Bumblebees forage on flowers of increasingly complex morphologies despite low success

2021

Front. Ecol. Evol.

Self Cite

The importance of pollinators as selective agents for many floral traits is well established, but understanding their role in the evolution of complex floral shapes remains challenging. This is because pollinators often need much practice to efficiently handle morphologically complex flowers and extract their food rewards. What induces foragers to persistently visit and pollinate complex flowers despite their initial low profitability? We previously found that naive bumblebees, and unsuccessful feeding attempts of experienced ones, contribute to the pollination of complex flowers. Here we tested a complementary hypothesis, positing that successful foraging on flowers of one complex shape prepares pollinators to visit other species of different complex morphologies. We trained bumblebees to computer-controlled artificial flowers that were either simple, complex or both simple and complex. We then recorded their feeding choices and handling times on a second array of simple and complex flowers that had different shapes and required another handling technique. Bees trained on a single flower type (whether simple or complex) preferred flowers of the same type in the testing array. The foragers’ preferences after training on both flower types depended on the reward schedule during training: when both flower types rewarded equally, simple flowers were preferred at the test phase; when complex flowers provided higher reward during training, they became the preferred flower type during testing. These results suggest that successful foraging on complex flowers, especially when highly rewarding, can indeed induce insect pollinators to attempt additional flower species with other complex shapes.

Section: Discussioncontrasting

confidence: 90%

Section: Discussioncontrasting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Generalization of Foraging Experience Biases Bees Toward Flowers With Complex Morphologies

Krishna

2021

Front. Ecol. Evol.

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“…Yet, new complex flowers become more profitable if bees persist and learn how to handle them, resulting in greatly reduced handling times and higher food intake rates. This is because a much larger improvement in handling proficiency occurs on complex than on simple flowers [13,[24][25][26], and because of their often higher food rewards.…”

Section: Introductionmentioning

confidence: 99%

Can sociality facilitate learning of complex tasks? Lessons from bees and flowers

Pourtallier

Wajnberg

2023

Phil. Trans. R. Soc. B

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The emergence of animal societies is a major evolutionary transition, but its implications for learning-dependent innovations are insufficiently understood. Bees, with lifestyles ranging from solitary to eusocial, are ideal models for exploring social evolution. Here, we ask how and why bees may acquire a new ‘technology’, foraging on morphologically complex flowers, and whether eusociality facilitates this technological shift. We consider ‘complex’ flowers that produce high food rewards but are difficult to access, versus ‘simple’ flowers offering easily accessible yet lower rewards. Complex flowers are less profitable than simple flowers to naive bees but become more rewarding after a learning period. We model how social bees optimally choose between simple and complex flowers over time, to maximize their colony's food balance. The model predicts no effect of colony size on the bees' flower choices. More foraging on complex flowers is predicted as colony longevity, its proportion of foragers, individual longevity and learning ability increase. Of these traits, only long-lived colonies and abundant foragers characterize eusocial bees. Thus, we predict that eusociality supports, but is not mandatory for, learning to exploit complex flowers. A re-analysis of a large published dataset of bee–flower interactions supports these conclusions. We discuss parallels between the evolution of insect sociality and other major transitions that provide scaffolds for learning innovations. This article is part of the theme issue ‘Human socio-cultural evolution in light of evolutionary transitions’.

Patterns of Flower Complexity in Plant Communities

Annual Plant Reviews Online

2020

Coevolution between plants and their animal pollinators has selected for diverse flower shapes. Simple flower morphologies are accessible to a wide range of animal visitors, whereas only a subset of specialised pollinators are able to feed from complex flowers and pollinate them. The implications of flower shape for plant reproductive success, and the genetic mechanisms that govern shape development, are well studied in some plant species. This article aims to synthesise a smaller body of research, which deals with the distribution of flower shapes at the plant community level. Simple, dish‐shaped radially symmetrical flowers or inflorescences comprise the most common morphology in many floras. It has been suggested that simple flowers are selectively favoured when generalised pollinators (such as flies and small bees) are dominant among the local flower visitors. This was proposed to occur (i) on islands, (ii) towards the end of flowering seasons, (iii) at high elevations, (iv) in forest canopies, and (v) during late successional stages. Predictions 1–4 are supported by field surveys of different floras, while there is only weak evidence for the last prediction. The last section of the paper discusses the need for a floral complexity index that will reflect the empirically measured accessibility of flowers to different pollinator guilds. Eco‐informatic approaches are advocated for future exploration of community‐level floral complexity patterns and their relation to the community composition of flower visitors.