Data from: revisiting niche divergence hypothesis in dimorphic birds: is diet overlap correlated with sexual size dimorphism?
Data files
Feb 01, 2024 version files 38.52 KB
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Database_revisiting_niche_divergence.xlsx
33.24 KB
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README.md
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Abstract
The evolution of sexual size dimorphism (SSD) is a long-standing topic in evolutionary biology, but there is little agreement on the extent to which SSD is driven by the different selective forces. While sexual selection and fecundity selection have traditionally been proposed as the two leading hypotheses, SSD may also result from natural selection through mechanisms such as sexual niche divergence, which might have reduced resource competition between sexes. Here, we revisited the niche divergence hypothesis by testing the relationship between the sexual overlap in diet and SSD of 56 bird species using phylogenetic comparative analyses. We then assessed how SSD variation relates to the three main hypotheses: sexual selection, fecundity selection, and sexual niche divergence using phylogenetic generalized least squares (PGLS). Then, we compared sexual selection, fecundity selection, and niche divergence selection as SSD drivers through phylogenetic confirmatory path analyses to disentangle the possible causal evolutionary relationships between SSD and the three hypotheses. Phylogenetic generalized least squares showed that SSD was negatively correlated with diet overlap, i. e., the greater the difference in body size between males and females, the less diet overlap. As predicted by sexual selection theory, the difference in body size between sexes was higher in polygynous species. Confirmatory phylogenetic path analyses suggested that the most likely evolutionary path might include mating system as a main driver in SSD and niche divergence as a result of SSD. We found no evidence of a role of fecundity selection in the evolution of female-biased SSD. Our study provides evidence that sexual selection has likely been the main cause of SSD and that dietary divergence is likely an indirect effect of SSD.
README: Revisiting niche divergence hypothesis in sexually dimorphic birds: is diet overlap correlated with sexual size dimorphism?
https://doi.org/10.5061/dryad.dfn2z358p
This study explores the relationship between Sexual Size Dimorphism (SSD) and ecological dynamics in bird species. The dataset includes information on the diet of 58 bird species, aiming to investigate the correlation between SSD and diet overlap, mating systems, sexual display behaviors, and clutch size.
*Dataset contents: * We compiled data from a thorough literature survey, sifting through 289 references to focus on 58 bird species. The dataset includes details on diet overlapping between both males and females. Mating systems were categorized, incorporating polyandry, monogamy, and polygyny. Male sexual display behaviors were classified based on a five-point scale, ranging from ground displays to acrobatic aerial displays. Clutch size, representing fecundity, was also documented. Morphometric traits, such as body mass, wing length, bill length, and tarsus length, offered a nuanced perspective on avian physical characteristics.
Description of the data and file structure
DATA-SPECIFIC INFORMATION FOR: Database_revisiting_niche_divergence.xlsx
These are the data used to explore the relationship between Sexual Size Dimorphism (SSD) and ecological dynamics in bird species. The dataset includes information on the diet of 58 bird species, aiming to investigate the correlation between SSD and diet overlap, mating systems, sexual display behaviors, and clutch size.
1. Number of variables: 25
2. Number of cases/rows: 58
3. Variable List:
Species information:
- Order: Order of the specie
- Family: Family of the species
- Species: Scientific name of the species
Biometric measures (BM_male, BM_female, Wing_male, Wing_female, Beak_male, Beak_female, Tarsus_male, Tarsus_female): Morphometric measurements were preferably obtained from the study from which the diet composition was taken. In case such biometric data were not available in that study, they were collected from other studies in the same area or from other published databases (Lislevand et al., 2007).
- BM_male: Body mass of males (grams)
- BM_female: Body mass of females (grams)
- Wing_male: Wing length of males (mm)
- Wing_female: Wing length of females (mm)
- Beak_male: Beak length of males (mm)
- Beak_female: Beak length of females (mm)
- Tarsus_male: Tarsus length of males (mm)
- Tarsus_female: Tarsus length of females (mm)
Sexual size dimorphism data (SSD_BM, SSD_wing, SSD_beak, SSD_tarsus): SSD was calculated as log10 (male size / female size), with values < 0 indicating female-biased SSD and values > 0 indicating male-biased SSD. We calculated SSD separately for four morphometric traits: body mass, wing length, bill length, and tarsus length.
- SSD_BM: log10 (BM_male / BM_female)
- SSD_wing: log10 (Wing_male / Wing_female)
- SSD_beak: log10 (Beak_male / Beak_female)
- SSD_tarsus: log10 (Tarsus_male / Tarsus_female)
Diet overlap data (CD_total, CD_non-breeding, CD_breeding, CD_annual, CD_prey): The database of diet overlap was compiled through a literature survey of all major ornithological journals. The ISI Web of Knowledge was systematically searched for original case studies in which data on the diet composition of males and females were provided. Diet overlap calculated with the simplified Morisita index CD (Horn, 1966), using FSAmisc package (Ogle, 2015) of R version 4.0.5 (R Core Team, 2021).
- CD_total: Diet overlap calculated with the simplified Morisita index (as described above) applied to the full dataset including species with breeding, non-breeding and annual overlap.
- CD_non-breeding: Diet overlap calculated with the simplified Morisita index (as described above) applied to species with diet data corresponding to the non-breeding season.
- CD_breeding: Diet overlap calculated with the simplified Morisita index (as described above) applied to species with diet data corresponding to the breeding season.
- CD_annual: Diet overlap calculated with the simplified Morisita index (as described above) applied to species whose diet data is an average of different seasons.
- CD_prey: Diet overlap calculated with the simplified Morisita index (as described above) applied to species whose diet data is the prey size.
Sexual selection and clutch size data (Clutch_size, Mating_system, Sexual_display):
- Clutch_size: Average clutch size of the species
- Mating_system: (1) polyandry; (2) monogamy (<5% polygyny); (3) mostly monogamy, but occasional polygyny (5–15% polygyny); (4) mostly polygyny (> 15% polygyny) and (5) lek or promiscuous (Lislevand et al., 2007).
- Sexual_display: (1) ground displays only, including displays on trees and bushes; (2) ground displays, but with occasional jumps/leaps into the air; (3) both ground and non-acrobatic flight displays; (4) mainly aerial displays, non-acrobatic; (5) mainly aerial displays, acrobatic (Lislevand et al., 2007).
Bibliography sources:
- Source_data_biometry: Bibliographic references of biometry data
- Source_data_diet: Bibliographic references of diet data
4. Missing data codes: NA (data not available)
Methods
The database of diet overlap was compiled through a literature survey of all major ornithological journals. The ISI Web of Knowledge was systematically searched for original case studies in which data on the diet composition of males and females were provided. A total of 289 references were examined, 62 of which provided data on the diet of both sexes for 58 species belonging to 32 families. We discarded studies based on prey types brought to the nest by adults (n=8) because food provisioning to chicks does not represent the actual nutritional requirements of males and females, or those based on isotope analyses (n=10), since both sexes might show overlapping isotopic niches, while having a different trophic niche, for instance, if both sexes feed on different prey with similar δ15N values (Bearhop et al., 2004). Diet composition was described using stomachs, esophageal contents, and regurgitations (80.3% of the studies), feces (13.1%), and direct observation (6.6%).
The description of the mating system, male display type, and clutch size were obtained from the Handbook of the birds of the world (del Hoyo et al., 1992), Lislevand et al. (2007) and BoW (Billerman et al., 2022).