© 2012 Eucalyptus Systems, Inc. Eucalyptus Internals Release 3.2 Rich Wolski CTO Eucalyptus Systems.
Biosphere Ecosystems Community Population ECOSYSTEM LEVEL Eucalyptus forest COMMUNITY LEVEL All...
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Transcript of Biosphere Ecosystems Community Population ECOSYSTEM LEVEL Eucalyptus forest COMMUNITY LEVEL All...
• Biosphere
• Ecosystems
• Community
• Population
ECOSYSTEM LEVELEucalyptus forest
COMMUNITY LEVELAll organisms ineucalyptus forest
POPULATION LEVELGroup of flying foxes
ORGANISM LEVELFlying fox
ORGAN SYSTEM LEVELNervous system
ORGAN LEVELBrain
Brain Spinal cord
Nerve
TISSUE LEVELNervous
tissue
CELLULAR LEVELNerve cell
MOLECULAR LEVELMolecule of DNA
Figure 1.1
POPULATIONS Population-all of the individuals of a
species that live together in one place at one time.
Demography-the statistical study of populations. It is used to predict how the size of a population will change.
COUNTING POPULATIONS
direct observation-count indirect observation-estimate sampling-count small number in a small area and multiply to get the number in the large area mark and recapture studies-capture, mark, release
KEY FEATURES OF POPULATIONS
1. Population size is the number of individuals in a population. had an important effect on the ability of the
population to survive.
A small population is more likely to become extinct: in the case of random events or natural
disaster due to inbreeding where the population is
more genetically alike. with reduced variability it is harder to adapt
to changes.
KEY FEATURES OF POPULATIONS, CON’T
2. Population density
– the number of individuals in a given area.
– if they are too far apart they may only rarely encounter one another resulting in little reproduction.
KEY FEATURES OF POPULATIONS, CON’TPOPULATION SIZE IS LIMITED BY:
density-dependent factors
Disease Competition Predators Parasites Food Crowding
The greater the population, the greater effect these factors have.
Ex. Black plague in the Middle Ages – more deaths in cities
density-independent factors
Volcanic eruptions Temperature Storms Floods Drought Chemical pesticides Major habitat disruption
(as in the New Orleans flooding)
Most are abiotic factors
KEY FEATURES OF POPULATIONS, CON’T
3. Dispersion – the way in which the individuals are
arranged.
Most common
POPULATION GROWTH
Population Growth Three factors can affect population size:
number of births (natality) the number of deaths (mortality) the number of individuals that enter or
leave the population (immigration and emigration).
* Simply put, a population will increase or decrease in size depending on how many individuals are added to it or removed from it
IMMIGRATION & EMMIGRATION Immigration
the movement of individuals into an area, is another factor that can cause a population to grow.
Emigration the movement of individuals out of an area, can cause a
population to decrease in size.
PREDICTING POPULATION GROWTH, CON’T Nearly all populations will tend to grow
exponentially as long as there are resources available.
Two of the most basic factors that affect the rate of population growth are the birth rate, and the death rate.
r(rate of growth)=birth rate – death rate
PREDICTING POPULATION GROWTH, CON’T
Exponential growth curve: population growth plotted against time.
As a population gets larger, it also grows at a faster rate.
Maximum population growth under ideal circumstances.
Includes plenty of room, unlimited resources (food, water) and no predators. FACT: No population exhibits this type of growth for long.
PREDICTING POPULATION GROWTH, CON’T Logistic model: This model accounts for the declining
resources available to populations as they grow. It assumes the birth and death rates are not
constant. As the population grows, births decline and death
rises. Eventually birth=death so the population stops
growing.
Carrying capacity (K): The number of organisms of one species that an environment can support indefinitely.
PREDICTING POPULATION GROWTH, CON’T TWO MODES OF POPULATION GROWTH.
The Exponential curve (also known as a J-curve) occurs when there is no limit to population size.
The Logistic curve (also known as an S-curve) shows the effect of a limiting factor (in this case the carrying capacity of the environment).
POPULATION GROWTH STRATEGIES
There are 2 ways a population can prosper:
1. Depends on the rate of growth (r)2. Influenced by the carrying capacity
(K)
POPULATION GROWTH STRATEGIES, CON’T
r-strategists: “boom and crash” characterized by exponential growth, which results in temporarily large populations, followed by sudden crashes in population size. Ex. Insects, bacteria, some plants live in unpredictable and rapidly changing
environments Reproduce quickly when conditions are favorable Many offspring: small, mature rapidly, no parental care r = rate of growth
POPULATION GROWTH STRATEGIES, CON’T
K-strategists: characterized by a high degree of specialization. Ex. Trees, whales, tigers, etc. Live in stable and
predictable environments Can compete effectively Reproduce late in life Few offspring: large, mature slowly, often much parental care K = carrying capacity
POPULATION GROWTH STRATEGIES, CON’T Human Populations: K- strategist characteristics But, recently, humans learned to expand carrying capacity of
environment by increasing food supply, combating pests and curing diseases.
Can Earth support this increase?
doubled three times in the last three centuries
about 7 billion and may reach 9.3 billion by the year 2050
improved health and technology have lowered death rates
THE HUMAN POPULATION