Passive partner choice through exploitation barrie

Authors: Miguel A RodríguezGironés Shan Sun Luis Santamaría

Publish Date: 2015/05/16

Volume: 29, Issue: 3, Pages: 323-340

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Abstract

Floral features that affect the efficiency with which pollinators can harvest their resources or the profitability they obtain from them affect the foraging decisions of pollinators Foraging choices of pollinators in turn affect pollen flow increases in flower constancy lead to more efficient pollen transport It follows that exploitation barriers—flower traits that differentially affect net intake rates of potential visitors—will promote resource partitioning and enhance pollen export In this paper we first generalise foraging models to show that exploitation barriers can lead to partial resource partitioning even when flowers are randomly distributed in space Then we develop a model to study how the foraging rules of pollinators pollen removal and pollen deposition affect pollen flow The model shows that resource partitioning even incomplete can substantially increase the efficiency of pollen flow Finally we use computer simulations to demonstrate that exploitation barriers promoting partial resource partitioning can evolve Many of the flower traits associated with pollination syndromes have small but consistent effects on the efficiency with which different taxonomic groups exploit flowers and can be considered exploitation barriers Even if these barriers are not strong enough to promote strict specialisation and may have little effect on the female component of fitness when pollinators are not a limiting resource they are likely to be selected because they enhance the male component of fitnessThis work was supported by the Ministerio de Ciencia e Innovación/FEDER Project CGL201016795 to MARG and LS SS acknowledges support by the National Natural Science Foundation of China grant No 31100277 and the Fundamental Research Funds for the Central Universities lzujbky201399We used a genetic algorithm to calculate the optimal foraging strategy of pollinators Each generation 200 pollinators 100 of each species foraged on a 100 × 100 square lattice with periodic boundary conditions containing one flower per cell Cells were randomly assigned to plant species each generation equal probability of belonging to each species no spatial correlations Pollinators endowed with a genetically determined foraging strategy foraged throughout the season for most generations 20000 time units At the end of the season a new generation of pollinators was produced pollinators that obtained more nectar produced more offspring and mutations were introduced to probe new foraging strategies The process was iterated for 10000 generationsAs a result of 13 and 14 if a pollinator specialised on a particular flower type it achieved the minimum handling time at that flower type—at the cost of experiencing the maximum handling time if it once visited the other flower species For pollinators visiting both flower types handling times oscillated between their maximum and minimum valuesPayoffs were used to select the “parents” of the pollinators that constituted the following generation We selected parents at random with probabilities proportional to ωk with the constraint that one individual could not produce more than five offspring Of every ten parents chosen nine produced identical offspring For the tenth parent preference genes αA and αB had a 02 probability of mutating Mutations steps were normally distributed with mean zero and standard deviation 003 Preference genes were constrained to lie in the interval 10−4 10

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