Temperature (latitude) and nutrient (seabird guano) effects on limno-terrestrial Tardigrada (Testechiniscus spitsbergensis and Pilatobius recamieri) body size

  • Krzysztof Zawierucha Department of Animal Taxonomy and Ecology, Adam Mickiewicz University https://orcid.org/0000-0002-0754-1411
  • Paweł Podkowa Department of Avian Biology and Ecology, Adam Mickiewicz University https://orcid.org/0000-0001-8148-9968
  • Martyna Marciniak Department of Animal Morphology, Adam Mickiewicz University
  • Piotr Gąsiorek Department of Entomology, Jagiellonian University https://orcid.org/0000-0002-2814-8117
  • Katarzyna Zmudczyńska-Skarbek Department of Vertebrate Ecology and Zoology, University of Gdańsk
  • Karel Janko Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic https://orcid.org/0000-0002-7866-4937
  • Maria Włodarska-Kowalczuk Department of Marine Ecology, Institute of Oceanology, Polish Academy of Sciences
Keywords: Arctic, Bergmann’s rule, body length, ectotherms, latitudinal patterns, temperature gradient

Abstract

Surveys of terrestrial microinvertebrate morphometry, especially spatial patterns of body size at wider geographical scales, including the polar regions, are very scarce. In this study, we focused on Tardigrada, common limno-terrestrial microinvertebrates. Considering Bergmann’s rule, originally formulated for endothermic animals, we tested the hypothesis that body length of limno-terrestrial tardigrades augments with increasing latitude and decreasing temperature. Since some of our sampling areas adjoined seabird colonies, we also explored the effects of nutrients from seabird guano deposits. Individual body length of Testechiniscus spitsbergensis was measured in populations obtained from seven localities distributed along a latitudinal gradient extending from 45°N (northern Italy) to 79°N (northern Svalbard), and for Pilatobius recamieri from three localities in Svalbard (77°N-80°N). Considering both latitude and proximity to a seabird colony there were significant effects of locality on the body length of T. spitsbergensis; however, no clear pattern of increasing individual body size with increasing latitude could be detected. Immense differences in body size may be a signal for cryptic species diversity within this genus. No effect of latitude, or proximity to a seabird colony, on the body length of Arctic populations of P. recamieri was documented. Evidently, there is no tendency towards body size increase along the latitudinal gradient in either T. spitsbergensis or P. recamieri. Our study, and recent literature, indicates that larger body size in polar regions reported for several groups of micro-fauna may be a taxon-dependent response, and cannot be taken as a universally applicable rule for limnoterrestrial animals.

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Published
2018-10-01
How to Cite
Zawierucha, K., Podkowa, P., Marciniak, M., Gąsiorek, P., Zmudczyńska-Skarbek, K., Janko, K., & Włodarska-Kowalczuk, M. (2018). Temperature (latitude) and nutrient (seabird guano) effects on limno-terrestrial Tardigrada (<em>Testechiniscus spitsbergensis</em> and <em>Pilatobius recamieri</em&gt;) body size. Polar Research, 37. Retrieved from https://polarresearch.net/index.php/polar/article/view/2668
Section
Research Articles

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