An Introduction To Ecology And The

Ecology and Evolutionary Biology „

Chapter 50

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An Introduction to Ecology and the Biosphere

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Organisms and the Environment

The Scope of Ecology „

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Ecology is the scientific study of the interactions interactions determine distribution of organisms and their abundance Ecology reveals the richness of the biosphere between organisms and the environment – Early science was basically ecology – New methods and computers have made ecology one of the more rigorous and robust sciences

Events that occur in ecological time affect life on the scale of evolutionary time The environment is constantly weeding out less fit individuals As the environment changes, so do the populations of organisms

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The environment of any organism includes: – Abiotic, or nonliving, components – Biotic, or living, components

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All the organisms that are part of the individual’ individual’s environment are collectively called the biota Environmental components affect the distribution and abundance of organisms

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Subfields of Ecology „

Organismal ecology studies how an organism’ organism’s structure, physiology, and (for animals) behavior meet environmental challenges

Community Ecology „

Community ecology deals with the whole array of interacting species in a community

Population Ecology

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Population ecology focuses on factors affecting how many individuals of a species live in an area

Ecosystem Ecology „

Ecosystem ecology emphasizes energy flow and chemical cycling among the various biotic and abiotic components

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Landscape Ecology

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Landscape ecology deals with arrays of ecosystems and how they are arranged in a geographic region

Ecology and Environmental Issues „

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Interactions between organisms and the environment determine the distribution of species „

Ecologists have long recognized global and regional patterns of distribution of organisms within the biosphere – Biogeographic realms - Biogeography

Flowchart of Factors limiting geographic distribution

Ecology provides the scientific understanding underlying environmental issues Rachel Carson is credited with starting the modern environmental movement Most ecologists follow the precautionary principle regarding environmental issues

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Species Transplants

Dispersal and Distribution

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Dispersal is movement of individuals away from centers of high population density or from their area of origin Dispersal contributes to global distribution of organisms If a species is absent from an area Æ Why?

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Species transplants include organisms that are intentionally or accidentally relocated from their original distribution Species transplants can disrupt the communities or ecosystems to which they have been introduced

Natural Range Expansions „

Natural range expansions show the influence of dispersal on distribution – Cattle Egrets – BrownBrown-headed Cowbirds

Behavior and Habitat Selection „

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Some organisms do not occupy all of their potential range Species distribution may be limited by habitat selection behavior

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Biotic Factors „

Biotic factors that affect the distribution of organisms may include: – Interactions with other species – Predation – Competition

Abiotic Factors

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Climate

Abiotic factors affecting distribution of organisms:

– Temperature affects biological processes – Water availability in habitats is another important factor in species distribution – Sunlight „ Light intensity and quality affects photosynthesis „ Light is also important to development and behavior of organisms sensitive to photoperiod – Wind „ Wind amplifies effects of temperature by increasing heat loss from evaporation and convection „ Wind can change morphology of plants – Rocks and soil „ Many characteristics of soil limit distribution of plants and thus thus the animals that feed upon them: „ Physical structure „ pH „ Mineral composition

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Four major abiotic components of climate: temperature, temperature, water, water, sunlight, sunlight, and wind Climate is the prevailing weather in an area Macroclimate consists of patterns on the global, regional, and local level Microclimate consists of very fine patterns, such as those encountered by the community of organisms underneath a fallen log

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Global Climate Patterns „

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Global climate patterns are determined largely by solar energy and the planet’ planet’s movement in space Sunlight intensity is a major determinant for Earth’ Earth’s climate patterns Seasonal variations increase steadily toward the poles

Regional, Local, and Seasonal Effects on Climate „ „ „ „

Various features of the landscape contribute to local variations in climate Seasonal variation also influences climate Oceans and their currents and large lakes moderate the climate of nearby terrestrial environments Mountains have a significant effect on

Seasonality „

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The angle of the sun leads to many seasonal changes in local environments Lakes are sensitive to seasonal temperature change and experience seasonal turnover

LongLong-Term Climate Change „ „

One way to predict future global climate change is to study previous changes Beech trees migrate at 0.2 km/year – too slow to keep up with climate change – must move at 77-9 km/year

– The amount of sunlight reaching an area – Local temperature – Rainfall

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Abiotic and biotic factors influence the structure and dynamics of aquatic biomes „ „ „ „ „

Varying combinations of biotic and abiotic factors determine the nature of biomes Biomes are the major ecological associations that occupy broad geographic regions of land or water Aquatic biomes account for the largest part of the biosphere in terms of area They can contain fresh water or salt water Oceans cover about 75% of Earth’ Earth’s surface and have an enormous impact on the biosphere

Climate largely determines the distribution and structure of terrestrial biomes „

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Climate is very important in determining why terrestrial biomes are found in certain areas Climate has a great impact on the distribution of organisms, as seen on a climograph

LE 5050-19

Aquatic Zonation 30°N Tropic of Cancer Equator Tropic of Capricorn 30°S

Key Tropical forest Savanna Desert

Chaparral Temperate grassland Temperate broadleaf forest Coniferous forest

Tundra High mountains Polar ice

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Climagraph

Trop. Forest Desert Savanna

Chaparral

Grasslands Conifers

Deciduous Tundra

General Features of Terrestrial Biomes „ „ „ „ „

Terrestrial biomes are often named for major physical or climatic factors and for vegetation Stratification is a key feature of terrestrial biomes Terrestrial biomes usually grade into each other, without sharp boundaries The area of intergradation, intergradation, called an ecotone, ecotone, may be wide or narrow Major terrestrial biomes: – – – – – – – –

Tropical forest Desert Savanna Chaparral Temperate grassland Coniferous forest Temperate broadleaf forest Tundra

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