Ecology seeks to explain the distribution and abundance of organisms on earth

• Autecology (physiological ecology)

• Population ecology

• Community ecology

• Landscape ecology

• Ecosystems ecology

Ecology seeks to explain the distribution and abundance of organisms on earth

• Autecology (physiological ecology)

• Population ecology

• Community ecology

• Landscape ecology

• Ecosystems ecology

Ecology seeks to explain the distribution and abundance of organisms on earth

• Autecology (physiological ecology)

• Population ecology

• Community ecology

• Landscape ecology

• Ecosystems ecology

The scientific process

• Identification of patterns

• Development of explanations or hypotheses for these patterns

• Development of predictions from the hypotheses

• Testing of predictions with data

Identification of patterns

• Temperate edges tend to have more bird species that forest interior

• Tropical edges tend to have fewer bird species than forest interior

Development of explanations or hypotheses for these patterns

Development of predictions from the hypotheses

Testing of predictions with data

Issues with study

• Not many studies, particularly in tropical regions

• Investigators used a variety of distance classes and techniques to assess edge responses

Ecology seeks to explain the distribution and abundance of organisms on earth

• Autecology (physiological ecology)

• Population ecology

• Community ecology

• Landscape ecology

• Ecosystems ecology

Levels of organization in ecology

• Individual

• Population

• Metapopulation

• Species

• Assemblage

• Community

• Ecosystem

• Geographic range (distribution)—geographic area permanently occupied by a plant or animal taxon.

• A geographic range is not equivalent to a home range or a territory of an individual.

Ecological biogeography

• Organisms’ distributions are affected by their interactions with both their physical and biological environments

Physical environment and effects on distributions—the example of temperature

regulation• Endotherms vs. ectotherms or

homeotherms vs. poikilotherms

Implications of endothermy in birds and mammals

• Ability to inhabit a wide range of environments

• Higher food and oxygen demands

• Limits to lower body size

Other examples of physical environment influencing distributions

• Loblolly pine

• Sugar maples

• Starlings and Crested Mynahs

Comparative data

European Starling

Crested Mynah

Eggs laid 5.2 5.1

Eggs hatched 82% 58%

Young fledged 69% 38%

Cross-fostering experiment

Percentage hatching

Mynah eggs in European Starling nest 90%

Starling eggs in Mynah nest 62%

Heater experiment

Percentage hatching

Mynah eggs in heated nest boxes 92%

Mynah eggs in unheated nest boxes 64%

Biotic environment and effects on distributions

Competition, predation, mutualism and herbivory are

other biotic interactions that may affect organisms’ distributions

and abundances

• Competition may at times control ranges, as in the example of the doves on islands off New Guinea, although this is difficult to say definitively.

Predators do not generally limit the geographic ranges of their

prey, except in the case of exotic species

• Species with tight mutualistic relationships with other species may be confined to a specific geographic range because of the relationship—for example Acacia plants and their ant mutualists of the genus Pseudomyrmex.

• Most parasite species can live on only one host species, for example many lice live on only one species of birds. Hence, the geographic range of the parasite is strictly controlled by that of the host.

Ways in which humans (a biotic factor) influence the distribution and abundance of

disease parasites• High human density necessary for

measles to survive• Humans influence the density of host

organisms besides themselves--White-tailed deer, bacteria, ticks and Lyme’s disease

• Humans spread parasites from one continent to another

• Humans change the landscape

Ways in which humans (a biotic factor) influence the distribution and abundance of

disease parasites• High human density necessary for

measles to survive• Humans influence the density of host

organisms besides themselves--White-tailed deer, bacteria, ticks and Lyme’s disease

• Humans spread parasites from one continent to another

• Humans change the landscape

Ways in which humans (a biotic factor) influence the distribution and abundance of

disease parasites• High human density necessary for

measles to survive• Humans influence the density of host

organisms besides themselves--White-tailed deer, bacteria, ticks and Lyme’s disease

• Humans spread parasites from one continent to another

• Humans change the landscape

• Before European contact, the indigenous population of South America was between 4 and 10 million.

• 100 years after contact, the population was approximately 100,000.

• In many cases both physical and biotic environments of organisms will influence their distributions

• Ex. Barnacles, Balanus balanoides and Chthamalus stellatus, on the Scottish coast

Biogeographers consider how physical and biotic factors shape geographic ranges

within a historical perspective• Coffee example

• New Zealand birds

Biogeographers consider these concepts and data within a historical perspective

• Coffee example

• New Zealand birds