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Do plants cooperate in reproduction? The effect of sharing pollination services on plant reproductive strategies

Periodic Reporting for period 1 - KinCoop (Do plants cooperate in reproduction? The effect of sharing pollination services on plant reproductive strategies)

Reporting period: 2015-08-01 to 2017-07-31

• What is the problem/issue being addressed?
KinCoop is studying how plants behave in a social context in terms of their reproductive strategies. Plants can facilitate pollination of their neighbours. I hypothesize that this process of sharing pollination services will influence plant reproduction, driving cooperative reproductive strategies.
• Why is it important for society?
KinCoop tests important questions about social evolution in the context of reproductive strategies that have previously been surprisingly little studied in plants. KinCoop is contributing then to our understanding of how plants cooperate during reproduction to alter plant population dynamics, with potentially useful outcomes for plant conservation, weed control, and crop breeding. Thus, KinCoop will have two main implications: i) it will help to build a sounder theoretical framework for life-history evolution in plants, which has hitherto not considered mutualistic social interactions; and ii) it will potentially inform human activities relevant to crop productivity. If plant social interactions affect reproductive traits, crop genotype selection should be reconsidered to select those more cooperative genotypes that behave better in groups. Crops are social environments and therefore we should look for social genotypes leading to higher group yields.
• What are the overall objectives?
KinCoop’s main goal is to test whether natural selection will favour social behaviours (from selfish to cooperative ones) in plant reproduction by assessing how different social environments, in terms of density and genetic relatedness of neighbours, might influence optimal allocation strategies through the effect of sharing pollinators and the effect this will have on mating patterns and plant fitness.
This report covers the period of the first two years involving the whole outgoing phase performed in the Department of Ecology and Evolution at the University of Lausanne. During this phase I have finished the first two Work Packages (WP) described in the proposal and also developed part of the tasks described in the WPs 4 and 5 related to career development, dissemination and public engagement

For the WP1, we aimed to comprehensively explore the way in which the intra-specific social environment influenced the evolution of resource allocation to pollinator attraction in plants. To this end, we have built a new model of evolutionarily stable strategies for obtaining quantitative predictions of the reproductive allocation considering the plant neighbourhood composition. This task has been performed in collaboration with Dr. Mauricio González-Forero, a former postdoc in the Department of Ecology and Evolution (UNIL) and currently working as Marie Sklodowska-Curie Fellow at St. Andrews University in UK. Using this theoretical model, we have found that the density and genetic relatedness of the neighbourhood regulate the optimal investment on floral structures to attract pollinators. Nevertheless, the shape of this functional link between both density and genetic relatedness of the neighbourhood and the optimal investment to pollinator attraction was moulded by different parameters controlling within- and between-group plant competition by pollinators. Namely, our model predicts that plants should cooperate when surrounded by siblings and the investment they do in their flowers help them to compete against other groups rather than to compete with their siblings within the group.

In addition, I have completed the WP2. This WP aimed to investigate in what extent the investment in advertising structures to attract pollinators (petal size, floral colour or nectar secretion) was a plastic response to changes in the social environment. For this, I performed a large common garden experiment under controlled glasshouse conditions involving more than 30,000 seeds and 700 plants where we characterized thousands of flowers. We grew plants in pots under controlled neighbourhoods with two levels of genetic relatedness (either siblings or genetically unrelated strangers) and three levels of density (one, four or seven plants per pot) in a full factorial experimental design.

The great success of the this experiment allowed us to collect a vast amount of data. We have collected data on reproductive allocation including: plant size in terms of height and biomass, flowering time, number of flowers produced, corolla diameter, flower-tube length, biomass allocated to petals, nectar volume and sugar concentration, quantitative estimation of colour by means of digital photographs, pollen production and ovule numbers.

The main finding of this experiment was that focal plants modified their behaviours depending on the social context. Namely, focal plants invested disproportionally more resources to floral advertisement when they were growing with relatives compared to when they were growing with strangers or alone. This result met the predictions of our theoretical model and support the hypthesis that cooperation in reproduction should be able to evolve in plants. Currently, we are working on an advanced version of the MS. The success of this experiment and its clear results set a base for at least one more manuscript on the effect of the neighbourhood conditions on the sex allocation of focal plants.

Besides these two main WPs, I have also worked and advanced some tasks of WP3. In particular, I have been working and collaborating with Yves Cuendot (lab technician of Pannell’s group) on the development of new microsatellites markers for our model species Moricandia moricandioides L. These markers are critical for assessing mating patterns and male success during WP3 experiment. Finally, we have performed a pilot experiment in the field (Baza,
The first two years of KinCoop have yielded significant results that will impact on the European Research Area and attitudes of European Society. First, the results of KinCoop showed the first evidence that plants may cooperate in reproduction, broadening the vision of how plants reproduce. The social context may have deep consequences for plant phenotypes but also for plant performance and fitness. Future research should therefore consider social selection theory into the research agenda of plant populations.

As the social context affects plant phenotypes and plant productivity, the results of KinCoop will boost the basis of research to improve crop efficiency by applying social theory into agronomic techniques. For that reason, during the next months I will work in coloration with plant breeders to work on a development plan for applying KinCoop findings into agriculture practices.
Moricandia moricandioides
Experimental groups
Rubén Torices working in the glasshouse