Community Ecology

• Assemblage: taxonomic group in an area

• Guild: functionally similar group

• Trophic level – Producer, consumer (1’, 2’,3’) omnivore

• Community: group of interacting species

• Ecosystem

Food web vs. Interaction web vs. Networks

Community Structure

• Species richness

• Evenness

– Rank abundance

• Diversity

– Species diversity

• Shannon index

– Taxonomic Diversity

s

i

ii ppH1

ln

Scale and Diversity

• α: within a habitat

• Β: among habitats

• gamma:across a region

Trophic Cascades

• Indirect versus direct effects

• Trophic cascades

Ecosystem Engineers

Keystone Species

Invasive Species • Endemic , Native

• Exotic, Introduced

• Invasive

• Biotic Resistance Hypothesis

• Disturbance

• Often lack predators, disease

Change in Communities

• Abiotic conditions are always changing

• Evolution happens (as it must)

• Communities are constantly changing

• Succession – Short-term changes after a disturbance

– Pioneer species -> old growth

– Species that grow fast, high dispersal, low shade tolerance

– Slow growers, low dispersal, high shade tolerance

• Species rich communities tend to recover from disturbances faster than species poor communities

Is Biodiversity Good For You

• $ – Homes with more diversity (trees and shrubs) are worth

more

– Homes with larger trees shading property pay less in heating and cooling

• Health – Homes surrounded by greater biodiversity are healthier

• Psychological

• Dilution Effect – Lyme’s Disease, West Nile virus

– Competent species mixed with incompetent species

– Species poor communities tend to be filled with competent species

Dilution Effect

Figure 2. The Lyme disease (LD) transmission cycle, according to three perspectives on how ecosystem disturbance alters the risk of LD. Circles and/or tick images represent tick stages (A, adult; L, larva; and N, nymph). Squares represent hosts (D, deer; H, humans; C, competent hosts; and N, noncompetent hosts). The size of a shape and/or image suggests abundance. Shading represents the proportion of hosts infected with Borrelia burgdorferi. Some parts of the life cycle are simplified. In particular, other large mammals besides deer can be hosts for adult ticks and nymphs will also feed on large mammals. Image of hiker reproduced, with permission, from Tracey Saxby, Integration and Application Network, University of Maryland Center for Environmental Science (ian.umces.edu/imagelibrary).

Figure 1. Path diagrams for three perspectives on how ecosystem disturbance alters the risk of Lyme disease (LD): (a)the traditional perspective, (b) the dilution effect perspective, and (c) the synthetic perspective. In all cases, risk to human health is best measured as the density of infected questing vectors (which is the product of nymphal tick infection prevalence and nymphal tick density). This is important to emphasize, because studies sometimes equate either tick density or prevalence with human disease risk, when it is instead their product that best predicts risk. For each path (i.e., arrow), the sign indicates whether the relationship between two variables is negative, positive, or either. To assess the overall indirect effect of increasing forestation and/or biodiversity on the density of infected vectors, signs along each compound path (i.e., all paths within a particular pathway between the two endpoints) are multiplied.

WOOD, C. L., and K. D. LAFFERTY. Biodiversity and disease: a synthesis of ecological perspectives on Lyme disease transmission. Trends in Ecology & Evolution.

What is conservation biology?

• Micheal Soulé: Science of scarcity – Endangered species

– Endangered populations

– Genetic diversity

– Endangered habitats (communities)‏

– Endangered ecosystem services • Pollination

• Flood protection

• Carbon sequestration

– Enhanced global warming/pollution

What is conservation biology

Basic or Theoretical

Ecology

Conservation Biology

Application

New Knowledge

Basic or Theoretical

Ecology

Conservation Biology

Application

New Knowledge

Before

Now

What is conservation biology?

Genetics- Evolution

Sociology/Economics

Ecology- Population Biology

Ethics

Example

Why even give a

• Value of nature – Utilitarian

• Nature only has value if useful

– Intrinsic • Nature has its own value

• Judeo-Christian Perspective – Utilitarian

• Traditional and majority view

– Intrinsic • Stewardship

Conservation Ethics

• Transcendental Ethic – Humans need wild places

– “good for the soul”

• Resource Conservation – Nature can “do it all”

– Provide natural resources, outdoor sports, place to hang

• Evolutionary-Ecological Ethic – Nature is a functioning whole

– Aldo Leopold

What conservation biology is not

• Total preservation

• Animal rights, tree-hugging

• Game management

Current Hot Issues

• Invasive Species

• Anthopogenic Global Warming

• Sustainability

• Urban Sprawl

• Pollution (pharmaceuticals, flame retardants) – Hg, PCB’s

• Ecosystem services

• Fragmentation

Introduction to Animal Behavior