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Abstract Detail

Tropical Biology

De Lima, Thales Moreira [1], Pinheiro, Fabio [2].

High phenotypic similarity despite the low climatic niche overlap between groups of populations of Epidendrum fulgens Brongn. (Orchidaceae: Epidendroideae).

Adaptation and phenotypic plasticity allow, in different time scales, species to occupy new environments. Through these two mechanisms, populations with contrasting niches can present phenotypic divergences associated with adaptation to local conditions. Epidendrum fulgens Brongn. is a species of terrestrial orchid whose range covers the Southeastern coastal area of Brazil. The Portal de Torres, a phytogeographic barrier between the Atlantic Forest and the Pampas, separates the populations of this orchid into two groups: the group to the north of this barrier occurs in sandy coastal plains, and the group to the south occurs in rocky outcrops. In light of these facts, we raised two hypotheses: 1) The overlap between the realized niches of these two groups of populations is small and 2) there is a clear phenotypic divergence between these two groups. To test the first hypothesis, we collected georeferenced occurrence data for each group and climatic variables mapped within the distribution of the species. Using principal component analysis and Kernel density estimates, we calculated the niche overlap between the two groups of populations. To test the second hypothesis, we recorded, for individuals of 4 populations to the north and 4 to the south, the length of the stem and of the inflorescence, the number of leaves, the leaf area, the leaf dry mass and the specific leaf area. The phenotypic data were analyzed using a nested ANOVA. The overlap of the realized niches was less than 1%, revealing a high climatic distinction between habitats. The phenotypic differences between the two groups were not significant for any of the characters measured, except for the length of the inflorescence. This apparent paradox of high phenotypic similarity and low niche overlap may be the result of a general adaptation to stress: the same set of adaptations helps to alleviate the environmental stress in both habitats. Nevertheless, the divergence in the length of the inflorescence may indicate a distinction in biotic factors related to reproduction between the two habitats, such as the pollinator community. Ecophysiological studies, exposing each group to the environmental conditions of the other, would reveal whether the hypothesis of general adaptation to stress is true. In addition, measuring more reproductive characteristics in the field and in 'common garden' would provide more robust evidence about the possible adaptive value of these divergences and whether they are genetic or not.

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1 - University of Campinas, Department of Plant Biology, Vitorino Antunes, 209, apt 3, 209, Campinas, São Paulo, 13.084-135, Brazil
2 - University of Campinas, Department of Plant Biology, R. Monteiro Lobato, 255 - Barão Geraldo, Campinas, São Paulo, 13083-862, Brasil

local adaptation
phenotypic plasticity.

Presentation Type: Poster
Session: P3, Tropical Biology Posters
Location: Virtual/Virtual
Date: Wednesday, July 21st, 2021
Time: 5:00 PM(EDT)
Number: P3TB003
Abstract ID:329
Candidate for Awards:None

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