Predicting Relative S0 Values of a System
- 1)Temp changes (S increases as temperature rises)
- 2)Physical States and phase changes (S increases as more ordered phase changes to a less ordered phase
- 3)Dissolution of a solid or liquid (S0 of a dissolved solid or liquid is usually greater than the S0 of the pure solute. However, the extent depends upon the nature of the solute and solvent.
- 4) Dissolution of a gas (A gas becomes more ordered when it dissolves in a liquid or gas)
- 5) Atomic size or molecular complexity (In similar substances, increases in mass relate directly to entrophy, In allotropic substances, increases in complexity (e.g. bond flexibility) relate directly to entropy
Concept 17.2: Global patterns of species diversity and composition are controlled
by geographic area and isolation, evolutionary history, and global climate.
Concept 17.1: Patterns of species diversity and distribution vary at
global, regional, and local spatial scales.
Concept 17.3: Regional differences of species diversity are controlled by
area and distance due to a balance between immigration and extinction rates.
In 50 years’ time, -----------of the rainforest has been converted to pastureland, towns, roads, and mines.
the study of patterns of species composition and diversity across geographic locations
is number of different species
The actual species that are in an area
The forest tour reveals several patterns:
- -Species richness and composition vary with latitude.
- -In general, the lower tropical latitudes have many more, and different, species than the higher temperate and polar latitudes.
- -Species richness and composition also vary from continent to continent, even where longitude or latitude is roughly similar.
- -The same community type or biome can vary in species richness and composition depending on its location on Earth.
Global scale—the entire world... of the forest tour results
- -Species have been isolated from one another, on different continents or in different oceans, by long distances and over long periods.
- -Rates of speciation, extinction, and migration help determine differences in species diversity and composition.
climate is roughly uniform and the species are bound by dispersal to that region.
Regional species pool—
- all the species contained within a
- region (gamma diversity).
equivalent to a community. Species physiology and interactions with other species weigh heavily in the resulting species diversity (alpha diversity).
change in species number and composition, or turnover of species, as one moves from one community type to another.Beta diversity represents the connection between local and regional scales of species diversity.
Wallace is best known, along with Charles Darwin, as the codiscoverer of the principles of natural selection.But his main contribution was
the study of species distributions across large spatial scales. He rightly earned his place as the father of biogeography.
Wallace overlaid species distributions and geographic regions and revealed two important global patterns:
- Earth’s land mass can be divided into six biogeographic regions.
- The gradient of species diversity with latitude.
The plates are sections of Earth’s crust that move or drift (called?)
(continental drift) through the action of currents generated deep within the molten rock mantle.
While the number of families increased at low latitudes, longitude also had an effect. So-called ?
hot spots or areas of high species richness occur at particular longitudes, sometimes secondary to latitude.
What ultimately controls the rates of speciation and extinction?
- Three of the theories are
- Temperature Hypothesis
- Evolutionary History Hypothesis
- Productivity Hypothesis
1) Temperature Hypothesis:
Terrestrial species diversity is highest in the tropics because the tropics have more land area than other latitudes.This area is also the most thermally stable—temperatures remain uniform year-round.
2) Evolutionary History Hypothesis:
Tropical regions have longer histories, they have been climatically stable and thus had a lot of time for evolution to occur.At higher latitudes, severe climatic conditions such as ice ages would increase extinction rates and hinder speciation.
Seabirds have highest density at
temperate and polar latitudes.This pattern correlates with marine productivity, which is substantially higher in temperate and polar oceans.
3) Productivity Hypothesis:
For terrestrial systems, species diversity is higher in the tropics because productivity is higher.Higher productivity should promote larger population sizes, which will lead to lower extinction rates.
An important concept in biogeography is the relationship between
species number and geographic area.
species richness increases with increasing area sampled.
A species-area curve is the relationship between
the spatial area of habitat and number of species found within that area.On a log-log plot, these relationships can assume a straight line.
The Species-Area Law
- S = number of species A = island area c = y-intercept (constant) z = line slope (constant
- log S = log (cAz)
- log S = (log c) + z(log A)
- y=mx +b creates a line
Pangaea first split into two land masses....
, Laurasia to the north and Gondwana to the south.
Gondwana separated into
present-day South America, Africa, India, Antarctica, and Australia.
Laurasia eventually split up into
North America, Europe, and Asia.
Some continents were separated from one another; others came together (e.g.....
, India collided with Asia, forming the Himalayas).