The xeric side of the Brazilian Atlantic Forest: The forces shaping phylogeographic structure of cacti

Abstract

In order to investigate biogeographic influences on xeric biota in the Brazilian Atlantic Forest (BAF), a biodiversity hotspot, we used a monophyletic group including three cactus taxa as a model to perform a phylogeographic study: Cereus fernambucensis subsp. fernambucensis, C. fernambucensis subsp. sericifer, and C. insularis. These cacti are allopatric and grow in xeric habitats along BAF, including isolated granite and gneiss rock outcrops (Inselbergs), sand dune vegetation (Restinga forest), and the rocky shore of an oceanic archipelago (islands of Fernando de Noronha). The nucleotide information from nuclear gene phytochrome C and plastid intergenic spacer trnS‐trnG was used to perform different approaches and statistical analyses, comprising population structure, demographic changes, phylogenetic relationships, and biogeographic reconstruction in both spatial and temporal scales. We recovered four allopatric population groups with highly supported branches in the phylogenetic tree with divergence initiated in the middle Pleistocene: southern distribution of C. fernambucensis subsp. fernambucensis, northern distribution of C. fernambucensis subsp. fernambucensis together with C. insularis, southern distribution of C. fernambucensis subsp. sericifer, and northern distribution of C. fernambucensis subsp. sericifer. Further, the results suggest that genetic diversity of population groups was strongly shaped by an initial colonization event from south to north followed by fragmentation. The phylogenetic pattern found for C. insularis is plausible with peripatric speciation in the archipelago of Fernando de Noronha. To explain the phylogeographic patterns, the putative effects of both climatic and sea level changes as well as neotectonic activity during the Pleistocene are discussed.

Cross-genera SSR transferability in cacti revealed by a case study using Cereus (Cereeae, Cactaceae)

“… * The classification in Southern and Northern group is based on phylogeographic data available for C. fernambucensis ( Franco et al , 2017b ) / N = number of individuals per populations. …”

Beyond endemism, expanding conservation efforts: a relictual Pleistocene distribution and first report of the prickly pear cactus, Opuntia bonaerensis, in Brazil and Uruguay

“…During the climatic fluctuations of the Quaternary, the Southern Hemisphere was not affected by extensive glaciations as in the Northern Hemisphere, but the impacts of the Pleistocene have been increasingly documented in the South American flora and revealed as an important epoch for diversification both at the generic, as well as at the species level (Rull, 2008; Ramos-Fregonezi et al, 2015; Turchetto-Zolet et al, 2013; Ramírez-Barahona and Eguiarte, 2013). In cacti, several studies uncovered Pleistocene events related with climatic oscillations and glacial/interglacial cycles as a decisive driver for disjunct distributions, microrefugia and diversification across disparate clades emphasizing Mesoamerica, as well central, eastern and southeastern South American regions, primarily in the Atlantic forest and Cerrado biomes (Ornelas and Rodríguez-Gomez, 2015; Bonatelli et al, 2014; Franco et al, 2017a, 2017b; Silva et al, 2018a). However, diversification and distribution patterns in southern South American regions during the Pleistocene have been neglected, especially in the Pampas and Chaco regions.…”

Dados filogenômicos para inferência de relações evolutivas entre espécies do gênero Cereus Mill. (Cactaceae, Cereeae)

“…Um outro estudo envolvendo espécies de Cereus também baseado em poucos marcadores moleculares (gene nuclear fitocromo C (PHYC) e no espaçador intergênico trnS-trnG) (FRANCO et al 2017b), usou as espécies do subclado A2 (C. fernambucensis e C. insularis) (Figura 2) para discutir os eventos que moldaram a vegetação em ambientes xéricos da Mata Atlântica e investigar a estrutura populacional e os mecanismos que levaram diversificação dessas espécies. Quatro grupos genéticos foram encontrados dentro dessas duas espécies, e uma íntima relação filogenética entre as populações do norte da distribuição de C.…”

“…fernambucensis com C. insularis, tornando C. fernambucensis um grupo parafilético (Franco et al 2017b).…”

“…As amostras de Cereus foram escolhidas com base nos táxons usados para estabelecimento da hipótese filogenética preliminar de Cereus (Figura 2). Uma amostragem maior foi definida para a espécie C. fernambucensis, considerando que essa espécie é composta por pelo menos quatro grupos populacionais e provavelmente parafilética, devido ao posicionamento de C. insularis como grupo irmão das populações mais ao norte da distribuição de C. fernambucensis(FRANCO et al 2017b). Além disso, foram incluídas espécies dos Descrição das amostras utilizadas na execução do presente trabalho, identificando qual amostra estava presente em cada um dos protocolos de biblioteca reduzida desenvolvidos.…”