Biology subjects

Zandona, E.

Publications and source records attributed to Zandona, E..

4 recordsLinked to original sources

bioRxiv2025

What determines trophic niche breadth? A global analysis of freshwater fishes using isospaces

Trophic niche is one of the most tractable dimensions of a species niche. Several hypotheses have been proposed to explain global variation in species trophic niches, but empirical tests are limited. Stable isotope analysis (SIA) of {delta}{superscript 1}3C (a proxy for basal sources) and {delta}{superscript 1} N (a proxy for vertical trophic position) has increasingly been used to estimate trophic niche variation. We performed SIA on a dataset of over 33,000 stable isotope samples from freshwater fishes across six ecoregions. For 541 populations (358 species), we estimated the size of {delta}{superscript 1}3C x {delta}{superscript 1} N isospace--a bivariate representation of trophic niche breadth. We evaluated isospace variation in relation to environmental factors, species traits, and sampling scale, testing both novel and long-standing hypotheses about the drivers of trophic niche variation. A Boosted Regression Tree Model best predicted isospace, with environmental and trait-based variables among the strongest predictors. Fish isospaces were broader in regions with warmer temperatures, higher humidity, and precipitation variability, suggesting that more productive, diverse, and seasonal ecosystems are associated with broader trophic niches. Conversely, isospace size declined with increasing basin fish richness, which may reflect heightened interspecific competition or historical competitive exclusion. Isospace size was slightly smaller in large lakes compared to rivers, streams, and small lakes. Within-population variation in body size was strongly and positively associated with isospace size, highlighting the role of ontogenetic dietary shifts. Fish with truncate-rounded fins had broader isospaces than those with forked-lunate fins, likely due to the former having more limited movement and greater spatial isolation that resulted in greater between-individual niche variation. Primary consumers had larger isospaces than intermediate and top consumers. Predators showed relationships consistent those observed from analysis encompassing all trophic guilds, but non-predators deviated with regards to four variables--solar radiation, basin richness, average body size, and caudal fin aspect ratio. Isospace size increased with the number of sampled individuals, habitats and years surveyed. Although isospace patterns have well-documented limitations as trophic ecology metrics, our findings nonetheless conform with several longstanding hypotheses for trophic niche variation and stimulate new ideas about environmental and biological drivers of niche breadth.

ecology↗

bioRxiv2024

Body size is a better predictor of intra- than interspecific variation of animal stoichiometry across realms

Animal stoichiometry affects fundamental processes ranging from organismal physiology to global element cycles. However, it is unknown whether animal stoichiometry follows predictable scaling relationships with body mass and whether adaptation to life on land or water constrains patterns of elemental allocation. To test both interspecific and intraspecific body-size scaling relationships of the nitrogen (N), phosphorus (P), and N:P content of animals, we used a subset of the StoichLife database encompassing 9,933 individual animals (vertebrates and invertebrates) belonging to 1,543 species spanning 10 orders of magnitude of body size from terrestrial, freshwater, and marine realms. Across species, body mass did not explain much variation in %N and %P composition, although the %P of invertebrates decreased with size. The effects of body size on species elemental content were small in comparison to the effects of taxonomy. Body size was a better predictor of intraspecific than interspecific elemental patterns. Between 42 to 45% in intraspecific stoichiometric variation was explained by body size for 27% of vertebrate species and 35% of invertebrate species. Further, differences between organisms inhabiting aquatic and terrestrial realms were observed only in invertebrate interspecific %N, suggesting that the realm does not play an important role in determining elemental allocation of animals. Based on our analysis of the most comprehensive animal stoichiometry database, we conclude that (i) both body size and realm are relatively weak predictors of animal stoichiometry across taxa, and (ii) body size is a good predictor of intraspecific variation in animal elemental content, which is consistent with tissue-scaling relationships that hold broadly across large groups of animals. This research reveals a lack of general scaling patterns in the elemental content across animals and instead points to a large variation in scaling relationships within and among lineages.

ecology↗

bioRxiv2020

The 100,000 most influential scientists rank: the underrepresentation of Brazilian women in academia.

Despite the progress observed in recent years, women are still underrepresented in science worldwide, especially at top positions. Many factors contribute to women progressively leaving academia at different stages of their career, including motherhood, harassment and conscious and unconscious discrimination. Implicit bias plays a major negative role in recognition, promotions and career advancement of female scientists. Recently, a rank on the most influential scientists in the world was created based on several metrics, including the number of published papers and citations. Here, we analyzed the representation of Brazilian scientists in this rank, focusing on gender. Female Brazilian scientists are greatly underrepresented in the rank (11% in the Top 100,000; 18% in the Top 2%). Male scientists have more self-citation than female scientists and positions in the rank varied when self-citations were included, suggesting that self-citation by male scientists increases their visibility. Moreover, male scientists had more papers never cited than female scientists. Possible reasons for this observed scenario are related to the metrics used to rank scientists, since these metrics reproduce and amplify the well-known implicit bias in peer-review and citations. Discussions on the repercussions of such ranks are pivotal to avoid deepening the gender gap in science.

scientific communication and education↗

bioRxiv2020

Gender, race and parenthood impact academic productivity during the COVID-19 pandemic: from survey to action.

While the Coronavirus disease 2019 (COVID-19) pandemic is altering academia dynamics, those juggling remote work and domestic demands - including childcare - have already felt the impacts on productivity. Female authors are facing a decrease in papers submission rates since the beginning of the pandemic period. The reasons for this decline in women productivity need to be further investigated. Here we show the influence of gender, parenthood and race in academics productivity during the pandemic period, based on a survey answered by 3,345 Brazilian academics from various knowledge areas and research institutions. Findings revealed that male academics - especially childless ones - were the least affected group, whereas female academics, especially Black women and mothers, were the most impacted group. This scenario will leave long-term effects on the career progression of the most affected groups. The results presented here are crucial for the development of actions and policies that aim to avoid further deepening the gender gap in science. This particular situation we are facing during the pandemic demands institutional flexibility and academia should foster the discussion about actions to benefit Black scientists and academics with families in the post-pandemic scenario.

scientific communication and education↗