12/1/10
Biomes
•
•
•
•
What defines a biome?
Where are the ‘lines’ drawn?
What are the major controlling factors?
What about aquatic ‘biomes’
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Tolerance limits
Biomes
• Animals and plants have narrow
ranges of tolerance to abiotic factors
• This in part determines the biotic
components of biomes. These are
broad geographic regions determined
by temperature and rainfall, and
described by their plant communities
Figure 50.3 A climograph for some major kinds of ecosystems (biomes) in North
America
Figure 3.2
3-1
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Figure 50.9 The distribution of major aquatic biomes
World biome map
Figure 5.3
5-1
1
12/1/10
Figure 50.13 Zonation in the marine environment
Figure 50.8 Lake stratification and seasonal turnover
Figure 50.10 Zonation in a lake
Currents
Aquatic Biomes
•
•
•
•
•
•
•
Temperature
Currents
Nutrients
Salinity
Oxygen
Depth
Sunlight
•  Physical as well as chemical boundaries
Some Key Points
•  Animals interact with biotic and abiotic factors in ways
which shape their survival and distributions
•  Biomes are delineated by abiotic factors, but biotic
factors play a role too.
•  Biomes are described by plant communities which are
‘controlled’ by temperature and precipitation
•  Oceans are different: currents and salinity/oxygen
distribution have a major impact - productivity
•  Organisms have tolerance ranges to abiotic factors both long term and short term effects.
2
12/1/10
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Biodiversity “hot spots”
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Natural medicinal products
Figure 5.20
5-6
5-7
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Biodiversity
Human disturbance
•  Species diversity: number of different
species
•  Genetic diversity: ensuring a healthy
gene pool-problems with bottlenecks
•  Ecological diversity: numbers of ‘habitat
types’ - relates directly with species
diversity
•  But WHY is it important??
5-9
Extinction
Natural extinction
•  Extinction is a natural process. As
earth changes, so does it’s flora and
fauna.
•  Periods of mass extinctions and
radiations (diversity)
•  Extinction has to keep up w/
speciation. (~1 per 1000 yrs.)
Extinction
Human accelerated extinction
•  Most major mass extinction in the last 65 mill yrs
is now (cretaceous), by us.
•  40-100 sp. going extinct every day: unparalleled
•  1000-10000 times natural background rate what’s cause?
•  possibly 20% of current species extinct in next 30
yrs - more than have been named yet!
•  Fastest moving aspect of global change
•  Irreversible
3
12/1/10
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Extinction
Mass extinctions
What causes extinctions?
•  Natural events - climate change, etc.
•  Habitat loss and disturbance
•  Commercial hunting and poaching
•  Predator and pest control
•  Pets/decorative plants
•  Introduction of non-natives
•  Population growth, affluence and
poverty
5-8
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Extinction
Reproductive strategies
What makes a species extinction prone?
•
•
•
•
•
•
•
Critical population size Passenger pigeon-now extinct
Specialists vrs. Generalists
Animal size (large)
Range (small)
Trophic position (high)
Tolerance to humans
Behavioral patterns
3-10
Carbon dioxide
Temperature
Sea level
Arctic ice
4
12/1/10
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
U.S. wetland acreage
Figure 5.24
CO2 in summary
320 ppm: occasional bleaching
345 ppm: sporadic mass bleaching
387 ppm: inevitable long-term decline
450 ppm: rapid decline, reefs cease to be biodiverse
600 ppm: acidification affecting all biota
800 ppm: mid Eocene extinction conditions
1000 ppm: reefs only geological structures. Sixth Mass Extinction
5-10
Life on Earth
Refugia and habitat
fragmentation
•  Living things cause change
•  Living things respond to change
•  Living things change their environments
•  Living and non-living components of our Earth
interact
•  Processes like global warming/climate change
follow large-scale patterns, but it is the composition
of life on earth that can affect those patterns
•  Ecological systems exist in balance - that balance
can be disturbed, and its evolution from there can be
difficult to predict.
Some organisms
CAN survive in
these refugia, but
may never get out,
or may emerge
quite changed
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Endangered species
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Protected lands
Figure 5.33
5-13
5-14
5