Chapter 52

1. Chapter 52 An Introduction to Ecology and the Biosphere

2. Overview: The Scope of Ecology • Ecology–the study of the interactions between organisms and the environment • These interactions determine distributionandabundance of organisms • Ecologists work at various levels, including: • Organismal Ecology • Population Ecology • Community Ecology • Ecosystem Ecology • Landscape Ecology • Global Ecology

3. Fig. 52-2 • Organismal • ecology • Population • ecology • Community • ecology • Ecosystem • ecology • Landscape • ecology • Global • ecology

4. Organismal ecology studies how an organism’s structure, physiology, and (for animals) behavior meet environmental challenges How do hammerhead sharks select a mate?

5. Population ecology focuses on factors affecting how many individuals of a species live in an area (A populationis a group of individuals of the same species living in an area) What environmental factors affect the reproductive rate of deer mice?

6. Community ecology deals with the whole array of interacting species in a community. (A communityis a group of populations of different species in an area) What factors influence the diversity of species that make up a forest?

7. Ecosystem ecology emphasizes energy flow and chemical cycling among the biotic and abiotic components. (An ecosystemis the community of organisms in an area and the physical factors with which they interact) What factors control photosynthetic productivity in a temperate grassland ecosystem?

8. Landscape ecology deals with arrays of ecosystems and how they are arranged in a geographic region. (A landscapeis a mosaic of connected ecosystems) To what extent do the trees lining a river serve as corridors of dispersal for animals?

9. Global ecology examines the influence of energy and materials on organisms across the biosphere. (The biosphereis the global ecosystem, the sum of all the planet’s ecosystems) How does ocean circulation affect the Global distribution of crustaceans?

10. Concept 52.1: Ecology integrates all areas of biological research and informs environmental decision making • Ecology is both a descriptive science (study observations in nature) and an experimental science (generate hypothesis, manipulate the environment and observe outcomes).

11. Fig. 52-3 • “Dry” • “Wet” • “Ambient” • Pipe • Trough • Illustrated is an ecology experiment conducted over a 10 yr. period. In it, • Scientists hypothesizedthat certain species of trees are susceptible to • drought than others. They manipulated the environmental conditions by • creating troughs that collect water from one area to mimic a drought and • send it to another area to make it more wet. The ambient area is the normal • rainfall. They then observedthe results.

12. Linking Ecology and Evolutionary Biology • Events that occur in ecological time affect life on the scale of evolutionary time • Ex: insect populations decrease after pesticide is used (ecological effect); insects develop resistance as a result of the pesticide forcing a change in the gene pool (evolutionary effect)

13. Concept 52.2: Interactions between organisms and the environment limit the distribution of species • Ecologists study the distribution of organisms. • They ask both wherespecies live and whydo they live there • Two factors that determine distribution are: biotic, or living factors, and abiotic, or nonliving factors

14. Fig. 52-5 • Kangaroos/km2 • What abiotic factors do you think contribute to • The distribution pattern of the Red Kangaroo? • Biotic factors? • 0–0.1 • 0.1–1 • 1–5 • 5–10 • 10–20 • Abiotic factors: Red Kangaroos are found in • semi-arid and arid regions of the • interior where precipitation is low and • variable from year to year. • Biotic factors: Could pathogens, parasites, • predators, competitors and food availability • also be factors? • > 20 • Limits of • distribution • Ecologists consider multiple factors when attempting to explain the distribution of species

15. Fig. 52-6 • Use the following flow chart to see how ecologists attempt • to explain the distribution of a species. • Why is species X absent • from an area? • Yes • Area inaccessible • or insufficient time • Yes • Habitat selection • Does dispersal • limit its • distribution? • Yes • Predation, parasitism, • competition, disease • Chemical • factors • Does behavior • limit its • distribution? • No • Do biotic factors • (other species) • limit its • distribution? • Water • Oxygen • Salinity • pH • Soil nutrients, etc. • No • Do abiotic factors • limit its • distribution? • No • Temperature • Light • Soil structure • Fire • Moisture, etc. • Physical • factors

16. Dispersal and Distribution • Dispersalis the actual movement of individuals away from centers of high population density or from their area of origin • Distribution is where the actually end up. i.e. where do we find them globally? • Physical barriers can impede dispersal • Organisms may not have had enough time to spread out.

17. Natural Range Expansions • Natural range expansions show the influence of dispersal on distribution • Observing the expansion of a natural range directly is rare because of the time factor. • Ecologists often use experimental methods to understand the role of dispersal in limiting distribution Current 1970 1966 1965 1960 1961 1943 1958 1937 1951 1956 1970

18. Species Transplants • Species transplants include organisms that are intentionally or accidentally relocated from their original distribution • They can be used to determine if the potentialrange of a species is larger than the actualrange. i.e. a species couldlive in a certain area where it currently does not. • Species transplants can disrupt the communities or ecosystems to which they have been introduced. Thus the use of this technique is often limited to observations of an accidental transplant.

19. Behavior and Habitat Selection • Some organisms do not occupy all of their potential range • Species distribution may be limited by habitat selection behavior • Ex: Female corn borer beetles only lay eggs on corn plants, even though the larva could eat other plants. (They are attracted by a scent)

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

21. Fig. 52-8 • RESULTS • 100 • Both limpets and urchins • removed • 80 • Sea urchin • Only urchins • removed • 60 • Seaweed cover (%) • Limpet • 40 • Only limpets removed • 20 • Control (both urchins • and limpets present) • 0 • August • 1982 • February • 1983 • August • 1983 • February • 1984

22. Abiotic Factors • Abiotic factors affecting distribution of organisms include: • Temperature: effects biological processes and therefore limits distribution. Ex: Cells freeze and rupture below 0oC; proteins denature above 45oC. Endotherms must expend energy in order to regulate temperature. • Water: availability of water limits where many organisms can live. Ex: Desert organisms have adaptations for water conservation. • Salinity: Aquatic organisms are usually restricted to either saltwater or freshwater. Few terrestrial organisms are adapted to high salinity habitats • Sunlight: Light intensity and quality affect photosynthesis. Plants compete with others for sunlight. Water absorbs light, thus most photosynthetic aquatic organisms live near the surface. In deserts, high light levels increase temperature and can stress plants and animals. • Rocks and Soil: Physical structure, pH and mineral composition of soil limit plant distribution and thus the animals that feed upon them

23. Climate • Climate—the long-term prevailing weather conditions in an area. This is the most significant influence on the distribution of organisms. • Abiotic components of climate that affect distribution of species: temperature, water, sunlight, and wind • Two scales of climate patterns: • Macroclimateconsists of patterns on the global, regional, and local level • Microclimateconsists of very fine patterns, such as those encountered by the community of organisms underneath a fallen log

24. 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 • Ex: More heat and light per unit of surface area reach the tropicsthan the high latitudes

25. Fig. 52-10b • 90ºN (North Pole) • 60ºN • Low angle of incoming sunlight • 30ºN • 23.5ºN (Tropic of • Cancer) • Sun directly overhead at equinoxes • 0º (equator) • 23.5ºS (Tropic of • Capricorn) • 30ºS • Low angle of incoming sunlight • 60ºS • 90ºS (South Pole) • Atmosphere

26. Seasonal variations of light and temperature increase steadily toward the poles • Tropics get the most solar radiation and the least variation due to the 23.5o tilt of the Earth on its axis.

27. Fig. 52-10c • 60ºN • 30ºN • March equinox: 12 hrs daylight and 12 hrs of • darkness all regions of Earth • 0º (equator) • June solstice • North: long days/short nights • South: short days/ long nights • 30ºS • December solstice • North: short days/long nights • South: Long days/short nights • Constant tilt • of 23.5º • September equinox • 12 hrs daylight/ 12 hrs darkness all • regions of Earth

28. Regional, Local, and Seasonal Effects on Climate • Proximity to bodies of water and topographic features such as mountain ranges contribute to local variations in climate • The Gulf Stream carries warm water from the equator to the North Atlantic

29. Fig. 52-11 • Labrador • current • Gulf • stream • Equator • water • Warm • Cold water • The great ocean conveyor belt. Water is warmed at the equator, flows • to the North Atlantic, cools, sinks thousands of meters for as long as • 1,000 years and eventually returns to the surface.

30. Oceans and their currents and large lakes moderate the climate of nearby terrestrial environments • During the day, air rises over warm land and draws a cool breeze from the water across the land • As the land cools at night, air rises over the warmer water and draws cooler air from land back over the water, which is replaced by warm air from offshore

31. Mountains • Mountains have a significant effect on the amount of sunlight reaching an area, the local temperature, and rainfall • Rising air releases moisture on the windward side of a peak and creates a “rain shadow” as it absorbs moisture on the leeward side Leeward side of mountain Wind direction Mountain range Ocean

32. 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

33. Microclimate • Microclimateis determined by fine-scale differences in the environment that affect light and wind patterns • Ex: Forested areas create a shade microclimate that experiences less extremes in temperature than the open areas. • Ex: A log creates a microclimate for salamanders and insects, protecting them from changes in temperature

34. Concept 52.3: Aquatic biomes are diverse and dynamic systems that cover most of Earth • Biomesare the major ecological associations that occupy broad geographic regions of land or water • Varying combinations of biotic and abiotic factors determine the nature of biomes

35. Aquatic biomes account for the largest part of the biosphere in terms of area • They can contain fresh water (less than 1% salt)or salt water (marine; 3% salt) • Oceans cover about 75%of Earth’s surface and have an enormous impact on the biosphere • Evaporationfrom oceans provides most of the world’s rainfall • Effect climate and wind patterns • Photosynthetic marine algae and bacteria supply oxygen and consume carbon dioxide

36. Fig. 52-15 • Lakes • Coral reefs • Rivers • Oceanic • pelagic and • benthic zones • Estuaries • 30ºN • Intertidal zones • Tropic of • Cancer • Equator • Tropic of • Capricorn • 30ºS

37. Fig. 52-16 • Many aquatic biomes are stratified into zones or layers defined by light penetration, temperature, and depth • Intertidal zone • Oceanic zone • Neritic zone • Littoral • zone • Limnetic • zone • 0 • Photic zone • 200 m • Continental • shelf • Pelagic • zone • Benthic • zone • Aphotic • zone • Photic • zone • Pelagic • zone • Benthic • zone • Aphotic • zone • 2,000–6,000 m • Abyssal zone • (a) Zonation in a lake • (b) Marine zonation

38. photic zone –receives sunlight for photosynthesis • aphotic --zone receives little/no light • benthic zone --the organic and inorganic sediment at the bottom of all aquatic zones • benthos --the collective communities of organisms in the benthic zone • Detritus—the dead organic matter, falls from the productive surface water and is an important source of food • abyssal zone --The most extensive/deepest part of the ocean; 2,000 to 6,000 m deep.

39. In oceans and most lakes, a temperature boundary called the thermoclineseparates the warm upper layer from the cold deeper water • Many lakes undergo a semiannual mixing of their waters called turnover • Turnover mixes oxygenated water from the surface with nutrient-rich water from the bottom. It happens in spring and fall

40. Fig. 52-17-5 • Summer • Winter • Spring • Autumn • 22º • 4º • 0º • 4º • 20º • 4º • 2º • 4º • 18º • 4º • 4º • 4º • 8º • 4º • 4º • 4º • 6º • 4º • 4º • 4º • 5º • 4ºC • 4ºC • 4ºC • 4ºC • Thermocline • **Water is most dense at 4oC

41. Aquatic Biomes • Major freshwater biomes can be characterized by their physical environment, chemical environment, geological features, photosynthetic organisms, and heterotrophs

42. Lakes • Oligotrophic lakes are nutrient-poor and generally oxygen-rich • Eutrophic lakes are nutrient-rich and often depleted of oxygen if ice covered in winter

43. Fig. 52-18a • A eutrophic lake in the • Okavango Delta, Botswana • An oligotrophic lake in Grand • Teton National Park, Wyoming

44. Wetlands • A wetlandis a habitat covered by water at least some of the time. Plants are adapted to water-saturated soil • They develop in shallow basins, along flooded river banks, or on the coasts of large lakes and seas • Wetlands are among the most productive biomes on earth and are home to diverse invertebrates and birds Okefenokee National Wetland Reserve in Georgia

45. Streams and Rivers • The most prominent physical characteristic of streams and rivers is current • Headwater streams: cold, clear, swift, oxygen rich, rocky bottom • Downstream: warm, turbid, slow, less oxygen, more organic material, silty bottom

46. Fig. 52-18d • A headwater stream in the Great • Smoky Mountains • The Mississippi River far from • its headwaters

47. Estuaries • An estuaryis a transition area between river and sea • Salinity varies with the rise and fall of the tides • Estuaries are nutrient rich and highly productive • An abundant supply of food attracts marine invertebrates and fish An estuary in a low coastal plain of Georgia Video: Flapping Geese

48. Intertidal Zones • An intertidal zone is periodically submerged and exposed by the tides • Intertidal organisms are challenged by variationsin temperatureand salinity and by the mechanical forces of wave action • Many animals of rocky intertidal environments have structural adaptations that enable them to attach to the hard substrate Rocky intertidal zone on the Oregon coast

49. Oceanic Pelagic Zone • The oceanic pelagic biome is the open ocean • Covers approximately 70% of Earth’s surface • Phytoplankton and zooplankton are the dominant organisms in this biome; also found are free-swimming animals Open ocean off the island of Hawaii Video: Shark Eating a Seal

50. Coral Reefs • Coral reefs are formed from the calcium carbonate skeletons of corals (phylum Cnidaria) • Coral animals attach to a solid substrate • Unicellular algae live within the tissues of the corals and form a mutualistic relationship that provides the corals with organic molecules A coral reef in the Red Sea Video: Coral Reef Video: Clownfish and Anemone