can look completely different.
65% of North American mosses are also found in Europe.
when did early vascular plants appear, and what were they like
- Vascular Plants with water-conducting tissue appeared in ordivician ~500 mya
- A classical examples is: Sporophyte of Rhyniagywnne-vaughni
- ~20cm high, lacked leaves or roots, simple branching stems with sporangia (spore-bearing organs)
- stems penetrated the soil
- found in scotland (which would have been Laurentia)
what are tracheophytes
- Tracheophytes first arose among polysporangiates. They possess tracheids.
- These cells expand lengthwise when young
- they then developed thick secondary cell walls
- and right before they die - they produced a burst of a tough polymer called lignin.
what problems did vascularity solve
- These transport vessels occured in a central strand. This new tissue - the vascular bundle (bundle of transport fibres) provided one elegant solution to two engineering problems experienced by early plants
- Problem 1: how to prevent dessiccation
- by having a system of dead cells dedicated to water transport, plants could grow taller without desiccating. Since they could transport water up to the higher cells they stay hydrated through indoor plumbin. Unlike how mosses evade dessication.
- Problem 2: How to grow upwards against gravity
- Hardened cells provided structural support, allowing greater height and size. Taller plants dispersed spores farther. Larger plants could produce more sporangia, more spores. Overall, fitness increased due to further dispersal.
- Problem 1: how to prevent dessiccation
what did early vascular plants evolve to “assist” their vascularity
- To make this work they needed a few add ons
- A cuticle which covered the outer surface of the plant to prevent water loss
- small openings (stomates) which allow evaporation of water, which creates suction to draw water up through the plant
- helps with cooling and providing water for photosynthesis
what change in growth occurred early in vascular plant evolution
The earlies Polysporangiate plants only had primary growth. So they grew from a primary growing point pr meristem of the plant. Soon, a new secondary meristem would evolve that produce rings of tracheids, known as wood.
how were polysporangiates discovered
- These kinds of Polysporangiate plant fossils were first found in New Brunswick by Patricia Gensel and her team.
- They found plants which due to these evolutionary adaptations were taller, with more sporangia, branching stems, and photosynthetic surfaces.
- They are called Polysporangiates since they can possess more than one sporangium, unlike mosses which have only one.
how did the dual lifecycle work in vascular plants
- In vascular plants the sporophytes are separate from the gametophytes. And they are also much larger.
- Early vascular plants (400 mya) had independent generations. (resulting in different scientific names for fossil plants, though to be in the same species, called form genera)
- In these plants only sporophytes had tracheids so the new adaptation was restricted to them.
what had established themselves on land before plants
- 450 mya, land was occupied by early plants, protists, bacteria, and fungi (or possibly lichens)
- these fungi had established themselves on land before plants and could grow to 8m high, the tallest organisms on land.
describe fungal evolution in relation to plants
- ame to land before plants
- broke down rocks to liberate minerals and form soils
- Fungi had an initial parasitic relationship with plants, resulting in co-evolution producing in a symbiosis and certain plants like Phynia sporophytic cells containing hyphae
- Mycorrhizas developed i.e mutualistic relationships with plants, in exchange for sugars from the plant, the fungus supplies nutrients, water and defence.
what are the 6 steps from early to modern vascular plants
- ominance of sporophyte
- Acquisition of water transport system (Xylem made up of tracheids)
- Acquisition of roots, which were derived from stems
- Acquision of leaves, both microphylls and megaphylls (moss “leaves” are actually called phyllids but don’t count)
- Evolution of presentation of sporangia
- i.e different types of clusters
- sorus in ferns
- Elaboration of type of spores, from plants having only one type of spore (homospory) to plants having two types of spores (heterospory, where male spores → microgametophytes (like sperm) and female spores → megagametophytes (like eggs)
What are monilophytes
- ferns are tracheophytes (vascular polysporangiates) that have alternation of generation in which the sporophyte is dominant.
- Their sporophytes vary from miniscule plants to tall trees in the andes
- Gametophytes are always small
- Ferns were in their heyday during the carboniferous, when they were the dominant land plants. Since gametophytes require water for reproduction, they were largely confined to wet regions and swamps
what are fern lifecycles and reproduction like
Ferns have a two part lifecycle, including Gametophyte which grows from the spores, then releases sperm from the Antheridium which fertilized an egg in the Archegonium (both on the underside of the mature gametophyte). (this whole section prior to fertilization is haploid)
The sperm and Eggs form a zygote (which is diploid) which grows on the gametophyte to make the sporophyte (the big main frond bit)
On the underside of a mature sporophytes leaves there is sporangium (together clumping in sorus) which releases spores restarting the cycle.
how do ferns survive droughts
They survive by taking in moisture from the fog and air. (through their leaves)
they also take advantage of the rare rainfalls to clear the embolisms in their circulatory system.
how do fern spores be epic
The spores can survive travel over long distances by air, through cold, dry and high irradiation environments.
They then lie in wait till conditions are good to germinate for up to 63 years. Though most spores will never germinate.
how do ferns prevent inbreeding.
Fern gametophytes have both male and female gamete producing organs: i.e bisexual
This could result in inbreeding
to avoid inbreeding and promote outbreeding ferns do a couple things:
- the antheridia and archegonia develop asynchronously
- the fastest growing gametophyte to have archegonia first releases a compound called Antheridiogen, which turns the other gametophytes male.
why are spores launched
- Spores are launched so they can:
- find a place suitable for the gametophyte to grow
- and increase the species’ dustribution
- Spores are the “little feet” of plants
- The more spores that germinate - the higher the plant’s fitness
what helps spore dispersal
- To help the spores spread as far as possible, the sporangia should be raised as high as possible
- for mosses which are very short, the sporophyte is always the highest point (on top of the gametophyte)
- In ferns, the sporophyte is independent of the gametophyte, and can even be a tree. Which can produce billions of spores.
what are the trade off of small spores
- small spores (like what ferns use) can travel farther and occupy distant lands, and it is possible to make more of them
- the disadvantage of small size, means low investment, dooming new plants to a slow start
why did some ferns make the female gamete bigger
- But some ferns changed their strategy, doing what many eukaryotes tend to, and invest more in the gender that takes care of the zygote
- In these heterosporous ferns, the female (or megagametophyte) is bigger, since it is carrying the next generation’s food.
- This nutrient loading is happening on the sporophyte, which is indirectly providing the next sporophyte with a head start by directly investing in the gametophyte.
what happens to the male gamete in the ferns with giant female gametes
- the male gametophyte became tiny, and the microgametophyte forms from cell division within the spore wall
- Microgametophytes can be blow thousands of miles
- and Megagametophytes just drop from the tree and don’t get around much
- having lots of microgametes ensures a higher chance of mating
what does a zygote need to be successful
- considering the young plant that develops from the zygote
- To become independent, the young plant must build infrastructure, namely
- a sufficient photosynthetic surface to produce nutrient
- an anchoring system to support its new “solar panels” and supply them with water for coolant and reactants.
- The gametophyte’s energy-rich reserves (such as the 3 main macros) give the sporophyte a head start in building infrastructure like (roots, leaves, shoots)
- Heterosporous plants can grow to 30+ m tall and dominated early landscapes like lycopophyte Lepidodendron in the Carboniferous
what are the 4 phyla of gymnosperms
4 phyla:
- Cycadophyta
- Coniferophyta
- Gingkophyta
- Gnetophyta
how did gymnosperms change the megagametophyte
The Sporophyte held on to the magagemtophyte eventually enclosing it. The new hybrid structure - part megagametophyte, part sporophyte is called an ovule.
what are the benefits and costs of a ovule
Benefits:
- Longer loading of nutrients and greater accumulation of storage reserves
- Sporophyte defends the gametophyte
Costs:
- More attractive to predators
- Cost borne by sporophyte
what does the sporophyte do to the microgametophytes before fertilization in gymnosperms
- The sporophyte provided liquid (pollination drop) to capture microgametophytes
- The sporophyte ovule used one of its own tissues (nucellus) to screen microgametophytes
what change did gymnosperms make to the megagametophyte
The megagametophyte stopped photosynthesizing ever again. We have one generation of plants, the gametophyte, that no longer is green. Instead it converted sugars and amino acids supplied by the sporophyte into starches, protein bodies, and fat bodies.
how did gymnosperms change gamete size
- Gamete size changedThe megagametophyte increased the size of its eggsthe sporophyte is investing in the future of the embryoSperm changes:
- it goes gigantic in cycads
- it becomes flagellae-free in conifers
how do gymnosperms pollinate
Now that megagametophytes are no longer in puddles on the ground, but held high in the air by the sporophye how does pollination happen, and do plants still use the rain?
Gymnosperms use two methods to get their pollen to the ovule
- wind
- insects
what are seeds and their advantages
a seed is a fertilized ovule
what are the advantages of seeds:
- they can go dormant, so can delay growing till conditions are optimal (like protist cysts)
- they can be transported long distances by wind or animals, which means dispersal is optimized.
how does wind pollination work
In most gymnosperms the male cones release pollen which is carried in large clouds by the wind.
The pollen blows into cones where the ovules are stacked in pairs on scales.
what is a pollination drop and what does it do
The ovule has an opening called a micropyle. Where a pollination drop appears at the opening and billows out like a sphere.
The pollination drop catches the pollen. The drop recedes into the ovule while carrying the pollen. The Ovule then shuts.
Using pollen drops, Gymnosperms don’t rely on rain for reproduction.
what does a pollination drop contain
- Calcium: helps pollen germinate
- Sugars: provide energy to germinated pollen
- Amino acids: provide energy to germinated pollen
- Proteins: Kill bacteria, fungi, and viruses that enter the ovule (safe sex)
what does the nucellus do
the nucellus is the equivalent of the megasporangium. It:
- Performs Meiosis
- and makes the pollination drop
what makes up a seed
Outside:
- Seed coat (equivalent or Integument) 2n
Inside:
- Megagametophyte n
- Embryo 2n
Seed coat has genotype of material
Embryo has mixed genotype
what groups of gymnosperms are insect pollinated
there are 4 groups of living gymnosperms, of them: 2 are insect pollinated
- Cycadephyla
- Gnetophyta
explain Push-Pull-Thermogenic Insect Pollination
-In australia, cycads of the genus Macrozamia are pollinated by and ancient insect group called thrips.
They have a weird pollination syndrop called:
Push-Pull-Thermogenic Insect Pollination
Here’s how it works:
- in the morning insects enter the male cones where they feed on the pollen (a reward)
- At noon there is a thermogenesis event, a 15º rise in the internal temperature of the male cones because of the unpleasant heat and an unpleasant scent the cones release the thrips leave the male cones (this is the push part)
- By mid afternoon, the cones cool to ambient temperature, but but by then the thrips have left.
- Female cones omit an odour that attracts the thrips to them, they enter the female cones (where they reproduce with other thrips) (this is the pull part)
- As the thrips enter, covered in pollen, they brush past ovules, and leave some pollen in the pollination drops.
describe the lifecycle of male lodgepole pine
Year 1: Tree grows and produces male cones
Year 2: meiosis occurs in the cone, resulting in microspores, which are dispersed by wind or insects, and pollinate by entering the ovule
Year 3: fertilization occurs
explain the lifecycle of female lodgepole pine
- Year 1: tree develops female cones
- Year 2: meiosis occurs in the cones resulting in 4 megaspores, where only 1 survives, pollination occurs when pollen from the male tree enters the ovule
- Year 3: the megagametophyte forms, and the seed is produced
describe an overview of lodgepole pine reproduction
- It takes 13 months from pollination to Fertilization
- Delayed fertilization is a hallmark of gymnosperms
The making of a gymnosperm seed is slow:
- year 1: initiation of male and female cones
- year 2: female cones open and receive pollen from moles
- year 3: pollen fertilizes megagemetophytes, the embryo develops within the seed.
what are flower parts
The Carpels: structures that house ovules
Stamens: have anthers that release pollen
Petals
Sepals
Ovary
Ovules:
where do most flower parts come from
All but the Ovule are modified leaves.
where are eggs found in a flower
eggs are found behind many sporophytic barriers (first type of plant to do this)
what do the stigma and style do
The stigma and style screen pollen, and defend against pathogens
where do you find seed in Angiosperms
The seeds develop with fruit, which is the ovary and its outside wall layers.
what are the micro and megasporangium like in angiosperms
The megasporangium is inside the ovule, and the microsporangium is inside the anthers on the stamen.
The microsporangium produces microspores. Within each microspore a male gametophyte will form.
The microgametophyte is pollen, one of its cells is a tube cell, which upon germination become the pollen tube that will deliver its two gametes into the egg.
how do angiosperms get pollinated
Pollination is mainly wind or animal mediated (including but not limited to insects)
coloured petals and scents attract pollinators
how do angiosperm ovules differ from gymnosperms
The ovule is different from that of gymnosperms:
- it is located inside an ovary
- the megagametophyte (=embryo sac) is reduced to 7 cells
- there are two female gametes (an egg and central cell)
what happens to pollen when it reaches the flower
When pollen lands on the stigma of the carpel, it germinates and the pollen tube pushes first through the stigma.
Then the style and into the ovary, a cavity that houses numerous ovules.
The pollen tube finds an ovule, enters and deposits its two male gametes.
what is double fertilization
One gamete fuses with the egg to form the zygote
the other fuses with the central cell to form the endosperm, a triploid tissue.
This is called double fertilization. The endosperm stores nutrients to feed the developing embryo.
Two-thirds of all calories consumed by humans on this planet are from seed, in particular endosperm.
Seed makes us possible.
why are seeds important for humans
Two-thirds of all calories consumed by humans on this planet are from seed, in particular endosperm.
Seed makes us possible.
what up with coco del mar
The endosperm in the seed of the palm Coco del Mar (which is the largest seed in the world), can be pretty significant.
It allows an embryo to survive for months while floating around the Indian Ocean. The seed will land on beaches and germinate.
how do photosynthesized affect the atmosphere
Plants produce oxygen during the day, and release carbon dioxide during the night
Over the course of life on earth, different groups like Cyanobacteria, Red alga, and plants evolved, and starting spewing Oxygen into the atmosphere, raising its level to 21% in earths atmosphere
How did flowers help angiosperms
the advent of flowers helped angiosperms exploded and take over the world, exploding in diversity between 126-65 mya
what is the difference, between petals, sepals, and tepals
- the petals and sepals are similar, but different in colour and form. (sepals are the green petal looking things in many flowers)
- if they are the same colour, petals and sepals are called Tepals
how can angiosperm species and their pollinators be closely entwined
- Some flowers have evolved specific shapes to accommodate particular pollinators, such as long tubular flowers for hummingbirds
- The co-evolution of flowers and their pollinators has led to intricate relationships and specialized adaptations
what is Hydnora africana
- Jackal food
- Some flowers have evolved specific shapes to accommodate particular pollinators, such as long tubular flowers for hummingbirds
- The co-evolution of flowers and their pollinators has led to intricate relationships and specialized adaptations
what’s up with Orchids
- lots of them (25,000+ species)
- really big petal called the labellum
- attracts insects
- insects fall in, the only exit is at the back of the labellum where the pollen is
- many groups of people organized around orchids (600+ orchid societies)
How did angiosperms take over
- halved their absolute genome size (compared to gymnosperms) promoting a higher mutation rate.
- Less DNA per cell allowed smaller cells, which meant more cells per leaf, including stomata per leaf. This led to better gas exchange and therefore better photosynthesis
- they reproduced more efficiently, taking less time then gymnosperms
- corn takes 7 hours, pine takes 15 months (pollination to fertilization)
what is Enhalus acoroides
Enhalus acoroides, eel grass or tape seagrass, grows on Iriomote Island, one of the southernmost islands of Okinawa, Japan.
Due to lowest tides being when there is a full moon, and especially in the full moon in July when this plant is flowering. The abiotic evets of tide and wind contribute to the only sea surface pollination mechanism known from any plant in the world.
how does Enhalus acoroides reproduce
Tide go up, males release flowers which rise to surface in air bubbles.
Tide goes down
Female flowers eat males
Female plant buries fruit in soil (called negative geotropism, growing against gravity)
what does inflorescence mean
A bunch of flowers on one stem
