Ecology the study of the distribution and abundance of organisms:

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1 Ecology the study of the distribution and abundance of organisms: Who is where, when and why! Different spins on ecology: Organismal (& physiological) Population Community Ecosystem/global

2 Organismal ecology How do individuals interact with each other and their physical environment? The interact physical environment hook is the physiological ecology part.

3 Population biology How and why does population size change over time? Each female salmon produces thousands of eggs. Only a few will survive to adulthood. On average, only two will return to the stream of their birth to breed.

4 Community ecology How do species interact, and what are the consequences? In this case the bear is interacting with the fish by eating it. The consequence for this fish is death!

5 Ecosystem ecology How do energy and nutrients cycle through the environment? (What happens to the dead fish?) Figure 50-1d Biological Science 2/e 2005 Pearson Prentice Hall, Inc.

6 Abiotic factors (but not just) control where you find organisms, and what types of organisms (physical and physiological features). For example, ambient temperature! The basic needs of organisms: 1. Water 2. Nutrients 3. Energy In general, life is an interface phenomenon!

7 North pole 60 N Small amount of sunlight per unit area Low angle of incoming sunlight Moderate angle of incoming sunlight 30 N Sunlight directly overhead Equator Large amount of sunlight per unit area

8 Uneven distribution of sunlight uneven heating BTW, life exists at the low end of the temperature scale

9 Sunlight limits photosynthesis Temperature depends on sunlight speed of chemical reactions in ectothermic organisms Wind depends on temperature So differential sunlight differential heating differential air movement Of the three essentials: Water Nutrients Energy

10 Differential sunlight differential heating air movement and air movement controls water movement in the terrestrial environment.

11 Differential sunlight differential heating air movement and air movement controls water movement critical for the terrestrial environment. 60 N 30 N Equator 30 S Dry Wet Dry Dense, dry air descends, warms, and absorbs moisture Hadley cell Cooled air is pushed north & south (only north shown) Warm air rises and cools, dropping rain Atmosphere (not to scale) 60 S Figure 50-3 Biological Science 2/e 2005 Pearson Prentice Hall, Inc.

12 Also seasonal differences in sunlight, temperature, air movement. Due to tilt of earth no tilt, no seasons! June 21: Northern Hemisphere faces Sun most directly March 20: Equator faces Sun directly December 21: Southern Hemisphere faces Sun most directly Sun 23.5 June 21 = solstice (longest day) in N. hemisphere September 22: Equator faces Sun directly

13 Rotational effects on air (& water) movement: A point at the equator is traveling at 1100 km/hour, but a point at the N. or S. pole is not moved by rotation. Air (or projectiles) moving across the Earth's surface are subject to Coriolis forces that cause apparent deflection of the motion.

14 Geographical effects on air (& water) movement West Moisture-laden air blows onshore from Pacific Ocean Air rises over mountains and cools; rain falls East Dry air creates desert conditions This area is in a rain shadow Cascade Mountains Figure 50-5 Biological Science 2/e 2005 Pearson Prentice Hall, Inc.

15 Based on temperature & water availability, terrestrial environment divided into biomes, types of ecosystems. Barrow Dawson 60 N Denver Yuma Chicago Belém 30 N Equator 30 S Arctic tundra Boreal forest Temperate forest Temperate grassland Subtropical desert Tropical wet forest So what happened to the Pacific NW?

16 Not everyone agrees on biomes. Here is another list: Polar ice Tundra Taiga (boreal forest cold, most of Canada) Temperate deciduous forest Temperate evergreen forest Tropical monsoon forest Rainforest (temperate and tropical) Chaparral Temperate grassland Savanna Semi-desert (desert-scrub) desert

17 40 Subtropical desert Minimal overlap of biome characteristics Average annual temperature ( C) Temperate grassland Arctic tundra Temperate forest Boreal forest Tropical wet forest Species are evolutionarily adapted to the temperature/rainfall profile. Ignoring dispersal, by convergence evolutionarily unrelated organisms will share traits common to their biome Average annual precipitation (cm) Figure 50-7 Biological Science 2/e 2005 Pearson Prentice Hall, Inc.

18 tropical wet forest Temperature ( C) Belém, Brazil Very low variation Average is HIGH, variation is LOW Precipitation (cm) Annual total is VERY HIGH, variation is HIGH J F M (Freezing) A M J J A S O N D the tropics often defined as the biome where seasonal rainfall variation is greater than seasonal (or diurnal!) temperature variation. Month

19 tropical wet forest Figure 50-8b Biological Science 2/e 2005 Pearson Prentice Hall, Inc.

20 Tropics: Less seasonality relative to sunlight, temperature and lots of water all-year growing season. This means there is high primary productivity, and high biomass accumulation. (Note biomass is not the same as biodiversity!) CO 2 + H 2 O + light CH 2 O + O 2 The number of carbon-carbon bonds produced is proportional to the amount of energy fixed. This is gross primary productivity. Some fixed energy is lost due to cellular respiration & some to maintain existing plant tissue.

21 The energy fixed that does not go into cellular respiration is used for growth, i.e., production of new tissue. The rate at which this happens is the rate at which biomass accumulates (BAR). Usually measured in kg of carbon/m 2 /yr

22 In addition to high productivity, tropical forests also have high species diversity. Why? Surprisingly, this is not known! The latest theory suggests that the more even temperature and abundant rainfall means just about anything that evolves in the tropics might do OK. So the tropics are the ancestral origin of many species. Thus there are more species in the tropics just because there have been plants and animals there longer (see next slide for details)!

23 More Species In The Tropics Because Species Have Been There Longer, Study Suggests Science Daily Why are there more species in the tropics than in the temperate regions of the globe? Many of the world's species live in the tropics (perhaps more than half), but the reason has been debated for more than 100 years. Many researchers have hypothesized that climatic factors somehow cause species to originate more quickly in tropical regions. In a paper appearing in the November issue of The American Naturalist, John Wiens and a group of researchers from Stony Brook University have shown that, contrary to expectations, species seem to evolve at similar rates in tropical and temperate regions. What causes the difference in species numbers between tropical and temperate regions is not something special about the tropics that leads to more rapid speciation, but rather that the temperate areas were colonized more recently, leaving less time for species to originate and accumulate in these regions. The researchers studied the causes of high tropical species richness in treefrogs in the Americas. Combining analyses of evolutionary trees based on DNA sequences with GIS-based methods for analyzing the effects of climate on species distributions, the researchers found no relationship between how quickly species originate within a group and whether that group is tropical or temperate. However, they did find a strong relationship between when each region was colonized and the number of species there today. Thus, the high species richness of tropical regions seems to be explained by the ancient origin of many groups in the tropics, more recent colonization of temperate regions, and by the inability of most tropical species to tolerate the variable temperatures of temperate areas. According to John Wiens, the study has important conservation implications: "If the pattern we see in treefrogs holds true for most other groups, then the tropics may have more ancient lineages and more genetic diversity per species than temperate regions. So there may be far more loss of diversity going on as we lose tropical rainforests than would be suggested by the number of species alone." John J. Wiens, Catherine H. Graham, Daniel S. Moen, Sarah A. Smith, and Tod W. Reeder, "Evolutionary and ecological causes of the latitudinal diversity gradient in hylid frogs: treefrog trees unearth the roots of high tropical diversity." The American Naturalist: November 2006.

24 subtropical desert 40 Yuma, Arizona Temperature ( C) 30 Average is HIGH, variation is MODERATE (Freezing) Precipitation (cm) 20 Annual total is VERY LOW, variation is LOW 10 0 J F M A M J J A S O N D Month

25 subtropical desert Clearly rainfall, not sunlight, is the limiting factor for plant growth. Figure 50-9b Biological Science 2/e 2005 Pearson Prentice Hall, Inc.

26 temperate grassland Temperature ( C) Denver, Colorado Average is MODERATE, variation is MODERATE (Freezing) Precipitation (cm) 20 Annual total is LOW, variation is MODERATE 10 0 J F M A M J J A S O N D Month

27 temperate grassland Figure 50-10b Biological Science 2/e 2005 Pearson Prentice Hall, Inc.

28 temperate forest Temperature ( C) Chicago, Illinois Average is MODERATE, Variation is MODERATE (Freezing) Precipitation (cm) 20 Annual total is MODERATE, variation is LOW 10 0 J F M A M J J A S O N D Month

29 temperate forest Figure 50-11b Biological Science 2/e 2005 Pearson Prentice Hall, Inc.

30 boreal forest Temperature ( C) Average is LOW, Variation is very high Dawson, Yukon, Canada 0 (Freezing) Precipitation (cm) 20 Annual total is LOW, variation is LOW 10 0 J F M A M J J A S O N D Month

31 boreal forest Figure 50-12b Biological Science 2/e 2005 Pearson Prentice Hall, Inc.

32 artic tundra Temperature ( C) Average is VERY LOW, Variation is HIGH Barrow, Alaska 0 (Freezing) Precipitation (cm) Annual total is VERY LOW, Variation is VERY LOW 10 0 J F M A M J J A S O N D This is essentially a cold desert Month

33 artic tundra

34 Just like terrestrial biomes, aquatic habitats are not all the same

35 Only certain wavelengths of light are available under water Percentage of visible light at 3 m depth in seawater Wavelength (nm) This is why the visible spectrum is the visible spectrum!

36 Relative light intensity Intensity of light declines with water depth. Pure seawater This sets up a photic zone where primary productivity can occur. Below this it is chemoautotrophic and heterotrophic only. Light penetrates farther in freshwater than in seawater Pure freshwater Depth (m) Figure 50-14b Biological Science 2/e 2005 Pearson Prentice Hall, Inc.

37 Littoral zone plants can root here Limnetic zone algae, cyanobacteria near surface Photic zone Aphotic zone Benthic (deep) zone detritivores at substrate Figure Biological Science 2/e 2005 Pearson Prentice Hall, Inc.