Species Interactions & Community Ecology

Environmental biology

Case Study Mussels & the Great Lakes

Border of US and Canada 5 giant lakes & a number of small ones These were formed by the last Ice Age More polluted in the past Took ‘Big Government’ intervention to clean up -

Clean Water act, 1970 Arrived by ship from Europe

Case Study cont… Within 2 years the mussels had established

themselves in all the Great Lakes Then spread even further to the great

Mississippi River Watershed - 40% of US land mass.

Their main limiters were absent here Predators Competitors Parasites

Case Study cont…….

IMPACT = Economic mostly

= industrial interference = infrastructure damage

= Ecological = Overeat the native phytoplankton = Kill local molluscs = Alter local ecology towards bottom dwellers

Permit more light penetration Deposit organic matter on bottom

Case Study cont…….

However, recently they are being replaced by another species

Quagga mussel is moving in It is reducing the zebra mussels What impact this new one shall have?

We will have to wait and see….

INVASION!!!!!

Look up and see. They are coming…

___________

What is ecology?

The study of how organisms interact with each other and their physical environment.

Species Interactions

Species interact with each other Many ways have been studied and

documented Some are beneficial to both species Other to one or the other And some to neither….

Species interaction types

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Intraspecific - within a species Example = _______________????

Interspecific - between species Example = _______________????

Solution is resource partitioning = basically sharing by adapting

There is a total negative effect on both!

Competition

Predation

One species kills the other to live Predator is the killer Prey is the victim

Example = _______________????

Drives evolution - Natural selection These interaction are direct and do

generally cycle…

Figure 5.2

Parasites

No immediate death involved Example = _______________????

Parasite depends on the host for food and shelter

The host is harmed to some degree! The parasite benefits entirely Co-evolution also works here

Herbivory

Animals feed on plants Insects on plants

Example = _______________????

Plant does not die (at least not initially) Plants defend themselves too

Example = _______________????

Evolutionary Arms Race!

Mutualists

Both are good for each other Provide other with something it needs

Example = _______________????

Symbiotic Example = _______________????

Pollination Example = _______________????

Ecological Communities

Each has its; Producers - make food Consumers -

Primary - grasshoppers Secondary - frogs Tertiary - birds

Decomposers - Nonliving organic consumers recyclers

Food chains & Energy

As one feeds on another, in a community, there is a relationship built - this is known as the food web.

As one moves further away from produces then amount of energy available is reduced (by 90% per level)

Energy Pyramid

Keystone Species

If you were to eliminate a single species from a community and see the effects of that action, one would notice:

Most have little impact One will devastate the ecosystem

This one species is the keystone species Example = _______________????

Ecological Succession

A new volcanic island will be populated by life in a predictable way; Primary succession - No life at beginning

Primary species = first Example = _______________????

Secondary succession - Some form of life or organic matter remains - and it starts with that.

WATCH ME!

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Biomes

What are they? Just regions of the planet with certain

similar communities of life. The Earth has 12 such regions

http://www.youtube.com/watch?v=ag5ATGEplbU

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Biomes…

In general, there is no sharp demarcation between biomes.

Life on Earth is a continuum based on moisture and heat…

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Other Biomes…

Also, there are aquatic biomes too… These are considered later in the

course