Biology 208 Study Notes
Evolution is the change in allelic frequency within a population over time
Evolution is common.
Genetic drift is the number one cause of evolution.
Fitness landscapes illustrate that natural selection does not optimize. In fat, it
favors higher fitness over other aspects.
Founder effect – the movement of a small number of individuals into a new
area. It results in a decreased level of heterozygosity.
There are stabilizing, directional, and disruptive forms of selection.
An ecocline is genetic in basis and occurs in a gradient.
An ecotype may or may not be genetic.
Biological species concept – a species is a group of reproductively isolates
organisms. It is only accurate with regards to vertebrates.
Phylogenetic species concept – based on the pattern of history, it uses
evolutionary past to determine species. The problem is that it is completely
arbitrary and not testable.
There is no correct definition of a species.
Mechanisms of isolation include ecological, temporal, behavioral, mechanical,
hybrid inviability, and hybrid sterility.
Biomes – classification of large areas of the earth.
Circulation – movement of air promotes deserts and forested areas.
Altitudinal gradient – as you move up higher above sea level, there is a drop
in temperature and an increase in precipitation.
Where does variation come from?
o Microhabitat – sub-environment that produce different conditions to
o Human impact
o Altered physical landform
o Introduction of non-native species
o Herd behavior
o Physical factors such as pH, soil acidity, nutrients, etc.
A graph of ‘# of species’ vs. ‘Area’ could produce different graphs. If the curve
saturates quickly, then there are few variations within the habitat. A
secondary jump in the graph indicates a new ecological zone.
Latitudinal gradients - there are more groups near the equator than farter
away. This is a general trend. At the equator, there is less climatic variability,
more space, the land is older (because of glacier movement), and it is
connected to more land.
Theory of Island Biogeography – by MacArthur and Wilson. The theory
focuses on prediction based on area and isolation. These two men created a
neutral theory, like the Hardy-Weinberg Theory. o Their graph shows an intersection between immigration and
o It is an equilibrium based model.
o The value of ‘T’ indicates the turnover at equilibrium.
o Their basic theory has been supported by various experiments.
Island Biogeography Theory can also be used on land, such as in areas of
mountains or clear-cut forests.
Principle of reserve design exists. In general, one large is better than several
small. This is because of edge effects.
Performance curves – depict the range of tolerances with which an individual
can survive, grow, and reproduce.
Law of Toleration – the performance of an organism is determines based on
maximum performance and environmental conditions.
Specialist – high performance under a specific set of abiotic conditions.
Generalist – high performance under an array of abiotic conditions.
Hutchinson – the niche is an “n-dimensional hypervolume”.
Fundamental niche – conditions which allow the species to survive
Realized niche – the reality of the species.
Time-Energy charts show that organisms spend time and energy on growth,
maintenance, activity, and reproduction.
o If a species uses more energy and time on maintenance, it may be
living outside of its niche.
Albedo – the reflection of light of a particular area.
Hs= H m +/H cd+/-Hcv+/-H r-H e
In the arctic, plants are slow growing, grow low to the ground, have leaves
perpendicular to the sun, and have a darker body.
In the desert, there is a decreased surface area of leaves, plants are tall,
round, and close to the ground. They are also parallel to the sun to minimize
Poikilotherm – body temperature varies over time.
Homeotherm – organism which has constant body temperature.
Endotherm – heat is derived from metabolic processes.
Ectotherm – heat comes from other sources.
Thermal Neutral Zone – the range of temperatures at which the body can
cope without additional metabolic regulation.
Opportunity Cost – a cost that isn’t measurable in terms of energy.
Size of carnivore and detritivore is dependent on si