Principles exam 2

Why do we care about monitoring population dynamics?

Trends

Population

number of individuals in a defined area

Population dynamics

How a population changes over time (BIDE)

Age Structure

proportion of individuals at each age

Sex Ratio

The proportion of males to females in a population

Abundance

The number of animals

Density and what does it tell?

The number of animals over a specific area. It is an abundance scaled to some area. It tells concentration

Population Growth Rate

Rate at which population numbers increase, decrease, or stay the same

Lambda

Rate of growth changes from one year to the next

Intrinsic Growth Rate ( r ) and why do we use it?

The ln of Lambda. We use it to compare numbers by putting them on the same scale

What is exponential growth in population dynamics

Population trajectory with no constraints

Population variation

The randomness (stochasticity) of a population and how it compares to other populations

Population uncertainty

The amount of confidence in your abundance

3 types of Stochastic Constraints (GED)

1. Genetic: Inbreeding depression

2. Demographic: Survival and reproduction

3. Environment: Impacts vital rates via disturbances, disease, etc

5 types of Deterministic constraints (HCAPP)

1. Habitat quality: food, cover, and water can impact vital rates

2. Predation: direct consumption vs fear (impacts age and sex)

3. Competition: interspecific and intraspecific

4. Anthropogenic effects

5. Positive interactions: Commensalism and mutualism

Carrying capacity

The maximum population size of a species that a specific environment can sustainably support due to limiting resources

How do constraints alter exponential growth?

Creates an upper limit that levels population growth based on constraints and limiting factors

Stochastic vs deterministic constraints

Stochastic is random and unpredictable, and deterministic is predictable and directional

BIDE depends on what?

Density (it is density dependent)

How does density dependence prevent exponential growth in a population?

As population density increases in an area it causes growth rate to slow as resources are being used up

What type of growth curve is created due to density dependence?

Logistic growth curve

What is happening at the bottom of a population logistic growth curve?

Births and deaths are increasing but it takes time

What is happening at the inflection point of a population logistic growth curve?

Max vital rates

Where would you want to begin harvest on a population following a logistic growth curve?

At the top of the curve that is reaching carrying capacity

Allee effect

When a population is so small that the growth rate is decreasing as population numbers are decreasing due to individuals having trouble finding mates or maintaining genetic diversity etc

Would you want to harvest at the inflection point when vitals are at their peak in a population?

No, because of uncertainty

Cyclic populations

act upon a single constraint with time lag

Why do we have competition?

establishes and creates ecosytems

Interspecific competition

Competition between species

Intraspecific competition

Competition within a species

Interference competition

indirect or direct competition done by guarding resources for ones own self

Exploitative competition

Indirect competition by taking resources for one’s own self

Apparent competition

Indirect competition interaction where two prey species negatively impact each other by having a shared predator.

If wolf eats moose and deer and deer goes up, so does wolf. Wolf then eats more moose

3 conditions of competition

• Overlap of resource in short supply

• impact on fitness

• The amount of the resource taken has an impact on individuals

Who wins in competition?

The individual better at getting the resource.

Does population growth have an impact on who wins in competition?

No

How does coexistence happen?

When you reduce competition to only within your own species

What is a niche?

Partitioning into a specific role within an ecological community

Competitive exclusion principle

2 species can’t coexist by using the same limited resource and have continuously have stable populations

N-Dimensional hypervolume

Geometric definition of a niche. All of the possible factors that can contribute to a niche (diet, temp, cover space, etc)

Fundamental Niche

All of the possible places an individual can live because of favorable conditions

Realized Niche

All of the places an individual can actually live due to competition keeping me from all of the places with favorable conditions

Habitat selection can be described as a (in terms of competitive exclusion principle):

(4 parts to the answer)

Gradient

2 species overlap → comp reduces fitness → individuals that use alternate resources gain an advantage → habitat selection occurs

Competition leads to which niche and what 5 factors are involved in it?

Realized niche (Space, food, cover, precipitation, temperature)

Life-Dinner Principle

The principle is that predators and prey face unbalanced consequences in their dynamic. If a predator misses the prey, he only misses a meal and can try again. If the prey is caught, he loses his life.

What are the two examples of direct predation effects?

Evolutionary arms race and life-dinner principle

Evolutionary arms race and what does it do to genetics?

Continuous adaptations and counter-adaptations between predator and prey. It alters the genetics available

Two types of indirect predation effects

Density mediated and Trait mediated

5 types of density mediated predation effects LC4

1. Lower competition by lowering prey density

2. Creates apparent competition

3. Creates indirect mutualism: one prey species density increases so predator spends more time focusing on that prey species instead of another prey species that shares that predator. Both prey species increase survival because increase of density increases overall survival rate of species 1

4. creates indirect commensalism: If prey species 1 survival doesn’t change, it is unaffected by the increase of survival of prey species 2, creating commensalism

5. Creates trophic cascade: If an apex predators species decline it can increase mesopredators which can cause prey species to decline

Trait mediated effects of predation and examples

Where a prey species alters its behavior in response to predation

ex. Avoiding certain spaces and increasing vigilance over foraging time

What are the 3 reasons predators dont annihilate prey and describe those reasons?

1. Self-regulation: limited space if territorial which can vary based on seasons

2. Competition: Multiple predator species can decrease forage success

3. Predator variation: Diagram of stages of predator encounter (further explained on diff card)

Predator variation and the diagram of stages for predator encounter. What are these factors moderated by?

search (ambush, packs etc) → detect (sight, smell, sonar) → pursue (impacted by habitat and experience) → capture (impacted by habitat and experience) → handle and consume

The factors are moderated by vulnerability of prey (diseased, age, etc) and habitats they are in

What are the models called that have 3 types and represent functional responses to how much a predator can consume?

Lotka-voltera models

Type 1 Lotka-voltera model

Apex eats at a proportional rate to prey

• this model is unlikely

• considers (change of prey)/time = growth rate of prey - prey of predation

• considers (change of predator)/time = growth rate of predator - death rate of predator

• Liner model

Type 2 Lotka-voltera model

The predator needs time to consume and become hungry again

• divide births/death by handling time

• Gives you an asymptote type curve

Type 3 Lotka-voltera model

The predator needs time to search

• Add (search)/handling time to the equation

• Makes a logistic curve

• adds a point of satiation towards top of logistic curve

What do the lotka-voltera models tell us as wildlife managers ?

The values of different parameters so we can alter them as needed

Predator Pit

When a prey population is consistently held at a low density due to predator consumption preventing recovery

Predator model type 1 equations

• change of prey/change of time = growth prey N - predation rate

• change of pred/ time = growth pred N - pred deaths

Predator model type 2 equations

• change of prey/change of time = growth prey N - (predation rate)/(handling time)

• change of pred/time = growth pred N/handling time - predation deaths

Predator model type 3 equations

• Growth prey N - pred rate

• change of predation/time = growth pred N x (search/handling time) - predation deaths

Why should we care about predation models?

We have a bad history of annihilating predator populations

When is it acceptable to cull predators?

When there is a predator pit

Memorize predator pit model

Disease is another example of a what?

Population constraint

Parasites

feed on living hosts and doesnt always kill them (killing the host is not ideal)

Microparasites

parasites you cant see: fungi, bacteria, virus

Macroparasites

parasites you can see: ticks, flease, tapeworms

How many parasites do humans have in their body that are fine to have?

149, causing only minor effects

What are endemic pathogens?

those that are constantly present within a host population at relatively stable levels rather than causing occasional epidemics

How can endemic pathogens influence host success?

they can decrease survival and reproductive success

What is the SIR model for?

3 compartments to divide the population into to track how an infectious disease spreads and changes over time

• Susceptible, infected, recovered

What do other parasites beyond the ones that live in harmony with humans cause? How can the symptoms vary (2)?

Other parasites cause disease, and the symptoms can be

• major or minor

• Short term or chronic

What does R0 represent? What does it equal? How does it increase?

The reproductive output of a virus

• R0= rate of infected/rate of recovered

• increases with an increase of infection

R0>1. What is occurring?

Pathogen is growing, epidemic is occuring

R0=1

disease is stable

R0<1

Mitigation of disease is possible through vaccination program

What is the equation for R0

R0= (1-proportion vaccinated)(rate of infected)/recovered

What is the proportion to vaccinate equation?

1-(1/R0)

• so if R0 = 2, then you would need to vaccinate 50% of the population

What does N stand for in terms of diseases?

Threshold of host density number that should be immune for disease to die out

How do you calculate N in terms of disease?

N= (natural mortality + disease based mortality + recovery rate)/ transmission rate

What are the individual effects pathogens can have on an animal?

Pathogens take ENERGY from the host and can

• Decrease reproductive success and survival (succumb to disease or be more vulnerable to predation)

Why can a pathogen change a hosts behavior?

To help it’s chances of transmission to another host

5 effects pathogens can have on an ecosystem and examples (CAAAC)

1. Cause of density-dependent regulation: Pneumonia in sheep keep them at lower carrying capacity

2. Alter exploitative competition: whitetail deer spread north with parasite decreasing moose and caribou populations creating more resource oppurtunities

3. Alter apparent competition: reindeer nematode decreases food intake increasing the variety of plants that can grow for other animals

4. Alter predator communities: canine distemper decreasing canid populations

5. Cause trophic cascades: rabbits in UK almost wiped out by myxomosis, increasing plants and increasing other small mammal communities

How are epizoonotic pathogens different? (4)

1. Involves a jump between species

2. involves human disturbance

3. changing climates

4. causes can be unknown

What do epizoonotic diseases usually cause in comparison to other pathogens?

rapid spread and high mortality

What do managers now understand about many epizoonotics?

There is a wildlife-human link

Managing game also involves disease. What is an example and what is a caveat to management?

• CWD

• Management can be socially contentious

What are the 4 ways diseases can be managed (HEAV management), and how do these typically get approached?

1. Host management (culling, separation/isolation, etc.)

2. Manage environment (spray for mosquitos, disperse water sources)

3. Vaccinate (dispersing bait on landscape to immunize)

4. Agent management (limit lead bullets, spread sterile flies)

Usually happen in an integrated approach

What are the 3 overlapping factors of one health?

Humans, wildlife, environment

Constraints (3)

Competition, predation, disease

Total Census count and how to achieve it

Count of all of the animals in a population

• can be done with animals that move in a clumped pattern

Index count of a population and how to achieve it? What are the benefits?

Using an indirect variable to reflect population numbers (tracks, scat, etc)

Benefits: useful to make comparisons overtime and can be done at a low cost

Sampling count of a population and how to achieve it

Sampling areas to get the average population number within a bigger, total area.

Ex. the count of plants in a quadrat, count of birds at a point, mussels along a strip, etc

Rules and considerations for sampling method to count populations

• spread counts out to prevent bias with overlap

Why is avoiding bias in a sampling population count not always possible? (3)

• error in counting technique (counting along roads)

• Lowered ability to detect animal (false positives/negatives)

• animal behavior (avoidance)

Accuracy

How close estimates are to the actual value

Precision

How close estimates are to each other

Bullseye

Best case scenario = accurate and precise

Accurate but not precise example

A good number of endangered species