Using realized thermal niche to validate thermal preferences from laboratory studies. How do they stand?

Abstract

Temperature is recongnised as the main factor controlling the species fitness and performance. Naturally, the thermal preferences (TP) of aquatic organisms obtained in controlled conditions have been used to relate physiological performance with field data since they are a good proxy to the fundamental niche. Literature suggests that dispersal capabilities, biological interactions, acclimatisation, adaptation, among others might play a role in species distribution; thus, in reality, species are usually occupying a realized thermal niche (RTN). Therefore, this study was designed to inquire into the following questions; Are the TP of tropical aquatic ectotherms found in laboratory conditions similar to their RTN? Can TP be validated with occurrences in the wild? To answer these questions, this study compared the TP obtained from previously published works with the RTN of the crabs Callinectes similis and C. sapidus, the fishes Centropomus undecimalis and Ocyurus chrysurus, the lobster Panulirus argus, and the octopus Octopus maya obtained from occurrences from 1693 documents. When RTN values were tested against the TPs obtained in laboratory, no significant differences were found for fish species (P > 0.05); in contrast, differences for the benthic invertebrates were reported (P < 0.05). At least two factors could have been affecting these results; differences in the average tolerances between geographically distinct populations (local adaptation) and the dispersal capabilities that might have been forcing a differ- entiation between populations If, as proposed, fishes can actively follow thermal optimum, their response to warming scenarios could be faster than benthic organisms. If our hypothesis is true, the uncertainty of climate change could be reduced when the local adaptation is taking into consideration.