Download Ecology and Populations

Ecology and Populations
What is ecology?
 Ecology is the scientific
study of interactions
between organisms and
their environment.
Ecology
 Ecological systems have both biotic and abiotic
components.
 What are a few examples of biotic and abiotic
factors?
Populations
 Individuals of the same species, at the same place, at
the same time.
 Demography- the study of populations and
population processes
Populations
 All populations have 3 characteristics: distribution,
density, and growth rate or age structure.
 Distribution- the range a population covers
 Density- The number of individuals per unit area;
measured by sampling or census
 Sampling- measuring a portion of a population to
estimate the whole population
 Census- a full count of the population
Populations
 Growth and Age Structure- Population sizes vary
year by year. Members of a population are
organized into an age structure, which separates
members by gender and age.
 Measuring growth Growth= Beginning pop+(birthdeaths)+(immigration-emigration)
 Immigration= the number of individuals entering a
population
 Emigration= the number of individuals leaving a
population
Practice Problem
 Suppose a population of cows with 523 members
has 124 births, 94 deaths, 13 emigrations and 24
immigrations. What is the new size of the
population?
 A population of 307 sparrows lives in the fields
surrounding the school. The following summer, the
population was re-counted and there were 270
sparrows. Assuming there were 57 births, 0
immigrations, and 14 emigrations, how many
deaths were there during the winter?
Population Growth
 Age structure diagrams help to give a visual
representation of how the population is made up in
terms of age and gender.
•There are 4 different types:
•Rapid growth
•Slow growth
•Zero growth
•Negative growth
Population Growth
Population Growth
 There are two types of growth models for
populations: exponential and logistic.
 Exponential: unregulated growth- the population
can grow forever. (Ideal)
 Logistic: limited growth with limiting factors. The
population grows until it reaches the carrying
capacity
Population Growth
 Growth factors:
 Density dependent: factors that depend on how many
individuals are in a given area.
 Density independent: factors that are not affected by
how dense the population is.
Population Growth
 Which of the following are density dependent?
Density independent?
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Food
Natural disaster
Weather and Climate
Disease
Predators
Human Activity
Living space
Population Growth
 Survival curves: Help to show the survivorship
rates through different ages and stages of life.
 3 types:
 Type I: High juvenile and adult survival, parental
care, and low fecundity (numbers of offspring)
 Type II: Constant survival/death rates throughout life
 Type III: low juvenile survival rates, high fecundity,
no parental care.
Population Growth
Human Population
 How does this all relate
to the human
population?
 What growth pattern
does the human
population follow?
 What will limit our
growth eventually?
Human Population
 The human
population
exhibits all 4
types of age
structure:
Human Population
 Consequences?
 Ecological footprint is huge- too many demands with
limited resources in the environment?
 What are some of these ecological demands?
Resources
 There are many resources I have posted online if
you would like to, or need, more review.
 www.sciencerules2.wikispaces.com
 www2.onu.edu/~k-morris.1