Mimicry Is An Outcome of Predator-Prey Interactions

If a potential prey species develops an effective defense system, other unprotected prey species may come to mimic the protected species.

This is Batsian mimicry.

One (of many) examples of Batsian mimicry: the stinging yellow jacket and its harmless mimic, the clearwing moth.

Batsian Mimicry

Disturbed hawkmoth larva. Snake

If a group of potential prey species develops an effective defense, the different species may coevolve to resemble one other.

This is Mullerian mimicry.

One example of Mullerian mimicry: the stinging yellow jacket and the stinging cicada-killer wasp – both are noxious.

Mimicry Is An Outcome of Predator-Prey Interactions

Mullerian Mimicry

Two noxious species of South American butterfly.

Mutualism

Mutualism occurs when species interact in a mutually beneficial manner.

The oxpecker gets food (ticks and insects disturbed in the grass) and a safe haven from the rhinoceros, and the rhinoceros has parasites (ticks) removed.

Mutualism

Mycorrhizal fungi (threads) covering aspen roots: fungi aid in water and nutrient absorption by the aspen and the aspen provides sugars and other food molecules to the fungi.

Ecological succession is the set of changes in community composition that occur over time in a new or disturbed community.

Succession at Mt. St. Helens.

Ecological Succession

Succession after the Yellowstone fires.

Retreating Glaciers at Glacier Bay Alaska Make It a Natural Laboratory for Studying Primary Succession

Primary succession occurs when organisms colonize a barren environment.

Primary Succession at Glacier Bay, Alaska

A climax community is the stable community at the final stage of succession.

Succession

Succession shows some general trends that include:

1) Biomass increase over time.

2) An increase in the number and proportion of longer-lived species.

3) Increased species diversity.

Succession on Mt. St. Helens – another site of intense study.

Biodiversity

There are many measures of biodiversity.

Considering species diversity, more diverse communities tend to be more productive.

The role of diversity in community stability is less clear.

Biodiversity

Remember, however, that this is one set of communities.

Why Worry About the Relationship Between Biodiversity and Community Stability?

Because this understanding is essential for knowing how many species and of what types can be lost before a community collapses.

Biodiversity Varies Naturally

There is a trend towards more species in warmer, wetter areas and fewer in colder and drier areas.

Numbers of bird species occupying areas of North America.