Unit 1.4 Analyzing Interactions Among Species

Do species usually exist in isolation?

No, they interact directly or indirectly with other species around them

For what 2 reasons is it important for us to understand the interactions among species?

To save Earth’s diminishing biodiversity and to manage our natural resources

What are the 3 types of species-species interaction?

Predation, competition, and symbiosis

Can a change in a single population affect the entire hierarchy of living things in that system?

Yes

What are the 4 levels of organization in ecological systems?

Individuals, populations, communities, and ecosystems

Describe what a population is and how they interact

When individuals of the same species combine; Populations interact with each other and with individuals from other species that live in the same habitat

Define what a community is

When populations of different species interact in an area

Describe the boundaries involved in defining a community

Can be hard to define. Could be small patch of soil or 100km² forest

Define what an ecosystem is

When communities interact with each other and with other biotic (living) and abiotic (non-living) processes

Define habitat

Space in which individuals of a species carry out their daily lives

Can more than one species occupy the same habitat?

Yes

Can many species live together in the same habitat? How would this work?

Yes. Each species will use different aspects present for their own survival

Define ecological niche

How an organism uses its habitat and the resources within in

What is a helpful way to remember the difference between habitat and niche?

Habitat = address; niche = way of life

What 2 groups can “interactions between organisms in an ecosystem” be divided into?

Interactions between two organisms or two species; community-level interactions

Define competition. If it a + or - outcome?

When two or more organisms are using the same set of resources in the same area to the disadvantage of both; interaction results in a negative outcome for each organism

What are the 2 different observed kinds of competition?

Interspecific and intraspecific

Define interspecific competition

Competition between members of different species

Define intraspecific competition

Competition among members of the same species

What are the 2 main categories of competition?

Interference competition and exploitative competition

Define interference competition

When individuals are directly interacting over access to a resource

Give an example of interference competition

Lions fighting over a kill

Define exploitative competition

Indirect competition. When an organism uses up a resource that would have been used by another (even if they are never in the same place at the same time)

Give an example of exploitative competition

When a vulture eats a whole carcass before another organism could come to feed

In interspecific competition, what will happen between two populations if there’s not enough resources?

Population of the least successful species will decrease; even the successful one, however, will have difficulty reaching their max population growth rate

In the barnacle case study, if the barnacle that lived solely under tide level was removed, what happened to the barnacle that could live above or below the tide?

That barnacle took up all available space

In the barnacle case study, what happened to the barnacle that lived solely underwater if the barnacle that lived above or below was removed?

No change. The barnacle, even without competition, cannot adapt to live outside the water

In the barnacle case study, when living together, what would happen is the barnacle who could live above or below the tide level tried to take over more space below the water?

The barnacle who lived solely underwater would pry them off!

Define fundamental niche

Entire niche an organism is able to use

Define realized niche

Actual niche that an organism occupies (based on local competition)

In the barnacle case study, describe the fundamental and realized niche of the barnacle that could live above or below the tide

Fundamental niche was everywhere but the realized niche was smaller because of competition

In the barnacle case study, describe the fundamental and realized niche for the barnacle that could only live below the tide

They were the same! Only below tidal level

What is an important conclusion regarding fundamental and realized niche?

Most species are restricted to existing only in their realized niche because of actions of other species with which they share their habitat

What would happen if two species shared a habitat and their fundamental niches were identical?

One of them would probably go extinct

Sumarize Gause’s 1930s experiment

Observed populations of two closely-related species of protozoa first separately then together. When separated the population would stabilize at its carrying capacity and persist indefinitely. When together, one would out-compete the other and drive it to extinction

What was Gause’s conclusion in his protozoa experiment? What was the conclusion called?

That two similar population could never coexist; called “Gause’s Principle of Competitive Exclusion”

In nature, one species should alway out-compete another but many coexist. How?

Through sharing!

Define resource partitioning

How species share resources. Divide up resources. Each species will specialize in harvesting one particular subset of the resource

Give an example of resource partitioning

Lizards in the Caribbean. They all eat the same diet so they’ve learned to share the tree- each species taking over a certain part

Define predation

Occurs when a predator feeds on its prey causing the prey’s immediate death

What are the 2 techniques predators get their prey? Give an example of each

Active hunting (lion → zebra) and sit and wait until prey is within striking distance (spider)

How do prey animals not immediately go extinct?

They have had to evolve ways to protect themselves

Give an example of how hares have evolved to protect themselves from lynx’s

Evolved to be faster and outrun them. Those that could be fast would survive to breed and pass down the speedy gene

Can predator-prey behaviour be seen with plants? Give an example

Yes. A deer eating young tree seedlings

What are the 3 types of predator defence?

Morphological, chemical, and protective colouration

What is morphological defence? Give an animal example

Involves the shape/structure of an organism like thorns, spines, hard outer shell; turtles or porcupines

What is a chemical defence? Give an example

A chemical compound produces to kill or turn away predators; skunks; even plants produce a chemical that can be toxic or fatal to predators

What are the 2 types of protective colouration?

Cryptic colouration and aposematic colouration

Define cryptic colouration

Camouflage! Used to hiding from predators, often seen in insects

Define aposematic colouration

Used to warn predators they are not good to eat. Instead of blending in, they have bright dramatic colours to ward off predators

Define symbiosis

Where two species live closely together and interact in ways that benefit one or both

What are the 3 main forms of symbiosis?

Mutualism, commensalism, and parasitism

Define mutualism. Give an example in nature and with humans

When both species benefit! Pollinators get nectar from a flower and transport pollen on their bodies to other flowers thus spreading their genes; gut bacteria in humans helps us digest food and they have a continuous supply of nutrients

Define commensalism and give an example

Where one species benefits and the other is unaffected. Sea anemones have stinging tentacles to paralyze prey but clownfish are immune. They will live inside anemones for protection and will feed off food remnants from the anemones meals

Define parasitism

Where one species benefits and the other is harmed

What are the 3 aspects to consider when defining parasitism?

Size of the parasite to the host, whether the parasites live inside or outside the host, and whether the parasites “parasitize” (infest, exploit) the behaviour of the host

Define microparasite and give an example

Parasites the are microscopic in size; plasmodium is a microparasite that causes malaria in humans

Define macroparasite and give an example

Parasites that are visible to the naked eye; can live inside the host (tapeworm) or outside (lice)

Define social parasitism and give an example

Where the parasite manipulates the social behaviour of the host; “brood parasitism” is where a bird will swap their eggs for another birds eggs, kill those eggs, and have the other bird incubate and feed their young

What are 2 ways to rank/classify community-level interactions into?

Trophic levels and food webs

Define trophic levels

Food chain. Species are grouped into energy-flow hierarchies based on what they eat

Define food web

The connections among species in a community analyzed as a network

In a food web, what could happen if one species has a dramatic population change?

Could have a ripple affect on many of the other species in the web

How are the 4 categories of a food web classified into? Give an example in a pond

Producers (algae), primary consumers (herbivorous fish), secondary consumers (carnivorous fish), and tertiary consumers (predatory birds like the blue heron)

Describe what happened to the Atlantic Cod Fishery

In 1497 there was an abundance of fish that were sustainably sourced for hundreds of years. Them modern tech meant they could be fished in bulk. Nets dragged across the ocean floor destroyed their breeding ground. Cod population decimated. Example of human overconsumption. After the fishing was stopped the population was expected to rise but didn’t. May never recover due to irreversible changes to the food chain (ex: small fish cod used to eat became top predator who now eat cod’s young)

Describe the different elements of the niche of a wolf

Includes what it eats, the way it reproduces, and other factors that describe its pattern of living

Describe the different elements of the niche of a squirrel

Includes the types of trees it likes to nest in, the seeds it eats, time of day it likes to be active

What is the scientific name for parasites who live on the outside and on the inside?

Outside is ectoparasites; inside is endoparasites