DIVERSITY OF LIFE 1. Prokaryotes 1a. Archaebacteria Archaea 1b. Eubacteria …web.as.uky.edu/biology/faculty/gleeson/BIO 102/Lectures... · Prokaryotes 1a. Archaebacteria Archaea

Kingdoms Domains

1. Prokaryotes 1a. Archaebacteria Archaea1b. Eubacteria Bacteria

2. Protists Eukarya3. Plants4. Fungi5. Animals

Current species are classified into 3 Domains and/or 5-6 KingdomsDIVERSITY OF LIFE

Major groups are related

All alive today

All equally “evolved”

But also represent different depths of branching, time since shared common ancestor

Diversification also involved a series of innovations that added new forms of life

Older modes persisted, possibly largely unchanged

“advanced” vs. “primitive”

Diverse species appeared then went extinct

Current diversity is a slice of a continuing process

3-1

1. Prokaryotes (bacteria)single celled DNA, lack nucleusno organellesmotility, incl. flagellaclosest to early life?

No sexual reproduction (meiosis) per se, but various modes of genetic exchange

Prokaryotes

The real “tree” of life?

Much of biochemistry evolved in this group

__________ (“self feeding”) – use CO2 as carbon sourcechemoautotroph – energy from chemicals (e.g. H2S)photoautotroph – energy from sun - photosynthesis

___________ (“other feeding”)– use organic molecules for carbon and energy

anaerobic – respiration without O2aerobic – respiration with O2

Prokaryotes

Both respiration and photosynthesis started here

Cyanobacteria (“blue-green algae”) are free living and photosynthetic

contain chlorophyll a, ancestor of __________

Prokaryotes

Some bacteria and cyanobacteria can also fix ________

Prokaryotes

Also involved in other Nitrogen transformations (discussed later)

In aquatic and terrestrial systems

Even in some plant roots

Important as ________________

Often closely related species

and Pathogens

Archaea – extreme environments – salty, high temperature

Prokaryotes

http://www.ocean.udel.edu/kiosk/bsmoker.htmlArchaea – “ancient”, origin of life?

“Black smoker” (hydrothermal vent)Prokaryotes

Eukaryotes – Protists, Plants, Fungi, Animals

_________ and Endomembrane

Organelles – mitochondria and chloroplasts

Sexual reproduction (meiosis)

Multicellularity (tissues, organs)

Sociality

2. Protists – mostly small, single celled & multicellular- Eukaryotes – true nucleus (containing DNA) and endomembrane- Many are heterotrophs, aquatic – highly diverse- Various parasites (e.g., amoebas, malaria, helminths)

Endosymbiotic origin of organelles

Mitochondria - ___________ Chloroplast - ___________

Key biochemistry done by bacteria or their descendants

Includes true ALGAE – single and multicellular forms that are photosynthetic, and mainly ________(main “producers”in _________ systems)

Unicellular algae- contain chloroplasts- chlorophyll a, b, & c

Protists

Multicellular algae – “___________”- various differentiated structures, food

conducting systems- not rooted - holdfast (nutrients from water)

Complex life cycles & Sexual Reproduction

Both diploid and haploid phases

Sexual (meiosis) and asexual (mitosis) components

Brown Alga (Laminaria)

Green Alga (Ulva) – haploid & diploid equivalent

What is Diploid? Haploid?

Life cycles often switch between these two states.

The zygote is “diploid” because it contains two complete sets of genes, one “haploid” set from each parent. This means two copies of genes of each gene type (“locus”). The two copies need not be identical (alternate “alleles”are common at each locus)

___________ are haploid and fuse to form diploid zygotes.

What is Meiosis? Mitosis?

When a phase of the life cycle duplicates itself asexually, it is a result of mitosis – the exact copying of the genes.

Sexual reproduction results from a much stranger process, where the diploid produces haploid cells by meiosis. The genes replicate once, then divide twice, creating (four) cells with only one set of genes each (haploid).

Meiosis

“Water Mold” (Oomycota) – mostly diploid

Both haploids and diploids can replicate asexually (mitotically) too

Malaria (Plasmodium) mostly haploid

Recombination – the real point?

At least as important as the production of haploid cells, is the recombination of alleles in meiosis. Before making haploid cells, the dividing cells undergoing meiosis essentially “shuffle” the two parental genotypes, creating new genotypes that are mixtures of the parents. Often, the resulting recombinant haploid gametes are fused with gametes from other individuals (___________) to make the zygotes. This creates new genetic variation. The offspring are different from each other and from either parent.

Independent assortment

Crossing overShuffling whole chromosomes(chromosomes = blocks of genes) Shuffling genes

within chromosomes

The paradox of sex - why meiosis?

We have emphasized that evolution favors organisms (autocatalysts) that are good at transforming resources into more self – but here is a widespread mode of reproduction that seems designed to create offspring that are different from the parents, that are deliberately NOT self.

Why? It is assumed there are good reasons, we just don’t know what they are for sure. But of course there have been many proposed explanations (hypotheses).

This is another good example of the difficulty of verifying functional explanations.

The Main Contenders1.

a.

b.

2. a.

b.

3.

4.

5.

3. Plants- primarily terrestrial, multicellular- evolved from ________________- photosynthetic (chloroplasts), rooted in soil (nutrients)- extensive _____________ tissue- widespread, diverse

Mosses and related species

Ferns and others

Includes tree ferns, once dominant

Coal Age – Carboniferous 290-360 MYBP

Petro future here

= _______ years

http://www.eia.doe.gov/oiaf/ieo/oil.html

How long will current oil supplies last?

Gymnosperms (conifers and others)

Ginko

Cycad Welwitschia

Read Sacks

Conifers

Angiosperms – flowering plants

Include most plants that dominate landscapes today

4. Fungi- eukaryotic, diverse ____________- unicellular (yeast) and multicelled (mushrooms)- with bacteria, the most important _________ (nutrient

releasers) in aquatic and terrestrial systems

Read Sacks

4. Fungi

- important __________, plant root fungal symbionts that enhance nutrient and water uptake

- many fungi are plant & animal pathogens (mostly plants)

4. Fungi- include photosynthetic _______ – a symbiotic association of a fungus and a green algae. Fungus gets carbohydrates for photosynthesis of algae. Live on bare substrate (rock, bark), tolerate drying.

Largest organism?

Blue Whale

Honey mushroom (Armillaria ostoyae) – one genotype

Aspen clone (Populustremuloides) – one genotype

Giant sequoia

5. Animals- evolved from ________- multicellular,

heterotrophic eukaryotes- 35 “body plans”, most

invertebrates, many marine- highly elaborated tissue

and organ systems- herbivores, carnivores,

parasites

Sponges

Jelly

Anemone

RotiferChiton (Mollusk)

Sea Slug (Gastropod)

Scallop (Bivalve)

Cephalopods: Nautilus & Octopus Leech (Annelid)

Sea Star

Corals - _______________- have a symbiotic association

with “zooxanthellae” which are themselves a symbiosis of a dinoflagellate (protist) and photosynthetic cyanobacteria(prokaryote).

Arthropods

Trilobite (extinct) Horseshoe Crab

Lobster

Shrimp

Barnacle

Trilobites developed one of the first advanced visual systems in the animal kingdom. This may have promoted the spectacular diversification of animals.

Compound eyes in living arthropods such as insects are very sensitive to motion, and it is likely that they were similarly important in predator detection in trilobites. It has also been suggested that stereoscopic vision was provided by closely spaced, but separate eyes

http://www.trilobites.info/eyes.htm http://ebiomedia.com/gall/eyes/octopus-insect.html

The majority of trilobites bore a pair of compound eyes(made up of many lensed units)

Trilobite Optics

Astaynax

Yamamoto Y, Stock DW, Jeffery WR (2004) Hedgehog signallingcontrols eye degeneration in blind cavefish. Nature 431:844-847.

crayfish

Some Trilobites “lost” vision, as have many existing species

The eyes of the Octopus and Squid (Cephalopods) are very similar to ours in structure and function, with lens and image forming retina.

Read Williams

http://en.wikipedia.org/wiki/Evidence_of_evolution

Eyes of the vertebrates and cephalopod molluscs (squid and octopus) are remarkably similar, an example of ___________evolution. One interesting difference – vertebrates have an inverted retina, the sensory cells lying beneath the nerve fibers. This results in the sensory cells being absent where the optic nerve is attached to the eye, thus creating a blind spot. The octopus eye has a non-inverted retina in which the sensory cells lie above the nerve fibres. There is therefore no blind spot in this kind of eye.

The Blind Spot The blind spot is the area on the retina without receptors that respond to light. Therefore an image that falls on this region will NOT be seen. It is in this region that the optic nerve exits the eye on its way to the brain.

http://staff.washington.edu/chudler/chvision.html

In the next two images, close your right eye. With your left eye, look at the numbers on the right side, starting with the number "1." You should be able to see the "sad face" (top image) or the gap in the blue line (bottom image) in your peripheral vision. Keep your head still, and with your left eye, look at the other numbers. The sad face should disappear when you get to "4" and reappear at about "7." Similarly the blue line will appear complete between "4" and "7.“ This is because your brain is "filling in" the missing information.

Here is another image to show your blind spot. Close your right eye. With your left eye, look at the +. You should see the red dot in your peripheral vision. Keep looking at the + with your left eye. The red dot will move from the left to the right and disappear and reappear as the dot moves into and out of your blind spot.

Arthropods – Spiders and Insects

Vertebrates (Chordates)

Animals - Sociality

End

End Part 3