Presentation on theme: "Pearson & Dawson Quiz 1. What is a bioclimatic envelope? 2. How might bioclimatic envelope models be useful for invasive species management? 3. List and."— Presentation transcript:
Pearson & Dawson Quiz 1. What is a bioclimatic envelope? 2. How might bioclimatic envelope models be useful for invasive species management? 3. List and describe two weaknesses of bioclimatic envelope models.
Pearson & Dawson Quiz 4. What is equilibrium in the context of bioclimatic envelope modeling? Do you think disequilibrium is likely to be a problem for modeling invasive species? 5. In addition to climate, what other environmental variables are likely important for the distribution of species?
Definition of an invasive species Non-native Capable of surviving without direct help from people (established or naturalized) Spreading away from sites of initial establishment Often with negative ecological and economic consequences Lockwood et al., 2007
Are resource opportunities from global change likely to be evenly or unevenly distributed globally? Give an example of an ecosystem or location at high risk of invasion due to higher resources Anthropogenic global changes: -Climate change -Nutrient addition -Invasive species -Habitat loss (disturbance & degradation)
At Risk: Ecosystems with scarce resources If resources are limited, native species are adapted to scarcity Anthropogenic addition of resources creates new ‘empty’ niches
Biogeography Definition: Understanding more about a species by using information from where the species is located Examples: – In what range of temperatures does the species establish? (Physiological tolerance) – Is the species located near human activity? (Disturbance responsive)
Biogeographical Modeling of Species Potential Distributions Relevant to invasive species because it can potentially predict invasion risk
BEMs use biogeography to empirically determine climatic tolerance
Problem: Equilibrium Assumption Assumes a species is at equilibrium with its environment (it exists everywhere that it could exist) The equilibrium assumption FAILS for invasive species Invasives are still spreading…
Vaclavik & Meentmeyer, 2011 At early stages of invasion (upper left), models of potential suitability are incomplete. Only at later stages of invasion (lower right), when the species has had time to spread, can models encompass environmental suitability
A way around the equilibrium problem? Use the native range to predict invasion Petitpierre et al., 2012 Only 7 out of 50 invasive plant species tested had invaded ranges that exceeded the climatic conditions of their native ranges by more than 10% Climatic Space Less than 10% of A+B
Climate matching Carpobrotus edulis (ice plant) Native to South Africa Thuiller et al., 2005
Realized vs. Fundamental Niche Fundamental Niche: All the environmental conditions in which a species can survive. Realized Niche: Fundamental niche minus dispersal limitations & competition with other species. Climatic Space Realized Niche Native Range Realized Niche Invaded Range Fundamental Niche
Use climatic conditions from all native and invaded range to define fundamental niche Kriticos et al., 2011
Another Approach: Use Species’ Physiological Tolerance
Physiological Tolerance to Extremes Responses of 7 grass species to a heat wave of +11°C Milbau et al. 2005
Use physiological characteristics to model potential geographic range Buckley, 2008
Biogeography team task 1.What are the spatial extents of invasion risk for your target species? 2.How do the results of a bioclimatic envelope model differ from an assumption based on physiology?
Reading assignment for Thursday: Find and read one paper (use Google Scholar or Web of Science!) describing the physiological tolerance or climatic limits of your target species. Search examples: Genus species + temperature tolerance, freezing tolerance, physiological limitation, heat stress, climatic limitation
Species of the day: Caulerpa taxifolia “Killer Algae” Forms dense, monotypic stands Crowds out native vegetation Toxic to herbivores Affects behavior of fish & other organisms
Impacts on (one example) fish Mullus surmuletus activity in the Mediterranean Levi and Francour, 2004 Established Not Established C. taxifolia:
Popular aquarium algae Jousson et al., 1998 Cold-tolerant strain developed in 1980 at an aquarium in Stuttgart Cold-tolerant strain shared with aquariums in Nancy, Geneva & Monaco Monaco aquarium likely source of release into the Mediterranean
Invasive strains are genetically identical to the aquarium strain Jousson et al., 1998 Branches of the tree denote genetic difference ‘Aquarium strain’ also found off the coasts of Australia and Southern California ‘Aquarium strain’ likely tolerant of lower temperatures than species in native range
Pearson & Dawson, 2003 Why do you think BEMs only include climate? Why not include biotic interactions?