Transcript Unit One “Biology Basics”

Unit One
“An Introduction to
Environmental Science”
Reasons for and Purpose of
Environmental Science
• Environment – sum total of one’s surroundings;
two categories that compose “surroundings”
– Biotic Factors – living organisms both plant (flora) and
animal (fauna)
– Abiotic Factors – nonliving things such as water, air,
and soil
Reasons for and Purpose of
Environmental Science cont’d
• Environmental Science studies how the
natural world functions and the specific
interactions between humans ( Homo
sapiens) and their surroundings
• It is highly interdisciplinary and
incorporates subjects such as: biology,
ecology, geology, meteorology,
oceanography, limnology, sociology, and
public policy….
Reasons for and Purpose of
Environmental Science cont’d
• If humans did not have an impact on the
natural world there would most likely not
be the discipline of Environmental Science
• Humans impact the earth specifically
through the extraction/acquisition of
resources
• Resources – various substances found in
nature that are needed for survival and
comfort
Reasons for and Purpose of
Environmental Science cont’d
• Two types of resources:
– Renewable resources – unlimited supply
assuming wise use (these resources are
usually biotic)
• Example
– Nonrenewable resources – limited supply
(these resources are abiotic)
• Example
Reasons for and Purpose of
Environmental Science cont’d
• The goal of an environmental scientist is to
understand how humans impact the earth (both
negatively and positively). Additionally, if there
are any negative impacts, environmental
scientists research and implement ways to
mitigate those impacts
• Environmental Science IS NOT the same as
Environmentalism
• Environmentalism is a social movement
dedicated to the preservation of the natural
world; this movement began in the early 1970’s
with the celebration of the 1st Earth Day
The “Science” behind
Environmental Science
• In order to properly conduct scientific research of
any kind the scientific method must be employed
• There are 5 steps to this method
• What are the steps?
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1) State problem
2) Formulate hypothesis
3) Experiment
4) Analyze results
5) Conclusion
The “Science” behind
Environmental Science cont’d
• When research/experiments are
conducted, quantitative data and not
qualitative data must be collected
• The collection of quantitative data allows
the scientist to remain objective in the
reporting of his/her data
– Quantitative = Objective
– Qualitative = Subjective
The “Science” behind
Environmental Science cont’d
• Bias should be avoided
• Control(s) should be used in experiments for the
purpose of comparison
• Variables that would negatively affect results of
an experiment should be eliminated
• Independent variable – variable scientist
manipulates (example: time)
• Dependent variable – it’s outcome depends on
independent variable (example: temperature)
• http://www.biologycorner.com/worksheets/
controls.html
Data should be plotted on a graph
The “Science” behind
Environmental Science cont’d
• Step 2 of Scientific Method requires one to form
a hypothesis a.k.a. “educated guess”
• Step 5 of Scientific Method requires one to
support or not support the hypothesis made in
step 2 based on data obtained in step 3
• If experiment is deemed worth by peers it can be
published in one of numerous scientific journals
for the purpose of disseminating
information/knowledge
Unfortunate Reality in Science
• One in seven scientists say they are aware of
colleagues that have invented results
• Dishonesty and misrepresentation are
widespread due to several factors:
– Inherent bias
– Professional pressure
– Monetary gain
“One in Seven Scientists Say Colleagues Fake
Data” in The Times; June 5th, 2009
The “Science” behind
Environmental Science cont’d
• Theory - statement based on a large
supporting body of evidence; is more
accepted in scientific community than a
hypothesis
– “Evolution”
• Law – scientific fact
– “For every action there is an equal and
opposite reaction”
Current State of Affairs
• Is our planet healthy? Are we having a net
negative impact on the Earth?
• The above questions will be
addressed/discussed throughout the
semester
Unit One
“Biology Basics”
“Evolution, Biodiversity, and
Population Ecology”
Concepts surrounding Evolution
• Evolution – the change in the genetic
composition of a population over time due to
chance alone
• Natural Selection – the process by which
mutations create certain traits that are more
suited to an environment than other traits
• Adaptation – individuals that possess those traits
that are more suited to the environment survive
and generally thrive
Concepts surrounding Evolution
cont’d
• Mutation – a random change in the genetic code
(DNA/RNA)
• These mutations lead to the development of new
traits both helpful and detrimental to a species
• Charles Darwin was the first person known to
propose these concepts; voyage of the HMS
Beagle in the 1800’s
• http://history1800s.about.com/od/innovators/a/h
msbeagle.htm
Concepts surrounding Evolution
cont’d
• Evolution leads to biological diversity
• Biodiversity is the variety of life in an
ecosystem or defined area
• Areas with high biodiversity are called hot
spots; these areas are usually in regions
with a moderate climate
Biodiversity Hot Spots
(red)
Concepts surrounding Evolution
cont’d
• Speciation leads to many new species several of
which may be wiped out by an extinction event
• Extinction causes the disappearance of many
species but also allows for the evolution of many
new species
• Extirpation is the extinction of a species in a
specific area
• All past mass extinctions were most likely due to
catastrophic natural occurrences like Ice ages,
meteorites, and volcanic eruptions
Levels of Ecological Organization
• Ecology – study of the biotic and abiotic
factors in an area
• Species - organisms that look similar and
can breed to produce reproductively
capable offspring
• Population – a group of individuals of the
same species living together
• Community - several populations that live
in the same area
Levels of Ecological Organization
cont’d
• Ecosystem – a defined area with a specific
set of biotic and abiotic factors; usually
defined by vegetative associations
• Speciation is demonstrated by using a
Phylogenetic Tree
• Habitat versus Niche – habitat is where an
organism lives a niche is how an organism
lives in its habitat
Levels of Ecological Organization
cont’d
• Specialist versus Generalist - a specialist
requires a specific set of resources
whereas a generalist can live off a broader
range of resources
– Example: Scrub Jay and Raccoon
Population Ecology
• Population Ecology – study of the
dynamics of populations such as density,
distribution, sex ratio, age structure, and
mortality/natality
– Population density – how many individuals
there are of a species per unit area
– Population distribution - spatial arrangement
of individuals within an area
Population Ecology cont’d
• Survivorship curves – show the distribution
of ages across a population; predicts the
likelihood of death at various ages per
species
Population Ecology cont’d
• Immigration versus Emigration
– How many enter an area versus how many
leave an area
– Formula for Growth Rate
(Birth Rate + Immigration Rate) –
(Death Rate + Emigration Rate) = Growth rate
Population Ecology cont’d
• Population growth is dependent on biotic
potential
• Some species can reproduce many offspring per
reproductive event, and can have several
reproductive events per year
• Those species that fit into the above-mentioned
category are “r – selected”: mice and rabbits
• Species that seldom reproduce, and when they
do reproduce only have one or two offspring are
“k-selected”: whales and humans
Population Ecology cont’d
• Limiting Factor – a resource that prevents a
population from increasing in size
• Carrying Capacity – total number of individuals
an ecosystem can sustain based on resource
availability
• Limiting factors can vary from ecosystem to
ecosystem and populations of different species
can vary in size within the same ecosystem
• What are some examples of limiting factors?
Population Ecology cont’d
• Exponential Growth – the global human
population began to increase rapidly at onset of
the Industrial Revolution but has since slowed
appreciably with growth only continuing in less
developed nations
• Now there is a population paradox globally – will
discuss human population in unit 2