Lecture 2-cont.. Flashcards
What constitutes an introduce/alien or exotic species?
When a species is transplanted by humans to a new site and they have become established.
What constitutes an invasive species?
When an established alien species is able to expand its abundance and distribution
What do physiological ecologists study?
The reaction of organisms to changes in physical and chemical factors. can be helpful in explaining species distributions
What factors greatly influence the physiology of species?
Water and Temperature. play a large role in species distribution
What are critical physiological limits?
Levels of abiotic factors that a species cannot tolerate which restricts its distribution.
What is the difference between Acclimation and climatizing?
Acclimation is done through controlled conditions in an lab setting/experiment. climatizing is what an organism would do to achieve comfort in a new environment/climate.
What are complications to assesing critical physiological limits to an abiotic variable?
- limits vary by acclimation lever or lifecycle stage ( juveniles have a more narrow tolerance)
- concurrent abiotic factors affect critical limits
- Adaptions such as torpor, hibernation/aestivation, and migration also complicate determingin where species CAN live versus where they DO live.
What is Shelford’s law?
The distribution of a species is controlled by the abiotic factor fow which the organism has the narrowest range of tolerance
What is log-normal-distribution?
Within a site, most species are usually rare while few species are abundant. axis are adjusted to reveal a normal curve distribution
What is Distribution-abundance relationship? what are the 3 proposed explanations?
Across groups of related species, abundance tends to increase with geographic range
- Sampling model
- Ecological specialization model
- local population model
What is a sampling model?
Rare species are more difficult to observe, and thus only appear to have smaller ranges (the distribution-abundance relationship does not actually exist)
What is ecological specialization model?
Species that can exploit a wide range of resources becom widespread. thus, generalists have large ranges and specialists have small ranges.
What is local population model?
- both distribution and abundance depend on dispersal ability. thus, species with high dispersal ability become more abundant and more widespread.
What is Rapoports rule?
Latitudinal range size is larger for species closer to the poles. support for rapoports rule exists for trees, fish, reptiles, some birds and many mammals
What are 3 proposed explainations for rapoports rule?
- Climate variability increases with latitude, and thus only organisms that can tolerate a broad range of climes can live at higher latitudes
- pecies with larger geographic ranges have higher dispersal ability, and this ability also means these species quickly re-colonized northern areas following glacial retreat
- There are fewer species at high latitudes, and thus range sizes are larger because competition in lower.
What is biogeography?
The study of species distributions at relatively large spatial scales and of the environmental factors that influence those distributions
What mainly influences terrastrial biomes?
Climate (temp and precip)
What mainly influences aquatic biomes?
Light penetration and temperature
Is diversity evenly distributed?
No- it tends to be concentrated in “biodiversity hotspots”
What factors tend to increase species diversity in terrestrial biomes?
- Geological age is older
- Elevation is low
- topography is more complex
- Area Size is larger
- Insolation is high
- precipitation is high
What are 5 possible reasons why species diversity increases as one moves towards the tropics?
- climates become more favourable (Ambient energy)
- There are longer periods uninterupted by glaciation (Evolutionary speed)
- There are larger land masses (Geographic area)
- They provide more energy (Productivity)
- There may be greater competition and/or predation (Interspecific interactions)
- disturbance.
At large scales, What is the most important factor leading to greater species diversity in the tropics
Ambient energy (favourable climates)
At small scales, What is the most important factors affecting species diversity
- interspecies interactions- high levels are best siince more competition increses nich partitioning, and more predation retards competetive exclusion
- Disturbance levels- moderate levels are best according to the intermediate disturbance hypothesis.
