Living Together – Challenges and Opportunities

According to the discussion on pages 160-162 which of the following words best characterizes how often predators capture their prey-- frequently, some of the time, infrequently?

• Some of the time

Does this surprise you and why?

• NO

For equilibrium in the ecosystem, the predator must not always capture its prey. On the other hand, the predator has to feed itself and must find a way of capturing its prey.

1. a) What is size-selective predation?

This a technique of predation used by the carnivores predators to exclude large food items by favoring the presence of suboptimal prey populations.

1. b) Give the specific examples that the text records that show how the puma demonstrates this principle.

Male and female pumas selected different distributions of prey and pumas exhibited prey selection at both the individual and population level. Three of 9 pumas exhibited selection when we compared individual prey use to prey availability within individual pumas’ home ranges. One puma selected endangered huemul (Hippocamelus bisulcus) and 2 selected sheep. Go outside and look around you at the animals or plants that you see as part of your life. Direct observation is required. (If you don’t see many plants or animals go where you can observe some.)  Choose three different creatures (One may be a pet; the other two should be “wild.”)  And describe the defenses each uses against its potential predators.

• Chameleon

Defends itself by camouflaging

• Monarch Butterfly

The butterfly sucks the juices from milkweed plant as it eats its leaves. These juices are stored in the caterpillar and are toxic to some of its predators, giving it chemical defense.

• Rabbits

Rabbits hide in crevices large enough for them to fit in, that other predators may not fit in. List three different kinds of chemicals that plants use for defense.

• Poison ivy secretions serve as an irritant which discourages any contact with the plant. The oleo resin is non-volatile but affects the skin of the herbivorous severely.
• Butter cups in a pasture can so strongly inflame the mucous membranes of grazing cattle that the cattle will curtail their feeding on the good grasses that are all around.
• Juices of the milkweed plant as it eats its leaves. These juices are stored in the caterpillar and are toxic to some of its predators giving it a chemical defense.

List 3 different kinds of refuges named in the text

• Temporal Refuge

This kind of refuge involves the animal hiding, staying silent or changing of color until the predator passes away.

• Physical Refuge

This is a defense mechanism that incorporates the use of speed and strength or the power of numbers to conquer the predator. Animals like buffaloes use the power of numbers to fight against the lions and cheetahs. They also possess a lot of strength and power within their horns which they use to defend themselves.

• Chemical Refuge

Some species use the chemicals to dismay their predators. The monarch butterfly uses the oleo resin to kill its predators while the snake has a poisonous liquid it releases to kill its predator with a single bite.

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