•Climates and Biomes •Individual species...
Transcript of •Climates and Biomes •Individual species...
1
• Climates and Biomes• Individual species distributions
–Invasive species
Lecture 3:Distributions and abundance Climates and Biomes
• Climate varies tremendously over globe– abiotic factors such as rainfall and temperature
• Enormous impact on plants and animalsand the resulting communities
Two big factors affect global climate:1. Curvature of the earth -->temp gradient2. Tilt of Earth axis --> Seasons
Climates and Biomes
• Global temp differences create windand drive atmospheric circulation
• formation of distinct temperature andmoisture “bands” from low to highlatitudes
• Results in distinctive plant assemblagesthat are also formed in these distinctzones = BIOMES
Biomes• Major categories of world’s distinctive plant
assemblages• Different biomes correlate well with climatic
factors• Illustrate how organisms match their environments
2
Biomes• Tundra
– Very seasonal, very cold, very dry• Taiga (Boreal Forest, N. Coniferous Forest)
– Highly seasonal, very vold, lots snow• Temperate
– Seasonal, temperature fluctuates, rain+snow– Grasslands & Forests
• Tropical– HOT!, little seasonality, rainfall varies– Savannas, Rainforests, and Deserts
• Deserts– Hot & Dry, distributed throughout the world
Individual Distributions
• There are different scales of individualsdistributions:– Geographic– Regional– Populations (habitat-related)– Individual locations (e.g. territories)
Worldwide Continental
RegionCluster/Population
Locality IndividualLocations
Individual Distributions
• How do we study what factors determine thedistributions of organisms?
• Old way: Leibig’s law of the minimum– Look where organisms are found and ask why– Hypothesis: distribution of organism determined by
single environmental factor for which the organismhas narrowest range of control or adaptability
3
Individual Distributions
• Leibig’s law of the minimum– Use tolerance curves to determine which
environmental factors organism wasinfluenced by: GRAPH
– Problem: focuses on abiotic conditionsand the physiology of organisms but doesnot consider potential effects of otherfactors
– Realized vs. potential performance -GRAPH!
Individual Distributions• Alternative way to Leibig:
– Look where organisms are NOT found andask why
– Hypothesis: distribution of organismsdetermined by factors keeping them out of orfrom being successful in other areas
Individual Distributions• Factors that can limit species distributions:
–Abiotic env. conditions• Temperature, water, nutrients, etc.
–Species Interactions• predation, competition, disease, etc.
–Dispersal barrier• Land or water barriers
–Behavior• Habitat selection/preference
DesertsNumber/km2
Red Kangaroo Distribution andAbundance - Australia
Distribution of DesertConditions - Australia
>2010-205-101-50.1-1<0.1
Abiotic factors limiting distribution
4
Abiotic factors limiting distributionBarnacle Distributions and Climate - UK
Chthamalus sp. –southern species
Balanus sp. – northernspecies Colder water
Warmer water
Species interactions & distributions
Red Kangaroo Abundance relative to a predator – DingosDingos Absent Dingos Present
Kangaroo Density#/km2
Distance from Fence (km)
4
8
12
16
102030 10 20 30
Dispersal limiting distributions
Gypsy moth distribution before and after human-inducedintroduction to the U.S.
Before introduction to U.S. After introduction to U.S.
Habitat selection limiting distributions
addition of shelter
C = control,
E = experimentaladdition)
Result: Kangaroo ratprefers open areas,pocket mice prefersheltered areas
Kangaroo rat
Pocket mouse
5
Distributions - CA examples
• California Salamanders ( Ensatina eschscholtzi spp.)
– Ring Species• Monterey Pines (Pinus radiata)
• Likely have both biotic & abiotic constraints
Individual Distributions• How do we determine which factors limit species
distributions?• Can do transplant experiments or change
conditions to distinguish between differentfactors
Dispersal?
Behavior?
Other organisms?
Abiotic factors?
“Natural Experiments”
• Introduced Species– Overcome dispersal barrier– Novel species interactions– Different abiotic conditions– -->Alters distribution dramatically!
• Examples– Kudzu vine (Pueraria montana)– Cane Toads! (Bufo marinus)