Flashcards in Lecture 4- abiotic factors that limit species distribution Deck (24)
What are the 3 main abiotic factors that affect species distribution?
1. Climate (temp, water availabilty, sunlight and wind)
What is climate and its 2 subdivisions?
Climate is the composite or generally prevailing weather in an area
1. Macroclimate- patterns on the global, regional and local level
2. Microclimate- very fine patterns, such as those encountered by the community of organisms underneath a fallen log
What are important factors of temperature and water availability
- dominant factors affecting distributions of terrestrial biomes, affecting geographical ranges of organisms in these biomes
-more important is the balance between Temp and water availability.
What are the 2 ways drought can occur?
1. Soil drought occurs when water is deficient( low precip, high temps)
2. Freeze drought occurs when low temps make water unavailable
What is a widely used metric of surface water availability?
Precipitation / potential evapotranspiration (P/PET)
-The amount of incoming water (P) adjusted for water loss due to drying (PET)
What does Evaporation include?
1. Evaporative water loss from soil and water surfaces, Plus
2. Water loss due to transpiration through plant stomata
What is potential evapotranspiration?
The estimated rate of evapotranspiration that would occur given and unlimited supply of water. this is an index of drying power
What 2 variables drive earth surface temperature variations?
1. incoming solar radiation (Insolation) compared to the equator, insolation at the poles occurs at more oblique angles during most of the year. temp is lower and more seasonally variable at the poles
2. Distribution of land and water
compared to land, water cools/heats more slowly because it has a higher specific heat capacity. areas near large water bodies have lower daily and seasonal temp fluctuations
What 4 effects do Temp and water availability have on species distributions?
3. Development of young
4. Interactions with other species (effects greater near the edges of a species range.
How is knowing threshold levels beneficial to conservation?
controlling species with abiotic factors
where will climate do your job for you?
What 2 options do organisms have for dealing with local temp and water availability?
1. Simply tolerate them
2. 'Escape' them using adaptations
-physical, psychological, behavioral
What 2 ways does sunlight limit species distributions?
1. Indirectly through its effect on temperature and water availability
2. Directly through effects of light intensity and light quality on rates of photosynthesis.
What is a specific trait that determines photosynthetic rate?
-The chemical pathwa by which CO2 is converted to sugar.
What are 3 types of photosynthetic pathways?
1. C3 plants- 20-25*, high water, low light
2. C4 plants- 30-35*, medium water, high light
3. CAM plants- 35* low water, medium light
How does wind modify the effects of temp and water availability?
Increasing heat loss due to convection and water loss due to evaporation (mainly affecting plants)
How does Topography affect species distributions?
mainly indirectly by modifying other abiotic factors:
How do soil trait limit distribution?
1. Mineral and organic composition
3. Physical structure (porosity, grain size)
plants can also influence these soil properties
How does seasonality impact species distributions?
1. Seasonal variability of temp/light increase steadily toward the poles. many species migrate to higher latitudes to take advantage of resources made available by longer summer days
2. Lakes are sensitive to seasonal temp change, which results in turnover of water and associated nutrients
How is the importance of abiotic factors to species distributions assessed?
1. Identify which life cycle stage (Egg, seed, juvenile, adult) is most sensitive to the variable
2. Then identify the tolerance zone to that variable (critical physiological limits)
3. Evidence that the variable may limit the species distribution exists if the variable is within this tolerance zone inside the species range, but is not within the tolerance zone outside the species range
Common garden experiments can help assess whether ecotypes are:
Different genotypes (genetic differences between ecotypes) or
Different phenotypes (no genetic difference between ecotypes)
What are 2 estimated impacts of anthopogenic climate change on the ranges of terrestrial species?
1. Shift toward the poles/high altitude at a rate of 16.9km/decade
2. Shift towards higher elevations at a rate of 11m/decade
What does a species ability to deal with climate change depend on?
1. Whether they can tolerate or adapt to climate changes or
2. Whether they can disperse to acceptable climates.
one caveat is that adaptation evolution rates or dispersal rates may not occur fast enough to keep pace with rates of anthropogenic climate change
how is the range of chthamalus barnacles affected by both biotic and abiotic factors?
They are limited by 2 factors:
1. exposure to air (drying) in the upper intertidal
2. Competition for space with semibalanus barnacles in the lower intertidal.