Maternal effects and the evolution of aposematic signals

Aposematic signals that warn predators of the noxious qualities of prey gain their greatest selective advantage when predators have already experienced similar signals. Existing theory explains how such signals can spread through selective advantage after they are present at some critical frequency, but is unclear about how warning signals can be selectively advantageous when the trait is initially rare (i.e., when it first arises through mutation) and predators are naive. When aposematism is controlled by a maternal effect gene, the difficulty of initial rarity may be overcome. Unlike a zygotically expressed gene, a maternally expressed aposematism gene will be hidden from selection because it is not phenotypically expressed in the first individual with the mutation. Furthermore, the first individual carrying the new mutation will produce an entire family of aposematic offspring, thereby providing an immediate fitness advantage to this gene.

Driver understanding of work zone flagger signals and signaling devices. Interim report.

Texas State Department of Highways and Public Transportation, Transportation Planning Division, Austin

An evaluation of detectable warning surfaces for sidewalk curb ramps. Final report.

Virginia Department of Transportation, Richmond

Enhancements to passive warning devices at railroad-highway grade crossings.

Texas Department of Transportation, Austin

Detectable warning surfaces: color, contrast, and reflectance.

Federal Transit Administration, Washington, D.C.

Motorists' requirements for active grade crossing warning devices. Final report.

Federal Highway Administration, Traffic Systems Division, Washington, D.C.

Effectiveness of motorist warning devices at rail-highway crossings. Final report.

Federal Highway Administration, Office of Research, Development and Technology, Washington, D.C.

Experimental design for evaluating the safety benefits of railroad advance warning signs. Final report.

Federal Highway Administration, Office of Research and Development, Washington, D.C.

Executive summary and abstract for the report entitled "An evaluation of warning and regulatory signs for curves on rural roads."".

Federal Highway Administration, Office of Research, Washington, D.C.

Driver response in active advanced warning signs at high-speed signalized intersections. Final report.

Federal Highway Administration, Washington, D.C.

An evaluation of warning and regulatory signs for curves on rural roads. Final report.

Federal Highway Administration, Office of Research and Development, Washington, D.C.

Feasibility of an automatic truck warning system. Final report.

Federal Highway Administration, Office of Safety and Traffic Operations Research and Development, McLean, Va.

Advance traffic control warning systems for maintenance. Final report.

Federal Highway Administration, Baton Rouge, Fla.

Rail-highway crossing warning device - life cycle cost analysis. Final report.

Federal Railroad Administration, Office of Safety, Washington, D.C.

Innovative concepts and technology for railroad-highway grade crossing motorist warning systems. Vol. I: overview and concept generation and analysis. Final report.

Transportation Systems Center, Cambridge, Mass.