OutlineOutline

QuizQuiz Assignment: Peer review due after Assignment: Peer review due after

Spring BreakSpring Break Lecture: Invasive species and Lecture: Invasive species and

communitiescommunities BreakBreak Second half of WI Fishes (ID’s)Second half of WI Fishes (ID’s)

Invasive Invasive species and species and

communitiescommunities

A prelim exam question…A prelim exam question…“Are invasive species more likely to have large impacts on native communities via

predation or via competition?”

First, communities…First, communities…

5 Basic types of species interactions

2

1?

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Competition is important...just not as important as predation

What is competition?What is competition?

Competition ...common use of a limited resource

food space or habitat

What can be limiting....?

Between and within speciesBetween and within speciesIntraspecific competition

Interspecific competition

How do we see it or How do we see it or measure it?measure it?

Individual Responses

•Behavior – feeding rate

•Physiology – growth rate

•Morphological – body size

Population responses

•Abundance

•Distribution

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Time

3 types of competition3 types of competition

Interference competition Exploitation competition

Apparent competition

Interference competition - occurs directly between individuals via aggression etc. when the

individuals interfere with foraging, survival, reproduction of others, or by directly preventing their physical establishment in a portion of the

habitat.

A B(-)

(-)

Exploitation competition - occurs indirectly through a common, limiting resource, which acts as an intermediate. Ex. depletes the amount of

food or fill up all the available space.

A B(-)

(-)

R

- + + -

Apparent competition - occurs indirectly between two species which are both preyed

upon by the same predator.

A

P- +-

+

- BB

P

- +

Competition's role in Competition's role in ecology and evolution ecology and evolution

Resource partitioning

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Resource Gradient

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Resource Gradient

"species packing"

Evolution to minimize competitionDifficult (or impossible) to prove

Species evolve within communities to Species evolve within communities to utilize resources along a gradientutilize resources along a gradient Food particle sizeFood particle size TemperatureTemperature HabitatHabitat

0

10

20

30

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50

60

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1 2 3 4 5 6 7 8 9 10 11 12

Station (1=downstream)

Fis

h A

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Sculpin

Dace

Warmer Temps Cooler Temps

Lake Tanganyika Lake Malawi

Community Assembly and Community Assembly and Invasive SpeciesInvasive Species

Sequence of invasions is importantSequence of invasions is important As species #’s increase, so does partitioning As species #’s increase, so does partitioning

of resourcesof resources Eventually, resources cannot be partitioned Eventually, resources cannot be partitioned

any further, and species will be excludedany further, and species will be excluded Logical extension: Species-rich Logical extension: Species-rich

environments will be resistant to invasionsenvironments will be resistant to invasions This has not held true due to disturbance, This has not held true due to disturbance,

importance of abiotic factors, extirpations, importance of abiotic factors, extirpations, unsaturated communitiesunsaturated communities

However, diverse communities may be less However, diverse communities may be less impactedimpacted

M.J. Vander Zanden. 2005. The Success of Animal Invaders, PNAS 102: 7055-7056

Invasive SpeciesInvasive Species

Why should we care?Why should we care?

-Leading cause of global biodiversity loss-Leading cause of global biodiversity loss

-Particularly severe in freshwater -Particularly severe in freshwater ecosystemsecosystems

- Contributing factor in 68% of fish - Contributing factor in 68% of fish extinctions in US and Mexicoextinctions in US and Mexico

- Cost $137 billion/year in US alone- Cost $137 billion/year in US alone

- Numbers are increasing- Numbers are increasing BUT…most do not establish or have BUT…most do not establish or have

negative effects…negative effects…

Why are species Why are species introduced?introduced?

Food Food Familiar or “superior” speciesFamiliar or “superior” species Enhancement (or creation) of Enhancement (or creation) of

fisheriesfisheries Manipulation of systems (biological Manipulation of systems (biological

control)control) AccidentalAccidental

Accidental IntroductionsAccidental Introductions

Canal building Canal building Ballast waterBallast water Bait bucket Bait bucket

introductionsintroductions Hitchhiking on boatsHitchhiking on boats Angler introductionAngler introduction Aquarium escapeAquarium escape Aquaculture escapeAquaculture escape

Invasive species that affect the ecology of native Wisconsin FishesPelagic planktivores - Alewife, Rainbow smelt, white perch, bythotrephesBenthic omnivores - round goby, rusty crayfish, common carpPelagic piscivores – Pacific salmon, brown trout, rainbow troutPelagic/benthic parasite – Sea lamprey

Stream insectivores – brown trout, rainbow trout

Pelagic filter-feeders – silver carp, bighead carp

Benthic filter-feeders – zebra mussel, quagga mussel

Steps to InvasivenessSteps to Invasiveness

Impact

Colonization

Establishment and IntegrationAdapted From

Vander Zanden et al. 2004

ImpactsImpacts Niche: the ecological role of a species in Niche: the ecological role of a species in

relation to other species and the non-relation to other species and the non-biological environmentbiological environment

  The niche represents the range of The niche represents the range of conditions within which a species can conditions within which a species can survive and reproducesurvive and reproduce

The niche of a species in the The niche of a species in the absenceabsence of of competition is called the competition is called the fundamental fundamental nicheniche..

The niche of a species The niche of a species in equilibrium with in equilibrium with competitorscompetitors is called the is called the realized nicherealized niche

Fundamental vs. Fundamental vs. Realized NicheRealized Niche

Realized niche

Fundamental nicheFundamentalPre

y C

on

sum

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Prey Size

Realized

Impacts: Misunderstanding Impacts: Misunderstanding of Nicheof Niche

Niche changes throughout life historyNiche changes throughout life history Forage fish can compete with/prey upon Forage fish can compete with/prey upon

juvenile game fish (Example: smelt, alewives)juvenile game fish (Example: smelt, alewives) Introductions to fill “vacant” nichesIntroductions to fill “vacant” niches Assumption: An organism will occupy the Assumption: An organism will occupy the

same habitats and roles in a new system as it same habitats and roles in a new system as it does in native rangedoes in native range Not always true – organism may be bound Not always true – organism may be bound

geographically or ecologically in native geographically or ecologically in native rangerange

ImpactsImpacts Classic example of changes in realized Classic example of changes in realized

niche: Opossum shrimp (niche: Opossum shrimp (Mysis relictaMysis relicta)) Introduced to enhance fish populationsIntroduced to enhance fish populations Detritus/phytoplankton feeder in native Detritus/phytoplankton feeder in native

ecosystem (realized niche)ecosystem (realized niche) Niche expansion upon introduction lead Niche expansion upon introduction lead

to zooplankton depletion – eliminated to zooplankton depletion – eliminated food resources for populations it was food resources for populations it was supposed to enhancesupposed to enhance

Impacts: MechanismsImpacts: MechanismsSpecies levelSpecies level CompetitionCompetition (interference: brown/brook trout (interference: brown/brook trout

exploitation: alewives/ coregonids)exploitation: alewives/ coregonids) Predator-PreyPredator-Prey (Nile perch/ cichlids) (Nile perch/ cichlids) Parsite-HostParsite-Host (Crayfish)(Crayfish)

Community levelCommunity level Trophic CascadeTrophic Cascade Ecosystem Engineer (alters abiotic Ecosystem Engineer (alters abiotic

factors)factors) HybidizationHybidization

Management of Invasive Management of Invasive SpeciesSpecies

EradicationEradication Chemical controlChemical control Biological controlBiological control Mechanical controlMechanical control

PreventionPrevention Risk analysis approaches that incorporate Risk analysis approaches that incorporate

ecological, economic, and social welfare ecological, economic, and social welfare show that prevention is cost-effective show that prevention is cost-effective

Predictions of invaders with the biggest Predictions of invaders with the biggest impact, or predictions of which ecosystems impact, or predictions of which ecosystems are most vulnerable to a specific invader, are most vulnerable to a specific invader, are emerging as standard methods for are emerging as standard methods for directing management. directing management.

Management of Invasive Management of Invasive SpeciesSpecies

Predictions of Invasive Predictions of Invasive SpeciesSpecies

Mercado-Silva, N., J.D. Olden, J.T. Maxted, T.R. Hrabik, M.J. Vander Zanden. 2006. Forecasting the spread of invasive rainbow smelt in the Laurentian Great Lakes region of North America. Conservation Biology 20: 1740-1749.

42% (1,369 km) identified as suitable(7% of state)

44% (8,878 km) identified as suitable

More predictions…

Kornis, M.S., and Vander Zanden, M.J. 2010. Forecasting the distribution of the invasive round goby (Neogobisu melanostomus) in Wisconsin tributaries to Lake Michigan. Can. J. Fish. Aquat. Sci. 67: 553-562.

ConclusionsConclusions Invasive species are an increasingly Invasive species are an increasingly

important threat to native species and important threat to native species and biodiversitybiodiversity

Invasive species affect native ecosystems Invasive species affect native ecosystems through numerous pathways that are not through numerous pathways that are not mutually exclusivemutually exclusive

Invasive species management is sometimes Invasive species management is sometimes possible once the invader has establishedpossible once the invader has established

Prevention of invasions is key for future Prevention of invasions is key for future managementmanagement

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