Final Exam Flashcards
null hypothesis
There is no difference in DV between experimental and control groups
alternative hypothesis
there is a difference in the DV between experimental and control groups
Community ecology
assemblage of populations of different species in one area at one time
focus: species interactions
Types of interactions and examples
Mutualism (++)
Predation (+-)
Parasitism (+-)
Commensalism (+0)
Competition (–)
Niche
- n-dimensional hypervolume that describes the conditions for species persistence
- 2 dimensional area that describes the conditions for species persistence
- 3 dimensional volume that describes the conditions
for for species persistence
Two types of niche
fundamental: individuals react with physiology in the space
- could be occupied
- no enemies
- bigger
realized: organism interacting with one another in the space
- niche occupied
- enemies present
- smaller
Competition
two organisms require the same resources which is in short supply
intra-specific
within species; logistics, density dependent
inter-specific
between species
competitive exclusion principle
exclusion if one species by another due to competition (when competitive ability is asymmetrical)
Evidence of competition in nature
- niche partitioning of lizards in the Dominican republic
- competition exclusion of barnacles in scotland
- character displacement of finches in the Galapagos island
Niche partitioning
- given that competition can be costly to both species
- mechanisms that avoid costs are favored
- niches can be divided so that competition is avoided
- eg division in space (occupy different locations)
*lizards in the Dominican republic partition in space to avoid competition
Barnacles in Scotland
- crustaceans
- located in inter tidal zone
- filter food from water
- planktonic dispersal stage
- settle on rock for life
- survivorship curve; type III
*Chthalamus were excluded from preferred locations by Balanus through competition
*the experiment was to see if there was competition between both species; so when the Balanus were removed there was no competition and the chthalamus extended their niche
Character Displacement
evidence of competition revealed by difference in traits among populations
- in closely related species that share a resource
- traits are similar when the species are apart (allopatry)
- when together (sympatry) traits are different
*birds had similar beak sizes so they ate the same food which created competition but then they evolved and changed their beak size which helped them get different food and now no more competition
*finches in the Galapagos
Ecological Succession
predictable change in the species competition of a community over time following a disturbance
- fire
- volcano
- leaf falling in stream
- dead whale sinking to bottom of ocean
*each species comes a bit later than the other
*when species B comes its better at competition so A goes away but when C comes its better than B at competition then B goes away and same with D; after D comes no one left to fight so only one left
*amount of organisms at that point has to do with previous graph low-high-low
Keystone Species
species has a big impact on community dynamics
- can influence species diversity
- if removed = diversity decreases
Keystone Predation
sea stars (predator) - limpets, mussels, barnacles (prey)
Observation
Hypothesis
Experiment
Conclusion
- on beaches barnacles in the pacific northwest of the sea star abundance was correlated positively with prey species diversity
- sea star presence –> prey diversity
- remove sea stars in some areas but not others, record prey diversity
*two treatment groups: group 1 sea stars absent (experimental); group 2 sea stars present (control-natural state) - sea stars are keystone predators that maintain community diversity. Sea stars prevent one species (mussels) from excluding the others (prevent competitive exclusion)
Ecosystem
community of organisms in an area and the physical factors with which these organisms interact
Ecosystem Ecology
emphasis on ENERGY FLOW and CHEMICAL (nutrient cycling)
- critical organisms: prokaryotes, protist, fungi
Diversity of Life
image
Energy base
set by producers
- photoautotrophs (photosynthetic)
- 6CO2 + 6H2O -energy light-> 6O2 + glucose
- chemoautotrophs (chemosynthetic); eg hydrothermal vents in ocean
food chain
linear sequence of feeding relationships that describe energy transfer
- trophic level: each step in chain
food web
network of food chains
energy transfer
- most energy is not transferred between trophic levels
- 80-90% used or lost
- 10-20% transfers
- energy pyramids
*caterpillar eating leaves
caterpillar:
Feces(100J) New biomass(33J) Respiration(67J)
(gives energy)
Energy (2000J)
leaf:
Energy pyramid
(10% energy transfer)
Primary Producers- 10,000J
Primary Consumer- 1,000J
Secondary Consumer- 100J
Biological Magnification
- accumulation of toxins at higher trophic levels
- biomass at each trophic level depends on much greater biomass at lower levels
- eg PCB or polychlorinated biphenyl
-chart remember
Chemical (nutrient) cycling
chemical elements available in limited amounts
- essential chemicals must be recycled
- chemicals move through resources
- movement can occur over short and long time periods
- cycles: carbon, phosphorus, nitrogen
Reservoirs
Carbon Cycle
Chart thingie
Human Impacts
Eutrophication
- nitrogen and phosphorus cycles
- increases fertilizers and sewages
- effects on aquatic systems (eg lakes)
- algae and bacteria grow rapidly –> bloom
- followed by “crash”
- accumulation of dead organisms
- decomposition–> increase CO2; decrease O2
- death of other organisms (dead zone)
evolution, ecology, and diversity
they are all connected
what is the unity of life?
DNA, shared genetics, ancestry
what is the diversity of life?
- evolution (natural selection)
- ecology (competition, niches)
Are Eukarya generally more complex than Bacteria and Archaea?
Yes
Are Eukarya better adapted than Bacteria and Archaea?
No not better just different
Why sexual reproduction?
Red Queen hypothesis
- alice through look glass
- have to change to stay alive
costs of sex?
- finding mates (time, energy)
- fight with rivals
- lost of genetic fitness (females 50%)
- STDs
Which came first the chicken or the egg?
egg because of phylogeny
Evolution: antibiotic resistances
Two major causes:
- patient non-compliance-evolution
non compliant patients ‘select’ for increased resistance
- overuse of antibiotics- ecology
in the absence of antibiotics, non resistant bacteria outcompete resistant bacteria
What if there was no antibiotics what would happen?
They will go to the left of the graph; energy tradeoffs- if you don’t need resistance then you wont have it because its costly
Toxic environmental insult
toxic bacteria in reproductive tract
- influence developing fetus
solutions:
- introduce toxins (traditional approach)
- introduce non toxic bacteria to outcompete toxic bacteria
how do organisms deal with unpredictable conditions?
flexibility = phenotypic plasticity
- one genotype produces multiple phenotypes
- based on conditions encountered during life
Euglena (protist)
- autotrophs: photosynthetic
- heterotrophs: predatory
- mixotrophs: both
Why not always have plasticity?
energy tradeoffs
Behavior of Bacteria
- non random movement
- exhibit taxis - movement towards or away from a stimulus
- positive taxis - move towards
- eg photosynthetic bacteria (move to light)
Behavior and dispersion of food
- uniform; bacteria can get all foods
- clumped; bacteria miss food and might not get any (doesn’t do this cause of tradeoff)
Scale of population dispersion
Lake:
- surface algae (photosynthetic): random dispersion
- whole lake; algae: clumped dispersion
Fungi
- heterotrophs
- penetrate food items, secrete enzymes, absorb nutrients
- morphology
- body is network of filaments; hyphae
- interwoven mass of hyphae; mycelium
- exposed portion; spore dispersal
Species interactions
- mutualism
- parasitism
- competition
- commensalism
- predation
Prokaryotes
- unicellular
- small (0.001-0.005mm)
- short generation time
- asexual reproduction
- autotrophs, heterotrophs
- photosynthetic, chemosynthetic
rapid evolution
- short generation time
- mutation and binary fusion
- also engage in horizontal gene transfer: conjugation-exchange genetic material with other prokaryotes
- exchange genetic information across ‘species lines’
problems with phylogeny?
how is prokaryotes a problem for phylogenetic reconstruction
- different taxa can exchange genetic info
- difficult to reconstruct evolutionary relationships
problems for species definitions?
- exchange genetic information across species lines
- asexual reproduction
euglena and prokaryotes
homoplasy
flagella of prokaryotes and protists
- homoplasy
- convergent evolution
key roles
evolution
- gave rise to all eukaryotes (endosymosis)
ecology
- critical role in nutrient cycling
carbon cycle
explain….
nitrogen cycle
explain…
biofilms
- slimy film on teeth
- community of prokaryotes live on surfaces
- leaf slime; medical tube slime
- multiple species of prokaryotes secrete a chemical to attract others
- collectively produce protective layer over community
- hard to remove
- more resistant to bacteria
bioremediation
prokaryotes used to help clean up environment
- oil spill clean up
- promote growth of the bacteria
- add genetically modified bacteria (with short life span to do the job then die)
protists
- eukaryotes that are not plants, animals, or fungi
- nucleus, membrane bound organelles
- typically unicellular; highly complex organization within cell
- protist group not well defined evolutionarily
Apicomplexans
- parasites
- name: one end of the body ‘apex’ contains ‘complex’ of organism specialized for penetrating host tissue
- plasmodium causes malaria
- 250 million people in tropics infected
- 900,000 people die each year
mosquito and human
back and forth cycle where mosquitos salivary glands go to human liver and blood cells
malaria prevention
genetic resistance:
- plasmodium-human
- mechanism: prevent parasite entering blood stream
vaccines:
- mechanism: attacks plasmodium cells
-concern: vaccine resistant plasmodium
pesticides:
- mechanisms: kill mosquitos
- concern: biological magnification, evolution of resistance
GM mosquitos:
Biological control:
- mechanism: predators consume mosquitos
