Individual body mass and sex of a frugivorous bird affect the quality of seed dispersal
Data files
Oct 19, 2023 version files 4.08 KB
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Dataset_Campagnoli_et_al._2023.csv
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README.md
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Abstract
Frugivorous animals play crucial roles dispersing seeds away from parental plants and influencing plant recruitment. Most studies focus on comparisons of seed dispersal services provided by distinct species of animals, but neglect how within-species variation may affect dispersal. Individual traits, such as body mass and sex, are related to metabolic rates, gut load capacity, and transit times that potentially influence dispersal quantity and quality. Here, we aim to answer if individual traits (body mass and sex) of Pale-breasted Thrushes (Turdus leucomelas) affect seed dispersal quality by testing the following hypotheses (a) individual traits influence seed retention time and germination, (b) seed retention time affects seed germination and (c) seed passage through the gut enhances germination. We found that females retained seeds in the gut for longer periods than males. Gut-passed and manually depulped seeds had similar germination success. However, heavier birds, irrespective of sex, had longer seed retention times and promoted higher germination. Our results indicate that intraspecific differences in the morphological traits of frugivores are a source of variation in dispersal outputs and may help to explain complex patterns of seed dispersal. We highlight the importance of considering the quality of seed dispersal at an individual level, as well as at a species level, and reinforce that some individuals may contribute more to seed germination, and potentially recruitment, than others. Finally, a decrease in body masses of tropical birds in response to global warming may cascade to a decrease in seed dispersal quality.
README: Dataset Campagnoli et al. 2023
https://doi.org/10.5061/dryad.6djh9w16x
Dataset from Campagnoli et al. 2023 - Individual body mass and sex of a frugivorous bird affect the quality of seed dispersal. In this article, we aimed to unravel the role of individual traits (more specifically body mass and sex) of the Pale-Breasted-Trush Turdus leucomelas Vieillot, 1818, a widespread Neotropical passerine, on the seed dispersal quality of a plant species that provides a key resource for the frugivore community in the Cerrado (Miconia rubiginosa (Bonpl.) DC. (Melastomataceae)). To this end, we offered fruits of M. rubiginosa to 21 captive T. leucomelas individuals, recording gut passage times, and collecting seeds from their feces. Seeds were sowed in Petri dishes and kept in germination chambers. All T. leucomelas individuals were weighed, and their sexes were identified through the Polymerase Chain Reaction method, using sex-specific DNA sequences.
We found that females retained seeds in the gut for longer periods than males. Gut-passed and manually depulped seeds had similar germination success. However, heavier birds, irrespective of sex, had longer seed retention times, and promoted higher germination. Our results indicate that intraspecific differences in morphological traits of frugivores are a source of variation in dispersal outputs and may help to explain complex patterns of seed dispersal.
Description of the data and file structure
The dataset contains the following columns:
- bird_id - how we identified each T. leucomelas individual by a number;
- sex - the sex of the individual: if male or female;
- body_mass - the weight of individuals in g;
- gut_retention_time_(s) - the amount of time seeds took to pass through the gut of individuals in seconds;
- treatment - if seeds were gut-passed or manually depulped;
- seeded - number of seeds sowed in Petri dishes;
- germinated - number of seeds germinated;
- proportion_germinated - the proportion of seeds germinated, given by the number of seeds germinated divided by the number of seeds sowed.
Code/Software
We used R Software for all analyses performed (R Core Team, 2022). For GLMs, we used the package “lme4” (Bates et al., 2015). To validate GLMs, we used the function "simulateResiduals" from the package “DHARMa” (Hartig & Hartig, 2017).
References
Bates, D., Mächler, M., Bolker, B. M., & Walker, S. C. (2015). Fitting linear mixed-effects models using lme4. Journal of Statistifcal Software, 67(1), 1–48. https://doi.org/10.18637/jss.v067.i01
Hartig, F. (2017). DHARMa - Residual Diagnostics for HierArchical (Multi-level / Mixed) Regression Models (bl 65). https://cran.r-project.org/package=DHARMa
R Core Team (2022). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL https://www.R-project.org/
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