Abstract
BackgroundThe 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.MethodsThis study assessed freshwater macroinvertebrate diversity associated with lakes and ponds along the altitudinal gradient of a Magellanic sub-Antarctic watershed.ResultsA 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.DiscussionThe 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.
Highlights
Since the times of the early naturalists such as Linnaeus, Humboldt, Darwin and Wallace, understanding how living organisms distribute and change along spatial gradients has been key for the development of theories about their origins and diversification (Lomolino, 2001)
Embedded within the ecoregion is the Cape Horn Biosphere Reserve (CHBR; Fig. 1), an area designated to protect the ecoregion from the pressures of global change (Rozzi et al, 2006)
The mountain ranges in Navarino Island are characterized by short and steep altitudinal gradients, with associated changes in air and water temperatures with elevation (Contador et al, 2015)
Summary
Since the times of the early naturalists such as Linnaeus, Humboldt, Darwin and Wallace, understanding how living organisms distribute and change along spatial gradients has been key for the development of theories about their origins and diversification (Lomolino, 2001). Latitudinal and elevational gradients can be considered analogues in terms of associated environmental clines and ecological features (Bozinovic, Calosi & Spicer, 2011; Rahbek, 1995) In this context, faunal (and floral) research along elevational gradients is of critical importance in the study of global biodiversity drivers (McCain & Grytnes, 2010). 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. 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. In conjunction with previous research, this study provides a watershed-scale platform of information underpinning future long-term research in the region
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