207 Flashcards
(179 cards)
Limnology:
Multidisciplinary to the study of all inland water communities, and their interactions with physical, chemical and biological environments
-euphotic zone:
littoral zone (intertidal zone), neritic zone, epipelagic zone
littoral zone (intertidal zone)
shallow shoreline, influence of tides- high productivity gets sufficient light and gets nutrients from ocean and terrestrial run off- waves - most things live in this zone
aphotic zone
reduced -> no light
benthic
bottom sediment
If the conditions exceed the optimum species
ranges, the species may have to:
– Migrate to more suitable locations
– Dormancy
– Adapt/acclimate to changing conditions
Stabilizing selection
- Extreme phenotypes are selected against and average phenotypes are favoured
- Average traits have the best survival
- Eliminates harmful mutations
– Maintains status quo
(no evolution)
natural selection mechanisms
- Stabilizing selection
- Directional selection
- Disruptive selection
Directional selection
- An extreme trait has increased survival, traits move toward the “better” or “most adapted” trait
- New beneficial mutations are fixed in the population
Disruptive selection
- 2 traits have increased fitness, traits move to bimodal
- Or intermediate trait is selected against
- Responsible in part for sympatric speciation
Microevolution
– operates at the population level
– random and selection processes
Macroevolution:
– operates at the species and higher taxonomic levels
– speciation
Species
species:
– Organisms that form a natural
population
– Reproductively isolated
– Will transmit specific characteristics
from parent to offspring
BIOLOGICAL SPECIES CONCEPT (BSC)
– A group of organisms reproductively isolated from
similar organivsms =
* Infertile organisms will arise when different species crossed
ecocline
a gradual change in a genotype or a phenotype of a species over a large geographic area
ecotype
individuals of a species on opposite ends may appear very diff from eachother. if genetically distinct from each other they may be called a subspecies or separate species
Allopatric Speciation
-Geographic isolation,
no movement of population
-Genetic differentiation
Parapatric Speciation
– Movement into a new habitat, no isolation
– New genes dominant and excel in new habitat
– Habitat expansion
– Divergence may occur because of reduced gene flow
Sympatric Speciation
– Genetic drift occurring when populations are free moving with no barriers
– New niche exploited
– Randomly mating species
– may result due to assortative mating
To avoid heating, plants have (3)
options:
- Decrease heating via conduction (Hcd)
- Increase convective cooling (Hcv)
- Reduce radiative heating (Hr)
response to water stress
– Plant stomata are typically more active in cooler, humid part
of the day. (reduction in water loss)
– Alter leaf shape or plant shape (short term vs. evolved)
– Prematurely drop leaves
– Water stress inhibits the production of chlorophyll
– Increase root development
Consequences of water stress
A reduction in the growth rate of the plant with a smaller leaf area
Plants in a high temperature environment must to maintain heat balance by
– Place leaves above the ground to avoid the ground convective heat
– Small leaves to promote convective cooling (and increase air flow to the
stem)
– Hairs on leaves will reflect light
– Leaves will orientate parallel to the sunlight to reduce radiative heat gain
population
is a group of individuals of the same species living in a given area at the
same time.