NEU Ecology Fall 2013 Lec set 4

Temperature and moisture (and interactions between these) are central to what?
How are temperature gradients on Earth determined?
Incoming solar radiation (40% at poles vs 100% at the equator) and the distribution of land and water
Is there greater precipitation at the poles or at the equator?
Do mountains get more or less precipitation than flatter, more even surfaces?
What two factors are ultimately important to organisms when it comes to precipitation?
Evaporation (how much water is returned to the atmosphere) and transpiration (how much water an organism loses through biological process); both of these are highly dependent on temperature
What makes polar regions not as (generally) bad as desert conditions for habitats?
The lower temperature at polar regions means there is less evaporation
Survival, reproduction, development of young and interactions with other species can all be impacted by what two important abiotic factors?
Temperature and moisture
What important limiting factor is often created by temperature fluctuations?
There is often a limitation tied to increased energetic demands caused by cold weather
Plants are (blank) sensitive to water availability and show (blank) variability to drought resistance
Very, wide
Increasing the depths of their roots is one way in which plants can do what?
Increase water uptake and thereby resist drought easier
Closing the stoma, preventing cuticular respiration (making thicker cuticles), reducing leaf surface area and shedding leaves altogether during a drought season are all ways for plants to do what?
Reduce water loss and thereby resist drought
What is one important issue to note about colder temperatures in winter and how they relate to water accumulation/loss?
There is such a thing as a “winter drought” where cold temperatures severely limit the amount of water that pine trees are able to take up; this is more concentrated in cold, northern areas
What is the process by which phenotypes have become genetically fixed and constant across different environments?
This is the process by which individuals differ genetically for traits that improve survivorship in different environments
Genetic polymorphism
What is the idea behind phenotypic plasticity?
It is the process where intrageneration changes in a trait are caused by environmental cues
What did Clausen et al. (1948) show with regard to plant height?
They showed that plant height in yarrow is strongly dictated by the winter temperature and precipitation
What is so important to note regarding phenotypic plasticity and how it is generated?
It is likely under genetic control and can thus evolve by means of natural selection if put under evolutionary pressure
What does the term “ecotype” refer to?
It is the genetic varieties within a species
What would you expect to see if a trait or condition is plastic?
All individuals will respond the same to the common environment and produce different phenotypes in different environments
These responses are irreversible and produce discrete rather than continuous phenotypic variation; these responses occur early in ontogeny and organisms ultimately have to commit to one phenotype or the other
Developmental conversion
These responses are reversible and produce continuous rather than discrete phenotypic variation; these responses can occur at multiple stages of ontogeny
Phenotypic modulation