Testing the regeneration niche hypothesis with Gesneriaceae (tribe Sinningiae) in Brazil: Implications for the conservation of rare species

Abstract

The germination requirements of sexually reproducing plants are regulated by environmental factors such as temperature. Those factors acting at the germination phase are part of the regeneration niche, which is fundamental in the processes that contribute to habitat suitability and geographic distribution. We tested the hypothesis that rarity is associated with regeneration niche in three species of plants in the family Gesneriaceae (tribe Sinningieae), Sinningia rupicola (Mart.) Wiehler, Paliavana sericiflora Benth and Sinningia allagophylla (Mart.) Wiehler, which vary in their distribution and habitat specificity but share a small zone of sympatry in rocky fields south of Belo Horizonte in Minas Gerais, Brazil. The regeneration niche was tested using a seed germination experiment under controlled light conditions at seven fixed temperatures (10-40°C at 5°C intervals). Each of the three species germinated differently at the various temperatures. The species with the smallest geographic range, S. rupicola, also had the most restricted germination: germination peaked at 15°C when relatively few seeds germinated (45%), and even fewer germinated at other temperatures. The regeneration niche was wider in P. sericiflora and wider still in S. allagophylla, with germination greater than 90% between 15-25°C and greater than 80% between 15-30°C, respectively. Our germination results provide qualified support for the hypothesis of correlation of the regeneration niche with geographic distribution of related plant taxa, with important conservation implications for rare and endangered species.

Estudo fenológico de Bactris gasipaes Kunth,Euterpe edulis Mart. e Syagrus romanzoffiana (Cham.) Glassman no Vale do Ribeira, SP, Brasil

“…O sucesso da reprodução e do potencial de dispersão determina a capacidade de sobrevivência das espécies vegetais, podendo afetar a sua distribuição, abundância e especificidade de habitat (Ranieri et al 2012). Assim, a adaptação do período de produção das sementes pode estar relacionada a atividade de polinizadores e dispersores, ao desenvolvimento do fruto e da semente, ao comportamento de predadores de sementes e às necessidades específicas para a germinação (Janzen 1976).…”

Germination Phenological Response Identifies Flora Risk to Climate Change

“…The effect of temperature treatment on the success of species germination was tested using survival analysis following the methods of Rawal et al [36] and Ranieri et al [45]. Cox's proportional hazard analysis [46] was performed to calculate the proportional hazard of temperature factors on germinated seeds using SPSS version20 [47].…”

“…Cox's proportional hazard analysis [46] was performed to calculate the proportional hazard of temperature factors on germinated seeds using SPSS version20 [47]. For the purpose of analysis, germinated seeds were considered analogous to survival and seeds that did not germinate were considered equivalent to mortality [45].…”

Fenologia reprodutiva, sazonalidade e germinação de Kielmeyera regalis Saddi (Clusiaceae), espécie endêmica dos campos rupestres da Cadeia do Espinhaço, Brasil

“…Sob a temperatura de 35 °C o processo de germinação foi inibido para as sementes de K. regalis, assim como verificado por outros estudos sobre a germinação de sementes de espécies de campos rupestres, nos quais foram detectados efeitos negativos de temperaturas iguais ou superiores a 30 °C na germinação de sementes (Ranieri et al 2003;Silveira et al 2004;Oliveira & Garcia 2005;Ranieri et al 2012). Entretanto, Garcia & Diniz (2003) verificaram o favorecimento da germinação em Vellozia spp.…”

“…Os estudos anteriormente citados com espécies arbustivas de campos rupestres detectaram velocidades consideradas altas dentro das faixas ótimas de temperatura para cada espécie (Garcia & Diniz 2003;Ranieri et al 2003;Silveira et al 2004;Oliveira & Garcia 2005;Ranieri et al 2012). A alta velocidade na germinação de sementes é uma adaptação atribuída à ocorrência de solos que apresentam maiores taxas de infiltração de água (Gutterman et al 1967).…”