Outline Quiz Quiz Assignment: Peer review due after Spring Break Assignment: Peer review due after Spring Break Lecture: Invasive species and communities Lecture: Invasive species and communities Break Break Second half of WI Fishes (ID’s) Second half of WI Fishes (ID’s)

Invasive species and communities

A prelim exam question… “Are invasive species more likely to have large impacts on native communities via predation or via competition?”

First, communities…

5 Basic types of species interactions 2 1 ? XXXXXXXXXX Competition is important...just not as important as predation

What is competition?

Competition...common use of a limited resource food space or habitat What can be limiting....?

Between and within species Intraspecific competition Interspecific competition

How do we see it or measure it? Individual Responses Behavior – feeding rate Physiology – growth rate Morphological – body size Population responses Abundance Distribution Population Abundance Time

3 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 ecology and evolution Resource partitioning Population Abundance Resource Gradient Population Abundance Resource Gradient "species packing" Evolution to minimize competition Difficult (or impossible) to prove

Species evolve within communities to utilize resources along a gradient Food particle size Food particle size Temperature Temperature Habitat Habitat

Warmer Temps Cooler Temps

Lake TanganyikaLake Malawi

Community Assembly and Invasive Species Sequence of invasions is important Sequence of invasions is important As species #’s increase, so does partitioning of resources As species #’s increase, so does partitioning of resources Eventually, resources cannot be partitioned any further, and species will be excluded Eventually, resources cannot be partitioned any further, and species will be excluded Logical extension: Species-rich environments will be resistant to invasions Logical extension: Species-rich environments will be resistant to invasions This has not held true due to disturbance, importance of abiotic factors, extirpations, unsaturated communities This has not held true due to disturbance, importance of abiotic factors, extirpations, unsaturated communities However, diverse communities may be less impacted However, diverse communities may be less impacted

M.J. Vander Zanden The Success of Animal Invaders, PNAS 102:

Invasive Species Why should we care? Why should we care? -Leading cause of global biodiversity loss -Particularly severe in freshwater ecosystems - Contributing factor in 68% of fish extinctions in US and Mexico - Cost $137 billion/year in US alone - Numbers are increasing BUT…most do not establish or have negative effects… BUT…most do not establish or have negative effects…

Why are species introduced? Food Food Familiar or “superior” species Familiar or “superior” species Enhancement (or creation) of fisheries Enhancement (or creation) of fisheries Manipulation of systems (biological control) Manipulation of systems (biological control) Accidental Accidental

Accidental Introductions Canal building Canal building Ballast water Ballast water Bait bucket introductions Bait bucket introductions Hitchhiking on boats Hitchhiking on boats Angler introduction Angler introduction Aquarium escape Aquarium escape Aquaculture escape Aquaculture escape

Invasive species that affect the ecology of native Wisconsin Fishes Pelagic planktivores - Alewife, Rainbow smelt, white perch, bythotrephes Benthic omnivores - round goby, rusty crayfish, common carp Pelagic piscivores – Pacific salmon, brown trout, rainbow trout Pelagic/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 Invasiveness Impact Colonization Establishment and Integration Adapted From Vander Zanden et al. 2004

Impacts Niche: the ecological role of a species in relation to other species and the non-biological environment Niche: the ecological role of a species in relation to other species and the non-biological environment The niche represents the range of conditions within which a species can survive and reproduce The niche represents the range of conditions within which a species can survive and reproduce The niche of a species in the absence of competition is called the fundamental niche. The niche of a species in the absence of competition is called the fundamental niche. The niche of a species in equilibrium with competitors is called the realized niche The niche of a species in equilibrium with competitors is called the realized niche

Fundamental vs. Realized Niche Realized niche Fundamental nicheFundamental Prey Consumed Prey Size Realized

Impacts: Misunderstanding of Niche Niche changes throughout life history Niche changes throughout life history Forage fish can compete with/prey upon juvenile game fish (Example: smelt, alewives) Forage fish can compete with/prey upon juvenile game fish (Example: smelt, alewives) Introductions to fill “vacant” niches Introductions to fill “vacant” niches Assumption: An organism will occupy the same habitats and roles in a new system as it does in native range Assumption: An organism will occupy the same habitats and roles in a new system as it does in native range Not always true – organism may be bound geographically or ecologically in native range Not always true – organism may be bound geographically or ecologically in native range

Impacts Classic example of changes in realized niche: Opossum shrimp (Mysis relicta) Classic example of changes in realized niche: Opossum shrimp (Mysis relicta) Introduced to enhance fish populations Introduced to enhance fish populations Detritus/phytoplankton feeder in native ecosystem (realized niche) Detritus/phytoplankton feeder in native ecosystem (realized niche) Niche expansion upon introduction lead to zooplankton depletion – eliminated food resources for populations it was supposed to enhance Niche expansion upon introduction lead to zooplankton depletion – eliminated food resources for populations it was supposed to enhance

Impacts: Mechanisms Species level Competition (interference: brown/brook trout exploitation: alewives/ coregonids) Competition (interference: brown/brook trout exploitation: alewives/ coregonids) Predator-Prey (Nile perch/ cichlids) Predator-Prey (Nile perch/ cichlids) Parsite-Host (Crayfish) Parsite-Host (Crayfish) Community level Trophic Cascade Trophic Cascade Ecosystem Engineer (alters abiotic factors) Ecosystem Engineer (alters abiotic factors) Hybidization Hybidization

Management of Invasive Species Eradication Chemical control Chemical control Biological control Biological control Mechanical control Mechanical control

Prevention Risk analysis approaches that incorporate ecological, economic, and social welfare show that prevention is cost-effective Risk analysis approaches that incorporate ecological, economic, and social welfare show that prevention is cost-effective Predictions of invaders with the biggest impact, or predictions of which ecosystems are most vulnerable to a specific invader, are emerging as standard methods for directing management. Predictions of invaders with the biggest impact, or predictions of which ecosystems are most vulnerable to a specific invader, are emerging as standard methods for directing management. Management of Invasive Species

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

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 Forecasting the distribution of the invasive round goby (Neogobisu melanostomus) in Wisconsin tributaries to Lake Michigan. Can. J. Fish. Aquat. Sci. 67:

Conclusions Invasive species are an increasingly important threat to native species and biodiversity Invasive species are an increasingly important threat to native species and biodiversity Invasive species affect native ecosystems through numerous pathways that are not mutually exclusive Invasive species affect native ecosystems through numerous pathways that are not mutually exclusive Invasive species management is sometimes possible once the invader has established Invasive species management is sometimes possible once the invader has established Prevention of invasions is key for future management Prevention of invasions is key for future management

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