Pollinator Foraging Adaptation and Coexistence of Competing Plants

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.

Coexistence and competitive exclusion in mutualism

“…There has been recent theoretical interest in coexistence of mutualists that compete for shared commodities (Lee and Inouye , Benadi et al. , , Song and Feldman , Benadi , Revilla and Křivan ). These models, however, do not yield clear criteria for competitive exclusion, as R * and P * theories do for other consumer–resource interactions.…”

“…Indeed, the vast majority of mutualism models do not mechanistically consider competition for mutualistic commodities (Johnson and Amarasekare 2013), either because they focus on tightly coupled pairwise mutualisms in which interspecific competition is irrelevant, or because commodities are implicitly modeled such that they do not constitute limiting factors. There has been recent theoretical interest in coexistence of mutualists that compete for shared commodities (Lee and Inouye 2010, Benadi et al 2012, Song and Feldman 2014, Benadi 2015, Revilla and K rivan 2016. These models, however, do not yield clear criteria for competitive exclusion, as R* and P* theories do for other consumerresource interactions.…”

“…For example, some models predict that mutualistic interactions may undermine competitor coexistence by amplifying existing competitive asymmetries (e.g., Benadi 2015). Other studies predict that competitors engaging with shared mutualists may coexist when mutualists adaptively forage (e.g., Song andFeldman 2014, Revilla andK rivan 2016), are sufficiently specialized (e.g., Benadi et al 2013, Benadi 2015, or influence partners in a way that benefits competitors (e.g., Bever 2003, Lee andInouye 2010). It is difficult, however, to distill concrete coexistence criteria from these models as do R* and P* theories for predator-prey interactions.…”

From antagonistic larvae to mutualistic adults: coevolution of diet niches within life cycles

“…If the juvenile is not a full specialist, that is the two plant species share a predator (herbivore), then they are involved in apparent competition (Holt ). Similarly, even though pollen dilution may happen, observations suggest that pollinator sharing may create dominant facilitative effects among plant species (Tur et al ). Therefore, apparent mutualism among plant species is possible, when the adult stage is not a full specialist.…”

Speed reading

“…arXiv mainly holds studies in physical and 'quantitative' science, although some of the studies mentioned above can be found there [1][2][3] . A significant feature of arXiv is that articles can be revised and updated, something that is difficult to achieve in formal literature.…”