Exam 3 Ecology Flashcards
Explain the experiment by Brooks and Dodson
Predator-prey relationships. Predators can have significant effects on prey population dynamics. Size selective fish eliminate large- bodied zooplankton species. W/O Alosa, zooplankton length size is about 0.8 mm. With Alosa, zooplanton length size is about 0.3 mm.
Any interaction between individuals that enhances the fitness of one individual of a species and reduces the fitness of an exploited individual of another species.
Predators kill and consume other organisms
Parasites live on host tissue reducing the host's fitness, but do not generally kill the host.
Insect larva that consumes the host
Pathogens induce disease
Give the example of parasites that alter host behavior that deals with the spring-headed worm BUT give scientific name of spring-headed worm.
Spring-headed worm (Acanthocephalans) infects amphipods and changes their behavior in ways that make them more likely to be eaten by vertebrates. Example, infected amphipods swim towards light, which is usually indicative of shallow water, and thus closer to predators. (Bethel and Holmes 1977)
Explain the cycle of how Plagiorhynchus alters the host behavior
See predation and parasitism slide # 6
Janice Moore studied this parasite-host interaction. She ran an experiment in which she had a control group on uninfected terrestrial isopods and infected the other group with the parasite by feeding them carrot pieces covered in the plagiorhynchus eggs. The proportion of infected nestling was about twice the rate of infection predicted if starlings fed randomly on the terrestrial isopod population. These results supported Janice Moore's hypothesis that the altered behavior of infected terrestrial isopods increase the probability of being eaten by starlings.
TRUE or FALSE:
There are may similarities in the relationships between predators and prey, herbivores and plants, or parasites and their host. The same basic mathematical models work pretty well for all.
MAJOR DIFFERENCE: A predator kills and eats its prey (same as herbivore/ plant relationship). Does a parasite kill its host? Why or why not? Does it matter if it is an ectoparasite or endoparasite?
A parasite generally does not kill its host. The parasite lives on the tissue of the host, so the host needs to be alive to actually give the parasite and enhancement of fitness. It does matter if it is an ectoparasite or endoparasite. An endoparasite lives within the host, so if host dies the endoparasite dies. Ectoparasites could potentially move on to another host if originally host dies.
Give an example of parasitoid and plant coevolution
Caterpillar begins consuming plant leaf, the plant releases a volatile "green leaf" order that attracts parasitods. Parasitod in this case is a female wasp that stings the caterpillar. The caterpillar is then paralyzed and the wasp lays eggs on it. The larva emerge and feed on the caterpillar but not the leaf.
Explain the Lotka-Volterra model for predator/ prey (parasite/host) interaction. Give both the model for prey and predator. Explain what each variable is indicative of.
For prey (host): dN/dt= aN-bNP
For predator (parasite): dP/dt= cNP-dP
a= the per capita rate change of prey (parasite) w/o predators (parasites)
N= # of prey (host)
b= rate change of prey in response to prey and predator interaction
P= # of predators
c= rate change of predator in response to prey and predator interaction
d= per capita rate change of predator w/o prey
Explain the Gause and Predator-Prey Model. Draw the graph that indicated what happened.
Gause (1934- 1935) studied Paramecium (prey) and Didinium (predator). Paramecium and Didinium together, Didinium overate its food supply and then starved to death. See Predation and Parasitism slide 10 for graph.
**side, The Lotka-Volterra model assumes a closed system. Gause introduced new individuals at regular time intervals. Immigrations resulted in two complete predator-prey cycles.
Expalin the Huffaker experiment of predator prey cycling
Huffaker set out to test whether Gause's results could be reproduced in a situation in which the predator and prey are responsible for their own immigration and emigration among patches of suitable habitat. Huffaker set up a complex array of 120 oranges with numerous barriers of petroleum jelly and about 5% of the area of each orange exposed to attack by mites. Huffaker observed 3 oscillations that spanned about 6 months. They were maintained by the dispersal of predator and prey among oranges in a deadly game of hide and seek, in which the prey managed to keep ahead of the predator for three full oscillations. These results are similar to those obtained by Gause. Need to remember that huffaker (1958) did not directly manipulate dispersal.
What are the effects of prey density?
There is an increasing percent of consumption of prey at low to medium prey densities. However, at higher prey densities the the percentage of prey consumed declines with increased prey density. THINK- just too many baby bunnies to eat!
What is the most famous predator-prey cycle of all?
Snowshoe Hare- Lynx cycling. One of the best-studied cases of animal populations cycles. The population of cycles of these two species are especially well documented because of the Hudson Bay Company kept trapping records during most of the 18th, 19th and 20th century.
Drawing on this unique historical record, ecologists were able to estimate the relative abundance of Canadian lynx and snowshoe hare over a period of 200 years.
What if the prey had a place to hide? Explain what happened when Gause (1934) tried this experiment. Draw a graph that indicates the results from this experiment.
Gause (1934) added sediment providing a safe site for prey. Gause turned a homogeneous environment into a heterogeneous environment. Didinium ended up going extinct and Paramecium recovered. See predation and parasitism slide 15 for an example of how this graph looks.
Animal defenses against predators
What are chemical defenses and coloration defenses of animals?
Chemical defenses: poisons and stings
-Aposemtaic coloration (warning)EXAMPLE: poison arrow frog
individuals advertise their poisonous nature.
-Cryptic coloration EXAMPLE: leafy seadragon
camouglage (blending coloration)
Plant defenses against herbivores
Morphological: thorns, spines, etc.
Chemical: secondary chemical compounds
What is commensalism? Give an example.
commensalism is an interaction in which one individual of a species is benefited and the other individual of another species is neither harmed nor benefited. Example, Clown Fish and sea anemones. The clown fish is protected from many predators by the stinging cells of the anemone.
What is mutualism? Give an example.
Interaction in which both individuals of different species are benefited. Ants and acacias. Ants protect acacias from herbivores, while the ants get food (fungus grown by plants) and refuge.
What is predator swamping? Another term used to describe this? Draw a graph that gives an example of how this looks.
predator swamping is the synchronization of social groups that reduces predation risk (Darling effect). See predation and parasitism slide 23 for graph. Examples: cicadas, horseshoe crabs,
Give an example of extreme synchrony
periodical cicadas! Broods emerge in prime year intervals: 5 year cicada, 7 year cicada, 11 year cicadas
Info of periodical cicadas satiation from lecture slides
Periodical cicadas emerge as adults every 13-17 years.
densities approach 4x10^6 ind/ha
Williams estimated 1,063,000 cicadas emerge from 16 ha study site.
50% emerge from 4 consecutive nights
15% lose to birds
Explain the Williams predator satiation experiment
Williams (1993) tested predator satiation in Arkansas cicadas. An emergence trap and inverted emergence trap were both set up. Cicadas emerging from ground were caught by emergence trap and rates and cause of mortality estimated by inverted emergence trap. Wings in inverted emergence trap indicate bird predation. Whole cicadas indicate mortality due to other causes. patterns of mortality and predation rates relative to populations size support the predator satiation hypothesis. Estimated 1,063,000 cicadas emerged during 4 consecutive nights from the 16 ha study site. Predator satiation tactic was effective to reduce cicada lose to birds to only 15% of total population.
Is size a refuge?
Yes, if large individuals are ignored by predators, then large size may offer a form of refuge. Elephants are herbivores with few predators.
Describe what Peckarsky observed in concerns to size as a refuge.
Peckarsky (1980) observed mayflies making themselves look larger in the face of foraging stoneflies. By assuming a "scorpion" posture, mayflies may make themselves appear larger and reduce the probability of being attacked by stone flies.
*** IN TERMS OF OPTIMAL FORAGING THEORY, LARGE SIZE EQUATES TO LOWER PROFITABILITY***
What is "the ecology of fear?"
The presence of predators can alter the behavior of prey to avoid high-risk locations.
What did Ripple and Beschta observe in concerns to the ecology of fear?
Ripple and Beschta (2004) found that increasing wolf populations in Yellow Stone National Park have affected their prey distribution. Elk are more likely to be attacked by wolves in riparian areas and have greatly reduced their foraging in these habitats
Discuss the plant pathogen that mimics flowers (pg. 306 from textbook).
Puccinia (fungus) alters the life history of Arabis (mustard plant). Puccinia attacks the rosette stage and manipulates its development to produce a growth form that promotes reproduction by the fungus and usually kills the plant. Puccinia invades meristematic tissue. The pseudoflowers formed by the fungus attract pollinating insects. Arabis that survive attack by Puccinia may go on to flower but do not form seeds.
How did Moore's laboratory and field experiment complement each other?
Moore's field observation showed that the parasite was only infecting 1 percent of the terrestrial isopod but 40 percent of the sterlings were infected. She hypothesized that the parasite must be altering host behavior in becoming more available to sterlings. Infected a group of terrestrial isopods with carrots covered in eggs of the parasite. Combined the experimental and control group. Infected terrestrial isopods wandered to the open and went on light-colored substrates rather than dark ones. In a lab experiment, Janice Moore covered 10 infected terrestrial isopods with light sand and 10 uninfected isopods with dark sands. Captive sterling were more likely to eat the white sand covered isopods. This showed that the altering of behavior to be on light-colored substrates does increase predation by birds.
****ASK DR. BERRY ABOUT THESE THREE FUNCTIONAL RESPONSES OF PREDATORS**** Draw the effects of prey density for all three functional predator responses and the overall all three predators response. Explain all three types.
See slide 13 in predation and parasitism.
TYPE 1: Linear increase in consumption rate until satiation, then no change in consumption rate above satiation. In this case, satiation= predator does not need to or physically cannot eat at a higher rate.
TYPE 2: Consumption rate increase at a deceleration rate, gradually leveling off at a max rate.
Type 3: Sigmoid increase in consumption rate as prey density increase.