Gross mismatch between thermal tolerances and environmental temperatures in a tropical freshwater snail: Climate warming and evolutionary implications. (January 2015)

• Record Type: Journal Article
• Authors: Polgar, Gianluca; Khang, Tsung Fei; Chua, Teddy; Marshall, David J.
• Is Part Of: Journal of thermal biology. Volume 47(2015)
• Page Start: 99
• Page End: 108
• Publication Date: 2015-01
• Subjects: Animal ectotherms -- Buccinidae -- Clea nigricans -- Cold tolerance -- Heat tolerance -- Thermal safety margins; Thermobiology -- Periodicals; Temperature -- Periodicals; Biology -- Periodicals; Thermobiologie -- Périodiques; Thermobiology; Periodicals; 571.46
• DOI: 10.1016/j.jtherbio.2014.11.009
• Languages: English
• ISSNs: 0306-4565

Abstract

Abstract: The relationship between acute thermal tolerance and habitat temperature in ectotherm animals informs about their thermal adaptation and is used to assess thermal safety margins and sensitivity to climate warming. We studied this relationship in an equatorial freshwater snail ( Clea nigricans ), belonging to a predominantly marine gastropod lineage (Neogastropoda, Buccinidae). We found that tolerance of heating and cooling exceeded average daily maximum and minimum temperatures, by roughly 20 °C in each case. Because habitat temperature is generally assumed to be the main selective factor acting on the fundamental thermal niche, the discordance between thermal tolerance and environmental temperature implies trait conservation following 'in situ' environmental change, or following novel colonisation of a thermally less-variable habitat. Whereas heat tolerance could relate to an historical association with the thermally variable and extreme marine intertidal fringe zone, cold tolerance could associate with either an ancestral life at higher latitudes, or represent adaptation to cooler, higher-altitudinal, tropical lotic systems. The broad upper thermal safety margin (difference between heat tolerance and maximum environmental temperature) observed in this snail is grossly incompatible with the very narrow safety margins typically found in most terrestrial tropical ectotherms (insects and lizards), and hence with the emerging prediction that tropical ectotherms, are especially vulnerable to environmental warming. A more comprehensive understanding of climatic vulnerability of animal ectotherms thus requires greater consideration of taxonomic diversity, ecological transition and evolutionary history. Graphical abstract: Highlights: We measured the heating and cooling tolerance of a tropical freshwater snail. Tolerance limits exceeded max and min environmental temperatures each by 20 °C. Thermal safety margins are discordant with those found in other tropical ectotherms. The generality of climatic vulnerability of tropical ectotherms is in question.