BIOL MN HISTORY EXAM 5

Origins-

• Glaciers
– Path of drainage ways developed
under glaciers
– Some drained glacial lakes
• Some begin as wetlands and lakes
• Springs
• Receive water from drainage basin aka
watershed

Watersheds- drainage basins

Eight major river basins in MN
1. Rainy River Basin
2. Red River Basin
3. Lake Superior Basin
4. Mississippi River Basin
5. Minnesota River Basin
6. St. Croix River Basin
7. Missouri River Basin
8. Des Moines River Basin

Drainage basins and stream orders

• First order
– Smallest, youngest
– No tributaries
• Second order
– Two first orders join
• Third order
• Fourth order...
• Tenth order- Mississippi River

Physical characteristics

• More important than chemical and
biological
• Features often interrelated
• Physical characteristics:
– Shape, length, gradient
– Slope, bed composition
– Turbidity, temperature
– Water velocity

Changes in flow rate

• Flow rates differ at different points along a stream or river
• Flow rate changes seasonally and annually

Chemical characteristics

• Hardness- soft vs. hard water streams
– Influenced by rocks
• pH
– Hard water streams- neutral/based pH 7-9 (alkaline)
– Soft water streams, pH

Ecosystem function

• Primary productivity
– Production of stream vegetation AND plant parts fallen into
stream
– Washed up organic matter important
• Vegetation growing in stream usually
sparse
• Plants along banks more important
• Leaves, twigs provide food and
habitat
• Decompose- release nutrients
• Called ‘dissolved organic matter

Organisms grouped by relationship to moving
water

• Organisms habitat is dynamic
• Four groups
– Fixed, sedentary living at bottom
– Drifting
– Floating on surface
– Active swimmers

Ecosystem function

• Detritus food web more
important than grazing food web
• Aquatic plants
– Growth influenced by:
• Light
• Nutrients
• Shape of stream
• Mosses common at headwaters
• Algae more common at lower
reaches
• Primary consumers grouped by
feeding habits

Herbivores grouped by feeding habits

-Shredders (Scuds, Stonefly larvae)
-Secondary consumers-Predators
-Collectors-filterers and gathers
-Piercers
-Scrappers/grazers

Forms of organic matter in streams and rivers

• Coarse organic matter (CPOM)
– Leaves, branches
• Dissolved organic matter (DOM)
– Small organic compounds
dissolved in water
• Fine Particulate Organic Matter
(FPOM)
– Broken up CPOM or
– DOM that clusters via
flocculation
• “foam” on streams

River continuum concept

• Describe the energy flow and nutrient uptake and release with
stream movement
– Nutrients displaced downstream
Continuum concept divides a river into three sections:

Headwaters, Midstream, Lower Reaches

Macroinvertebrates

• Most important herbivores
• Insect body parts
- Head, Thorax, Abdomen

Macroinvertebrate life cycles

• Two life cycles
• Complete metamorphosis
• Incomplete metamorphosis
• Metamorphosis-
• process changing from an
immature form to an adult
form in two or more stages

Complete Metamorphosis

• Complete change from immature stage (worm like larvae) to a different shaped adult
egg------>larvae ------>pupae------->adult

Incomplete Metamorphosis

Immature stage looks somewhat like a miniature adult
egg -->nymph --> Adult
examples: mayflies, stone flies, dragon flies

Macroinvertebrates

Odonata= Dragonflies
and Damselflies
Coleoptera= BeetlesTrichoptera= CaddisfliesPlecoptera= Stoneflies
Ephemeroptera= mayflies
Diptera= Flies

Cold water streams

• Trout streams- cool, clear water, fast flowing
• Unglaciated parts of MN (SE)
• High alkalinity
• High aquatic insect diversity
• High nitrogen

Warm water streams

• Higher alkalinity than cold water streams
• Lower transparency
– Higher sedimentation
• Slow moving
• Higher pollution
• High productivity

Minnesota River is one of most polluted rivers
in MN

• Four categories of pollutants
– Bacteria
– Sediments
– Nutrients
– Other substances that reduce dissolved oxygen

• Ways to improve:
– Control erosion and runoff
– Create and enforce vegetative buffers

Mississippi River

• Split by St. Anthony Falls
– Divides into two parts
– Barrier for many aquatic species
• Ten lock and dams built between Minneapolis and Iowa border

Identify the four ways that a river might originate

• Paths developed under glacial ice
• Drainage of glacial lakes
• Begin as wetlands or lakes
• Spring fed

Contrast the form of the Mississippi River at Itasca to its form as it flows out of our state

At Itasca- shallow, narrow, fast moving and cold
At Iowa border- wide, deep, slow, and warm

Where does most of the water flowing in rivers and streams come from

Subsurface flow aka ground water

What factors determine discharge rate

Current velocity, depth and width (shape of river bed)

What are some of the typical features of lowland, downstream rivers?

Deeper water, warm, slow moving, higher loads of sediment, reduced transparency (high turbidity),
and low algae growth

What kinds of seasonal events might produce a current that dislodges invertebrates living on the
stream bed?

Seasonal flooding, most often associate with spring

Why are headwater streams generally cool, but downstream, higher-order streams are warm?

Many factors-primarily flow rate and source of water- spring fed=very cold. Also headwaters tend
to be more shaded than the lower reaches

Describe the relationship between temperature and the amount of dissolved oxygen that water can
hold

Cold water can hold more oxygen than warm water. This does not mean that all cold water has
more oxygen, it just has the potential to hold more. The warmer the water, the more gases like
oxygen have a tendency to diffuse into the air from the water.

Where does nitrogen come from in a stream? Phosphorous?

Significant portions enter from the atmosphere, but also from runoff and groundwater-primarily
from agriculture land but in some natural deposition occurs

List the sources of oxygen in streams. How is oxygen depleted

Agitation of water infuses streams with oxygen.
Photosynthetic organisms are the primary input of oxygen into streams.
Organisms that deplete oxygen include animals, plants, bacteria, protists. Anything that lives in a
stream will consume oxygen (including photosynthetic organisms

Identify the adaptation(s) of the following organisms to cope with current. More than one maybe
appropriate.

Attachment Devices---> snails and black flies
Streamlined Body ---> Trout
Heavy cases or shells --> caddis flies
Flattened body---> mayflies
Lifeline--> Black flies
"Hiding from current"---> Crayfish and Caddis flies

The energy sources of a stream can be classified according to the list below. After each, describe
and list what organisms and/or materials are found in each category.

• Producers (P)
Algae, phytoplankton
• Coarse particulate organic matter (CPOM)
Leaves, branches, fungi and bacteria on the leaves and branches
Shredders primarily feed on CPOM
• Fine particulate organic matter (FPOM)
Broken down CPOM and/or clumped DOM
Collectors primarily eat FPOM
• Dissolved organic matter (DOM)
Very small particles dissolved in water
Collectors feed on DOM

In what parts of a river system (upper stream, middle reaches, lower reaches) would you find the
most abundant quantities of the following

Bacteria and fungi- Upper stream
Oxygen- highly variable but least in the lower reaches
Turgid water (or turbid water)- lower reaches
CPOM- Upper stream/ headwaters
DOM- middle and lower reaches
FPOM- middle and lower reaches
Plankton- middle reaches
Shade- headwaters
Sun- lower reaches

If so many organisms are washed downstream with the current, how are the upper reaches of the
stream repopulated?

Repopulation of upper portion by flying adults.
Some actively swim upstream or pull themselves back upstream

In most streams, the vegetation along the banks of a stream is a more important factor in stream
productivity than green plants growing in the stream. Explain.

More organic matter enters (falls in) the stream from surrounding vegetation than is actually
produced in the stream

Most of the organic input in streams in our area occurs in autumn. Explain.

Leaves falling of trees in autumn.

Distinguish among the following categories of herbivorous invertebrates.

-Shredders
Actively break up CPOM- most common in upper reaches
-Collectors
Filterers
Gatherers
Fed on FPOM and DOM- most common in middle river and especially in lower reaches
Filter food out from water
-Scrapers (grazers)
Feed on algae uses mouthparts to scrape rocks. Most common in middle reaches
-Piercers
Use mouthparts to suck out juices of plants

What is the most nutritious part of food eaten by shredders and some collectors?

Fungi and bacteria- high protein

Relate the course of primary productivity in the three sections of a river (headwaters, middle and
lower reaches) to the physical environmental conditions in these sections by filling out the table
below.

River section Physical conditions Primary productivity source
Headwaters
Middle section
Lower reaches
Cool, fast flowing, shaded, high
oxygen, high transparency
partial sun, warmer water, less
oxygen, lower transparency
full sun, warm water, deep,
wide, slow moving water,
lowest transparency (highest
turbidity)
CPOM
Some CPOM, FPOM (and DOM),
algae and plankton
FPOM and DOM

What is the history of beaver populations in Minnesota?

Populations were highly reduced due to hunting for pelts in 1700s. Populations have recovered
considerably.

Describe the winter food cache of a beaver

Reserves of food anchored in the mud below the ice in a stream, river or lake

What is the greatest distance away from trees that beavers are likely to build lodges and dams?

400ft at the maximum.

Describe the positive and negative aspects of beaver activity

They actively create and maintain their own habitat (are ecosystem engineers), which can create
flooding in areas with valuable farmland. Alternatively, by creating dams they increase areas of lakes
and wetlands and create habitat for other organisms.

What are two general locations of cold water streams in Minnesota? What is the primary DNR focus
on these streams?

SE MN in Driftless Area (unglaciated) and along North Shore.
They are managed for trout (and fly fishing).

As you read the next section on warm water rivers, create a list of human activities that are
detrimental to these river ecosystems and indicate the problems caused by each activity.
Four categories of pollutants

a. Bacteria
b. Sediments
c. Nutrients
d. Other substances that reduce dissolved oxygen
Mismanagement of farmland- nutrient loading into waterways
Creation of dams- changes in water flow and ecological dynamics
Urbanization- increased sedimentation

Construct another list showing the value and uses of rivers by the human population.

Recreation
Transport
Industry- food
Power generation
And more

Evolution

change in gene frequency in a population over time

True/or False:

• Evolution happened only in the past and is not
occurring today
• Evolution has a predetermined goal, or “it was
meant to be”
• Changes in the environment cause the mutations
that are needed to survive under the new
environmental conditions
• Individual organisms evolve
• Many of the current species can be shown to be
derived from other present-day species (e.g. apes
gave rise to humans)

--->All false!

By 1800s new views about species and history of Earth emerged.

• Lamarck was one of first to suggest that species change
over time (evolution).
• Lyell suggested that an old Earth had gradually changed
through slow, accumulating processes.

Darwin’s influences and experiences led him to his theory
of evolution.

Darwin began an in-depth study of change over time
(evolution).

• First to propose a mechanism to
explain how species could
evolve: natural selection

Darwin first observed that populations produce more
individuals than can survive

Overproduction
Limited resources
Competition and Predation
Variation

Individuals with variations that
make them best suited to the
environment will be more likely
to survive and reproduce

Mechanisms of evolution

• Gene flow (migration)
• Genetic drift
• Bottleneck and founder effect
• Natural selection
• Sexual selection

Microevolution is a generation-to-generation change in a
population

Migration aka gene flow

•Movement of
individual(s) between
populations

•Makes populations more
similar BUT increases
genetic diversity within a
population

Genetic drift

•Random change in gene
frequencies in a population
•Decreases genetic diversity
•Occurs mainly in small populations
• Huge problem in endangered
species

Genetic bottleneck and founder effects

• If a population is drastically reduced in
numbers- bottleneck.
• If a few individuals migrate to a new isolated
habitat- founder effect.
• some genes will be lost from gene pool

Natural Selection and the evolution of antibiotic
resistance

Process of natural selection

1.More organisms than can survive

2.No two organisms are exactly alike (genetic differences!)
• What causes genetic variation?

3.Aspects of environment exert selective pressure (limited
food or resources, disease, predators, etc.)

4.Individuals with favorable traits for environment have a
higher rate of survival and produce more offspring
(higher fitness)

5. Individuals with genetically based favorable traits
become more common in population
Favorable trait= adaptation

Predation leads to adaptation

• Predator-prey relationships exert selective
pressures
• Favors adaptation
• Predators become more efficient, and
prey become more effective at escaping
• Close adaptation of two species =
coevolution

Coevolution does not only occur in predator-prey
relationship

Symbiotic relationships

Sexual selection

• Sexual selection- depends on
an individual’s ability to obtain a
mate
• Females may choose males for
their traits.
• Male competition

Traits must be genetically based

• Traits acquired during an individual’s lifetime are
not be passed on ---> acquired characteristics

Important points about evolution

• Individuals don’t evolve.
–Natural selection acts on individuals, but only
populations evolve.
• Natural selection works with heritable traits.
–Only genetically coded traits are subject to natural
selection.
• Evolution does not have a goal.
–Evolution occurs in response to local environmental
conditions, not future ones.

How does evolution affect our daily
lives?

• Darwin noted that humans have been selecting for traits
for millennia. He called this artificial selection

Artificial selection created the foods we eat

Fossils provide a glimpse into the past.

• Reveals an ordered
appearance of life on Earth,
from prokaryotes to today’s life
forms.
• Transitional forms provide
evidence of change within
lineages.

The geographic distribution of species provides
much evidence of evolution.

• Biogeography -study of geographic
distribution of species.
• Isolation of Australia accounts for
dominance of marsupial mammals.

Comparative anatomy provides much evidence of
evolution.

• Comparisons of body structures of modern organisms is
called comparative anatomy.

Comparative anatomy can provide insight into
evolutionary history.

• Examination of animal forelimbs shows they are all constructed
from similar bones.

DNA and bioinformatics provide much evidence of
evolution.

• All life uses DNA for genetic
code.
• Closely related
species will have similar DNA
and protein sequences.
– Such as in primates
• Bioinformatics employs
computational tools to
process genetic data.

Taxonomy is the classification of life.

• Taxonomy- identification, naming, and classification of
species.
• All life is classified into one of three large groups called
domains based on cell type.

Taxonomic levels

• Domain
• Kingdom
• Phylum
• Class
• Order
• Family
• Genus
• Species

Reproductive barriers maintain species

• Reproductive barriers prevent members of different
species from breeding

Reproductive barriers maintain species

• Behavioral isolation
• Mating time differences
• Habitat isolation
• Mechanical incompatibility
• Gametic incompatibility
• Hybrid weakness:

Macroevolution encompasses the major
changes in the history of life

• Macroevolution is genetic
change on a large scale.
• Speciation is the
evolutionary formation of
new species.

How do we get new species?

• Speciation occurs when
one ancestral species
evolves into one or more
new species.
• Some event separates a
population:
– Time, space, or genetics
• Populations then diverge along their own evolutionary
path.
Original Population
Species A Species B

New species may form after geographic
isolation

• Allopatric speciation

New species may arise due to other types of isolation,
such as genetic

• Sympatric speciation occurs with no geographic
isolation.

Review the process of natural selection. Use the steps to explain how PCB resistance
became so common among tomcod in the Hudson. Be sure to include the terms mutation,
fitness, selective pressure, and adaptation in your explanation.

First there must be genetic variation in the tomcod population for natural selection to
operate on. This genetic variation can come from sexual reproduction and/or mutation
during the production of gametes (sex cells). When DNA is replicated before meiosis (to
produce gametes- sperm or egg cells), the enzyme that replicates the DNA can make
mistakes, called mutations, which changes the sequence of nucleotides in DNA. When this
occurs, the resulting offspring will inherit this mutation (called a germline mutation).
Mutations are random and every once in a while they are beneficial under the
environmental conditions at the time. In the case of tomcod and PCB resistance, if a fish is
born with the resistance mutation and PCBs are present this will be beneficial. PCBs act as a
selective pressure, meaning individuals that possess the resistance mutation will survive
and reproduce more than individuals that don’t (this is termed fitness). An individual’s
fitness is its contribution in offspring to the next generation. So those with the mutation
have higher fitness (leave more offspring) and their offspring will also possess the resistance
mutation and also have high fitness as long as PCBs are still present. In this way, the gene
conferring resistance will increase in frequency in the tomcod population. We call this an
adaptation when most/all tomcod in the area have the resistance gene, a trait that
increases fitness in a certain environment. Adaptations are the product of natural selection

the author describes the tomcod as "a quick learner" because of the
population's adaptation to PCBs. Is "learning" an accurate way to describe the change in the
Hudson River tomcod population? Why or why not?

This is NOT an accurate way to describe the evolution of resistance. Evolution by definition is
the change in gene (allele) frequency in a population over time. The unit of evolution is
the population not the individual. Learning is an individual-level phenomenon, so it is
not a good analogy to use. Individuals do not evolve, populations do and there are four
forces of evolution: mutation, gene flow (aka migration), genetic drift, and natural
selection.

The data shown on the map above support the hypothesis that natural selection for PCB
resistance has occurred among tomcod in the Hudson. What sort of evidence regarding
gene frequencies in different populations would argue against this hypothesis (i.e., imagine
what the scientists would have observed in this study if natural selection on the AHR gene
had not occurred among Hudson River tomcod)?

One possible pattern would be that the pie charts across the coast have a random
proportion of the population having the resistance deletion regardless of the presence of
PCBs. Another would be seeing a 50/50 ratio of the deletion or seeing a very low
proportion of any fish having the deletion that confers resistance. There are a few different
patterns you could imagine that was not support the hypothesis

Why is it not accurate to assume that species that feed on tomcod will also evolve
resistance to PCBs. What misconception about the process of evolution by natural selection
is highlighted under the thinking that natural selection “provides organisms with the
traits they ‘need’ to survive”? Be sure to explain why this misconception is incorrect
using what you know about how natural selection operates.

Natural selection can only operate on existing genetic variation. So if the mutation
that confers resistance does not ever occur, then natural selection cannot act on the
population. While certain environments can increase mutation rates, they do not
direct where and what mutations should be. Mutations are completely random.
The environment DOES NOT cause the mutation. This is a common
misconception. (Hence, my emphatic bolding and capitalization. If we were in a
face-to-face class, my arms would be flailing as I proclaimed this.) If a mutation is
present and is beneficial, then natural selection can amplify or increase its frequency
in a population through individuals possessing the mutation having high fitness and
passing on the mutation to their offspring. So natural selection cannot provide what
organisms need, but it is a response to environmental conditions based on the
genetic make-up of the population. Natural selection is not forward looking nor is it
unidirectional. However, natural selection is NOT random, it is an incredibly ordered
process, it’s just the source of variation for natural selection to operate on is random.

What Threatens Biodiversity?

• Extinction
• Studies of fossil record
suggest that more than 99%
of all species that ever existed
are now extinct

HIPPO Summarizes Human Impacts

• HIPPO
• Habitat destruction
• Invasive species
• Pollution
• Population of humans
• Overharvesting.

Historical Decrease in Forested Area in Southern Wisconsin

• Habitat fragmentation
• Reduces biodiversity
• Can divide populations into
isolated groups
• Island Biogeography-
• Species-area relationship

Invasive Species in North America

Invasive species are organisms that thrive in new territory

How does humans population growth
threaten biodiversity?

• In past 40 years, the global population has doubled from about 3.5 billion to about 7 billion

Overharvesting Depletes or Eliminates Species

• Overharvesting
• American passenger pigeon
• American Bison
• Fish stocks have been seriously depleted by overharvesting
• 3/4 of all commercial oceanic species are overharvested!

Predator and Pest Control Is Expensive But Widely Practiced

• Some animal populations have been greatly reduced, or even deliberately
exterminated
• regarded as dangerous to humans or livestock
• or because they compete with our use of resources

5.6 Biodiversity Protection

Endangered Species Act:
1. Establishes criteria for identifying species at risk
2. Provides guidelines for planning species recovery
3. Provide assistance to landowners to help find ways to meet
requirements
4. Enforces measures protecting species and habitat

Endangered Species Act Terminology

• ESA identifies three levels of risk:
– Endangered species-
– Threatened species-
– Vulnerable species-

Recovery Plans Aim to Rebuild Populations

• Fish and Wildlife Service (FWS)
• How populations will be stabilized or rebuilt:
• buying habitat areas
• restoring habitat
• reintroducing a species to its historic ranges,
• captive breeding programs

ESA Species Terminology

Keystone species
Indicator species
Umbrella species
Flagship species

The ESA has Seen Successes and Controversies

• Has held off the extinction of
hundreds of species
• Political and legal debates
• Several famous controversies

What is the best way to protect species?

• Species-by-species battle is not the way
• Need preservation of ecosystems that supports maximal biological diversity

Species Survival Can Depend on Preserve Size and Shape

Large enough to support endangered
species and keep ecosystems intact
• Increase core habitat
• Decrease edge effects

• Smaller reserves can be connected by
corridors

Ecosystem Management

• In 1990s U.S. Forest Service began to
shift its policies to ecosystem
management
• Integrates sustainable ecological,
economic, and social goals in a
unified, systems approach

Principles of Ecosystem Management

• Manage across landscapes or regions over ecological time scales
• Depend ecologically credible data for decision making
• Maintain biological diversity and essential ecosystem processes
• Promote sustainable economic development
• Generate stakeholders and public involvement
• Revise management over time based on experimentation and monitoring

Parks and Preserves

• ~13% of land area of Earth is protected
• 7.3 million mi2 in 122,000 different preserves

Conservation and Economic Development Can Work Together

• Zones of use
• Ecotourism is tourism that is
ecologically and socially
sustainable

World Forests

• Forests, woodlands, pastures, and rangelands together occupy almost 60
percent of global land cover.
• Provide many of our essential resources such as lumber, paper pulp, and
grazing lands for livestock.
• Provide essential ecological services including regulating climate, controlling
water runoff, providing wildlife habitat, purifying air and water, and
supporting rainfall.
• Forests and grasslands also have scenic, cultural, and historic value.