Trophic ecology of the fish Leporinus piau (Characiformes: Anostomidae) in an area influenced by a dam in the Parnaíba River

Introduction: Hydroelectric dams have several impacts on migratory fish, such as decreasing their abundance, local extinctions, and changes in the assemblage structure. Objective: To investigate the trophic and reproductive strategies of Leporinus piau upstream and downstream from a hydroelectric dam in the Parnaíba River. Methods: We identified food items and calculated trophic niche breadth in both sites to characterize the feeding strategy. We conducted permutational multivariate analysis of variance (PERMANOVA) to determine differences in diet between sites, followed by a SIMPER analysis in order to show which items were the most dissimilar. To characterize the reproductive strategy, we analyzed weight/length relationship, body condition factor, gonadosomatic index, and size at first maturity. Results: Leporinus piau was classified as an omnivore with a predominantly plant-based diet at both sites. The diet and niche breadth varied between sites. The condition factor differed between sites while size at first maturity differed between sites and sexes. Conclusions: Leporinus piauvariations upstream and downstream from a hydroelectric dam in the Parnaíba River are results of differences in life histories traits, as identified in the life history theory, which clarifies the differences on trophic and reproductive strategies.

Introducción: Los embalses hidroeléctricos tienen varios impactos en los peces migratorios, como la disminución de su abundancia, extinciones locales y cambios en la estructura del ensamblaje. Objetivo: Investigar las estrategias tróficas y reproductivas de Leporinus piau en aguas arriba y aguas abajo de un embalse hidroeléctrico en el río Parnaíba. Métodos: Para caracterizar la estrategia de alimentación, identificamos los alimentos consumidos y calculamos la amplitud del nicho trófico en ambos sitios. Para determinar diferencias en la dieta entre los sitios, realizamos un análisis Permutacional Multivariado de Varianza (PERMANOVA), seguido de un análisis SIMPER para mostrar cuales elementos generaron las diferencias. Para caracterizar la estrategia reproductiva, analizamos relación longitud/peso, factor de condición, índice gonadosomático y talla en la primera madurez. Resultados: Leporinus piau se clasificó como omnívoro con una dieta predominantemente de origen vegetal en ambos sitios. La dieta y la amplitud de nicho variaron entre sitios. El factor de condición difirió entre sitios mientras que la talla en la primera madurez difirió entre sitios y sexos. Conclusiones: Las variaciones de Leporinus piau aguas arriba y aguas abajo del embalse hidroeléctrico en el río Parnaíba, son resultado de diferencias en los rasgos de historias de vida, como es propuesto en la teoría de historia de vida que aclara las diferencias en las estrategias tróficas y reproductivas.

Consideraciones teóricas sobre la perspectiva ecológica-evolutiva del cáncer / Theoretical considerations on the ecological-evolutionary perspective of cancer

RESUMEN El cáncer constituye un serio problema de salud a nivel mundial. La introducción de una perspectiva ecológica y evolutiva de las neoplasias malignas tiene como propósito un enfoque más sistémico y objetivo a la naturaleza de este heterogéneo grupo de enfermedades. Con el objetivo de un acercamiento a las ideas más generalizadas existentes en la actualidad sobre la perspectiva ecológica-evolutiva del cáncer, se realizó la presente revisión. El cáncer es un fenómeno universal que afecta a todas las formas de organismos pluricelulares. El riesgo de desarrollar tumores malignos se encuentra estrechamente relacionado con los patrones de historias de vida trazados por el proceso evolutivo, acorde a la necesidad adaptativa de los organismos a los diferentes nichos ecológicos que ocupan. Existe asociación entre el desarrollo evolutivo de mecanismos protectores contra tumores malignos y el costo evolutivo de estos en términos de éxito reproductivo. El éxito reproductivo parece depender del tamaño corporal, la distribución de energía hacia procesos básicos y el riesgo basal de cáncer. La selección natural favorece mecanismos efectivos, que protejan contra el cáncer siempre que permitan una optimización de otros rasgos que determinen el éxito adaptativo. Las conclusiones derivadas de estos principios ecológicos y evolutivos, deben servir para una mejor caracterización de los factores dependientes tanto de los factores biológicos como de los ambientales que influyen en el riesgo de la carcinogénesis. Más del 90 por ciento del incremento del riesgo basal de cáncer, incluso en especies naturales, obedecen a la actividad humana, y por tanto, pueden ser modificables(AU)

ABSTRACT Cancer is a serious health problem worldwide. The introduction of an ecological and evolutionary perspective of malignant neoplasms is aimed at a more systemic and objective approach to the nature of this heterogeneous group of diseases. This paper will review current thinking in the ecological-evolutionary perspective of cancer. Cancer is a universal phenomenon that affects all forms of multicellular organisms. The risk of developing malignant tumors closely associates to the patterns of life histories traced by the evolutionary process according to the adaptive need of organisms to the different ecological niches they occupy. There is an association between the evolutionary development of protective mechanisms against malignant tumors and their evolutionary cost in terms of reproductive success. The later seems to depend on body size, distribution of energy towards basic processes and basal risk of cancer. Natural selection favors effective mechanisms that protect against cancer if they allow optimization of other traits that determine adaptive success. These ecological and evolutionary principles allow concluding that they should serve to better characterize the factors depending on both biological and environmental factors that influence the risk of carcinogenesis. More than 90 percent of the increase in cancer basal risk, even in natural species, is due to human activity, and therefore, modification is possible(AU)

Ambiente de desenvolvimento e início da vida reprodutiva em mulheres Brasileiras / Environment of development and the start of Brazilian women's reproductive life

Modelos teóricos inspirados na teoria da história de vida têm avaliado padrões de reprodução humanos em países desenvolvidos, com resultados ainda não conclusivos. Em vista das condições de vida na população brasileira, foram investigadas relações entre marcos da carreira reprodutiva feminina, condições ambientais e variáveis psicossociais relacionadas às condições de criação. Foram entrevistadas 606 mulheres em seis estados. Os resultados apóiam a teoria da história de vida, mostrando associações entre condições de vida na infância e início da vida sexual e da reprodução, mas não com a idade da menarca. Sugerimos que diferentes marcadores da vida reprodutiva podem estar sob controle de diferentes fenômenos e que a diversidade de condições da população brasileira oferece contextos alternativos para testar hipóteses.

Several models inspired by the life history theory have assessed the patterns of human reproduction in developed countries with promising but inconclusive results. Considering the diversity of life conditions in Brazil, we investigated the relationship between the time of main events in female reproductive life, environmental conditions and psychosocial variables related to child-rearing. We interviewed 606 women in six different states in Brazil. Results corroborate the life history theory, showing associations among the investigated factors, especially between life conditions during childhood and the beginning of sexual life and reproduction, but not to sexual maturity. We suggest that landmarks in reproductive life, although related, can be under the influence of several phenomena. Diversity of life conditions in Brazil offers alternative contexts to hypotheses testing.

Investimento materno e história reprodutiva de mães residentes em contextos com diferentes graus de urbanização / Maternal investment and reproductive history of mothers living in contexts with different degrees of urbanization

A presente pesquisa tem como objetivo caracterizar o investimento materno e a história reprodutiva de mães que vivem em diferentes contextos. Para tal, 150 mães que residiam em três contextos com diferentes graus de urbanização foram entrevistadas. Por meio da análise estatística dos dados constatou-se que houve diferenças significativas entre os contextos, além de correlações positivas entre os núcleos reprodutivos, como idade da primeira relação sexual e idade da mãe no nascimento do primeiro filho. Conclui-se que as estratégias reprodutivas são influenciadas pela história de vida das mães, das condições sociodemográficas atuais e do contexto onde vivem.

The present study has the purpose to characterize both the maternal investment and the reproductive history of mothers from different contexts. To this end, 150 mothers living in three contexts with different degrees of urbanization were interviewed. Through statistical analysis of the data, it was found that there were significant differences between contexts as well as positive correlations between reproductive cores, such as age at first sexual intercourse and mother' age at the birth of the first child. It was concluded that reproductive strategies are influenced by the mothers' life history, current sociodemographic conditions, and the context where they live.