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Ceratozamia Brongn. is one of the species-rich genera of Cycadales comprising 38 species that are mainly distributed in Mexico, with a few species reported from neighboring regions. Phylogenetic relationships within the genus need detailed investigation based on extensive datasets and reliable systematic approaches. Therefore, we used 30 of the known 38 species to reconstruct the phylogeny based on transcriptome data of 3954 single-copy nuclear genes (SCGs) via coalescent and concatenated approaches and three comparative datasets (nt/nt12/aa). Based on all these methods, Ceratozamia is divided into six phylogenetic subclades within three major clades. There were a few discrepancies regarding phylogenetic position of some species within these subclades. Using these phylogenetic trees, biogeographic history and morphological diversity of the genus are explored. Ceratozamia originated from ancestors in southern Mexico since the mid-Miocene. There is a distinct distribution pattern of species through the Trans-Mexican Volcanic Belt (TMVB), that act as a barrier for the species dispersal at TMVB and its southern and northern part. Limited dispersal events occurred during the late Miocene, and maximum diversification happened during the Pliocene epoch. Our study provides a new insight into phylogenetic relationships, the origin and dispersal routes, and morphological diversity of the genus Ceratozamia. We also explain how past climatic changes affected the diversification of this Mesoamerica-native genus.
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Phylotranscriptomics reveal the spatio-temporal distribution and morphological evolution of Macrozamia , an Australian endemic genus of Cycadales
Abstract Background and Aims Cycads are regarded as an ancient lineage of living seed plants, and hold important clues to understand the early evolutionary trends of seed plants. The molecular phylogeny and spatio-temporal diversification of one of the species-rich genera of cycads, Macrozamia, have not been well reconstructed. Methods We analysed a transcriptome dataset of 4740 single-copy nuclear genes (SCGs) of 39 Macrozamia species and two outgroup taxa. Based on concatenated (maximum parsimony, maximum likelihood) and multispecies coalescent analyses, we first establish a well-resolved phylogenetic tree of Macrozamia. To identify cyto-nuclear incongruence, the plastid protein coding genes (PCGs) from transcriptome data are extracted using the software HybPiper. Furthermore, we explore the biogeographical history of the genus and shed light on the pattern of floristic exchange between three distinct areas of Australia. Six key diagnostic characters are traced on the phylogenetic framework using two comparative methods, and infra-generic classification is investigated. Key Results The tree topologies of concatenated and multi-species coalescent analyses of SCGs are mostly congruent with a few conflicting nodes, while those from plastid PCGs show poorly supported relationships. The genus contains three major clades that correspond to their distinct distributional areas in Australia. The crown group of Macrozamia is estimated to around 11.80 Ma, with a major expansion in the last 5–6 Myr. Six morphological characters show homoplasy, and the traditional phenetic sectional division of the genus is inconsistent with this current phylogeny. Conclusions This first detailed phylogenetic investigation of Macrozamia demonstrates promising prospects of SCGs in resolving phylogenetic relationships within cycads. Our study suggests that Macrozamia, once widely distributed in Australia, underwent major extinctions because of fluctuating climatic conditions such as cooling and mesic biome disappearance in the past. The current close placement of morphologically distinct species in the phylogenetic tree may be related to neotenic events that occurred in the genus.
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- Award ID(s):
- 2140319
- PAR ID:
- 10417825
- Date Published:
- Journal Name:
- Annals of Botany
- Volume:
- 130
- Issue:
- 5
- ISSN:
- 0305-7364
- Page Range / eLocation ID:
- 671 to 685
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1093/aob/mcac117
