Biology subjects

Tonnabel, J.

Publications and source records attributed to Tonnabel, J..

7 recordsLinked to original sources

bioRxiv2026

Wildlife damage to tropical agroforests: predicting primate-induced fruit loss using species' energy requirements

1. Quantitatively assessing wildlife damage to food crops in tropical agroforestry systems is notoriously problematic. At the same time, the animal species likely to destroy these crops, such as primates, are often endangered and a source of conflict. Resolving these conflicts may require the implementation of financial compensation where non-monetary solutions are unavailable. Currently, however, there is no suitable method for assessing fruit losses due to the complexities of agroforestry plots used by most small households practising polyculture-based agriculture. 2. We constructed an energy balance model to predict the quantity of cultivated fruit and other locally sourced food required by crop-dependent primates to meet their metabolic needs. The proposed method is based on the principle that, under conditions of energy balance, an animal's daily energy intake corresponds to its total energy expenditure. The ecophysiological model incorporated the daily food and energy intake of wild primates, measured using the bite-size method and the nutritional composition of food, as well as their total energy expenditure and body composition, measured using doubly labelled water. We tested the model's predictions on lemurs foraging in several agroforests in Mayotte, and on two frugivorous primate species in Madagascar during different seasons. Additionally, we evaluated whether more conventional dietary analysis methods (feeding-time sampling), or published energetics data could reliably inform the model, and reduce the costs and constraints of field observations. 3. The predictions were generally consistent with direct estimates of food intake (91% +- 25%, n = 14 across different seasons), though this was influenced by the lemurs evolutionary-driven seasonal fattening strategy. Time-derived estimates using correction factors or published measurements of total energy expenditure were also consistent, but further studies are required to confirm these findings. 4. Policy implications. The study provides proof of concept for a promising approach to quantifying wildlife-related agricultural losses in small-scale agroforestry. This innovative method provides policymakers, farmers' associations, and non-governmental organisations with sufficiently accurate quantitative estimates to support the development of evidence-based financial compensation schemes.

ecology↗

bioRxiv2026

Physical interactions between pollen and pistil tissues mediate cryptic female choice in Brassica rapa

Cryptic female choice - female-mediated bias in fertilization after mating - is well established in animals and can also occur in plants when multiple pollens compete on the same pistil. However, whether interactions between pollen and pistil tissues after pollen deposition contribute to this process remains unknown. Here, we experimentally test whether such interactions mediate cryptic female choice in the angiosperm Brassica rapa. We quantified fertilization success of pollen donors competing on the same pistil using paternity analyses, and in parallel, made semi-in vivo assays to measure pollen tubes trajectories emerging from the excised styles and growing toward unfertilized ovules for each donor-recipient pair. We show that pollen tube growth towards ovules predicts higher fertilization success under pollen competition. Thus, we document a previously unobserved mechanism of cryptic female choice based on physical interactions between male and female components of reproduction. In addition, different recipient plants favour different pollen donors, consistent with non-directional female choice. Plants with longer styles bias paternities more strongly towards the most successful pollen donor. Overall, our study demonstrates that interactions between pollen tubes and pistil tissues after pollen germination enable plants to bias paternity toward particular donors.

evolutionary biology↗

bioRxiv2026

Experimental evidence for female choice in an angiosperm

Female choice is a central process of sexual selection that has shaped numerous phenotypes in animals. It may operate broadly across sexually reproducing organisms, including plants, not only because sex differences in sexual selection arise from anisogamy, wich refers to the unequal investment in gametes between sexes, but also because it can emerge from simple variation in female reproductive morphology. Here, we provide the first empirical test of cryptic female choice in an angiosperm by examining whether pollen and pistil traits jointly influence paternal fertilization success. Using experimental pollen competition, paternity analyses, and trait measurements, we show that pistil traits can bias paternity toward pollen donors with specific pollen traits. These results demonstrate that cryptic female choice operates in plants, paralleling mechanisms described in animals.

evolutionary biology↗

bioRxiv2025

Environmental complexity constrains evolutionary adaptation across taxa

Complex environments combining multiple stressors are the new norm worldwide. Adaptive evolution will be critical to population persistence under these combined challenges, but how environmental complexity affects the pace of evolution remains poorly understood. Using a meta-experimental evolution approach, we exposed 14 species, from bacteria to unicellular eukaryotes and plants, to single stressors and their pairwise combinations for multiple generations, while keeping the overall stress level comparable. Populations evolving under combined stressors tended to have lower fitness increase in the selective environments, higher fitness reductions in the control environment, and shallower relation between initial maladaptation and fitness gain, than under single stressors. However, these responses varied with species and stressor type. Accounting for such constraints on evolutionary dynamics should prove crucial for the management of biodiversity. Significance StatementA pressing challenges for modern science and society in the face of ongoing global change is understanding what limits the capacity of living organisms to adapt to complex environments combining multiple stressors. To answer to this question, we conducted a large-scale meta-experimental evolution design across a diversity of organisms, exposing them for multiple generations to either single or combined-stress treatments. Combined stressors led to less adaptive fitness gain than single stressors, and imposed additional costs through reduced fitness in non-stressful conditions. This unique combination of meta-experimental approach with a careful distinction between environmental complexity and overall stress allowed us to gain robust quantitative evidence on how environmental complexity can impact the pace of evolution.

evolutionary biology↗

bioRxiv2025

Pollinator abundance shapes sexual selection in an angiosperm

Sexual selection is a cornerstone of evolutionary biology potentially operating in all sexually-reproducing organisms. Modern developments in the field revealed that this selective force extends beyond Darwins initial focus on access to mates in terms of competition for access to gametes of the other sex. Despite its presumed universality, sexual selection theory remains largely untested in plants compared to animals. This gap may partly stem from challenges in quantifying sexual selection using approaches that account for a critical plant-specific factor: the reliance on pollinators as third-party agents for accessing mates. Here, we quantified sexual selection along consecutive episodes of selection in the hermaphroditic plant Brassica rapa by integrating the monitoring of pollinator movements with genetic paternity analyses in experimental populations. Our approach identifies pollen competition for ovules as the primary arena for sexual selection in B. rapa. Darwinian competition for access to mates constitutes a secondary force, and was stronger in the male compared to the female sex function, as predicted by classic theory. Importantly, experimentally induced variation in pollinator abundance modulated the balance between pre- and post-pollination sexual selection. Under reduced pollinator abundance, the opportunity for selection on mate acquisition increased. Crucially, we demonstrate that ignoring pollinator movements among plants leads to erroneous quantification of pre-pollination sexual selection. We argue that a unifying theory of sexual selection requires a more comprehensive quantification of pre- and post-pollination episodes of selection, taking into account the specificities of gamete transfer in plants.

evolutionary biology↗

bioRxiv2021

Rapid divergence in vegetative morphology of a wind-pollinated plant between populations at contrasting densities

Plant sexual dimorphism is thought to evolve in response to sex-specific selection associated with competition for access to mates or resources, both of which will often be density-dependent. In wind-pollinated plants in particular, vegetative traits can have an important influence on both resource acquisition and the pollen dispersal and receipt, with potential conflict between these two components of fitness. We evaluated the role of plant density in shaping plant traits by measuring evolutionary responses in experimental populations of the sexually dimorphic wind-pollinated plant Mercurialis annua. After three generations of evolution, we observed divergence between high- and low-density populations in several vegetative traits, whereas there was no divergence for reproductive traits. A reversal in the direction of sexually dimorphic traits expressed in young plants evolved in both low- and high-density populations compared to the original population (stored as seeds). Compared to the source population, males at high density evolved to be taller when young, whereas at low density young females tended to become smaller. These results demonstrate that a simple change in plant density can induce rapid, age-dependent and sex-specific evolution in the ontogeny of vegetative organs, and illustrates the power of experimental evolution for investigating plant trait evolution.

evolutionary biology↗

bioRxiv2019

Mismatches between niches and geographic ranges of plants depend on life history traits

The ecological niche of a species describes the variation in population growth rates along environmental gradients that drives geographic range dynamics. Niches are thus central for understanding and forecasting species geographic distributions. However, theory predicts that migration limitation, source-sink dynamics and time-lagged local extinction can cause mismatches between niches and geographic distributions. It is still unclear how relevant these niche-distribution mismatches are for biodiversity dynamics and how they depend on species life history traits. This is mainly due to a lack of the comprehensive, range-wide demographic data needed to directly infer ecological niches for multiple species. Here we quantify niches from extensive demographic measurements along environmental gradients across the geographic ranges of 26 plant species (Proteaceae; South Africa). We then test whether life history explains variation in species niches and niche-distribution mismatches. Niches are generally wider for species with high seed dispersal or persistence abilities. Life history traits also explain the considerable interspecific variation in niche-distribution mismatches: poorer dispersers are absent from larger parts of their potential geographic ranges, whereas species with higher persistence ability more frequently occupy environments outside their ecological niche. Our study thus identifies major demographic and functional determinants of species niches and geographic distributions. It highlights that the inference of ecological niches from geographical distributions is most problematic for poorly dispersed and highly persistent species. We conclude that the direct quantification of ecological niches from demographic responses to environmental variation is a crucial step towards a better predictive understanding of biodiversity dynamics under environmental change.

ecology↗