Why life?

Why life?

1.Earth is 4.6 bya, life is .38 bya, what happened in the 800 millions between them?

2.timing is everything: fossil record is incomplete, geologic data has big range of measurement –give or take a few million years, radiometric dating depends on various half lives of common elements, genetics-commonalities and rate of drift

3.Life in a flask….

•Oparin and Haldane: water vapor, nitrogen, carbon dioxide, ammonia, hydrogen, hydrogen sulfide and energy from UV or lightning

•Miller and Urey tested and generated amino acids

1. What is the biogenesis paradox?

2. What are some alternatives to this conundrum?

Protobionts and amphipathic molecules

3. To UV or not to UV….

Yes we need it for protobionts

NO it kills protobionts! Hydrothermal vents are now being considered for cradle of life.

4. At what point does an aggregate of molecules be considered alive?

Protobionts? Prions? Virions? Viruses? Prokaryotes!

Prokaryotes, especially those that could photosynthesize, altered the earth and the atmosphere-more oxygen break down of rock.

Eukaryotes appeared about 2.1 bya and continued to alter the environment.

Endosymbiosis greatly contributed to diversity of eukaryotes. Mitochondria, chloroplasts, plastids

Multicellular eukaryotes appeared about 1.2 bya. Reproduction and other basic processes are still easier to conduct w the support of an aquatic environment.

Colonization of land occurred about 500mya.

5. one of a kind or will there be a next generation?

RNA

4 nitrogenous bases

What’s an INTRON!!!!

Ribozyme? Ribosome?

1. evolution is necessary to survive changing environmental conditions

2. if the change is rapid, SUDDEN, mass extinctions occur

3. continental drift is a slow change that leads to different environmental conditions

Creates new habitats-mountains, new edges-coastlines as continents split, deserts

behind mountain ranges-orographic rain shadow

contributes to allopatric speciation

4. mass extinctions cause loss of entire evolutionary lineages (dinosaurs) but as

ecological niches are altered or left unoccupied, adaptive radiation occurs to fill

them

Changes in ecological niches also lead to the development of complex symbiotic

leg development

Novel features don’t suddenly appear: exaptation can explain how features may

acquire new functions-feathers may have originally been used, like fur, for thermoregulation but were co-opted for flight when that niche became available

evo-devo: evolutionary biology and developmental biology converge to study

how small changes in genes (exp hox genes) can be expressed as major morphological differences between species

heterochrony is an evolutionary change in timing or rate development-for

example extending the larval stages when it is easier for the organism to feed and shortening the adult, reproductive phase

homeotic genes are master regulatory genes that control location and organization

of body parts (examples of environmental changes on individual’s expression of homeotic genes can result in additional frog legs)

hox genes are one type of homeotic genes; alterations of hox genes greatly alters

morphology; expression of hox genes may be different from one species to another (leg/fin bud expressing hox gene causes fin development, but in chickens extension of the skeleton for leg development

1. phylogeny is the evolutionary history of a species

2. taxonomy is the organizing of organisms based on relatedness (NO longer based

primarily on morphology-similarities and differences)

3. what’s in a name?: species and genus-binomial nomenclature developed by Carolus

Linnaeus

4. classification hierarchy: domain, kingdom, phylum, class, order, family, genus, species

A taxon is any level of classification

“King Phillip climbed over the fence and got shot.)

5. phylogenetic trees depict hypotheses about evolutionary relationships: species are

more closely related than genus or family…

group of species that share characteristics of a single common ancester are

clades; depiction of clades is a cladogram

In the past homologous structures could be confusing-bones of a whale’s flipper

are the same bones found in a tiger’s paw, but the use and appearance is different

Convergent evolution leads to development of analogous structures; similarities

of environment or niche contributes to development of similar structures or features.

Butterfly wings have same function as bat wings, but they aren’t constructed the same way.

Molecular systematics uses DNA and other molecular data to determine

relatedness. Many old systems of classification will alter as DNA sequencing and

hybridization demonstrates unknown evolutionary relationships.

Molecular clocks measure the absolute time of evolutionary change based

on the observation that some genes and other regions of the genome

appear to evolve at constant rates. DNA for ribosomal RNA changes

slowly-yields information about taxa that diverged hundreds of millions of years ago.

Mitochondrial DNA evolves rapidly and helps to determine more recent events.

the mass of bacteria outweighs

the mass of all eukaryotes by 10 fold

Dinner time

1. photoautotrophs sun and a little CO2

2. chemoautotrophs CO2 and a little elemental redox

3. photoheterotrophs photophosphorylation and CO2 in ready-to-eat packages

4. chemoheterotrophs-room service-CO2 and energy from organic compounds

Less is more…

1. shape: cocci-spherical, bacters-rods, spiros-helices

2. one chromosome + plamids

3. binary fission

4. fortifying the wall: gram positive-simple peptidoglycans; gram-negative complex walls

5. getting around-pili, flagella dispersal agents

Change it up

1. transformation picking up chewing gum off the floor

2. conjugation

3. transduction viral invasions

4. mutation

To breathe or not to breathe

1. obligate anaerobes -toxic oxygen

2. facultative anaerobes

3. obligate aerobes

Old school style

1. extremeophiles: halophiles and thermophiles

2. methanogens

It’s a bacteria free for all

1. yogurt or salmonella?

2. decomposers-bioremediation

3. symbionts: E coli the good guys and E. coli on the wanted list

4. vectors transgenic organisms

Protists-when a kingdom just isn’t enough (paraphyletic)

1. most are unicellular and possess mitochondria

2. photosynthetic, ingestive, or absorptive organisms

3. most are aquatic or in symbiotic relationships

4. from amoeba to kelp

Eukaryote evolution contributions

1. membrane-enclosed nucleus

2. endomembrane system, mitochondria, chloroplasts

3. cytoskeleton, 9 + 2 flagella

4. multiple chromosomes of linear DNA with organizing proteins

5. life cycles with mitosis, meiosis, and sex

Seaweeds

1. marine multicellular

2. brown, red (phycoerythrin, phycobilins-Rhodophyta), and green algae (Chlorophyta and Charophyceans)

3. thallus, body; holdfast, “root”, stipe, stem; blade, leaf

Alteration of generations

1. sporophyte diploid and gametophyte haploid

2. spores are produced by meiosis

3. gametes are produced by mitosis

Large size and complexity in chlorophytes has evolved by three different mechanisms:

1. formation of colonies of individual cells (Volvox)

2. the repeated division of nuclei without cytoplasmic division to form multinucleate

filaments (Caulerpa)

3. formation of true multicellular forms by cell division and cell differentiation

3 groups have pseudopodia

1. rhizopods-amoeba

2. actinopods-radiolarians, heliozoans

3. formaniferans (formaniferous ooze!)

Slime molds-Mycetozoa

1. plasmodial slime molds (Myxogastrida) are brightly pigmented, heterotrophic

Organisms-feed in a plasmodial mass-not multicellular but is multinucleate

2. cellular slime molds (Dictyostelida) straddle the line between individuality and

Multicellularity-feeds as individuals, but bad environmental conditions will cause

it to aggregate

Exploring new territory-colonization of land

1. charophytes not quite plants

Cellulose for cell wall, peroxisomes have enzymes that counteract

photorespiration, sperm structure similar, cell plates, nuclear and chloroplast genes similar

2. terrestrial advantages: more sunlight less filtering, more CO2, soils rich in nutrients,

less predation

3. terrestrial disadvantages: desiccation, lack of water, gravity

4. alternation of generations: gametophyte (haploid-produce gametes mitotically &

sporophyte –produce spores meiotically) generations

5. gametes produced in gametangia (archegonia or antheridia)

6. mosses gametophyte is dominant generation; ferns sporophyte is dominant generation (sporangia-sori)

7. nonvascular plants have two clades: lycophyta and pterophytes

Pterophytes in Carboniferous period were like trees and eventually formed coal

Deposits

four main groups of land plants: bryophytes, pteridophytes, gymnosperms, and angiosperms.

1. bryophytes are mosses-alternation of generations

2. pteridophytes include ferns- vascular tissues

3. gymnosperms include pines and other conifers-seeds

4. angiosperms are the flowering plants-flowers

Characteristics of land plants that differentiate them from algae

1. apical meristems

2. multicellular embryos dependent on the parent plant

3. alternation of generations

4. sporangia that produce walled spores

5. gametangia that produce gametes

6. CO2 and water in two different locations (need leaves and roots)

7. adaptations for acquiring, transporting, and conserving water

8. adaptations for reducing the harmful effect of UV radiation

9. adaptations for repelling terrestrial herbivores and resisting pathogens.

Special structures

1. cuticle

2. stomata

3. xylem and phloem

Specialized compounds

secondary compounds in plants include

alkaloids, terpenes, tannins, and

phenolics such as flavonoids

Bryophytes are represented by three phyla:

•phylum Hepatophyta - liverworts

•phylum Anthocerophyta - hornworts

•phylum Bryophyta – mosses Sphagnum

Transport in Xylem and Phloem

Vascular plants have two types of vascular tissue: xylem and phloem

Xylem conducts most of the water and minerals and includes dead cells called tracheids

Phloem consists of living cells and distributes sugars, amino acids, and other organic products

Water-conducting cells are strengthened by lignin and provide structural support

Increased height was an evolutionary advantage

Evolution of Roots

Roots are organs that anchor vascular plants

They enable vascular plants to absorb water and nutrients from the soil

Roots may have evolved from subterranean stems

Leaves are categorized by two types:

Microphylls, leaves with a single vein

Megaphylls, leaves with a highly branched vascular system

According to one model of evolution, microphylls evolved first, as outgrowths of stems

Seed Plants

enabled plants to become the dominant producers in most terrestrial ecosystems

A seed consists of an embryo and nutrients surrounded by a protective coat

In addition to seeds, the following are common to all seed plants

Reduced gametophytes

Heterospory

Ovules

Pollen

The gametophytes of seed plants develop within the walls of spores that are retained within tissues of the parent sporophyte

Heterospory is always the case w seed plants

Megasporangia produce megaspores that give rise to female gametophytes

Microsporangia produce microspores that give rise to male gametophytes

The Evolutionary Advantage of Seeds

A seed develops from the whole ovule

A seed is a sporophyte embryo, along with its food supply, packaged in a protective coat

Seeds provide some evolutionary advantages over spores:

They may remain dormant for days to years, until conditions are favorable for germination

They may be transported long distances by wind or animals

Gymnosperms bear “naked” seeds, typically on cones

The gymnosperms have “naked” seeds not enclosed by ovaries and consist of four phyla:

Cycadophyta (cycads)

Gingkophyta (one living species: Ginkgo biloba)

Gnetophyta (three genera: Gnetum, Ephedra, Welwitschia)

Coniferophyta (conifers, such as pine, fir, and redwood)

The Life Cycle of a Pine

Three key features of the gymnosperm life cycle are:

Dominance of the sporophyte generation

Development of seeds from fertilized ovules

The transfer of sperm to ovules by pollen

The life cycle of a pine provides an example

The pine tree is the sporophyte and produces sporangia in male and female cones

Small cones produce microspores called pollen grains, each of which contains a male gametophyte

The familiar larger cones contain ovules, which produce megaspores that develop into female gametophytes

It takes nearly three years from cone production to mature seed

reproductive adaptations of angiosperms include flowers and fruits

•Angiosperms are seed plants with reproductive structures called flowers and fruits

•They are the most widespread and diverse of all plants

Flowers

The flower is an angiosperm structure specialized for sexual reproduction

Many species are pollinated by insects or animals, while some species are wind-pollinated

A flower is a specialized shoot with up to four types of modified leaves:

Sepals, which enclose the flower

Petals, which are brightly colored and attract pollinators

Stamens, which produce pollen on their terminal anthers

Carpels, which produce ovules

A carpel consists of an ovary at the base and a style leading up to a stigma, where pollen is received

Fruits

A fruit typically consists of a mature ovary but can also include other flower parts

Fruits protect seeds and aid in their dispersal

Mature fruits can be either fleshy or dry

Various fruit adaptations help disperse seeds

Seeds can be carried by wind, water, or animals to new locations

People depend on seed plants

No group of plants is more important to human survival than seed plants

Plants are key sources of food, fuel, wood products, and medicine

Our reliance on seed plants makes preservation of plant diversity critical

Most of our food comes from angiosperms

Six crops (wheat, rice, maize, potatoes, cassava, and sweet potatoes) yield 80% of the calories consumed by humans

Modern crops are products of relatively recent genetic change resulting from artificial selection

Many seed plants provide wood

Secondary compounds of seed plants are used in medicines

Threats to Plant Diversity

Destruction of habitat is causing extinction of many plant species

Loss of plant habitat is often accompanied by loss of the animal species that plants support

At the current rate of habitat loss, 50% of Earth’s species will become extinct within the next 100–200 years

For life to evolve, something has to change

What is alive? How do you know?

• Earth’s age and why did it take so long to get to us?

http://www.solcomhouse.com/images/specie6.jpg

http://www.safariconsultant.com/Herd.jpg

5. populations evolve, not individuals

http://www.solcomhouse.com/images/specie6.jpg

http://www.physorg.com/news85033468.html

family reunion and second and third cousins removed 2 times

Age of Bacteria

6. shared characters are used to help construct phylogenetic trees

http://www.daviddarling.info/images/Carboniferous.jpg

spore: sporopollinen