Bio. 230 --- Evolution II

Evolutionary Advances (I) 1) CELL COMPLEXITY Prokaryote ----------> Eukaryote

 2) ORGANISM COMPLEXITY Unicellular ---> Colonial ---> Multicellular

3) ORGANISM SIZE Smaller -------> Larger [?? ---------> Less Large]

 4) ORGANISM LIFESPAN Short --------> Longer [?? ----------> Shorter]

 5) TYPE OF NUTRITION Heterotrophic ----------> Autotrophic

 6) GENOME CONTENT Haploid -------> Diploid

7) TYPE OF NUCLEAR DIVISION PROCESS Mitosis Meiosis (Zygotic, Gametic, Sporic)

 

Evolutionary Advances (II)

8) TYPE OF LIFE CYCLE  Haplobiontic Haploid Diplobiontic Isomorphic Haplobiontic Diploid Diplobiontic Heteromorphic

  9) MODE OF REPRODUCTION Asexual --------> Sexual [?? ----------> Asexual]

 10) SEXUAL REPRODUCTION AS REGARDS GAMETE DIFFERENTIATION Isogamy --------> Anisogamy --------> Oogamy

 11) NUMBER OF OFFSPRING MANY ----------> FEW

 12) PROTECTION GIVEN REPRODUCTIVE PROCESS: NONE ----> MUCH

Cell Complexity (I)

Prokaryote to Eukaryote --- 1.5+ byaSerial Endosymbiosis Theory (SET)??? Motility before nucleus ??? (? one origin ?)Nucleus --- endogenous origin in a thermoplasma type archeanMitochondrion --- from an aerobic bacterium (? one origin ?)Chloroplasts --- at least three separate origins

Cell Complexity (II)

Motility StructuresFlagella in prokaryotesFlagella and cilia (? Undulipodia) in eukaryotesNOT the same thing as in prokaryotesWhy use different names?Are undulipodia derived from spirochete bacteria?Did motility (undulipodia) come before the nucleus?

SET (Lynn Margulis)

Primary Endosymbiosis

Secondary Endosymbiosis

Organism Complexity

UnicellularColonialMulticellularAdvantages? SpecializationOrganisms do not always get more complex (e.g. – yeast, some parasites)

Organism Size

Generally smaller to largerBUT sometimes larger to smallerAdvantages of being smaller?Smaller habitats / fewer resources neededShorter life cycle (more chance for genetic change) (? faster evolution ?)

Organism Life SpanGenerally shorter to longerBUT sometimes longer to shorterAdvantages of shorter life span?Reach reproductive maturity soonerGo through more generations in a shorter period of timeThus more chance for genetic change) (? faster evolution ?)

Type of Nutrition

SEE HANDOUT3.5+ bya --- heterotrophic (anaerobic)??? --- anaerobic chemoautotrophs3.0+ bya --- Type I photoautotrophs2.8+ bya --- Type II photoautotrophs??? --- aerobic heterotrophs??? --- aerobic chemoautotrophs

ChemoautotrophismANAEROBIC -- Methanogens -- Domain Archaea

 XH + CO2 ---> XCOOH ---> XCHO ----*-----> XCH3 ------#---------> CH3

*Some energy release # methylcobalamin + HSO3(CH2)2SH (X is an unknown carrier molecule)

 

AEROBIC -– Domain BacteriaNitrosomonas spp. (Nitrifying Bacteria)NH4 + 2O2 -----> 2H2O + NO2

- + energy Nitrobacter spp. (Nitrifying Bacteria)2NO2

- + O2 -----> 2NO3- + energy

 Ferrobacillus ferrooxidans (Iron Bacteria)4FeCO3 + O2 + 6H2O -----> Fe(OH)3 + 4CO2 + energy  Thiobacillus thioxidans (non-photosynthetic Sulfur Bacteria)2S + 3O2 + 2H2O -----> 2H2SO4 + energy

Photoautotrophism

light

CO2 + 2H2X -------> (CH2O) + H2O + 2X

 

Type I Photosynthesis (non-oxygenic):  light

CO2 + 2H2S -------> (CH2O) + H2O + 2S  Type II Photosynthesis (oxygenic):  light

CO2 + 2H2O -------> (CH2O) + H2O + O2

 

Genome Content

Haploid (n) to Diploid (2n)

Terms refer to nuclear content

Advantages of Diploidy?

Type of Nuclear ProcessMitosis (1.5+ bya)What does mitosis do?A ‘conservative’ division

Meiosis (1.2+ bya)What does meiosis do?Sexually reproducing organisms MUST have meiosis somewhere in their life cycle!Meiosis & sexual reproduction make for VARIATION!

Mode of Reproduction

Asexual to sexualBUT, sexual to asexual in some casesAdvantages / disadvantages of sex? Or Why is variation “good” and why is it “bad”?Advantages of haplodiploidy?

Complexity of Life Cycle (I)Haplobiontic Haploid (has zygotic meiosis)

Haplobiontic Diploid (has gametic meiosis)

Diplobiontic (has sporic meiosis) -- isomorphic or heteromorphic -- in heteromorphic either the n or 2n phase can be the dominant one

Haplobiontic Haploid Life Cycle

Haplobiontic Diploid Life Cycle

Diplobiontic Life Cycle

Gamete Differentiation

Isogamy

Anisogamy

Oogamy

Number of Offspring /Protection Given to Reproduction

ManyUsually with little or no care; often with external fertilization

FewUsually with considerable care; usually with internal fertilization