Media Releases

Herbivore populations will go down as temperatures go up, U of T study says

October 4, 2011

TORONTO, ON – As cli­mate change caus­es tem­per­a­tures to rise, the num­ber of her­bi­vores will decrease, affect­ing the human food sup­ply, accord­ing to new research from the Uni­ver­si­ty of Toron­to.

In a paper being pub­lished this month in Amer­i­can Nat­u­ral­ist, a team of ecol­o­gists describe how dif­fer­ences in the gen­er­al respons­es of plants and her­bi­vores to tem­per­a­ture change pro­duces pre­dictable declines in her­bi­vore pop­u­la­tions. This decrease occurs because her­bi­vores grow more quick­ly at high tem­per­a­tures than plants do, and as a result the her­bi­vores run out of food.

“If warmer tem­per­a­tures decrease zoo­plank­ton in the ocean, as pre­dict­ed by our study, this will ulti­mate­ly lead to less food for fish and less seafood for humans,” says co-author Ben­jamin Gilbert of U of T’s ecol­o­gy and evo­lu­tion­ary biol­o­gy depart­ment.

Sev­er­al stud­ies have shown how the meta­bol­ic rates of plants or ani­mals change with tem­per­a­ture. Gilbert and his col­leagues incor­po­rat­ed these rates into com­mon­ly-used, math­e­mat­i­cal mod­els of plants and her­bi­vores to pre­dict how the abun­dance of each should change with warm­ing. They then com­pared their pre­dic­tions to the results from an exper­i­men­tal study in which phy­to­plank­ton and zoo­plank­ton pop­u­la­tions in tanks of water shift­ed sig­nif­i­cant­ly with changes in water tem­per­a­ture.

Gilbert cau­tions that long-term tests are required. Nev­er­the­less, if their pre­dic­tions are right, glob­al warm­ing will cause large shifts in food chains with con­se­quences for glob­al food secu­ri­ty and species con­ser­va­tion.

The paper enti­tled “The­o­ret­i­cal pre­dic­tions for how tem­per­a­ture affects the dynam­ics of inter­act­ing her­bi­vores and plants” was writ­ten by co-authors Gilbert and Mary O’Connor with Chris Brown of the Uni­ver­si­ty of Queens­land.


For more infor­ma­tion, please con­tact:

Ben­jamin Gilbert
Ecol­o­gy and Evo­lu­tion­ary Biol­o­gy
Office: 416–978-4065
Cell: 647–778-0900

Jes­si­ca Lewis
Fac­ul­ty of Arts and Sci­ence