Evolution, Ecosystems and

Living Organisms.Chapters 5, 8 & 9.

A. How Populations change over time.1. We often think of evolution as the idea that all living

organisms descended from earlier species.2. Most accepted take on evolution was stated by

Charles Darwin.• Darwin believed that the environment played an

important role in shaping species.• Traits that increased the chance of survival would

be preserved while unfavorable traits would eventually be eliminated. These adaptations(physical or behavioral) increased the overall success of the species.

3. Darwin summarized this as evolution by natural selection. (1859 The Origin of Species by Means of Natural Selection.)

4. Evolution by natural selection consists of four observations about the natural world: overproduction, variation, limits on population growth, and differential reproductive success.

6. Overproduction – Each species produces more offspring than will survive to maturity. Why?

7. Variation – Each individual in a population has a unique combination of traits (size, color, and resiliency). Some traits increase the survival of the organism and some do not.

8. Limits on population growth (the struggle for existence) – Organism compete for the limited resources made available for them.

What are the basic resources?

9. Differential reproductive success – Only the individuals that possess the most favorable combination of characteristics are more likely to survive, reproduce, and pass their traits to the next generation. Reproduction is key to natural selection.

In some cases, enough changes may accumulate over time in geographically separated populations to produce new species. (speciation)

Different types of speciation

10. The modern synthesis of evolution is more of a result of combining parts of several theories (evolution by natural selection, genetics, the fossil record, comparative anatomy, biogeography, and molecular biology) to arrive at the current understanding of evolution.

B. The Domains and Kingdoms of Life.1. Most biologists accept a three

domain/six kingdom system of classification.

2. The three domains are: Archaea, Bacteria and Eukaryota.

3. The six kingdoms are:a. Archaea – prokaryotes.These organismslive in harsh conditionswith very little oxygen.

a. Methanogens b. Halophiles, acidophiles, alkaliphiles, c. Thermophiles d. Thermophiles.

b. Bacteria – all other prokaryotes. Mainly decomposers. Some are pathogens, parasites, or photosynthetic.

Eukaryotab. Protista – eukaryotes

that are unicellular or simple multicellular organisms. Can be photosynthetic, pathogens, parasites, and decomposers.

d. Fungi – most are complex multicellular eukaryotes. Some are decomposers, pathogens or parasites.

e. Plantae – complex multicellular eukaryotes. Most are photosynthetic.

f. Animalia – complex multicellular eukaryotes. All are consumers.

C. What is a community?– The community are all the populations (plant,

animal, other) found in a particular location at the same time. (In an ecosystem)

D. What factors most influence the size and number of populations?(or the amount of biodiversity) Temperature and Precipitation. – Also latitude and altitude, (remember 0º is the equator) the

amount of species diversity decreases.– Also : amount of food, space, water, weather conditions,

climate, etc…E. Where is most of the world’s biodiversity found?

– The most species rich environments are:Tropical Rain Forests. Coral ReefsOcean floor Large tropical lakes.Tropical dry habitats. (Savannas)(Chaparral)Wetlands.

F. What are the different types of species found in the communities?

1. Native species –– Species that normally live

in an ecosystemEx. Black Cherry trees

2. Non-native species (exotic, alien) –– species that migrate,

are deliberately, or accidentally introduced to an ecosystem.

Ex. Tree of Heaven, Kudzu, starlings

3. Indicator speciesSpecies that serve as early warnings that a community or an ecosystem is being damaged.

Ex. Amphibians

4. Keystone species –– Species play a pivotal

role in the structure, function, and integrity of an ecosystem because they have a greater influence when compared to their size or numbers

Ex. Pgs 178-180

H. How do species interact?

1. There are five basic interactions between species.a. Competitionb. Predationc. Parasitismd. Mutualisme. Commensalism

a. Competition( - \ -)

Intraspecific –between the same species.

Ex. Weeds. Can be reduced

due to territoriality.

a. Competition cont.

Interspecific –between two or more species.

Ex. Paramecium. Could be interference

or exploitation. Can be reduced by

resource partitioning by varying niches.

b. Predation (+ \ - )

A predator-prey relationship.

Can cause physical and behavioral changes in both the predator and prey to increase survival.

What are some possible examples?

Symbiosis

A long lasting relationship between two different species that live together in intimate association.

The three basic types are Parasitism, Mutualism and Commensalism.

c. Parasitism ( + \ - )

A parasite-host relationship

One species feeds on part of another species. Can live in or on the host.

Ex. How is parasitism

different from predation?

d. Mutualism (+ \+ )

Two species in a relationship where both benefit.

Ex.

e. Commensalism (+ \ 0 )

Two species in a relationship where only one benefits but the other is neither helped nor harmed.

Ex.

I. How these relationships affect species?

1. Niche – All the needs of a species to allow them to live and reproduce. – Fundamental niche – the potential amount of

resources a species can use without any competition.

– Realized niche – the actual amount of resources used by a species.

– Specialists – species that have very specific range of requirements to live and reproduce.

– Ex.– Generalists – species that have a very broad

range of requirements to live and reproduce.– Ex.

J. Characteristics of a population.

1. Size – the number of individual organisms present at a given time.

2. Density – the number of individuals within a population per unit area.

What are some advantages/disadvantages of having high density? Low density?

K. Characteristics of a population. cont.

3. Distribution /Dispersion – the spatial arrangement of organisms within an area. Random Uniform Clumped

L. Exponential Growth

population growth is very rapid, reflecting the maximum intrinsic rate of growth. This is described by the equation:

dN/dt = r N in which... dN = the change in population size (in small

increments) dt = the time interval (change in time) r = population growth rate N = population size

I. Exponential Growth

M. Logistic Growth

- exponential growth with environmental resistance (carrying capacity of the environment = K) incorporated into the equation:

dN/dt = [r N][K-N/K] in which... dN = the change in population size (in small increments) dt = the time interval (change in time) r = population growth rate N = population size K = carrying capacity (maximum number of individuals the

environment can sustain indefinitely)

J. Logistic Growth

J. Logistic Growth

N. Density-dependent and density-independent factors

D-D factors - the density of the population increase or decreases the impact of certain factors.– Mating– Predation– Competition– Disease

D-I Factors –density of the population has no influence on the impact of certain factors.– Natural disasters– Climatic changes

L. Reproductive Strategies.