Biology 1407: Labs 11-12 Predator-Prey, Diversity, Food Webs & Ecological Footprints

Is the study of predator-prey interactions relevant to a population ecologist or a community ecologist, or both? Explain.

*BOTH* the study of how populations are affected by factors such as interspecific competition and predator-prey interactions (and along the same lines, parasitehost interactions) falls somewhere in between population ecology and community ecology. why ecology? Technically, the study of interspecific competition, because it involves more than 1 species, also qualifies as community ecology. The interaction between predators and prey would fall under this category as well since predators and prey are most often of a different species (minus acts of cannibalism)

purpose of measuring diversity

Biodiversity is often measured because high biodiversity is perceived a synonymous with ecosystem health. In general diverse communities are believed to have increased stability, increased productivity, and resistance to invasion and other disturbances.

What factors go into calculating an ecological footprint?

By land type: Built-Up Land, Forest Products, Cropland, Grazing Land, Fishing Grounds, Carbon Footprint By consumption category: food,shelter,mobility,goods,services

Explain how the study of food webs fits under the discipline of community ecology.

Community ecology is the study of the interactions of different populations living in an area at a time. Consuming one another (as you do in food webs) is an example of populations interacting.

Explain how interspecific competition and predator-prey interactions shape a community.

Competition between different species for the same resources forces the different species to occupy different ecological niches, which can shape the community. Predator-prey interactions can force prey and predators to adapt to avoid being eaten or to get their food. This also shapes a community.

If you wanted to lower your ecological footprint as much as possible, what sort of habits would you need to adopt?

Eat more produce,and less meat. Use less plastic, and recycle whenever possible. Try to insulate your home well, and to carpool, or use cleaner methods of transportation. Eat food that's grown/harvested locally.

trophic level

Food chain level. Examples: primary producer, primary consumer(photosynthesizing organisms), secondary consumer, tertiary consumer...

How do food chains differ from food webs?

Food webs show multiple food chains. More accurately because they think that a predator for one kind of organism can be the prey of many other different kinds of organisms. Also, food webs can show decomposers, which brings a higher level of accuracy.

How does a community form from the ground up?

Forms from ground up because plants(usually 1st organism to colonize), provide the most energy out of all the organisms, and provide it to the primary consumers, which can they be utilized by omnivores/carnivores for energy

How did simulation 2 (addition of herbivore A) change the population growth patterns for plants A and B?

If herbivore eats plant A only: plant A=4,998 plant B=3335 Plant B gets a fighting chance to live, as it's competitor now has to deal with herbivores. ------ If herbivore eats plant B only: plant A=10,000 plant B=0 Plant B already has a hard time, but herbivore drives B to local extinction faster, and the herbivore population dies here because they don't have any food ------ If herbivore eats both plants A and B:plant A=0, plant B=3333 Plant A has less favorable adaptations to the herbivore, and gets eaten more, so plant B has the opportunity to increase its population. Plant B outcompetes plant A, and plant A is driven to local extinction.

Which countries are likely to have the lowest ecological footprint and why?

Likely to have a lower ecological footprint if the country has a small population and large area, not industrialized, or has great efforts to reduce ecological footprint (like recycling centers, and educated people dedicated to lowering their footprints).

What were the results of the first simulation with Plant A and Plant B?

Plant A completely outcompeted plant B, driving plant B to local extinction (10,000 vs 0 after 100 days). The 2 plants were not able to coexist without any sort of outside influence. Probably because plant A has better adaptations to the environment than plant B

For the food web simulations, provide examples of each trophic level (primary producer, primary consumer, etc.)

Primary producer-plants A,B,C Primary consumer-herbivores A,B,C Secondary consumer-omnivore A,B, Tertiary consumer/top predator-wolf

Does the United States population, on average, have the largest ecological footprint compared to other countries?

The U.S., on average, has a higher ecological footprint because of our huge population, and our lifestyle habits.

Compare simulation 3 and 4. How did food chain versus food web interactions change how the populations generally grew and declined?

The food chain interactions were a lot more predictable, due to the decreased amount of interactions you had to monitor. The consumers at a trophic level above an organism helped curb the population growth of any trophic level beneath them. The food web mapped several different species interactions, and showed that sometimes, a species could outcompete other species, and drive it to local extinction.

Explain why you needed to have before the lab your gas and electric bill or know the size of your home or apartment. What does this approximate?

This approximates how much fossil fuels you are using to power your home,which ties into your carbon footprint.

ecological footprint

This is the amount of land and ocean (on earth or the equivalent) it would take to support your lifestyle. Your ecological footprint includes the amount of land and ocean needed for resources used by you and any needed for holding waste you produce. -measured in hectares (100 meters x 100 meters =0.4 acres)

What parameters maximized coexistence of all species in the food web for simulation 4?

To maximize coexistence of all species in the food web, I had to make sure that all consumers had a varied diet. They couldn't exclusively prey on 1 kind of organism, especially if they didn't have any predator to curb their population growth. If these measures weren't taken, especially for less hardy plants/organisms, their species would collapse.

keystone species or top predator

a species that, if it wasn't there, would allow the rest of the community's food web to fall apart. Mostly top predator, but not always. In the case of the top predator as a keystone species, the top predator curbs the population of its prey source, which in turn allows other organisms competing with the top predator's prey more of a chance to get their resources, and prevents total consumption of a community's vegetation.

Lotka-Volterra equation/model

classic mathematical model that has been used to reflect possible predator-prey cycles *Prey (V) Equation*: dV/dt = rV-αVP r = prey growth rate α = capture efficiency of predator P=# predators V=prey *Predator Equation (P):* dP/dt = βVP (assumes no deaths of predators) β = predator conversion efficiency Term βVP = the ability of predators to convert each new victim into additional per capita growth for the predator population. Therefore growth of predators under this equation is exclusively dictated by the number of prey captured.

Which differed MORE between the different levels of pollution, species richness or species Evenness?

eveness

species evenness

how well each species is represented (the number of individuals per species; if that number is the same across all, is considered the most even)

Species richness

is the number of different species present in a community

Ecological theory

predicts that predator and prey populations will follow oscillating (up and down) cycles as follows: predator populations will begin small and then rise as they consume prey, prey populations will decline as a result of predation, predator populations will begin to decline as prey starts to become scarce from overeating, prey populations will "bounce back" as predator populations decline, and predator populations will begin to grow again as a result of more available prey

Predators prey relationship

represent a *positive-negative species interaction* where the predators benefit and the prey do not. This is also known as an antagonistic relationship and it is one relationship in which coevolution of predators and prey may occur (though the predators' dependence on their prey needs to be quite strong

Provide an example of species richness versus species evenness from the stream diversity Simulation

richness: # of species we had In this lab we had 16 species So i=16 EXAMPLE SPECIES EVENESS: We know species evenness is the number of individuals per species and it is pi so Calculated by taking i/ni

birth conversion rate

the number of prey required for a predator to produce 1 offspring

Shannon Diversity index

this index helps us quantify diversity by accounting for species richness and species evenness equation 1 must be calculated first and then plugged into equation 2 to complete calculation of H. If H is high, it means the diversity is higher in a community versus one with a lower H. The range for H is typically between 1.5-3.5 and rarely above 4.5. ----- Equation 1: pi = ni/ N Equation 2: is the image ni = number of individuals of species "i" (a particular species) N = total number of individuals of every and all species in the community pi = relative abundance of species "i" or evenness (see equation 1) S = total number of species