Body Temperature and Adaptability of Odonata in Amazonian Streams

In ecology, scientists study how different species of animals and plants live together and how their needs influence where they are found. One important aspect of this is understanding the ecological niche, which refers to the role a species plays in its environment. This includes what it eats, where it lives, and how it interacts with other species. Two key ideas that help explain why some species are more common than others are niche breadth and niche position.

Niche breadth refers to how adaptable a species is to different environmental conditions. Species that can thrive in various conditions are called generalists, while those that need specific conditions are called specialists. Niche position looks at where a species is found within its environment. Species found in many different habitats tend to be more abundant.

The connection between these concepts can help explain why some species are more common in certain areas. For example, generalist species are likely to be found in a variety of environments, while specialists may struggle if their specific needs aren't met. Additionally, environmental factors like temperature and vegetation can impact which species are present in a given area.

#Odonata Overview

Odonata, commonly known as dragonflies and damselflies, are aquatic insects that rely on temperature for their survival and distribution. Their body size and behavior determine how they regulate their body temperature, which is crucial for their activity. Different species have various strategies to manage their temperature, leading to differences in how they occupy habitats.

Larger species tend to be more active in sunny areas, while smaller species may prefer shaded spots with more consistent temperatures. Understanding these temperature preferences can shed light on how Odonata populations are distributed in different environments, especially in tropical areas like the Amazon.

#Environmental Impact on Odonata

The abundance and distribution of Odonata in tropical streams are greatly influenced by environmental factors such as vegetation cover and temperature. Streams that lack vegetation and shade tend to favor larger species, as they benefit from direct sunlight. In contrast, smaller species, which typically need stable temperatures, may not thrive in these conditions.

Odonata are sensitive to changes in their environment, and those that cannot adapt to new conditions may decline in number. Therefore, studying these insects can provide insight into the health of freshwater ecosystems and the impact of human activity on natural habitats.

#Research Focus

In this study, we wanted to understand how body temperature and the ability of Odonata to adapt to their environment affect their abundance in Amazonian streams. We hypothesized that:

1. The body temperature of Odonata differs between the two main groups, Anisoptera (dragonflies) and Zygoptera (damselflies). Larger Anisoptera may have higher Body Temperatures compared to Zygoptera, which may have temperatures more similar to the surrounding air.

2. The body temperature of Odonata and their Adaptability to different conditions might be more important in predicting how many individuals of each species are present and their contribution to local diversity than other niche characteristics.

#Study Area

The research took place in several streams in the northeastern and southeastern regions of Pará, Brazil. This area features a tropical rainforest climate and a savanna climate, with temperatures ranging from 22°C to 34°C. The streams varied in size and depth, providing different habitats for Odonata.

#Sampling Odonata

We collected samples from 46 streams during a period when rainfall was low. In each stream, we captured adult Odonata using specialized nets at peak activity times. This ensured we accurately represented the species present in the area. After collection, the specimens were preserved for identification and analysis.

#Measuring Traits

To study the temperature and size of the Odonata, we measured their body temperature quickly to avoid affecting their conditions. We focused on male individuals, as they are easier to identify. We also measured the width of their thorax, as this could relate to their thermoregulation ability. Additionally, we recorded the environmental variables of each stream, including depth, width, and habitat integrity.

#Data Analysis

We analyzed how the species' body temperature, adaptability, and environmental factors influenced their abundance. By comparing various species and their traits, we aimed to determine which factors were most significant in predicting where they lived and how many were present.

#Findings on Body Temperature and Size

Our results indicated that dragonflies had higher body temperatures and larger thorax widths compared to damselflies. On average, dragonflies were about 5°C warmer than the air surrounding them, while damselflies maintained temperatures closer to the air temperature.

We also found that body temperature was influenced by both air temperature and the size of the insect. For dragonflies, there was a noticeable difference that allowed them to regulate their heat more efficiently than damselflies, which relied more on the ambient conditions.

#Environmental Structure and Odonata

The study revealed a strong relationship between environmental conditions and the variety of Odonata species found in the streams. Streams with healthier habitats, characterized by more vegetation and stability, supported a greater number of dragonfly and damselfly species. On the other hand, streams that were altered by human activities had fewer species.

#Niche Characteristics and Abundance

We observed that species with broader ecological niches tended to be more abundant. For instance, species that could survive in a wider range of conditions were found more frequently. However, the expected relationship between body temperature and abundance didn't fully hold up-we saw that while body temperature was related to abundance, it was more evident when looking at the groups separately.

#Contribution to Local Diversity

The contribution of different Odonata species to local diversity varied based on their niche breadth and position. Species with larger niches played a significant role in enhancing local diversity, while those with narrower niches were more vulnerable to environmental changes.

Surprisingly, while we initially thought that body temperature would be a strong predictor of diversity, it turned out that niche characteristics were more important. This means that the ability of a species to adapt to its surroundings is crucial for its survival and contribution to local ecosystems.

#Conclusion

Our research shows that in Amazonian streams, both the body temperature and niche characteristics of Odonata play important roles in determining their abundance and distribution. Species that are better adapted to changes in the environment tend to be more common, while those unable to cope with habitat alteration may decline.

Monitoring Odonata populations can provide valuable information about the health of freshwater ecosystems. Their sensitivity to environmental changes makes them useful indicators of riparian zone quality. By focusing on the relationships between body temperature, environmental conditions, and species adaptability, we can better understand the dynamics of these fascinating insects and the ecosystems they inhabit.