Notes 8.2

Section 2 – How Species Interact with Each Other

An Organism’s Niche

What is a niche?

• The unique role of a species within an ecosystem

What does a niche include?

• Species physical home, the environmental factors necessary for the species’ survival,  and all of the species’ interactions with other organisms

What is a habitat?

• An organism’s location

How is a niche related to habitat?

• Niche is a pattern of use of an organism’s habitat

What niche of large grazing herbivore is similar in which two species?

• American bison and kangaroo – large grazing herbivore

Ways in Which Species Interact

How are interactions between species categorized?

• At the level where one population interacts with another

What are the 5 major types of interactions?

• Competition, predation, parasitism, mutualism, commensalism

What are the categories of interactions based on?

• Whether each species causes benefit or harm to the other species

Competition

What is competition and what is its result?

• Relationship in which different individuals or populations attempt to use the same limited resource – each individual has less access to resources and so is harmed by the competition

How can competition occur?

• Within and between species

How do members of the same species compete?

• Require same resources – same niche

What is called when two species compete?

• overlap

Indirect Competition

Explain how species can compete even if they never come into direct contact with each other?

• If two species use the same resource, but at different times of the day

Adaptations to Competition

What is one of the ways competition can be reduced between species?

• Dividing up the niche in time or space

What is niche restriction and when is it observed?

• When each species uses less of the niche than they are capable of using, in closely related species that use the same resources within a habitat

Explain how the barnacles use niche restriction?

• Two species of barnacles divide space.  One (C. stellus) is found in upper level of intertidal zone and other in deeper (S. balanoides).  When deeper one is not present the upper level one (C. stellus) will occupy all levels

Predation

What is a predator?

• An organism that feeds on another organism

What is prey?

• The organism that is fed upon

In complex food webs what may happen to predators?

• They may become prey

What have most organisms evolved against predators?

• Mechanisms to avoid or defend against predators

Explain how the Canadian lynx and the snowshoe hare are linked?

• Lynx feeds mainly on hares and so its population shows linked patterns – as one goes up so goes the other and vice versa

Case Study – Predator Prey Adaptations

Since most organisms are vulnerable to predation, what is there pressure for?

• Adaptations that serve as defenses against predators

What is camouflage?

• Disguise so that organisms are hard to see even when they are in view

What were the examples of camouflage?

• Black stripes across the eyes, dark bands of color

What animals wait for their prey and how are they camouflaged?

• Praying mantises and frogs – so prey does not notice them waiting to attack

What often contain toxic chemicals?

• plants

What do animals with toxic defenses usually have?

• Striking coloration

Which predators does warning coloration work well against?

• Ones that can learn and that have good vision

What is mimicry and its advantage?

• When one species resembles another – the more individual organisms that have the same pattern, the less chance of any one organism being killed.  Predator also learn to avoid all animals with similar warning patterns

What is a simple defense against predators and give examples?

• Protective covering, quills of porcupine, spines of cactus, shell of turtle

Parasitism

What is a parasite?

• An organism that lives in or on another organism and feeds on the other organism

What is a host?

• The organism the parasite takes its nourishment from

What is parasitism?

• The relationship between the parasite and its host

What are examples of parasites?

• Ticks, fleas, tapeworms, heartworms, bloodsucking leeches, and mistletoe

Why do parasites usually not kill its host?

• Have an evolutionary advantage if they do not

What may happen to the host because of the parasite?

• Weakened or exposed to disease

Mutualism

What is mutualism?

• A close relationship between two species in which each species provides a benefit to the other

What do mutualistic bacteria in you intestine do for you?

• Help break down food you could not digest, produce vitamins your body could not

What do you do for them?

• Warm, food-rich habitat

How are the acacia trees and the ants mutualistic?

• Trees provide ants shelter and food , ants defend the trees against herbivores and other threats

Commensalism

What is commensalism?

• Relationship in which one species benefits and the other species is neither harmed nor helped

How are remoras and sharks commensalistic?

• Remoras attach to sharks and feed on scraps or food left over from shark’s meals

How are birds nest in trees commensalistic and how could it possibly not be?

• If birds do not cause harm to trees – might cause damage to tree

Symbiosis and Coevolution

What is symbiosis?

• A relationship in which two organisms live in close association

Why do organisms coevolve?

• To reduce the harm or improve the benefit of the relationship