Pollinator foraging flexibility and coexistence of competing plants

TL;DR

This study uses optimal foraging theory to explore how adaptive and non-adaptive pollinators influence the coexistence of competing plant species, revealing conditions that promote or hinder plant diversity.

Contribution

It compares the effects of fixed versus adaptive pollinator foraging strategies on plant coexistence, highlighting the role of adaptation in community stability.

Findings

Fixed pollinator preferences require weak plant competition for coexistence.

Adaptive foraging can either hinder or promote coexistence depending on pollinator competition.

Adaptive foraging enhances pollinator resilience to plant loss.

Abstract

We use the optimal foraging theory to study coexistence between two plant species and a generalist pollinator. We compare conditions for plant coexistence for non-adaptive vs. adaptive pollinators that adjust their foraging strategy to maximize fitness. When pollinators have fixed preferences, we show that plant coexistence typically requires both weak competition between plants for resources (e.g., space or nutrients) and pollinator preferences that are not too biased in favour of either plant. We also show how plant coexistence is promoted by indirect facilitation via the pollinator. When pollinators are adaptive foragers, pollinator's diet maximizes pollinator's fitness measured as the per capita population growth rate. Simulations show that this has two conflicting consequences for plant coexistence. On the one hand, when competition between pollinators is weak, adaptation favours pollinator specialization on the more profitable plant which increases asymmetries in plant competition and makes their coexistence less likely. On the other hand, when competition between pollinators is strong, adaptation promotes generalism, which facilitates plant coexistence. In addition, adaptive foraging allows pollinators to survive sudden loss of the preferred plant host, thus preventing further collapse of the entire community. Keywords: mutualism, competition, optimal foraging, evolutionarily stable strategy, coexistence, adaptation rate