Multitrophic interactions and novel ecosystems Christoph Kffer - - PowerPoint PPT Presentation

Christoph Küffer

kueffer@env.ethz.ch CHN G 26.1

Multitrophic interactions and novel ecosystems

• A. Novel ecosystems

and trophic impoverishment

• B. Multitrophic interactions:

some basics

Overview

Novel ecosystems and trophic impoverishment

‘Novel ecosystems’ have species compositions and relative abundances that have not occurred previously within a given biome. The key characteristics are: (1) novelty: new species combinations, with the potential for changes in ecosystem functioning (2) human agency: ecosystems that are the result of deliberate or inadvertent human action, but do not depend

• n continued human intervention for their maintenance.

Novel ecosystems

Hobbs et al. Global Ecology and Biogeography, 2006

What is the role of biotic change for (anthropogenic) ecosystem change?

Novel ecosystems

Hobbs & Cramer, Ann. Rev. Env. 2009

Alternative stable states: plant-soil feedbacks

For instance invasion of N-fixing non-native species such as Morella [Myrica) faya in island ecosystems (e.g. Hawaii Volcanoes National Park). These species increase soil fertility and thereby facilitate further invasions by other non-native species (“invasional meltdown”)

Alternative stable states: fire cycles

For instance invasion of fire-tolerant and fire-enhancing non-native species in habitat without a long history of fires and thus no native fire-adapted species

Novel multitrophic interactions?

Trophic impoverishment of Europe’s fauna

Wolf Bear Lion Lynx Aurochs Wild cat European mink Fish otter Moose Wild horses Wisent (European bison)

The loss of mega-frugivores in past < 50k years

7580 kg 300 kg (9 kg) 100 kg 0.54 kg (0.009 kg)

Hansen & Galetti, Science, 2009

Loss of marine megafauna

increased anthrop. disturbances

sharks

Ferretti et al., Ecology Letters 2010

Loss of marine megafauna

sharks

Springer al., PNAS 2003

Loss of marine megafauna

Jackson, PNAS 2001

Loss of marine megafauna

Jackson, PNAS 2001

Mauritius ?? alien, naturalized insects 10 alien, nat. reptiles 20 alien, nat. birds 2 rats, mouse, dog, shrew, feral cats, mongoose, tenrec feral pig monkey deer, goat, hare, rabbit 1865 sq km

Cheke & Hume, Lost Land of the Dodo, 2008

flightless Dodo giant & grey parrot 2 giant tortoises

• wl, harrier

giant lizard 3 snakes ?? insects (DDT) 2 fruitbats

Multitrophic interactions: some basics

Tri-trophic interactions and trophic cascades

Predator-herbivore-plant

bottom-up v. top-down control? extreme climate events abiotic resources wolf-deer-forest lynx-snow hare African savannah tropical forests (Terborgh’s islands)

• tter-urchin-kelp

biological control predator consumer primary producer

Avoidance / tolerance behavior

flocking behavior nocturnal activity habitat use patterns increased plant defense switch in vegetation composition

• R. hawaiiensis

alien Rubus predator consumer primary producer

to eat costs

Townsend et al., Ecology, 3rd edition, 2008

Consumer - producer coevolution: consumer change induces producer change (1/2)

Keane & Crawley TREE, 2002

enemy release hypothesis

Consumer - producer coevolution: consumer change induces producer change (2/2)

Lambers et al. Plant Physiological Ecology, after: Rhoades, Am Nat. 1985

Phenotypic response (e.g. enemy release)

• r genetic response

(evolution of increased competitive ability, EICA)?

Blossey & Nötzold J Ecology, 1995

Consumer - producer feedback: producer change induces consumer change

infertile vegetation fertile vegetation high-quality litter low-quality litter fungi bacteria fungal-feeding fauna (“grazing”, e.g. collembolans or mites) bacteria-f. fauna (“predation”, e.g. protozoans or nematodes) predatory fauna predatory fauna SOIL

Predator-mesopredator-prey “mesopredator release”

native dingo alien cat or fox native marsupials alien cat or fox alien rat native seabirds

more than one species on a trophic level

native dingo alien cat or fox native marsupials alien cat or fox alien rat native seabirds + +

• apparent

competition

bushmeat hunting and fish supply in West Africa

Brashares et al., Science, 2004

mountain pigmy possum bogong moth

trophic interactions in the landscape

plant-animal mutualisms

cascading effects of extinction of mutualist

Anderson et al., Science, 2011

Reproduction of an endemic shrub in New Zealand without (on rat- infested mainland) and with (on rat-free islets) pollinating bird species

competition for higher trophic levels

Number of pollinators visiting Raphanus flowers at different densities of Cirsium flowers.

Ghazoul, J Ecol, 2006

From food chains to food webs

Bascompte et al. Science, 2009

Network analysis (1/2)

Bascompte & Jordano, Annu. Rev. Ecol. Evol. Syst., 2007

Rarity of interactions (k)

Network analysis (2/2)

Nestedness analysis Randomness

• f distribution of

interactions between species

The diversity - stability debate

May 1973 http://www.multimedia.ethz.ch/conferences/2009/latsis Haldane & May, Nature, 2011