bio120 lecture02

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Lecture 2: Climate & biomes; ranges; introduction to physiological ecology

1. Climatic factors and geographic distribution of biomes 2. Sources of climate variation beyond the basic latitudinal

belts 3. Example of one environmental challenge to physiology:

Heat balance/thermal ecology of animals a. Modes of heat gain and loss; homeostasis b. Size, shape, insulation, evaporative cooling c. Tradeoff principle and adaptive compromises (example

of weasel body shape)

Coypright 2014 James D Thomson

General trends of terrestrial vegetation with climatic variables

Vegetation growth (primary productivity) increases with moisture and temperature

Vegetation stature also increases so regions with certain combinations of

moisture and temperature develop predictable, characteristic types of vegetation = biomes

Seasonality is secondarily important 2 Coypright 2014 James D Thomson

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Biome types depend on combination of temperature and precipitation

From Krebs after R.H. Whittaker

Highest productivity Lowest productivity

My examples from: Central America, Vietnam Ontario Colorado Arizona

Compare version in text Coypright 2014 James D Thomson

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Latitude mostly determines major terrestrial biomes; learn classification in SFE

Deserts near 30 deg N & S


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Additional climate patchiness overlaid on basic latitudinal belts

Temperature: land changes temperature more readily than water; maritime climates are moderate, continental climates are extreme; oceans provide thermal inertia

Precipitation: where does atmosphere get laden with moisture; where does it condense? Evaporation high from warm bodies of water, low from cold Prevailing winds Orogenic precipitation: air forced up mountainsides undergoes

adiabatic cooling, precipitates on upper windward slopes Rain shadows created on leeward slopes of mountain ranges Seasonality of moisture also important


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Earths tilt (23.5 ) produces seasonality

Ricklefs Fig. 4.2

Latitudinal patterns complicated by distribution of landmasses

Width of red ribbon shows annual variation in temp.


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Where are grapes and cherries grown in cold climates? Maritime pockets

Door Co., Wisc.

Niagara & Pelee, Ontario

North Fork, Long Island


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The driest deserts occur inland of cold-water upwellings: cold water => dry air


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Montane rain shadows: Sierras and Rockies

Yellow = grassland (drier), east of Rockies Coypright 2014 James D Thomson

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Biomes across elevational gradient: Arizona mountains


South-facing side of Round Mountain, western Colorado

11 Valley floor = irrigated hay pasture

Dry sagebrush scrub

Forest only at higher elevations & eastern flank


North-facing side of Round Mountain, western Colorado

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Forest across entire face


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Mt. Lemmon transect, AZ: Elevation correlated with both temperature and precipitation; change of

100 m in elevation equals ~ 150 km of latitude

More info: http://www.saguaro-juniper.com/i_and_i/san_pedro/ecoregions/desert_to_skyisland.htm Coypright 2014 James D Thomson

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Mt. Lemmon transect: Sonoran desert, 712 m


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Mt. Lemmon transect: Oak grassland, 1338 m


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Mt. Lemmon transect: Pinyon pine-oak woodland, 1612 m


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Mt. Lemmon transect: Ponderosa pine, 1916 m


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Mt. Lemmon transect: Aspen, 2402 m


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Mt. Lemmon transect: Spruce-fir forest, 2750 m


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Mt. Lemmon transect: Spruce-fir forest, 2750 m


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Core ideas in physiological ecology Ranges of tolerance (Lecture 1) ultimately limit

distribution Organisms are complex chemical reactions Reactions occur (enzymes function) best at

optimum temperature and osmotic conditions, where fitness is maximized

Many mechanisms for homeostasis have evolved to challenge hostile environments

Maintenance of homeostasis requires energy and is often limited by constraints & tradeoffs


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Two types of range: ranges of tolerance and geographical ranges

Animals geographical ranges often correspond to biomes, i.e., limited by climate and/or vegetation

but sometimes not. Possibilities include: Limited to special habitats (behavioural habitat

selection) Limited by other organisms (enemies, friends) Transcend biomes (ecological versatility, super

generalists) Not at limits because of recent history (e.g.,

limited dispersal) Next slides: a sample of ranges


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Limited by habitat: Pronghorn (Antilocapra americana): broad climate tolerance, narrow habitat range (short-grass prairie biome, American High Plains)

South Park, Colorado April 2012 Coypright 2014 James D Thomson

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www.ownbyphotography.com

Yellow-rumped warbler Dendroica coronata

Kirtlands warbler Dendroica kirtlandii

www.birds.cornell.edu/

Idiosyncratic, species-specific habitat selection behaviour can greatly influence distributions

Extreme habitat

generalist

Paradoxically extreme habitat

specialist (cognitive

limitation?) Coypright 2014 James D Thomson

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Transcending biomes: broad

temperature tolerance,

broad habitat range

Tropical rainforest, Sumatra

Boreal forest, Siberia

Tiger, Panthera tigris


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Range limited not by climate or habitat type but by other animals: recent coyote expansion due to

humans, extirpation of wolves?

Coyote, Canis latrans


Animals, size, heat budgets

27 Rufous hummingbird Merriam shrew Coypright 2014 James D Thomson

bio120 lecture02

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