Variability in Fruit and Seed Morphology Among and Within Populations of Plathymenia (Leguminosae - Mimosoideae) in Areas of the Cerrado, the Atlantic Forest, and Transitional Sites

Abstract

Plathymenia reticulata is a tree species that occurs in two different Brazilian biomes, the Cerrado (a savannah environment), and the Atlantic Forest. In the present study, we evaluated morphological variation within and among five populations located in these vegetation types and in transitional sites in order to test the hypothesis that habitat selective pressures, being different in the Cerrado and the Atlantic Forest, would cause adaptive differences in morphological traits in individuals occurring under these different circumstances. Thirteen morphological traits of fruits, seeds, and of the membranous endocarp were obtained from 30 fruits and 20 seeds from each of nine to 10 individuals per population. Significant variation was found for all traits while comparing individuals within populations, and most traits varied significantly among populations as well. Some traits differed significantly between forest and Cerrado populations, while transition sites showed intermediate patterns and higher within-population variation. Contrary to our hypothesis, variation in seed size and mass among populations from different habitats was not significant. However, as predicted, the membranous endocarp was shorter for the seeds from Cerrado populations than from the Atlantic Forest. These data suggest the existence of P. reticulata ecotypes from Cerrado and Atlantic Forest; the relevance to Plathymenia evolution and to its wide ecological distribution is discussed.

Biometria de frutos e sementes e germinação de Plathymenia reticulata benth. e Plathymenia foliolosa benth. (Fabaceae - mimosoideae)

“…Esse fato pode ser responsável pela similaridade encontrada no comprimento dos frutos dessas duas espécies. Goulart et al (2006) também não constataram diferenças estatísticas entre comprimento dos frutos de P. reticulata (considerando-se o gênero monoespecífico) oriundos de diferentes populações da Floresta Atlântica e do Cerrado.…”

“…Contudo, não houve diferenças na massa da matéria fresca e seca entre as duas espécies (Tabela 1). Goulart et al (2006) não encontraram diferenças significativas entre a massa da matéria fresca e tamanho de sementes de P. reticulata provenientes de diferentes populações dos biomas Cerrado e Floresta Atlântica, mas verificaram que as sementes dos indivíduos da Floresta Atlântica são mais compridas, conforme os resultados deste estudo. Da mesma forma que nos frutos, as dimensões das sementes de P. foliolosa apresentaram maiores coeficientes de variação do que as de P. reticulata, exceto para massa da matéria fresca, que teve coeficiente de variação pouco menor (Tabela 1).…”

Populational approach in ecophysiological studies: the case of Plathymenia reticulata, a tree from Cerrado and Atlantic Forest

“…Previous studies have demonstrated the existence of significant variation of these traits within and among populations of P. reticulata (Lacerda et al, 2004;Goulart et al, 2006). Individuals within populations are significantly different in at least 13 morphological fruit and seed traits, including seed mass as shown in Figure 3 (Goulart et al, 2006). These differences may be attributed to habitat differences that promote phenotypic variation (Bañuelos and Obeso, 2003;Murray et al, 2003;Murray et al, 2004) or may be caused by random process as genetic drift.…”

“…Previous studies have demonstrated the existence of significant variation of these traits within and among populations of P. reticulata (Lacerda et al, 2004;Goulart et al, 2006). Individuals within populations are significantly different in at least 13 morphological fruit and seed traits, including seed mass as shown in Figure 3 (Goulart et al, 2006).…”

“…There are a lot of data (Goulart et al, 2005;Goulart et al, 2006;the present article) showing adaptative traits on P. reticulata populations related to their habitat of origin. The high ecophysiological diversity of this species permits its occurrence in a broad geographical range from Cerrado to Atlantic Forest.…”