An Introduction to Ecology and the Biosphere Chapter 50 An Introduction to Ecology and the Biosphere

Overview: The Scope of Ecology Ecology is the scientific study of the interactions between organisms and the environment These interactions determine distribution of organisms and their abundance Ecology reveals the richness of the biosphere

Concept 50.1: Ecology is the study of interactions between organisms and the environment Ecology has a long history as a descriptive science It is also a rigorous experimental science

Ecology and Evolutionary Biology Events that occur in ecological time affect life on the scale of evolutionary time

Organisms and the Environment The environment of any organism includes: Abiotic, or nonliving, components Biotic, or living, components All the organisms that are part of the individual’s environment are collectively called the biota Environmental components affect the distribution and abundance of organisms

LE 50-2 Kangaroos/km2 > 20 10–20 5–10 1–5 0.1–1 < 0.1 Limits of distribution Tasmania

Ecologists use observations and experiments to test explanations for the distribution and abundance of species

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

LE 50-3a Organismal ecology

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

LE 50-3b Population ecology

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

LE 50-3c Community ecology

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

LE 50-3d Ecosystem ecology

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

LE 50-3e Landscape ecology

The biosphere is the global ecosystem, the sum of all the planet’s ecosystems

Ecology and Environmental Issues 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 It states that humans need to be concerned with how their actions affect the environment

Concept 50.2: Interactions between organisms and the environment limit the distribution of species Ecologists have long recognized global and regional patterns of distribution of organisms within the biosphere Many naturalists began to identify broad patterns of distribution by naming biogeographic realms

LE 50-5 Palearctic Nearctic Tropic of Cancer (23.5°N) Oriental Ethiopian Equator Neotropical (23.5°S) Tropic of Capricorn Australian

Biogeography is a good starting point for understanding what limits geographic distribution of species

LE 50-6 Species absent because Yes Area inaccessible or insufficient time Yes Dispersal limits distribution? Habitat selection Yes Predation, parasitism, competition, disease Behavior limits distribution? Chemical factors No Biotic factors (other species) limit distribution? Water Oxygen Salinity pH Soil nutrients, etc. No Abiotic factors limit distribution? No Temperature Light Soil structure Fire Moisture, etc. Physical factors

Dispersal and Distribution 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

Natural Range Expansions Natural range expansions show the influence of dispersal on distribution

LE 50-7 New areas occupied Year 1996 1989 1974

Species Transplants 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

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

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

August 1982 February 1983 August 1983 February 1984 LE 50-8 100 Sea urchin Both limpets and urchins removed 80 Only urchins removed 60 Seaweed cover (%) Limpet 40 Only limpets removed 20 Control (both urchins and limpets present) August 1982 February 1983 August 1983 February 1984

Abiotic Factors Abiotic factors affecting distribution of organisms: Temperature Water Sunlight Wind Rocks and soil

Temperature Environmental temperature is an important factor in distribution of organisms because of its effects on biological processes

Water 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 the animals that feed upon them: Physical structure pH Mineral composition

Climate Four major abiotic components of climate: temperature, water, 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

Global Climate Patterns Global climate patterns are determined largely by solar energy and the planet’s movement in space

Sunlight intensity plays a major part in determining the Earth’s climate patterns

LE 50-10a North Pole 60°N Low angle of incoming sunlight 30°N Tropic of Cancer Sunlight directly overhead at equinoxes 0° (equator) Tropic of Capricorn 30°S Low angle of incoming sunlight 60°S South Pole Atmosphere

Seasonal variations of light and temperature increase steadily toward the poles

LE 50-10b March equinox: Equator faces sun directly; neither pole tilts toward sun; all regions on Earth experience 12 hours of daylight and 12 hours of darkness. 60°N 30°N June solstice: Northern Hemisphere tilts toward sun; summer begins in Northern Hemisphere; winter begins in Southern Hemisphere. 0° (equator) 30°S December solstice: Northern Hemisphere tilts away from sun; winter begins in Northern Hemisphere; summer begins in Southern Hemisphere. Constant tilt of 23.5° September equinox: Equator faces sun directly; neither pole tilts toward sun; all regions on Earth experience 12 hours of daylight and 12 hours of darkness.

Global air circulation and wind patterns play major roles in determining climate patterns

LE 50-10c 60°N 30°N 0° (equator) 30°S 60°S Descending dry air absorbs moisture Descending dry air absorbs moisture 0° (equator) Ascending moist air releases moisture 30°S 60°S 30° 23.5° 0° 23.5° 30° Arid zone Tropics Arid zone

Arctic Circle 60°N Westerlies 30°N Northeast trades Doldrums 0° LE 50-10d Arctic Circle 60°N Westerlies 30°N Northeast trades Doldrums 0° (equator) Southeast trades 30°S Westerlies 60°S Antarctic Circle

Regional, Local, and Seasonal Effects on Climate Various features of the landscape contribute to local variations in climate Seasonal variation also influences climate

Bodies of Water Oceans and their currents and large lakes moderate the climate of nearby terrestrial environments

Mountains Mountains have a significant effect on The amount of sunlight reaching an area Local temperature Rainfall

Wind direction East Pacific Ocean Sierra Nevada Coast Range LE 50-12 Wind direction East Pacific Ocean Sierra Nevada Coast Range

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

LE 50-13 Winter Spring Autumn Thermocline Summer O2 (mg/L) O2 (mg/L) 4 4 8 12 4 8 12 Lake depth (m) Lake depth (m) 8 8 16 16 0° 4° 2° 4° 24 4° 4° 24 4° 4° 4° 4° 4°C 4°C O2 concentration High (>8 mg/L) Medium (4–8 mg/L) Low (<4 mg/L) O2 (mg/L) O2 (mg/L) 4 8 12 4 8 12 Lake depth (m) Lake depth (m) 8 4° 22° 8 4° 20° 4° 18° 16 4° 8° 4° 6° 16 5° 24 4°C 4°C 24 Autumn Thermocline Summer

Microclimate Microclimate is determined by fine-scale differences in abiotic factors

Long-Term Climate Change One way to predict future global climate change is to study previous changes

Current range Predicted range Overlap 4.5°C warming over LE 50-14 Current range Predicted range Overlap 4.5°C warming over next century 6.5°C warming over next century

Concept 50.3: 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’s surface and have an enormous impact on the biosphere

LE 50-15 30°N Tropic of Cancer Equator Continental shelf Tropic of Capricorn 30°S Key Lakes Rivers Estuaries Abyssal zone (below oceanic pelagic zone) Coral reefs Oceanic pelagic zone Intertidal zone

Many aquatic biomes are stratified into zones or layers defined by light penetration, temperature, and depth

Littoral zone Limnetic zone Photic zone Pelagic zone Benthic zone LE 50-16a Littoral zone Limnetic zone Photic zone Pelagic zone Benthic zone Aphotic zone Zonation in a lake

(deepest regions of ocean floor) LE 50-16b Intertidal zone Neritic zone Oceanic zone Photic zone 200 m Continental shelf Pelagic zone Benthic zone Aphotic zone 2,500–6,000 m Abyssal zone (deepest regions of ocean floor) Marine zonation

Major aquatic biomes: Lakes Wetlands Streams and rivers Estuaries Intertidal zones Oceanic pelagic biome Coral reefs Marine benthic zone

Video: Clownfish and Anemone Video: Coral Reef Video: Flapping Geese Video: Hydrothermal Vent Video: Shark Eating a Seal Video: Tubeworms

Concept 50.4: Climate largely determines the distribution and structure of terrestrial biomes Climate is very important in determining why terrestrial biomes are found in certain areas

Climate and Terrestrial Biomes Climate has a great impact on the distribution of organisms, as seen on a climograph

Annual mean temperature (°C) LE 50-18 Desert Temperate grassland Tropical forest 30 Temperate broadleaf forest 15 Annual mean temperature (°C) Coniferous forest Arctic and alpine tundra –15 100 200 300 400 Annual mean precipitation (cm)

LE 50-19 30°N Tropic of Cancer Equator Tropic of Capricorn 30°S Chaparral Key Tundra Temperate grassland High mountains Tropical forest Temperate broadleaf forest Polar ice Savanna Coniferous forest Desert

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, called an ecotone, may be wide or narrow

Major terrestrial biomes: Tropical forest Desert Savanna Chaparral Temperate grassland Coniferous forest Temperate broadleaf forest Tundra

Video: Swans Taking Flight