Ant Food Foraging Behaviors

Transcription

1 nt Food Foraging ehaviors Katie Kinzler Journal Club June 5, 2008

2 rticle Details From nonlinearity to optimality: pheromone trail foraging by ants David J.T. Sumpter and Madeleine eekman Journal of nimal ehavior 2003 Volume 66 pp

3 Foraging ehaviors Colonies thrive due to communication abilities Lay pheromones to and from food source Maximize energy and workforce efficiency Previous Findings Follow shortest path to food source sses food volume Trails will lead to large food sources

4 Goal of Paper To understand the pheromone laying mechanism Determine how the ants divide workforce between multiple food sources Mathematically model the observed behaviors

5 Methods Colony of Monomorium pharaonis Three different experimental conditions Deprived from food for 1-3 days Drops of food about 1.5 cm Counted ants crossing line 5 cm in front of feeder for 1 minute fter discovery fter 5 minutes t 10 minute intervals Maximum exploitation Differences from previous experiments More replicates nts had free roam of the foraging area

6 Two Feeders Unequal food quality 1M and 0.1M sugar solutions Exploited the feeder of better quality

7 The Model dx dt dx ( α + X )( N X X ) = β sx ( K + X ) sx = ( α + β )( ) X N X X dt Pheromone trails were left to both feeders Did not compare feeders Main mechanism is pheromones Model to understand pheromone dynamics Extended from eekman et al 2001 model ( K + X )

8 Terms dx dt dx dt ( α + X )( N X X ) = β = ( α + β X )( N X X ) sx ( K + X ) sx ( K + X ) X and X are the number of ants engaged with the respective food source N- X X represents the roaming ants Saturating function determines the rate at which ants will lose the trail Parameters α is the rate of random discoveries = β determines the strength of recruitment β = while β = K= 10 s=1

9 Numerical Solution Eventually choose 1M source Can make choice as to which feeder to exploit simply by having a faster recruitment rate to the better food Lay weaker pheromones in response to lower quality food

10 Single Feeder Trial to 1M food builds faster Maximum exploitation ti equal for both sources s

11 Two Feeders Model Predictions for two feeders with equal food quality If the number of initial visitors are equal then the feeders will be exploited equally Unequal number of initial visitors then the feeder with more initial visitors will receive the majority of foraging ants

12 Two Feeders Equal food quality verage of data suggests that there was an equal number of ants visiting each feeder nalysis of individual experiments showed bias to one feeder

13 Conclusion Three clear patterns Colony allocates same number of ants Focused on the better food source or only one of the two equal feeders Simple mechanism of positive feedback Slower build up of pheromones to less profitable food source Feedback in natural foraging environment ehavior does not require complex central organization

14 References Sumpter, David, and Madeleine eekman. "From nonlinearity to optimality: pheromone trail foraging by ants." nimal ehavior 66(2003): Holldobler, ert, and Edward Wilson. The nts. 1st. Cambridge: Harvard University it Press, Images: /i l cularbody.typepad.com/vernacularbody/images/ant.jpg&imgrefurl cutter%20francis%20ratnieks.jpg %20R t i

15 Questions?