Lecture 21- Northern Ecological Concepts Flashcards
What is the latitudinal diversity gradient?
Species diversity declines with increasing distance from the equator
Species accumulate ____ as you move towards the equator
Accumulate faster than expected
____ climates support more species per number of individuals sampled
Warmer
What is sympatric speciation?
- Arises within populations that continue to occupy same regions
- Arises as a result of random genetic mutations
Sympatric speciation allows for?
Allows for niche partitioning
What is allopatric speciation?
- Arises when 2 populations are geographically seperated
- Genetics and occupied niche change over time
What are some limitations to species diversity?
- Niche theories
- Equilibrium theories
- Stabilizing mechanism
- Equalizing mechanism
What is niche theory?
Competition for resources drives limits to new species establishing
What is equilibrium theory?
Populations exist in equilibrium in a saturated environments
What is a stabilizing mechanism?
Reduce competition between species to encourage higher diversity (ie. resource partitioning)
What is equalizing mechanism?
Reduces competitive advantage of some species
What are the three broad theories to cause diversity decline?
- Productivity = Solar radiation, rainfall in relation to temperature, resource availability
- Interactions = self-reinforcing effect of diversity
- Stability = lack of glaciation
Rainfall affects potential ______
Evapotranspiration (PET)
How does rainfall affect the potential evapotranspiration?
- Amount of water that could be evaporated from the soil and transpired by plants
- Takes into account local average temperature and humidiy
- Good indicator of drought
What causes changes in diversity?
- Solar radiation
- Rainfall
- Resource Availability
- Self-reinforcing effect of diversity
- Glaciation
Once more species of plants live together, more species _______
More species of herbivores with evolve
Greater diversity of herbivores may result in more ______
Species of predators
Competition increases ______
Niche partitioning
Rate new species evolve is slow in polar areas so never manage to _____
Recover to maximum number species
What are the effects of climate instability?
Why do different regions vary in number of species and type of species they contain?
- No single mechanims explains all patterns
- Likely different mechanisms between different taxa (plant energy driven, mammals area-dependent)
What is rapoports rule?
- Geographic ranges of species are larger at high latitudes
- Explanation for higher diversity near equator
- Small ranges = more species in same are
- Large species ranges = no room for new species
What are some limitations to species ranges?
- Dispersal
- Biotic
- Abiotic
What is niche conservatism?
- Refers to climate niche
- Range of temperatures and precipitation a species can tolerate
- Moderates where species occur and how they adapt
- Species retain fundamental niche over time
- Species does not adapt to local changes in environment
