Lecture 4: Dispersal and Habitat Selection

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Lecture 4 Dispersal and Habitat Selection

• EEES3050

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Outline

• Background on dispersal
• Introduction to invasive species
• Zebra mussel example
• Habitat selection

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Why do species live where they do?

• Or ratherwhy are they not in particular places?
• Dispersal
• Habitat Selection
• Biotic factors
• Abiotic factors

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Types of Movement

• Local e.g. foraging
• Migration birds or elk
• synchronized, directional mass movement of
  individuals
• Dispersal
• nonsynchronized, non-directional movement of
  individuals

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Costs and benefits of migration

• Costs
• Increased mortality
• Energy expenditure
• Benefits
• Breeding
• Escape mortality
• Resource gain

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Patterns of migration

• Types of migration
• Long-distance birds, reindeer, whales
• Seasonal movements among habitats elk, deer
• Tides constant habitat changing site
• 'One return journey' migration
• eels, salmon, monarch butterfly
• 'One way migration a European butterfly

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Monarchs
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Warblers
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Dispersal

• Why?
• Home can be a dangerous place
• Dispersal as escape and discovery
• exploratory (mobile) discovery
• nonexploratory (sessile) discovery propagules
• plants cocoanuts dandelions
• invertebrates spiders

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Why do species disperse?

• Balance between
• Staying put in a suitable habitat with the small
  probability of out competing others and
  reproducing.
• Taking off with the low probability of landing
  somewhere else that is suitable and then
  reproducing.

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Dispersal

• Passive dispersal by an active agent
• seeds, fruits
• phoresey beetles mites, remoras sharks

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Costs and constraints of dispersal

• Cost
• energy and nutrients required for structures
  reduces the number of propagules produced
• Ability to disperse (vs. survival) and capital
  investment
• weight of seed is directly related to viability
  and inversely related to ability to disperse

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Types of Dispersal

• Diffusion
• Gradual movement of a population across
  hospitable terrain
• Jump dispersal
• Movement across large distances usually across
  uninhabitable terrain.

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Invasion Biology

• What is an invasive species?
• A non-native species that was released (on
  purpose or accidentally) and is affecting the
  environment or economy in a negative manner.
• Sometimes called introduced species.
• Usually an invasive species is one that is
  causing harm.
• Other terms, nuisance, non-native,
  non-indigenous,

Suggested reading The Ecology of Invasions by
Animals and Plants by C.S. Elton
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Invasion Process
Source Region of Species
Pathway quantification
Transport/Survival in Pathway
Statistical Population models
Establishment
Dispersal/population models
Abundance??Spread
Statistical models
Impact
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Assessing the dispersal potential of zebra
mussels Evaluating the ecological and economic
value of the 100th Meridian Initiative

• Jonathan M. Bossenbroek, Ph.D.

University of Toledo Lake Erie Center Dept. of
Earth, Ecological and Env. Sciences
In Collaboration with David Lodge, Dave Finnoff
and Jean-Daniel Saphores,
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100th Meridian initiative
Columbia River Basin
Colorado River Basin
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Assessing the Potential Impacts of Zebra Mussels

• Background on Zebra Mussels
• Spread
• Impacts
• Environmental
• Economic
• Dispersal
• Human-mediated
• Natural

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Assessing the Potential Impacts of Zebra Mussels

• Background on Zebra Mussels
• Spread
• Impacts
• Environmental
• Economic
• Dispersal
• Human-mediated
• Natural

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1988
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1989
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1990
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1991
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1992
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1993
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2003
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NEWS RELEASE WASHINGTON DEPARTMENT OF FISH AND
WILDLIFE 600 Capitol Way North, Olympia,
Washington 98501-1091 Internet Address
http//wdfw.wa.gov May 25, 2004 Contact Pam
Meacham, 360-902-2741 Or Mike
Whorton, 509-456-3182 Zebra mussels discovered
at Washington-Idaho border SPOKANE Zebra
mussels, invasive species that could harm
Washington fish and wildlife and damage
hydroelectric dams and public water systems, were
discovered this month on a large boat being
trailered cross-country by commercial vehicle,
the Washington Department of Fish and Wildlife
(WDFW) reported today. Despite the successful
discovery at the Washington-Idaho border, WDFW
officials are concerned that zebra mussels could
be slipping in on smaller boats that are not
required to stop at highway weigh stations.
Zebra mussels, fingernail-size freshwater
mollusks native to the Black, Caspian and Aral
Seas, were first introduced to the Great Lakes in
1986 in the ballast water of transoceanic ships.
They can spread quickly, altering entire
ecosystems of some waters by smothering native
mussels and consuming food sources of other fish
and wildlife.
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• Date 06/08/04
• Contact Geoffrey Schneider
• Phone [phone]
• MENACING MOLLUSKS DISCOVERED ON A HOUSEBOAT AT
  LAKE MEADBy Rory Aikens, Arizona Game Fish
  Department
• Zebra mussels, which have been devastating in
  the Great Lakes, were discovered on a 54-foot
  houseboat from Kentucky that was attempting to
  launch at Temple Bar on Lake Mead over the
  Memorial Day holiday weekend. The marina is
  located on the shoreline of Temple Basin on the
  Arizona side of the lake.
• Arizona and Nevada wildlife officials say the
  zebra mussel discovery highlights the need for
  all boaters to be vigilant and conscientious when
  taking their crafts from one waterway to another,
  even when its within the state.

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Assessing the Potential Impacts of Zebra Mussels

• Background on Zebra Mussels
• Spread
• Impacts
• Environmental
• Economic
• Dispersal
• Human-mediated
• Natural

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Zebra Mussel Basics

• Small bi-valve
• Not like native clams
• Attaches to things
• Origin Ponto-Caspian sea region
• Very high reproductive rates.
• Over 40,000 eggs can be laid in a reproductive
  cycle and up to one million in a spawning season
• Filter feeders

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Mussel Beach
Courtesy of Dr. Clifford Kraft
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Ecological Impacts
Courtesy of Dr. Clifford Kraft
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Economic Impacts
Courtesy of Dr. Clifford Kraft
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Potential Impacts in Columbia River

• Columbia River Basin
• 67 municipalities
• Fish passage facilities
• 39 BOR projects
• 72 dams, dikes and diversions
• 4,700 miles of canals
• Grand Coulee Dam is the largest hydroelectric dam
  in North America
• Twelve of the worlds largest pumps remove water
  from the Franklin Delano Roosevelt reservoir

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Assessing the Potential Impacts of Zebra Mussels

• Background on Zebra Mussels
• Spread
• Impacts
• Environmental
• Economic
• Dispersal
• Human-mediated
• Natural

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Dispersal

• Zebra mussel spread from 1986 to present
• Patterns of Invasion
• Long-distance Dispersal
• Importance of Navigable Waterways
• Gravity Models
• Spread via diffusion
• Importance of streams

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2006 Distribution
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1993 Distribution
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1993 Distribution 2006 Distribution
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Modes of Dispersal

• Natural Dispersal downstream
• Shipping
• Recreational Boating

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Spread along rivers
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Inland Lake Distance to Great Lakes
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Inland Lake Distance to 1993 Distribution
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Inland lake infestation rates
From Johnson, Bossenbroek Kraft. 2006
Biological Invasions
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Inland lake infestation rates
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3 Possible Explanations

• Outreach
• Zebra mussel fatigue
• Decreasing probabilities of new infestations

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Dispersal

• Zebra mussel spread from 1986 to present
• Patterns of Invasion
• Long-distance Dispersal
• Importance of Navigable Waterways
• Gravity Models
• Spread via diffusion
• Importance of streams

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Navigable Waterways
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Navigable Waterways
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Gravity Models primary spread from the Great
Lakes
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United States Gravity Model

• Basic Information -
• Based on 210 Watersheds
• Used a GIS to calculate distance
• Sum lake area/watershed
• Estimate of boaters/watershed
• Primary Question
• How many boaters from areas with zebra mussels
  are traveling to western waters?

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United States Gravity Model
From Bossenbroek et al. 2007 to Conservation
Biology
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January 2007
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Dispersal

• Zebra mussel spread from 1986 to present
• Patterns of Invasion
• Long-distance Dispersal
• Importance of Navigable Waterways
• Gravity Models
• Spread via diffusion
• Importance of streams

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Secondary spread in lake-stream systems
From Bobeldyk, Bossenbroek, Evans-White, Lodge
Lamberti. 2005 Ecoscience
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Secondary spread questions

• How does abundance of zebra mussels change with
  time and distance from source lake?
• Are connectedness and downstream distance both
  important in predicting whether a lake will be
  invaded?

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Secondary spread predictions

• How does abundance of zebra mussels change with
  time and distance from source lake?

Abundance
Distance
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Abundance in outflow streams
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Connectedness

• Are connectedness and downstream distance both
  important in predicting whether a lake will be
  invaded?

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Secondary spread of zebra mussels

• Is connectedness important?
• Identified all lakes within 1 km of invaded
  lakes.
• Categorized each lakes as
• Invaded or uninvaded
• Not connected or connected
• Upstream or downstream

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Secondary spread of zebra mussels

• Is distance from source lake important?
• Categorized outflow of each invade lake as
• Outflow to large river or Great Lake
• No outflow or wetland
• Outflow to another inland lake
• Calculated stream distance to next inland lake
• Determined if next lake was invaded or
  non-invaded.

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Importance of connectedness

• 295 invaded inland lakes
• 194 lakes within 1 km of invaded lake

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Distance from invaded lakes
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Secondary spread results

• How does abundance of zebra mussels change with
  time and distance from source lake?
• Zebra mussel abundance declines with distance in
  streams
• Are connectedness and downstream distance both
  important in predicting whether a lake will be
  invaded?
• Distance and connectedness are important

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Conclusions

• Dispersal of zebra mussels has resulted from
• Shipping pathways
• Recreational Boating
• Downstream spread via stream flow.
• Which is most important?
• Shipping early invasion
• Boating and downstream later invasion

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Habitat Selection

• What is habitat selection?
• Organisms choose not to live in a particular
  location despite the fact that they can get
  there and the habitat appears suitable.
• Typically an idea limited to animals.
• But can be argued about.
• What is habitat?
• any part of the biosphere where a particular
  species can live.

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Two approaches

• Again proximate vs. ultimate which means?
• Proximate
• Habitat choice is a result of behavioral
  mechanisms.
• Ultimate
• Adaptive reasons for habitat choice.

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Selection in hierarchical levels.
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Wiens conceptual model.
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Example Desert pocket mouse vs. kangaroo rat.
Kangaroo Rat
Desert pocket mouse
LO large open, SO small open, LB large
bush, T tree
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Rodent example continued

• Observation
• More kangaroo rats are found in open habitat.
  Pocket mice in sheltered habitat.
• Hypothesis 1
• K-rats select areas with more open space.
• Hypothesis 2
• Pocket mice select areas with more shelter.
• Experiment
• Three habitats more shelter, more open, control.

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A link between selection and dispersal.

• Species disperse to increase fitness.
• Ideal Free Distribution (IFD)
• Fretwell and Lucas 1970
• Individuals should freely disperse among habitats
  so as to gain maximum fitness
• Creates equal fitness of individuals in all
  habitats
• Maximizes the average realized fitness of each
  individual in the overall population.
• Abundance Habitat Quality

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A link between selection and dispersal

• Ideal Despotic Distribution
• Individuals not free to move among all habitats
• Constrained by aggression of others
• Subordinate individuals forced into marginal
  habitat.
• Fitness is expected to be lower in poorer
  habitats.
• Abundance ? Habitat Quality

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Summary for Habitat Selection

• Organisms choose to live/or avoid different
  locations.
• Multiple factors lead to habitat selection
• Idea Free Distribution
• Individuals disperse to maximize fitness
• Ideal Despotic Distribution
• Subordinate individuals forced into marginal
  habitat