The trophic ecology of guppies (poecilia reticulata) from the streams of Trinidad

Several factors may influence intraspecific niche differentiation, such as the different levels of resources or degrees of competition and predation organisms experience. Resource use polymorphism can lead to morphological differentiation and to the evolution of different life history traits. Trinidadian Guppies (Poecilia reticulata) inhabit streams where they experience high or low predation pressure. Guppies living in high (HP) and low predation (LP) sites have evolved different life history traits: HP guppies mature earlier, produce more and smaller offspring, and have higher overall fecundity and reproductive allotment than their LP counterparts.The objective of this dissertation was to investigate the trophic ecology of guppies and its correlation with their life histories patterns. Three methodologies were employed: gut content analysis, gut length measurement, and stable isotope analysis. In the dry season, guppies in HP sites had a higher quality diet, which consisted of a greater proportion of invertebrates. Guppies in HP sites were more selective than guppies in LP sites, avoiding invertebrates of poor quality, as measured by a high carbon:nitrogen ratio. Gut morphology data confirmed these results, as guppies with lower quality diets (from LP sites) had longer guts. Comparisons between dry and wet seasons revealed that the diet of guppies shifted during the wet season, thereby eliminating dietary differences between HP and LP guppies found during the dry season.A survey of HP and LP population pairs from six different rivers conducted in the wet season showed some similarity within stream types in their environmental and biological characteristics but with some differences between rivers. 15N and 13C stable isotope analysis across the surveyed sites showed that LP guppies generally occupied a higher trophic position than HP guppies, but that this relationship was highly influenced by the river of origin. Stable isotopes also indicated that guppies assimilated invertebrates into their tissues more than other dietary items and that the variation in diet composition between sites was high.The results of this dissertation help distinguish the mechanisms by which guppy phenotypes (HP vs. LP) affect their environment, improving the understanding of the feedback between evolutionary and ecological processes in nature.Ph.D., Environmental Science/Ecology -- Drexel University, 201

Intraspecific variability modulates interspecific variability in animal organismal stoichiometry.

Interspecific differences in organismal stoichiometry (OS) have been documented in a wide range of animal taxa and are of significant interest for understanding evolutionary patterns in OS. In contrast, intraspecific variation in animal OS has generally been treated as analytical noise or random variation, even though available data suggest intraspecific variability in OS is widespread. Here, we assess how intraspecific variation in OS affects inferences about interspecific OS differences using two co-occurring Neotropical fishes: Poecilia reticulata and Rivulus hartii. A wide range of OS has been observed within both species and has been attributed to environmental differences among stream systems. We assess the contributions of species identity, stream system, and the interactions between stream and species to variability in N:P, C:P, and C:N. Because predation pressure can impact the foraging ecology and life-history traits of fishes, we compare predictors of OS between communities that include predators, and communities where predators are absent. We find that species identity is the strongest predictor of N:P, while stream or the interaction of stream and species contribute more to the overall variation in C:P and C:N. Interspecific differences in N:P, C:P, and C:N are therefore not consistent among streams. The relative contribution of stream or species to OS qualitatively changes between the two predation communities, but these differences do not have appreciable effects in interspecific patterns. We conclude that although species identity is a significant predictor of OS, intraspecific OS is sometimes sufficient to overwhelm or obfuscate interspecific differences in OS

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 of 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%). Possible reasons for this observed scenario are related to the metrics used to rank scientists, which reproduce and amplify the well-known implicit bias in peer-review and citations. 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. Discussions on the repercussions of such ranks are pivotal to avoid deepening the gender gap in science

Bias against parents in science hits women harder

Worldwide, parenthood remains a major driver for the reduced participation of women in the job market, where discrimination stems from people’s biases against mothers, based on stereotypes and misconceptions surrounding the vision of motherhood in our society. In academia, parenthood may be perceived as negatively affecting scientists’ commitment and dedication, especially women’s. We conducted a survey amongst Brazilian scientists and found that mothers self-reported a higher prevalence of negative bias in their workplace when compared to fathers. The perception of a negative bias was influenced by gender and career status, but not by race, scientific field or number of children. Regarding intersections, mothers with less than 15 years of hiring reported having suffered a higher rate of negative bias against themselves. We discuss implications of these results and suggest how this negative bias should be addressed in order to promote an equitable environment that does not harm women in science

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

The coronavirus disease 2019 (COVID-19) pandemic is altering dynamics in academia, and people juggling remote work and domestic demands – including childcare – have felt impacts on their productivity. Female authors have faced a decrease in paper submission rates since the beginning of the pandemic period. The reasons for this decline in women’s productivity need to be further investigated. Here, we analyzed the influence of gender, parenthood and race on academic productivity during the pandemic period based on a survey answered by 3,345 Brazilian academics from various knowledge areas and research institutions. Productivity was assessed by the ability to submit papers as planned and to meet deadlines during the initial period of social isolation in Brazil. The findings revealed that male academics – especially those without children – are the least affected group, whereas Black women and mothers are the most impacted groups. These impacts are likely a consequence of the well-known unequal division of domestic labor between men and women, which has been exacerbated during the pandemic. Additionally, our results highlight that racism strongly persists in academia, especially against Black women. The pandemic will have 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 academia

Maternity in the Brazilian CV Lattes : when will it become a reality?

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