Javier Rendoll-Cárcamo

In aquatic insects, body size and shape are key traits that may indicate phenotypic plasticity or adaptations to their hydrological landscape. Liodessus chilensis is a small and poorly-known aquatic beetle that inhabits permanent and temporary bodies of water. Accompanying the report of the species in different habitats of Navarino Island, an update of its description is presented. Additionally, body shape variation of different populations of L. chilensis is evaluated. Geometric morphometric analysis and multivariate regressions on the body shape of L. chilensis show variation mainly in the posterior part of the elytra and could indicate plasticity linked to the nature of the habitats in which they occur. The population of temporary pools presents shorter and broader elytra in their terminal part, while those that inhabit peat bogs and wetlands are longer and elongated. Additionally, a positive allometric effect was found, indicating that in addition to the differences in body shape, populations inhabiting temporary pools tend to be smaller in size. The plasticity of forms of L. chilensis as well as their permanent and temporary habitats can be considered as sentinels of environmental changes. These results are relevant for the Magallanes region, which has recently been declared prone to drought.

In aquatic insects, body size and shape are key traits that may indicate phenotypic plasticity or adaptations to their hydrological landscape. Liodessus chilensis is a small and poorly-known aquatic beetle that inhabits permanent and temporary bodies of water. Accompanying the report of the species in different habitats of Navarino Island, an update of its description is presented. Additionally, body shape variation of different populations of L. chilensis is evaluated. Geometric morphometric analysis and multivariate regressions on the body shape of L. chilensis show variation mainly in the posterior part of the elytra and could indicate plasticity linked to the nature of the habitats in which they occur. The population of temporary pools presents shorter and broader elytra in their terminal part, while those that inhabit peat bogs and wetlands are longer and elongated. Additionally, a positive allometric effect was found, indicating that in addition to the differences in body shape, populations inhabiting temporary pools tend to be smaller in size. The plasticity of forms of L. chilensis as well as their permanent and temporary habitats can be considered as sentinels of environmental changes. These results are relevant for the Magallanes region, which has recently been declared prone to drought.

Invasive alien species may cause substantial changes and damaging impacts in the ecosystems they invade. Here, we document the current distribution and ecological interactions with native biota of the relatively recently introduced wasp, Vespula vulgaris, in the southern part of the Cape Horn Biosphere Reserve. We conducted surveys and field studies in four different habitats on Navarino Island: evergreen, deciduous and mixed forests, and shrublands. The spread of V. vulgaris through the island since its first detection has led to it occupying suitable habitats for nesting and foraging, both in urban and rural settings. The presence of V. vulgaris on islands and remote areas of the CHBR is likely the result of marine human movement through the channels withing the reserve. Wasp foraging composition was different on each of the four studied habitats, yet strongly linked to each habitat’s resources, indicating the inherent ability of V. vulgaris of exploiting surrounding resources efficiently. The lack of natural competitors and availability of multiple resources as allowed V. vulgaris to rapidly become a common pest in urban and rural settings in the southern extreme of South America. In this context, we believe that eradication would be impossible, although it would be possible to control populations at localized scales with proper planning and long-term management. Our results can act as a base for management planning, and we strongly recommend social engagement and dialog with pertinent governmental institutions to achieve this challenging task.

En un mundo aceleradamente cambiante, para confrontar las pérdidas de biodiversidad, el desconocimiento y falta de valoración de los grupos de organismos más diversos, son necesarios cambios culturales que trasciendan a los ámbitos puramente científicos y tecnológicos. En este trabajo se aborda esta problemática al enfocarse en uno de los grupos de organismos menos conocidos en una de las regiones más remotas del planeta: los insectos dulceacuícolas en la ecorregión subantártica de Magallanes. El desarrollo de esta tesis consideró investigaciones científico-ecológicas y filosófico-ambientales que se integraron con prácticas de educación ambiental formal y no-formal que valoran a los insectos dulceacuícolas, particularmente como indicadores del cambio climático. La integración de las ciencias y la filosofía se realizó adaptando metodología de la Filosofía Ambiental de Campo que incluye un ciclo de cuatro pasos. La investigación transdisciplinaria sobre los insectos dulceacuícolas y sus ecosistemas subantárticos fue la base para la composición de metáforas y actividades educativas con escolares, otros miembros de la comunidad local y visitantes al Parque Omora, en Puerto Williams, Chile. A partir de esta tesis se diseñaron nuevas actividades educativas al aire libre cuyos objetivos son despertar el interés de la ciudadanía por los insectos, orientar las percepciones sobre estos organismos, sus hábitats y hábitos de vida. De esta manera, este trabajo aspira, a nivel local, a contribuir a un mayor conocimiento, valoración y conservación de esta singular biodiversidad subantártica y, a nivel global, a superar la subvaloración del grupo más diverso de organismos: los insectos.

The habitat of the intertidal flightless midge Telmatogeton magellanicus (Jacobs, 1900) is described for the first time from the northern coast of Navarino Island, Tierra del Fuego, Chile. Additionally, we report the first observations of adult behaviour in the wild. We delineate the species’ distribution across three tidal zones (high, mid and low), and identify substrate characteristics that favour the presence of the midge. The mid-tide zone was the key habitat utilized by T. magellanicus, with lower densities in the low-tide zone and no presence in the high-tide zone. There was a strong association between the presence of larvae and filamentous algae, especially Bostrychia spp. and, to a lesser extent, Ulva spp., as well as between larvae and the presence of larger, more stable boulders. As a result, the species’ overall distribution was widespread but patchy. We suggest that the main limiting factor is the relative humidity experienced in different habitats. One of the most striking features of the behavioural observations during data collection was the extremely active adults, which suggests high energy expenditure over a very short period of time. This may be due to the limited time available to find mates in a single low-tide period, when adults have about three hours after emerging from the pupa to complete mating and oviposition before inundation by the tide. The data presented here provide a baseline for future studies on this species’ ecology, phenology, physiology and general biology.

Physiological thermal limits of organisms are linked to their geographic distribution. The assessment of such limits can provide valuable insights when monitoring for environmental thermal alterations. Using the dynamic critical thermal method (CTM), we assessed the upper (CT_max) and lower (CT_min) thermal limits of three freshwater macroinvertebrate taxa with restricted low elevation distribution (20 m a.s.l.) and three taxa restricted to upper elevations (480 and 700 m a.s.l.) in the Magellanic sub-Antarctic ecoregion of southern Chile. In general terms, macroinvertebrates restricted to lower altitudinal ranges possess a broader thermal tolerance than those restricted to higher elevations. Upper and lower thermal limits are significantly different between taxa throughout the altitudinal gradient. Data presented here suggest that freshwater macroinvertebrates restricted to upper altitudinal ranges may be useful indicators of thermal alteration in their habitats, due to their relatively low tolerance to increasing temperatures and the ease with which behavioral responses can be detected.

Background: The study of altitudinal gradients provides insights about species diversity, distribution patterns and related drivers. The Magellanic sub-Antarctic ecoregion has a steep elevational gradient, peaking at around 1,000 m a.s.l., and marked changes in temperature and landscape composition can be observed over relatively short distances. Methods: This study assessed freshwater macroinvertebrate diversity associated with lakes and ponds along the altitudinal gradient of a Magellanic sub-Antarctic watershed. Results: A monotonic decline in species richness was observed with increasing elevation, with simpler and more even community composition at higher altitude. This pattern differs from the mid-peak trend found in streams of the same watershed. Functional feeding group structure also diminished with increasing elevation. Discussion: The study provides a descriptive baseline of macroinvertebrate community structure associated with lentic freshwater ecosystems in the Magellanic sub-Antarctic ecoregion, and confirms that elevation has substantial effects on community structure, function and environmental features, even in these relatively low elevation mountain ranges. The harsh environmental conditions of this ecoregion increase freshwater macroinvertebrate development time, as well as decreasing habitat availability and food supply, supporting simple but well adapted communities. In conjunction with previous research, this study provides a watershed-scale platform of information underpinning future long-term research in the region.