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Competitive interactions modify the temperature dependence of damselfly growth rates
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
2014 (English)In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 95, no 5, 1394-1406 p.Article in journal (Refereed) Published
Abstract [en]

Individual growth rates and survival are major determinants of individual fitness, population size structure, and community dynamics. The relationships between growth rate, survival, and temperature may thus be important for predicting biological responses to climate change. Although it is well known that growth rates and survival are affected by competition and predation in addition to temperature, the combined effect of these factors on growth rates, survival, and size structure has rarely been investigated simultaneously in the same ecological system. To address this question, we conducted experiments on the larvae of two species of damselflies and determined the temperature dependence of growth rate, survival, and cohort size structure under three scenarios of increasing ecological complexity: no competition, intraspecific competition, and interspecific competition. In one species, the relationship between growth rate and temperature became steeper in the presence of competitors, whereas that of survival remained unchanged. In the other species, the relationship between growth rate and temperature was unaffected by competitive interactions, but survival was greatly reduced at high temperatures in the presence of interspecific competitors. The combined effect of competitive interactions and temperature on cohort size structure differed from the effects of these factors in isolation. Together, these findings suggest that it will be challenging to scale up information from single-species laboratory studies to the population and community level.

Place, publisher, year, edition, pages
2014. Vol. 95, no 5, 1394-1406 p.
Keyword [en]
activation energy, Arrhenius equation, cannibalism, Coenagrion, damselflies, exploitation competition, interference competition, intraguild predation, microcosm experiment, size structure, thermal performance
National Category
URN: urn:nbn:se:umu:diva-90858DOI: 10.1890/13-0875.1ISI: 000336740500028OAI: diva2:734464

Originally included in thesis in manuscript form, with the title "Competition modifies the temperature dependence of damselfly growth rates".

Available from: 2014-07-17 Created: 2014-07-01 Last updated: 2014-07-17Bibliographically approved
In thesis
1. Thermal adaptation along a latitudinal gradient in damselflies
Open this publication in new window or tab >>Thermal adaptation along a latitudinal gradient in damselflies
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Understanding how temperature affects biological systems is a central question in ecology and evolutionary biology. Anthropogenic climate change adds urgency to this topic, as the demise or success of species under climate change is expected to depend on how temperature affects important aspects of organismal performance, such as growth, development, survival and reproduction. Rates of biological processes generally increase with increasing temperature up to some maximal temperature. Variation in the slope of the initial, rising phase has attracted considerable interest and forms the focus of this thesis. I explore variation in growth rate-temperature relationships over several levels of biological organization, both between and within species, over individuals’ lifetime, depending on the ecological context and in relation to important life history characteristics such as generation length and winter dormancy.

      Specifically, I examine how a clade of temperate damselflies have adapted to their thermal environment along a 3,600 km long latitudinal transect spanning from Southern Spain to Northern Sweden. For each of six species, I sampled populations from close to the northern and southern range margin, as well from the center of the latitudinal range. I reared larvae in the laboratory at several temperatures in order to measure indiviudal growth rates. Very few studies of thermal adaptation have employed such an extensive sampling approach, and my finding reveal variation in temperature responses at several levels of organization.

      My main finding was that temperature responses became steeper with increasing latitude, both between species but also between latitudinal populations of the same species. Additional genetic studies revealed that this trend was maintained despite strong gene flow. I highlight the need to use more refined characterizations of latitudinal temperature clines in order to explain these findings. I also show that species differ in their ability to acclimate to novel conditions during ontogeny, and propose that this may reflect a cost-benefit trade-off driven by whether seasonal transitions occur rapidly or gradually during ontogeny.

      I also carried out a microcosm experiment, where two of the six species were reared either separately or together, to determine the interacting effects of temperature and competition on larval growth rates and population size structure. The results revealed that the effects of competition can be strong enough to completely overcome the rate-depressing effects of low temperatures. I also found that competition had stronger effects on the amount of variation in growth rates than on the average value.

      In summary, my thesis offers several novel insights into how temperature affects biological systems, from individuals to populations and across species’ ranges. I also show how it is possible to refine our hypotheses about thermal adaptation by considering the interacting effects of ecology, life history and environmental variation.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2012. 35 p.
Growth rate, metabolic theory of ecology, universal temperature dependence, environmental gradients, thermal performance, thermal sensitivity, environmental variability, optimality theory, life history, acclimation, size structure, competition, cannibalism, intraguild predation
National Category
urn:nbn:se:umu:diva-62276 (URN)978-91-7459-529-1 (ISBN)
Public defence
2013-01-18, N450, Umeå Universitet, Johan Bures väg 14, Umeå, 13:00 (English)
Available from: 2012-12-21 Created: 2012-12-14 Last updated: 2014-07-17Bibliographically approved

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Nilsson-Örtman, ViktorJohansson, Frank
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