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Intraspe­cific com­pe­ti­tion can drive selec­tion favour­ing use of novel resources. How­ever, the genetic vari­a­tion for resource use on which this evo­lu­tion­ary step depends could also cause weaker com­pe­ti­tion. In a recent study

(Agashe and Bol­nick) tested the pos­si­ble alter­na­tive effects on niche expan­sion. They fac­to­ri­ally manip­u­lated both the degree of genetic vari­a­tion and pop­u­la­tion den­sity in flour bee­tles (Tri­bolium cas­ta­neum) exposed to both novel and famil­iar food resources. Using sta­ble car­bon iso­tope analy­sis, they mea­sured tem­po­ral change and indi­vid­ual vari­a­tion in bee­tle diet across eight gen­er­a­tions. Intraspe­cific com­pe­ti­tion and genetic vari­a­tion acted on dif­fer­ent com­po­nents of niche evo­lu­tion: com­pe­ti­tion facil­i­tated niche expan­sion, while genetic vari­a­tion increased indi­vid­ual vari­a­tion in niche use. In addi­tion, genetic vari­a­tion and com­pe­ti­tion together facil­i­tated niche expan­sion, but all these impacts were tem­po­rally vari­able. Thus, they show that the inter­ac­tion between genetic vari­a­tion and com­pe­ti­tion can also deter­mine niche evo­lu­tion at dif­fer­ent time scales.

(Source: Pro­ceed­ings of The Royal Soci­ety Bio­log­i­cal sci­ences, 12.05.2010)