RESUMO

Chironomids show a wide distribution and can occupy several habitats due to their high adaptive capacity in different freshwater environments. The genus Polypedilum is found along a wide elevational and environmental gradient in the neotropics, and its genetic variability could help to elucidate factors determining its distribution and tolerance to the environmental changes of different species or populations. This study examines the genetic variability of Polypedilum in an important biogeographic area that acts as a geographical barrier of biodiversity at the border of the Choco and Tumbes biomes. We identified five Polypedilum morphotypes using classic taxonomic methods. We examined 68 Polypedilum individuals from eight sampling sites in El Oro Province, Ecuador, analyzing the putative molecular species using the cytochrome c oxidase subunit 1 (CO1) mitochondrial gene fragment. Then, we calculated molecular diversity indices, Haplotype diversity (Hd), and θs and θπ estimators. Seven Polypedilum OTUs were determined from which a high molecular diversity was registered. A CCA was conducted to understand the population composition in relation to environmental characteristics. Results indicated that dissolved oxygen and temperature are the main environmental factors affecting Polypedilum distribution across elevational gradients and between basins.

RESUMO

Introduction: Chironomids (Diptera: Chironomidae) are the most globally diverse and widely distributed aquatic insects. Despite their prevalence in lotic systems, little is known about the ecology and diversity of tropical species relative to other aquatic insect taxa, particularly at the immature stages. Objective: Characterize chironomid diversity across an elevational gradient in Southwestern Ecuador and water quality parameters associated with their composition. Methods: Samples were collected using a Surber net in forty rivers within four watersheds in the Ecuadorian Andes comprised of montane and dry lowland forest and spanning an elevational gradient of 3 120 m.a.s.l. Various physic chemical variables were measured including oxygen, conductivity, total dissolved solids, temperature, and pH. Results: Generally, environmental variables were strongly correlated with the composition of chironomid communities. Variation in the chriomid communities was most strongly associated with oxygen, conductivity and pH. The presence of Parametriocnemus, Cricotopus f4, Cricotopus sp3., Cricotopus (Isocladius), Oliveiriella, Onconeura, Alotanypus and Pentaneura was associated with lower temperatures, high dissolved oxygen and low conductivity while assemblages of Cricotopus sp., Rheotanytarsus, Tanytarsus, and Chironomus were associated with high conductivity and low concentrations of dissolved oxygen. The RELATE analysis showed that local environmental characteristics are determine the composition of the chironomid community. Conclusions: Similarity among local environmental factors was strongly correlated to similarity among Chironomidae assemblages, especially with variables such as oxygen concentration, pH and conductivity, whose variables are highly correlated to land use and dominant vegetation in the watersheds sampled.

Introducción: Los quironómidos (Diptera: Chironomidae) son los insectos acuáticos de mayor diversidad y distribución mundial. A pesar de su prevalencia en los sistemas lóticos, se sabe poco acerca de su ecología y diversidad, especialmente de especies tropicales en relación con otros taxones de insectos acuáticos, particularmente en etapas inmaduras. Objetivo: Caracterizar la diversidad de quironómidos a través de un gradiente altitudinal en el suroeste de Ecuador, además de identificar los parámetros fisicoquímicos asociados con su composición. Métodos: Las muestras se recolectaron utilizando una red Surber en cuarenta ríos dentro de cuatro cuencas hidrográficas en los Andes Sur del Ecuador, en ecosistemas de bosques montanos y secos de tierras bajas abarcando un gradiente altitudinal de 3 120 m.s.n.m. Se midieron las variables fisicoquímicas: oxígeno, conductividad, sólidos disueltos totales, temperatura y pH. Resultados: En general, las variables ambientales se correlacionaron fuertemente con la composición de las comunidades de quironómidos. La variación en la comunidad de quironómidos se asoció fuertemente con el oxígeno, la conductividad y el pH. La presencia de los géneros Parametriocnemus, Cricotopus f4, Cricotopus sp3, Cricotopus (Isocladius), Oliveiriella, Onconeura, Alotanypus y Pentaneura se asoció a temperaturas bajas, alto oxígeno disuelto y baja conductividad, mientras que Cricotopus sp., Rheotanytarsus, Tanytarsus y Chironomus se asociaron con alta conductividad y bajas concentraciones de oxígeno disuelto. El análisis RELATE mostró que las características ambientales locales determinan la composición de la comunidad de quironómidos. Conclusiones: La similitud entre los factores ambientales locales se correlacionó fuertemente con la similitud entre los conjuntos de Chironomidae, especialmente con variables como la concentración de oxígeno, el pH y la conductividad, cuyas variables están altamente correlacionadas con el uso de la tierra y la vegetación dominante en las cuencas hidrográficas muestreadas.

Assuntos

RESUMO

This study provides data on the morphological characteristics of second and third larval instar from Dynastes hercules occidentallis Lachaume, 1985 (Coleoptera, Melolonthindae, Dynastynae), bred in captivity, a species highly manageable potential from the Metropolitan District of Quito, Ecuador. Chaetotaxy, mouthparts, internal and external structures of each tagma, weight, height, etc., are analyzed to produce a detailed characterization that allows precise differentiation of larval stages.

Este estudio proporciona datos sobre las características morfológicas de las larvas de segundo y tercer estadios Dynastes hercules occidentallis Lachaume, 1985 (Coleoptera, Melolonthindae, Dynastynae), criados en cautiverio, una especie con alto potencial de manejo para el Distrito Metropolitano de Quito, Ecuador. Se analizó la quetotaxia, aparato bucal, estructuras de cada tagma, peso, talla, entre otros. Se determinan las características en su etapa larval y se resaltan aquellas que permiten diferenciar de otras afines.

Assuntos

RESUMO

This study provides data on the morphological characteristics of second and third larval instar from Dynastes hercules occidentallis Lachaume, 1985 (Coleoptera, Melolonthindae, Dynastynae), bred in captivity, a species highly manageable potential from the Metropolitan District of Quito, Ecuador. Chaetotaxy, mouthparts, internal and external structures of each tagma, weight, height, etc., are analyzed to produce a detailed characterization that allows precise differentiation of larval stages.(AU)

Este estudio proporciona datos sobre las características morfológicas de las larvas de segundo y tercer estadios Dynastes hercules occidentallis Lachaume, 1985 (Coleoptera, Melolonthindae, Dynastynae), criados en cautiverio, una especie con alto potencial de manejo para el Distrito Metropolitano de Quito, Ecuador. Se analizó la quetotaxia, aparato bucal, estructuras de cada tagma, peso, talla, entre otros. Se determinan las características en su etapa larval y se resaltan aquellas que permiten diferenciar de otras afines.(AU)

Assuntos