Transcript Chapter 1 - Department of Biological Sciences

Biology 216 Ecology
Mark Pyron
Professor
CL 229
285-8852
[email protected]
Syllabus
Online:
Blackboard
ebook required:
Molles 7th edition
Attendance is required -
Assignments:
Reading assignments
Read online chapter
Answer questions
Written assignments
Cheating
• Zero grade for all involved
• Grade of F in course for cheating on
exam
Exams?
Blackboard – testing
center
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•
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•
Short answer
Matching
Multiple choice
Essay questions
Objectives
• Students will be able to describe the
nature and scope of Ecology
• Students will be able to explain the role
of Evolution theory in Ecology
• Students will be able to describe how
ecologists gain knowledge
Chap 1
What is ecology?
Many definitions:
“Scientific study of the
distribution and abundance
of organisms”
(Andrewartha and Birch)
Another definition:
“study of the structure and
function of nature”
(Odum)
Ecology tries to explain the
patterns that you find in the
real world:
Why are plants and animals
where they are, and how
many are there in those
locations?
Ecology is a broad science:
Plants, animals,
protists, monera,
fungi
Soils, air, water
Physiology,
taxonomy,
chemistry,
geography,
behavior, etc.
Community
ecology
Landscape
ecology
Population
ecology
Systems
ecology
Population
biology
Population
genetics
Physiological
ecology
Why be an ecologist?
Most ecologists develop a “love” for
their organism, for the
environment, and for asking
questions about their system.
Types of Ecological
Studies
• Observational
– Descriptive
– Random sampling or replication
– Describe some aspect of natural world
Observational
• Based on Representative Samples
– Random sampling from “population of
interest” to obtain “unbiased” information.
– Replication: Multiple individuals / areas
observed to document variation.
Types of Ecological
Studies
• Comparative studies
– What is influence of factor(s)
– Data from natural world
Hot
Environment
Warm
Environment
Cold
Environment
What is the effect of
temperature on the
abundance of ants ?
Comparative
Study
Comparative Studies
• Purpose: To determine the influence of
one or more “factors” on some aspect of
the natural world.
• Compare samples from populations,
communities, ecosystems – do they
change with the factor?
Disadvantage of
Comparative Studies
• Many environmental factors differ
among any two natural communities.
• Difficult to know if observed differences
in the “response” variable are caused by
the “treatment” variable or by some
other factor.
Types of Ecological
Studies
• Experimental
– Determine effect of treatment
– Randomize individuals or areas
– Replication = many samples
– Control
Controlled
Environments
Heated
Environment
What is the effect of
temperature on the
activity of ants ?
Random
Observe
Assignment
Compare
Cooled
Environment
Experimental
Study
Experimental Studies
• Purpose: To obtain most definitive evidence
that “treatment” causes “response”, Test
Cause-Effect Hypotheses.
• Main Difference From Comparative
Studies: Investigator imposes treatment on
study subjects.
• Can be done in Lab or Field
Aquatic Snails in Indiana
Mark Pyron and Jayson Beugly
Ball State University
Department of Biology
Historic distributions
• Museum records
– University Michigan
– Ohio State University
• > 100 lots
• Photograph individuals in each collection
Current distributions
• Visit historic sites
– 100+ sites revisited
– 20 new sites
• Collect in all habitats
• Water quality: hardness, DO, pH,
conductivity, Temp
Sites through-out Indiana: Eel River
Big Blue River at Edinburgh
E. Fork 14-mile Creek
E. Fork White River
Fall Creek in Indianapolis
Little Turkey Lake near Helmer
Ohio River at Aurora
Muscatatuck River
Campeloma decisum
Physa acuta
Lymnaea humilis
Elimia livescens
Pleurocera acuta
Bellamya chinensis
New Collection Results
• 15,227 individuals in
26 species
• 2.8 species per site
• 144 individuals per site
Status
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•
•
One extinction (Valvata bicarinata)
12 imperiled
3 vulnerable to extinction
9 widespread + abundant
Taxa with highest abundances
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Elimia livescens
Physa spp.
Pleurocera acuta
Fossaria spp.
Pleurocera canaliculata
Stagnicola elodes
Lymnaea catascopium
Campeloma spp.
• 10,564
• 1,769
• 990
• 759
• 279
• 108
• 103
• 96
Species Richness
Lakes in North have
higher species richness
Abundance patterns
Wabash River mainstem
has highest abundances
Results
• Latitude important at regional scale
• Habitat variation and water
chemistry important at local scale
Observational, comparative,
or experiment?
Experimental Design: Part 1
Random Assignment
of Study Subjects /Areas
to Treatment Groups
Equivalent Groups:
Similar as possible
BEFORE imposing
treatment.
Replication: Multiple
Study Subjects Assigned
to Each Treatment Group
Stronger evidence that
differences between
groups are caused
by treatment.
Experimental Design: Part 2
Control of all nontreatment factors
to be same for all
experimental groups
Differences observed
between groups caused by
treatment, NOT other
factors.
Comparison of
groups that received
different treatments
to determine response
Differences observed
between groups would
NOT have happened
without treatment.
Limitations of Experiments
• Subjects in controlled experimental
conditions may not respond the same
as when they are in their natural setting
(Less Realistic).
• Some subjects very difficult to study in
controlled settings (Lions, Trees,
Communities, Ecosystems)
Role of evolution
theory in ecology
• 1. What is evolution?
– Changes in populations of organisms over time
– Includes changes in gene frequencies = genetic
Role of evolution
theory in ecology
• 2. How does natural selection work?
– Cruel world
– Genetic variation
– Differential survival and repro
• Genes for advantageous traits spread
Role of evolution
theory in ecology
• 3. Some characteristics (traits) are “best
available” for survival and reproduction
(NOT the “BEST”)
• In a given environment
Evolution =
change in organisms with generations
not changes in
communities (=
extinctions or
more species)
Adaptation:
allow organisms to survive + reproduce design of organisms.
Darwin –– woodpecker
example:
Woodpecker adaptations
Beak, tongue,
tail, toes
Natural selection
• Some individuals survive and
produce more offspring than others.
• Their traits “work better” in that
environment.
On what level does
natural selection act?
• Individuals?
• Species or populations?
• What entity evolves over time?
Pioneering ecological
study:
• Robert MacArthur
• 5 forest warblers found in same forest
– How do they all live in same environment if
they are all same size and all eat insects?
MacArthur
• Divided trees into zones
• Recorded time that 5
species spent in zones
MacArthur results:
• Birds divided tree into zones
• Appears to reduce competition
Further studies confirmed that competition
maintains feeding zones experimentally:
Field studies can be
combined with lab
experiments
• Answer more detailed questions
– Field = natural settings
– Lab = controlled environment
Ecologists use
available tools
• Can include behavior + physiology,
• Or, geology + paleontology
• Etc., depending on the question