Evolutionary timing of cold tolerance in conifers

Fossil plant species Walchia piniformis, from the Lower Permian of the Saar-Nahe basin, Nonnweiler, Saarland, Germany. Black bar in the background is about 2 cm thick. Naturhistorisches Museum, Bern, Switzerland.

Fossil plant species Walchia piniformis, from the Lower Permian of the Saar-Nahe basin, Nonnweiler, Saarland, Germany. Black bar in the background is about 2 cm thick. Naturhistorisches Museum, Bern, Switzerland.

Conifers, when they first evolved in the Permian, were warm-adapted and likely did not exhibit any of the cold tolerance mechanisms observed in conifers today. Information on the physiological development of frost tolerance and cold hardiness of coniferous trees over geologic time is surprisingly lacking within the scientific literature. Conifers are the one plant functional group that are present in nearly all geologic periods and therefore span palaeoclimates ranging from global glaciations to hot-house temperatures. The author says that “the major reason for presenting our simple study is to highlight the huge knowledge gap on the development of conifer form, function and structure over geological time periods”. This study reveals that there is a statistically significant difference in conifer tree height between pre- and post-Cretaceous fossils that may be explained in part by trade-offs induced by the development of cold hardiness (full article by Opalinska & Cowling, Palaeogeography, Palaeoclimatology, Palaeoecology. Volume 392,  December 2013, 495–501) . Click here to read more

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