Ecology Part 1 (Population Study)

Front 1

Phylogenetic Tree

Back 1

-Tells an evolutionary story
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Front 2

Study of Ecology

Back 2

Ecology is the study of the interactions living things have with each other and with their environment.

Specializations
There are five scales of life that concern ecology:
Organism: the unit organism
Population: group of organisms of the same species living in one location
Community: populations of different species living in one location
Ecosystem: the physical (abiotic) and biological (biotic) components of a habitat
the biosphere: all locations on Earth where life exists

Front 3

Populations

Back 3

Populations experience changes in their size over time.

Population Size (N)
-------------------------------
Change in time (T)

-Two factors that can increase population size, birth (B) and immigration
-Two Factors that decrease population size (D) and migration

Front 4

Population Basics of Models

Back 4

Populations experience changes in their size over time.

-Intrinsic factors (such as reproductive rates) and extrinsic factors (such as food availability or predators).

-When studying changes in population size, we refer to ‘N’ (population size), or more precisely, ∆N/∆t (change in population size over a change in time). AKA, dN/dt

Front 5

3 Possible Sitatuations regarding population growth (LINEAR MODEL or Arithmatic Models)
And the 4 factors that affect growth

(N)
-----
(T)

Back 5

Two general factors increase a population size: births (b) and immigrations.
Two factors decrease population size: deaths (d) and emigration.

For a population that is closed (nobody in, nobody out) only births and deaths affect the population size at any time.

The models below shows three linear (arithmetic) situations of population growth.

B>D
B=D
B<D

Front 6

Exponential Growth; J Curve

Back 6

-A population will experience exponential growth if unchecked by (K)

Shaped like a J

The general equation is dN/dT=rN where R is growth rate and N is initial population growth

Arithmatic increase is also called lag phase

Exponential increase is called Acceleration Phase

Small changes in r(growth rate) can make a big difference on the graph.

Front 7

Arithmetic vs Exponential Growth

Back 7

An arithmetical increase occurs when, over a given interval of time, an unvarying number of new units is added to a population.

An exponential increase occurs when the number of new units added to a population is proportional to the number of units that exists….percent growth.

Front 8

Logistic Growth; S Curve

Back 8

-Realistically populations start growing exponentially but inevitably level off, resulting in the logistic growth

Where they start to level off is denoted as K, or Carrying Capacity

The equation for logistic growth is:
dN/dt = rN(K - N/K) which acts a brake

Front 9

Environmental Resistance

Back 9

-Environmental Resistance is Defined as all the forces that act to limit population growth.

-Carrying Capacity (K) is the maximum number of organisms that environment can support

-The carrying capacity is the result of extrinsic forces from the environment.

The equation for logistic growth is:
dN/dt = rN(K - N/K)

K - N/K acts like a brake, so that as the population (N) approaches K, K - N/K approaches 0 and the growth rate similarly approaches 0.

Front 10

Population Regulation Factors
(Density Dependent)

Back 10

Density Dependent Factors(Their effect is greater as the population grows)
-Competitors for limited resources

-Predation becomes more intense

-Diseases become more common

Front 11

Population Regulation Factors
(Density Independent)

Back 11

-Catastrophes (Earthquake, Flood, Fire)

-Seasonal cycles in rainfall and temperature

Front 12

The reality of Population Growth

Back 12

-Exponential growth models are better than arithmetic models because populations grow as a percent of the total population.

-Logistic growth models are better than exponential models because of the inclusion of the all-too-real carrying capacity

-Yet, in reality, actually population growth is a lot ‘noisier’ with fluctuations due to seasons, etc.

Front 13

Reproductive Strategies

Back 13

Different species have different reproductive strategies, meaning characteristics that have the effect of increasing the number of fertile offspring they bear.

-These are important elements of a species' life history.

Front 14

Reproductive Strategies
(K Selected Species or Equilibrium Species, Quality>Quanity)

Back 14

-Large

-Relatively stable environment

-Provide care for offspring

-Affected by density dependent factors.

-Produce few offspring

-Don't reproduce until current offspring are cared for.

-Experience a Type I Survivorship Curve

Front 15

Reproductive Strategies
R Selected Species, or Opportunistic Species (Quantity > Quality)

Back 15

-Smaller Species

-Experience environment as relatively unstable

-Affected by density independent factors

-Maximize Output

-Limited by Reproductive rate (R)

-Produce no care for Offspring

-Experience a Type III survivorship curve.

Front 16

How Abiogenesis produced Amino Acids

Back 16

Stanley Miller recreated the environment for which life began on earth

Building Blocks
-Methane
-Amonia
-No Oxygen
-Glass Bottle

Energy Source
-Electricity

Result was a black tar which happened to be amino acids

Front 17

How Amino acids from Abiogenesis created Cells

Steps 1-3 all lab achievable.

Back 17

-The formation of the building blocks of organic molecules

-The combining of these building blocks into bigger, more complex molecules

-The creation of a membrane (To protect building blocks from outside environment)

-The evolution of the first self replication molecules. (Ribozymes)

Front 18

Survivorship Curves

Back 18

-Survivorship curves describe how soon species members tend to die within the species’ life span.

-These curves form the basis of a cohort study, with a cohort being those members of a population of the same age.

Front 19

There are three idealized types of survivorship curves:

Back 19

-Late loss (Type I)--low juvenile mortality/high survival

-Constant loss (Type II)--Age-independent survivorship

-Early loss (Type III) high juvenile mortality/low survival

Front 20

Late Loss (Type I) Survivorship Curve

Back 20

-Late loss (Type I)--low juvenile mortality/high juvenile survival

-Members of late-loss species tend to survive into old age.

-Exhibit a Columnar Age Structure graph (high survival, low reproductive rate)

Front 21

Constant Loss (Type II) Survivorship Curve

Back 21

-Constant loss (Type II)--Age-independent survivorship


-Members of constant-loss species tend to die off at a nearly constant rate throughout their lifespan.

-

Front 22

Early Loss (Type III) Survivorship

What type of Species Exhibits this?

What age structure diagram does this exhibit?

Back 22

-Early loss (Type III) high juvenile mortality/low juvenile survival

-Members of early-loss species tend to have high death rates early in life, with these rates leveling out thereafter.

-Exhibit pyramidal age structure (low survival, high reproductive rate)

Front 23

Life Tables

Back 23

-Survivorship curves are made from life tables, which set forth the probabilities of a member of a species being alive after given intervals of time.

Front 24

Age Structure Diagram

Back 24

-An important step in calculating the future growth of human populations is to learn what proportion of the population is at or under reproductive age. An Age Structure diagram achieves this.

-Populations whose age-structure diagrams are heavily weighted toward younger age groups are likely to experience relatively large growth.

Front 25

Age Structure Diagram
(Columnar)

Back 25

--the result of low reproduction rates and high juvenile survival

Front 26

Age Structure Diagram
(Pyramidal)

Back 26

(shaped like a pyramid)--the result of high reproductive rates and low juvenile survival

Front 27

Global Population Increase

Back 27

-Following decades of explosive increase, the global population will stabilize to 9.5 billion in 2050+

-This stabilization brought about by a decrease in the total fertility rate, informally defined as the number of children born, on average, to each woman in a population.

Front 28

Fertility rate in More Developed vs Less Developed

Back 28

-The global reduction in fertility masks enormous, ongoing differences between fertility in more-developed and less-developed countries.

-Fertility in less-developed countries tends to be much higher than that in more-developed countries. The fertility in most European nations is now so low that the continent’s population stands to shrink significantly by mid-century.

Front 29

Population Growth in the United States

Back 29

-The population of the United States, however, is projected to grow significantly during this same period.

-The primary factors bringing the U.S. increase about are immigration and a high total fertility rate relative to other developed nations.

Front 30

Per Capita
How much many more resources does a person from irvine use compared to people in less developed countries?

What are two factors that scientists say contribute to environmental harm

Back 30

-Some scientists believe that there is no greater single threat to the environment than the continued growth of the human population.

-Others argue that a more important concern is the use of natural resources per person. The energy cost of maintaining the lifestyle of a person from Irvine is about 240 times greater than a person from a less-developed country.

Front 31

Cohort Study

Back 31

A cohort is specific age group within a population

Front 32

Life Tables(Cohort Study)

Back 32

-Set forth the probabilities of a member of a species being alive after given intervals of time

-

Front 33

Population Age Structure Diagram

Back 33

-Important step in calculating the future growth of human populations

-To learn what proportion is at or under reproductive age

-Shows each gender