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How do the Bromeliads Respond to Climate Change?




With more than 3 thousand species, bromeliads are the second largest family of epiphytes, plants characterized by living on top of trees. Unlike orchids, which are found all over the world, bromeliads are only concentrated on the American continent, with the exception of a single species that occurs in Africa.


By: Gabriela Andrietta


Asked how bromeliads respond to climate change, Cleber J. N. Chaves, Postdoctoral researcher at the Laboratory of Evolutionary Ecology and Genomics at Unicamp (LEEG), supervised by professor Clarisse Palma, highlighted that this is a complex issue from a biological point of view. . However, research is beginning to offer clues about this phenomenon, especially when we look at the diversity and adaptation mechanisms of these plants.


The diversification of bromeliads was driven by key mechanisms, such as epiphytism and the formation of tanks, which accumulate water and allow interactions with several other organisms. These tanks house amphibians, arthropods, algae and others, creating small ecosystems. Researcher Cléber Chaves highlighted that the diversification of bromeliads occurred in a relatively short period, as most species emerged in the last 10 million years.


In neotropical forests, bromeliads play a crucial role, especially in areas with great altitudinal variation. The bromeliad Pitcairnia flammea, a common species in the Atlantic Forest, which occurs in varied environments, from close to sea level to altitudes above 2,000 meters, presents great morphological diversity and low genetic exchange between populations, suggesting possible local adaptations.


In the recently published article co-authored with professor Clarice Palma, in the journal Functional Ecology, "Bromeliad Populations Adopt Distinct Ecological Strategies Along a Tropical Altitudinal Gradient", it was investigated how bromeliad populations, specifically Pitcairnia flammea, develop different strategies ecological responses to changing environmental conditions along a tropical altitudinal gradient.


The study analyzed 125 individuals of Pitcairnia flammea, collected at different altitudes. Plants were grown under uniform conditions to assess their specific ecological responses at different elevations. The study analyzed leaf temperature, tolerance to heat and cold, as well as structural, morphological, optical, physiological and biochemical traits of the leaves.


The results showed that water-saving traits decrease as altitude increases, while the fluidity of cell membranes, associated mainly with unsaturated and very long-chain lipids, increases. Low-altitude plants invest in water-storing tissues, preventing excessive water loss through intense rates of transpiration during hot periods. In contrast, high-altitude plants exhibit greater membrane fluidity, an adaptation to the stiffening caused by low temperatures.


These findings indicate a balance between tolerance and avoidance related to the thermal strategies of populations along the altitudinal gradient. Low-altitude plants avoid excess temperature in their leaves by investing in water-saving traits, while high-altitude plants adapt their membranes to tolerate thermal variations, especially cold events.


When investigating the physiological tolerance of these plants to heat and cold, the results showed that bromeliads from high altitudes have a greater tolerance to cold, as expected, but also to heat, which was a counterintuitive result. Cléber Chaves highlighted that "these findings challenge the conventional notion that the vulnerability of plants to warming depends only on the specific thermal tolerance of each species. We show that there are different thermal strategies in populations of the same species along an altitudinal gradient." This physiological tolerance was measured by the light absorption capacity of the photosynthetic apparatus, an indicator of plant stress.


The discoveries of Professor Clarice Palma's team contribute to understanding how bromeliads and other plants can respond to climate change, an essential field of study for the conservation of biodiversity and adaptation to future environmental conditions.


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