Ecology. Michael Begon

Ecology - Michael  Begon


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by each taxon along axis 1 of the ordination. The diameter of the circle is proportional to the total occurrence frequency of each taxon."/>

      Source: From Farinas et al. (2015).

      ecological niche modelling approach to the multidimensional niche

Schematic illustration of the ecological niche modelling. The first step is to characterise a species distribution in two-dimensional geographic space. Then the niche is modelled in ecological space, in terms of a number of influential dimensions of the n-dimensional hypervolume.

      Source: After Peterson (2003).

Schematic illustration of the modelling the potential range of an invasive starfish. (a) Current distribution records for the sea star Asterias amurensi in its native and invasive range. (b) Modelled distribution in its invasive range. Red regions represent areas with suitable mean winter and summer seafloor temperatures for the benthic adult stage.

      Source: From Byrne et al. (2016).

      APPLICATION 2.1 Ecological niche modelling and ordination as management tools

      Managers are frequently confronted by problems associated with invasive species and make use of climate envelope models or ordination to develop solutions.

      The Arctic sea star, Asterias amurensis, is among the most ecologically influential of marine invertebrates, being a voracious predator with a particular affinity for bivalves (frequently putting it in conflict with bivalve fishers) and capable of dramatically affecting local biodiversity. Its native range extends in the North Pacific from the Arctic to southern Japan (Figure 2.5a). Accidentally introduced in the early 1980s to Tasmania (probably through the release of pelagic larvae in ship’s ballast water), adults became established on the seabed where they caused the extinction of many species. A. amurensis has since spread to Victoria along the coast of mainland Australia (Figure 2.5a) but so far it has not invaded New Zealand or the sub‐Antarctic Islands. One critical dimension of its multidimensional niche is water depth: the species cannot survive below a depth of 200 m. Both summer and winter temperature ranges are also fundamentally important to the success of the sea stars, and so to assess the potential for range expansion, Byrne et al. (2016) used the climate envelope model MaxEnt to characterise the thermal niche of both adults and the dispersive larval stages. Figure 2.5b shows the predicted invasive range, which includes much of New Zealand, together with the sub‐Antarctic Macquarie, Heard and Kerguelen Islands. The red areas are considered suitable for adult sea stars (dark red highly suitable), while the blue zones are suitable for the development of dispersing larval stages (dark blue optimal). That the species may spread to many new locations is alarming enough, but there is also a strong possibility that global warming will put much of the Antarctic coastline in peril. Results of such analyses highlight the importance of vigilance and border biosecurity.


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