Ecology Exam 3

G.F. Gause

Prey predator experiments

• did it with microscopic organisms

Prey-Predator population relation

Prey populations increase which then causes predator populations to increase, which causes the prey population to decrease and then the predator population decreases. This pattern continues over and over.

American Dog tick

has lots of ornamentation on the back (marbled)

• contract rocky mountain spotted fever

Blacklegged Deer tick

No ornamentation

• contract lyme disease

Lone Star tick

ornamentation- one white spot

• STARI disease

STARI

Southern tick association rash illness

Rocky Mountain Spotted Fever

disease contracted from ticks

• often not directed towards humans but can become infected

• Dogs are susceptible

Lyme disease

“bullseye rash“

Reasons for increase in lyme disease

• increase of deer and tick populations

• greater recognition of the disease

• more wooded residences

Tick Control strategies

• barrier between lawn and yard- could just be a path

• trimmed shrubs

• feeding station for deer with paint rollers laced with tick insecticide (permethrin)

• wearing bug spray

• cover skin

Mosquito dimorphism

Males have large plumose antennae. Females have normal antennae

Mosquito feeding time

crepuscular

• Females feed at dusk

Mosquito-borne diseases

• Filariasis (elephantitis)

• Yellow Fever

• Dengue

• Encephalitis

• Rift Valley fever

• Heart worm

• Equine Encephalitis

• LAC (La Crosse encephalitis)

• SLE (Saint louis encephalitis)

• WNV (west nile virus)

Culex Pipiens

common house mosquito

Aedes Triseriatus

Mosquito with black and white spots. often problematic with vectors

Functional Response

The relationship between per capita rate of consumption and the number of prey

• The number of prey consumed/predator/unit of time

• ex. 4 mice/black rat snake/month

Numerical Response

The rate of reproduction of a predator in response to the availability of prey

Stages of Predation

• search time

• Handling time (chase time —> capture time —> consumption time)

Type I Functional Response

Type of predator-prey interaction in which the number of prey captured by a predator per unit time increases linearly with increasing number of prey

• Common with passive predators such as filter predators

• ex. the greater volume of water they filter the greater the number of prey they consume

Type II Functional Response

Type of predator-prey interaction in which the number of prey captured by a predator per unit time increases in a decelerating pattern, reaching a maximum at some high prey population size

• most common

• Produces a graph with an asymptote (upper limit) because handling time to consume captured prey places a limit on how many prey a predator can kill and consume in a given time

Type III Functional Response

Type of predator-prey interaction similar to type II response except the rate of prey consumption is initially low but increases as the rate of predation approaches the maximum

• produces an S-shaped curve

• available cover in which prey can hide

• search image of the predator

• availability of alternative food sources

Search Image

A method of recognizing a species as a potential food item

Switching

The action of a predator abandoning normal prey, when scarce, in favor of a more abundant prey

Aggregative response

Tendency of predators to aggregate in areas of high prey density

• salmon spawn

Optimal Foraging Theory

The idea that individuals will seek to maximize their efficiency of energy intake per unit of effort

• ex. balance between time and energy spent looking for food vs. energy value of food

Predation

The consumption of one living organism by another

Planktivore

Aquatic herbivores that feed on phytoplankton

Predator Defenses

The range of adaptations that enable prey to avoid being detected, selected, and/or captured by predators

Chemical Defense

A defense system against predators involving the use of chemicals

• a warning signal to other members of the species

• as an irritant to repel the predator

Cryptic coloration

A defense system using color patterns that enable an organism to blend into the surroundings

Object Resemblance

A defense system that enables an organism to closely resemble another object

Flashing Coloration

A defense system that equips an organism to flash highly visible warning colors and/or patterns

• distract or scare off predators

• warn other member of the species

• ex. red winged blackbird

Aposematism

A defense system that equips organisms with bright, bold coloring to warn predators

• often used in association with chemical defense

• warning coloration

• ex. skunks

Batesian Mimicry

A type of defense in which an organism possesses the same coloration and pattern as a toxic species

• looking like monarch butterfly

• intentional

Mullerian mimicry

A type of defense in which several species that use chemical defense possess the same coloration and pattern

• yellow and black stripes on insects

• coincidence

Protective Armor

A type of defense that equips an organism with a protective hardened or spiny coat/shell

Behavioral defenses

A type of defense in which organisms alter their behavior to avoid detection, flee from predators, or gather for safety in numbers

Constitutive Defenses

Permanent defense systems that are fixed features of an organism

• turtle shell

Structural defenses

Plant Defense system using physical features of the organism to deter predators

Secondary Compounds

Plant compounds produced exclusively for defense, rather than for basic metabolism

Quantitative inhibitors

Secondary compounds produced in large quantities to deter predators

• tannic acid

Qualitative inhibitors

Secondary compounds produced by plants in small but toxic doses

Constitutive plant defenses

A fixed feature of the organism

• spikes

Active plant defenses

initiated by an attacking herbivore

• resin release to damage