Regional assessment of the impact of climatic change on the distribution of a tropical conifer in the lowlands of South America

Abstract

For decades, palynologists working in tropical South America are using the genus Podocarpus as a climate indicator although without referring to any modern data concerning its distribution and limiting factors. With the aim to characterize the modern and past distribution of the southern conifer Podocarpus in Brazil and to obtain new information on the distribution of the Atlantic rainforest during the Quaternary, we examined herbarium data to locate the populations of three Brazilian endemic Podocarpus species: P. sellowii, P. lambertii, and P. brasiliensis, and extracted DNA from fresh leaves from 26 populations. Our conclusions are drawn in the light of the combination of these three disciplines: botany, palynology, and genetics. We find that the modern distribution of endemic Podocarpus populations shows that they are widely dispersed in eastern Brazil, from north to south and reveals that the expansion of Podocarpus recorded in single Amazonian pollen records may have come from either western or eastern populations. Genetic analysis enabled us to delimit regional expansion: between 5° and 15° S grouping northern and central populations of P. sellowii expanded c. 16,000 years ago; between 15° and 23° S populations of either P. lambertii or sellowii expanded at different times since at least the last glaciation; and between 23° and 30° S, P. lambertii appeared during the recent expansion of the Araucaria forest. The combination of botany, pollen, and molecular analysis proved to be a rapid tool for inferring distribution borders for sparse populations and their regional evolution within tropical ecosystems. Today the refugia of rainforest communities we identified are crucial hotspots to allow the Atlantic forest to survive under unfavourable climatic conditions and, as such, offer the only possible opportunity for this type of forest to expand in the event of a future climate change.

Las palmeras de América del Sur: diversidad, distribución e historia evolutiva

“…Esta zona corresponde a la Mata Atlántica sensu stricto. Hacia el interior, fuera de la influencia directa de la humedad Atlántica, el dominio de la Mata Atlántica sensu lato comprende bosques semi-deciduos y deciduos, en el límite con el dominio de los Cerrados (Ledru et al, 2007). Los bosques con régimen estacional del dominio de la Mata Atlántica incluyen especies como Attalea brejinhoensis, A.…”

Range-wide patterns of nuclear and chloroplast DNA diversity in Vriesea gigantea (Bromeliaceae), a neotropical forest species

“…In contrast, phylogeographic studies in southern and southeastern South America are rare and have thus far been limited to neotropical mammals (small mammals: Costa, 2003;Cerdocyon thous: Tchaicka et al, 2007), reptiles (Bothrops jararaca: Grazziotin et al, 2006) and birds (Xiphorhynchus fuscus: Cabanne et al, 2007Cabanne et al, , 2008. Few studies have reported phylogeography patterns in plants of the southern portion of the Brazilian Atlantic Rainforest, for example, those on Passiflora actinia and P. elegans from the Southern Brazilian States of Rio Grande do Sul, Santa Catarina and Paraná (Lorenz-Lemke et al, 2005) and for P. sellowii (Ledru et al, 2007). The phylogeographic patterns reported for these taxa are in agreement with those observed for V. gigantea.…”

“…Studies addressing the evolutionary history of the species-rich Southern part of the Brazilian Atlantic Rainforest taxa from a molecular phylogeographic perspective are extremely rare and include few studies of animals (Grazziotin et al, 2006;Cabanne et al, 2007Cabanne et al, , 2008Tchaicka et al, 2007) and plants (for example, Lorenz-Lemke et al, 2005;Ledru et al, 2007). These studies provide first insights into the effects of historical forest expansions and contractions on present-day patterns of intraspecific variation, suggesting demographic responses to Pleistocene climate-induced changes in forest cover with a conspicuous north-south phylogeographic split for several taxa.…”

O Ceará É Totalmente Circunscrito À Caatinga? O Que Dizem Os Livros Didáticos E Os Professores Do Ensino Médio?

“…A importância das Matas Úmidas Serranas é pontuada na literatura científica internacional por Ledru et al (2007) ao afirmar que as serras úmidas nordestinas, a exemplo da Serra de Baturité, são importantes refúgios para a fauna e flora de florestas tropicais e são por isso locais críticos para permitir que a Mata Atlântica sobreviva em condições climáticas desfavoráveis, oferecendo oportunidade para que este tipo de floresta se expanda em caso de mudança climática futura.…”