Day 22 December 2 Chapter 15

Dr. Amy B HollingsworthThe University of Akron

Fall 2014

15.9 Interacting species evolve together.

Natural Selection Causes organisms to become better adapted

to their environment

Does not distinguish between biotic and abiotic resources as selective forces

15.10. Each species’ role in a community is defined by its niche.

More than just a place for living, a niche is a complete way of living.

“You can’t always get what you want.”

Fundamental niche• the full range of environmental conditions under

which a species can live

Realized niche• where and how a species is actually living

15.11 Competition can be hard to see, but it still influences community structure.

Why is competition hard to see in nature?

The “ghost of competition past”

15.12 Predation produces adaptation in both predators and their prey.

Predation

One of the most important forces shaping the composition and abundance of species in a community

Why do exotic species often flourish when released into novel habitats, even though natural selection has not adapted them to this new environment?

Prey Adaptations for Reducing Predation

There are two broad categories of defenses against predators:

• Physical

• Behavioral

Physical Defenses

Include mechanical, chemical, warning coloration, and camouflage

mechanisms

1. Mechanical Defenses

2. Chemical Defenses

3. Warning Coloration

4. Camouflage

Behavioral defenses

Include both seemingly passive and active behaviors: hiding or escaping,

or alarm calling or fighting back

Predator adaptations for enhancing predation

Why don’t predators become so efficient at capturing prey that they drive the prey to extinction?

The “life-dinner hypothesis”

Parasite Predators

Parasites have some unique features and face some unusual challenges:• The parasite generally is much smaller than its host

and stays in contact with the host for extended periods of time.

• Complicated life cycles as means of getting from host to host.

Case 1: Parasites can induce foolish, fearless behavior in their hosts.

Toxoplasma

Rats and cats

Case 2: Parasites can induce inappropriate aggression in their hosts.

Case 3: Parasites can induce bizarre and risky behavior in their hosts.

The lancet fluke

15.14. Not all species interactions are negative: mutualism and commensalism.

15.15–15.16 Communities can change or remain stable over time.

15.15. Many communities change over time.

Secondary Succession

Much faster than primary succession• life and soil are already present

15.16. Some species are more important than others within a community.

Chapter 16: Conservation and Biodiversity

Human influences on the environmentLectures by Mark Manteuffel, St. Louis Community College

16.1–16.4 Measuring and defining biodiversity is complex.

16.1 Biodiversity benefits humans in many ways.

Consider also the following:

Vinblastine and vincristine

Ancrod

Epibatidine

16.2 Biodiversity is not easily defined.

16.3 Where is most biodiversity?

Why are there more species in an acre of tropical rain forest than in an acre farther from the equator, such as in a temperate forest or prairie?

Latitudinal Biodiversity Gradient