Community Ecology, Exam 1

Lectures 1-5 (last two slides of intro, idk what the hell I would put on here)

What is a community?

a group of populations living in the same area and

interacting with one another

What is community ecology?

The study of the interactions of species and their relationship to the

environment

What are the hierarchies in ecology?

Organism, Population, Community, Ecosystem, Biosphere

Why community ecology?

• Organisms do not live in isolation

  • Cannot understand parrotfish without understanding prey, predators, competitors, and habitat

• Ecosystems are not isolated

  • Coral reefs are affected by terrestrial and pelagic systems and are influenced by climate change

• Biosphere is interconnected

  • Climate change is influenced by carbon flux and forest transpiration

what is habitat?

where an organism lives

• Physical features: climate, chemical environment, dominate plant and/or

animals species

What is niche?

what an organism does

• Tolerable conditions:

temperature ranges

• Interspecific interactions:

what it eats, what eats it

What are community interactions?

How organisms interact with each other and their environments

• Resource acquisition

• Energy and matter flow

What is a resource?

anything used or consumed by an organism

• The act of consuming or using a resource manipulates, changes, or makes it unavailable for other organisms

Where do primary producer get their energy from? Where do they exist on the food web?

• energy from inorganic sources

  • sources outside of the food web

• base of the food web

  • where energy enters the food web

Where do primary producer get their energy from? Where do they exist on the food web?

• Acquire energy from other organisms

  • Consuming organic molecules

• Anywhere above the primary producers

What does a food web do?

Track energy in a community as it travels through species

What does a trophic pyramid do?

Track energy in a community as it travels through trophic levels

What are the different kinds of interspecific interactions? Aka multispecies interactions

What kinds of multispecies interactions are facilitation, and which are symbiosis? (they overlap)

Facilitation: Commensalism, Mutualism

Symbiosis: Commensalism, Mutualism, Parasitism

Describe predation in terms of Species A and Species B, who is who?

Species A consumes Species B

• Species A obtains resources, Species B is harmed or killed

• Species A = predator = all consumers plus some producers

• Species B = prey = organism consumed by a predator

What are the steps of predation?

1. Detecting prey

2. Pursuing prey

3. Capturing prey

4. Handling prey

5. Consuming prey

What is a consumer? Who is the consumer and who is the consumed?

Consume products or parts of other organisms

• Consumer = predator / parasite

• Consumed = prey / host

Are predators heterotrophs or autotrophs?

Predators can be heterotrophs or autotrophs

• Autotrophic predators are still classified as primary producers

• Vast majority of predators are heterotrophs

What are primary consumers classified as? What do they feed on? What do they do with their food? How are they specialized for this?

• Primary consumers = herbivores

• Feed on autotrophs/primary producers

• Take organic molecules from primary producers and transform them into consumer tissue

  • Usually only possible via mutualistic microbes in digestive system

  • Animals: long digestive systems with specialized organs

What are secondary consumers classified as? What do they feed on? Can other feed on them? What is their hunting strategy?

• Secondary consumers = carnivores, predators

• Feed on other consumers

• yes, they are prey for other consumers, so

  • Predator avoidance

• optimal foraging

What are apex predators classified as? What do they feed on? Can other feed on them? What is their hunting strategy? Why do they matter?

• Carnivore

• Feed on consumers

• are not (as adults) prey for consumers

  • But can still be hosts for parasites

• No concern for predators, are aware of competitors

• Often are keystone species

What are considered prey?

Everything except apex predators

What is optimal foraging?

Animals maximize net energy intake per unit of foraging time while minimizing energy expenditure (from google, if you can explain it you’re good)

What falls under the category primary producer consumers?

Carnivorous plants

Why do carnivorous plants exsist?

• Obtain nutrients but not energy from prey

• Live in habitats with poor soil quality

What are Hemiparasites? How do they obtain energy?

photosynthetic plants that obtain water and/or nutrients from a host

• Some photosynthesize and use host as water supply

• Some have limited photosynthetic ability

What is symbiosis?

Individuals of 2 or more species live in close physiological contact

Endosymbiosis and eukaryotic cells: what are the symbiotic features, and how do we know they are endosymbionts? How did Eukaryotes arise?

• Mitochondria and plastids

  • Contain DNA

  • Divide separately from cell

  • Are the same size and shape as bacteria

  • Surrounded by double membrane

• Eukaryotes are Archaea that developed a mutualist association with bacteria

Secondary endosymbiosis (no way we need to know this)

• Chloroplasts of alveolates, stramenopiles, and haptophytes are surrounded by a triple membrane

• Red algal ancestor of chloroplasts

Describe parasitism in terms of Species A and Species B, who is who?

• Species A obtains resources, Species B is harmed or killed

• Species A = parasite = consumer that eats a portion of or extracts nutrition from another organism without initially killing it

• Species B = host = prey of a parasite

What are the qualities of parasites in comparison to hosts? Who can be a parasite and who can have parasites?

• Parasites are usually smaller with shorter generation times than host

• All domains and major divisions/phyla have parasitic members

• All domains and major divisions/phyla are infected by parasites

What do parasites do? How does this affect the host? Briefly explain their life cycles, like one word. Can parasites be hosts to parasites?

• Impair their host

  • Infected prey are more likely to be consumed

  • Infected predators are less likely to catch prey

• Complex life cycles

• Yes, can be prey and host

What is a holoparasite?

heterotrophic plants that obtain all resources from the host

• Plants as primary consumers

What is the difference between a hemiparasite and a holoparasite?

Hemiparasites are plants that obtain water and/or nutrients from a host but still complete photosynthesis, while holoparasites are plants that obtain all resources from the host, plants as primary consumers

Describe parasitoids in terms of Species A and Species B, who is who? What animals are parasitoids? Who are their hosts?

• Species A consumes Species B slowly

  • Species A obtains resources, Species B is killed

  • Species A = parasitoid = consumer that eats another organism slowly eventually killing it

  • Species B = host = prey of a parasitoid

• All known parasitoids are insects

• Hosts are arthropods

What is Entomopathogenic fungi? Who are their hosts? How do they spread and how do they impact their hosts?

• parasitic fungi

• insects

• Spread via microscopic spores and penetrate insect cuticles

• Host may be killed quickly and fungus decomposes corpse

• Host may live until the fungus is ready to reproduce

  • Some influence host behavior, causing insect to seek out location favorable to the fungus

What is multiparasitism?

Hosts can host multiple species of parasites simultaneously

What is hyperparasitism?

Parasites can be hosts to parasites

Can parasitoids have parasitoids? Can hyperparasites be hosts to parasites? How many stacking levels of parasitism have we observed?

Yes, yes, and 3-5

What is a direct effect? In terms of species A and species B?

• when 2 species interact directly with one-another

  • Species A eats, parasitizes, competes, facilitates species B

    • Only species A and B involved

What is an indirect effect?

• when 2 species interact through an intermediate species

  • Species A eats, parasitizes, competes, facilitates species B

  • Species B eats, parasitizes, competes, facilitates species C

  • Species A has an indirect effect on species C

What are Cascading effects?

• Indirect effects that control ecosystem structure

• Web of indirect effects

Are food webs controlled by producers or consumers?

Both

What is bottom up control? What happens if there are more/less primary producers?

• When resources control ecosystem structure

  • Resources regulate primary producers

  • No primary producers, no organisms

  • More primary producers, more resources for higher trophic levels

What is top down control? What happens if there are more/less predators?

• predators control ecosystem structure

  • Predators suppress prey populations

  • Suppressed prey release own prey from control

  • Those prey then increase in abundance

  • Oscillating abundances as move to lower trophic levels

What is a density-mediated effect?

• act through population density

  • Predators consume prey reducing prey population density

  • Top-down effect is through direct consumption

What is a trait-mediated effect?

• act through phenotypic changes

  • Predator presence alters phenotype of prey

  • Alters how prey interact with environment and other species

  • Top-down effect is by changing prey traits

How often are bottom-up and top-down effects observed?

• Bottom-up effects are always present

  • May only provide resources

• Top-down effects are not always observed

  • Disrupted ecosystem function (humans like to kill apex predators and mess up ecosystems)

Describe commensalism in terms of Species A and Species B. What can be gained in commensalism? How are commensal species well-suited to that lifestyle?

• Species A benefits, Species B is not affected

  • Species B (host) is facilitating Species A (commensal species)

• Commensal species may gain

  • Food / nutrients

  • Shelter

  • Support

  • Transportation

• Commensal species may be specialized and specifically adapted for relationship

Describe mutualism in terms of Species A and Species B. What can be gained in mutualism? How are mutualistic species well-suited to that lifestyle?

• Species A and Species B benefit

  • Species A and B (mutualists) are facilitating one-another

• Mutualists may gain

  • Food / nutrients

  • Shelter

  • Protection

  • Enhanced reproduction

• Obligate vs facultative (necessary vs. optional)

• Specialist vs generalist (specific vs. flexible)

Give some examples of plant & fungus mutualism

• Legumes – nitrogen-fixing

  • Fabaceae and Rhizobia

• Pollination

  • Angiosperms (mostly) and animals

• Mycorrhizae

  • ~90% of land plants and fungi

• Lichens

  • Fungi and photoautotrophs

Give some examples of animal mutualism

• with autotrophs

  • Coral and zooxanthellae

  • Riftia and chemoautotroph

• Microfauna

  • Digestive

  • External

• Cleaners

Explain competition in terms of Species A and Species B. How are they affected? + or - ?What are some reasons that one acquires the resource and the other doesn't?

• Species A sequesters a resource before Species B

  • Species A and Species B (competitors) are both negatively affected

  • But Species B is more negatively affected

• Species A may

  • Be better able to obtain or sequester the resource

  • Take the resource from Species B

  • Not require as much of the resource

What is competitive exclusion?

when a species is excluded from a habitat due to competition with another species

Competition can alter the ________ _______ bahviour of competeitors. This can lead to what kind(s) of control?

• resource obtaining

• Bottom-ish, Middle and Top

What 2 things cab competition lead to?

• Competitive exclusion

• Niche partitioning

What is a keystone species?

• Species that have a disproportionate impact on community structure

• May not be numerous

• Can be

  • Predators/parasites

  • Competitors

  • Facilitators

  • Engineers

What are ecosystem engineers?

• Species that significantly alter the physical structure of their habitat

  • Keystone species

  • Often define the habitat

• Create, modify, or destroy habitat