BIOL 221 - Unit 3: Coevolution & Biodiversity

coevolution

reciprocally induced evolutionary change

What criteria must be met for coevolution to occur?

• two or more species in the same space at the same time

• each species affects the other species’ survival or reproduction

examples of coevolution

• predator-prey

• parasite-host

• plant-herbivore (leaf eater)

• plant-granivore (seed predator)

• plant-pollinator

coevolutionary arms race

occurs when two or more species evolve adaptations and counter-adaptations in response to each other, repeating cycle of reciprocal adaptation, escalation and counter-escalation driven by natural selection

Is the relationship between the rough-skinned newt and the common garter snake an example of a coevolutionary arms race? How so?

Yes because the rough-skinned newt has glands that secrete TTX (tetrodotoxin) and the common garter snake has evolved to become resistant to the toxins

What caused some snakes to be resistant of TTX?

Mutations in the DNA sequence of the sodium channel gene lead to changes in amino acid sequences

What causes the differences in resistance to TTX in snake populations?

Snake populations differ in the number of mutations

What is the relationship between proboscis length and corolla depth for coevolving species?

The longer the corolla, the bigger the proboscis length. In order to reach all the nectar at the bottom of the corolla, the proboscis must be long enough that the pollinator can comfortably (not shoving itself into the flower) absorb the nectar.

How can coevolution occur between flowers and pollinators?

Flowers adapt to attract specific pollinators and increase pollination frequency, pollinators adapt to increase feeding efficiency

What are the three domains in the tree of life?

• Domain bacteria

• Domain archaea

• Domain eukarya

True or false?

Domain archaea and domain eukarya are sister taxa.

True

True or false

Bacteria is a paraphyletic group.

False, bacteria is a monophyletic group

True or false

Archaea is a monophyletic group

True

Which group is Archaea more closely related to?

Eukarya

True or false

Prokaryotes (bacteria, archaea, eukaryote) are a paraphyletic group

True

General characteristics of prokaryotes

• single-celled organisms

• no organelles with a membrane

• asexual reproduction

Differences between bacteria and archaea

• cell wall

• cell membrane

• introns

• histones associated with DNA

• environments

• medical importance

Cell wall in bacteria

composed of peptidoglycan

Cell wall in archaea

composed of psuedopeptidoglycan

cell membrane in bacteria

lipid bilayer

cell membrane in archaea

lipid bilayer or monolayer

Introns are ____ in bacteria and _____ in archaea

absent; present

Does bacteria have histones associated with DNA?

No

Does archaea have histones associated with DNA?

Yes

Histone

protein that provides structural support for a chromosome

Bacteria environment

Found everywhere, but do not live in extremely high temperatures

Archaea environment

found in extreme environments (e.g. high temperatures, high salinity)

Bacteria’s medical importance

Pathogenic, sensitive to antibiotics

Archaea’s medical importance

Non-pathogenic, not sensitive to anti-biotics

Importance of prokaryotes

• abundance

• thrive in extreme environments

• medical importance- pathogens

• biofilms

• bioremediation

Why do prokaryotes have an important biological impact?

Abundance, found in a diversity of habitats, including in and on other organisms

What kinds of extreme environments do prokaryotes thrive in?

• high salt

• high temperature

• low temperature

• high pressure

What is one example of disease causing pathogen?

Mycrobacterium tuberculosis, affects the respiratory tract, results in tuberculosis

endospores

tough, thick-walled, dormant structures which are formed during times of environmental stress and are resistant to extreme temperatures, UV radiation, and antibiotics

biofilms

dense bacterial colonies enmeshed in a polysaccharide-rich matrix

where are biofilms usually found?

phone touchscreens, shower liners, sewage pipes, dental plaque

How do biofilms affect bacteria?

the biofilms help shield bacteria from antibiotics, which is a growing problem in hospitals

3 different methods of gene transfer

• conjugation

• transduction

• transformation

gene transfer

transfer of genetic material (all or part of a gene) between different species under natural conditions

how does gene transfer affect prokaryote diversity?

increases genetic diversity and has sped up the rate of evolution in prokaryotes

conjugation

genetic information is transferred by direct cell-to-cell contact

transduction

viruses pick up DNA from one prokaryotic cell and transfer it to another cell

transformation

bacteria or archaea naturally take up DNA from the environment that has been released by cell lysis or secreted

What does the morphological diversity of prokaryotes consist of?

• size and shape

• motility

• bacterial cell-wall composition

What is the smallest prokaryote?

Mycoplasma mycoides

What is the largest prokaryote?

Thiomargarita namibiensis

What are the sizes and shapes that prokaryotes can look like?

Rods, spheres, corkscrews, and spirals

motility

how it moves in the world

flagella

spiral filaments of protein subunits

gram-positive cell wall composition

cell wall consists of peptidoglycan and polysaccharides

gram-negative cell wall composition

cell wall consists of peptidoglycan and an outer membrane

metabolism

life-sustaining chemical transformations within the cells of living organisms

phototrophs

use light energy to excite electrons

chemoorganotrophs

oxidize organic molecules with high potential energy

chemolithotrophs

oxidize inorganic molecules with high potential energy

autotrophs

synthesize their own carbon compounds from simple starting materials (e.g. carbon dioxide or methane)

heterotrophs

absorb ready-to-use organic compounds produced by other organisms in their environment

energy source = sunlight

carbon source = CO_2 (carbon dioxide)

photoautotrophs

energy source = organic matter

carbon source = organic matter

chemoorganoheterotrophs

energy source = NH _4+ (ammonia)

carbon source = CO _2

chemolithoautotrophs

energy source = organic matter

carbon source = CH_4

chemoorganoautotrophs

energy source = H_2S (hydrogen sulfide)

carbon source = organic matter

chemolithoheterotrophs

energy source = sunlight

carbon source = organic matter

photoheterotrophs

ecological diversity of bacteria and archaea

metabolic diversity allows bacteria and archaea to live in a wide array of habitats

Where do photoautotrophs live?

In the photic zone of aquatic biomes and desert soil crusts

Where do chemoorganoheterotrophs live?

Lives in soils and bodies of animals

Where do chemoorganoautotrophs live?

In soils

Where do chemolithoautotrophs live?

In soils

Where do chemolithoheterotrophs live?

Hydrothermal vents

Where do methanogens live?

In wetland soils and bodies of animals

Where do methanotrophs live?

In soils

Characteristics of eukaryotes

• membrane-bound organelles

  • nuclear envelope

  • mitochondria

• mitochondrial cellular respiration

• cytoskeleton

• asexual or sexual reproduction

• larger cell size

• unicellular or multicellular

importance of protists

• ecological impacts

• impacts on human health

• human uses

protists’s ecological impacts

• carbon cycle

• decomposers

• base of food webs in aquatic biomes

• create habitat

protists’s impacts on human health

• agricultural losses

• plasmodium - causes malaria

• trypanosoma - causes sleeping sickness and Chagas disease

• macroalgae - deter predators from consuming them

  • potential for development of new drugs

protists’s human uses

• diatomaceus earth

• food

• agarose - gelling component in agar

• algin - used as a food additive

evolution of mitochondria

• host cell surrounds and engulfs bacterium

• bacterium lives within host cell

• endosymbiosis: host cell supplies bacterium with protection from carbon compounds. bacterium supplies host cell with ATP

evolution of chloroplasts

• photosynthetic protist is engulfed

• nucleus from photosynthetic protists is lost

• organelles has four membranes

evolution of nuclear envelope

• infoldings of plasma membrane surround the chromosomes

• eukaryotic cell arises, with infoldings forming nuclear envelope and ER

eukaryote lineages

• amoebozoa

• opisthokonta

• excavata

• plantae

• rhizaria

• alveolata

• stramenopila

What defines protists?

Eukaryotes that are not fungi, plants, or animals

what eukaryotic lineages only have protists?

amoebozoa, excavata, rhizaria, alveolata, stramenopila

supportive and protective features on protists

diatom- cell wall of silicon dioxide

dinoflagellate- cell wall of cellulose plates

foraminiferan- shell of calcium carbonate

euglenid- pellicle of protein strips

feeding methods of protists

• photosynthesis

• absorptive feeding

• ingestive feeding

photosynthesis

produce their own organic compounds

absorptive feeding

nutrients taken up directly from the environment, across the plasma membrane, usually through transport proteins

ingestive feeding

eating live or dead organisms or scavenging loose bits of organic debris

• psuedopodia surround and swallow prey

• cilia create water currents that sweep food particles in

How do dinoflagellates affect food webs?

dinoflagellates produce saxitoxin, which can be biomagnified up the food chain. eating poisoned shell fish results in paralytic shellfish poisoning (PSP)

interaction between zooxanthellae and coral

zooxanthellae gives the coral it’s color and carbon

What factors could contribute to an increase in the probability of coral bleaching?

• temperatures that were particularly higher than normal

• a high frequency of years with higher than normal temperatures

causes of coral bleaching

when water temp increases, coral expels zooxanthellae from its tissues which makes it turn completely white

consequences of coral bleaching

if the temps are too high, the coral won’t let the zooxanthellae back in. this could lead the corals to die. once they’re dead they rarely come back

function of bioluminescence

serve as protection from predators

How does bioluminescence occur?

Luciferase enzyme catalyzes the oxidation of light-emitting pigment luciferin. Luciferin reacts with oxygen to create light.

where do photoheterotrophs live?

in various aquatic habitats

importance of fungi

• plant pathogens

• food spoilage

• human microbiome

• source of pharmaceuticals

  • antibiotics

• human food supply

• increase plant growth

• mycorrhizal network

• carbon cycle

characteristics of fungi

• unicellular or multicellular eukaryotes

• hyphae

• absorptive chemoheterotrophs

• asexual or sexual reproduction

Multicellular forms are filamentous structures called

mycelia

hyphae

filaments that make up a mycelium

septa

cross-walls that divide the filament into cells