Browsing by Subject "BIOGEOGRAPHY"
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Item Open Access A worldwide phylogeny of Adiantum (Pteridaceae) reveals remarkable convergent evolution in leaf blade architecture(Taxon, 2018-06-01) Huiet, L; Li, F; Kao, T; Prado, J; Smith, AR; Schuettpelz, E; Pryeri, KM© International Association for Plant Taxonomy (IAPT) 2018, All rights reserved. Adiantum is among the most distinctive and easily recognized leptosporangiate fern genera. Despite encompassing an astonishing range of leaf complexity, all species of Adiantum share a unique character state not observed in other ferns: sporangia borne directly on the reflexed leaf margin or “false indusium” (pseudoindusium). The over 200 species of Adiantum span six continents and are nearly all terrestrial. Here, we present one of the most comprehensive phylogenies for any large (200+ spp.) monophyletic, subcosmopolitan genus of ferns to date. We build upon previous datasets, providing new data from four plastid markers (rbcL, atpA, rpoA, chlN) for 146 taxa. All sampled taxa can be unequivocally assigned to one of nine robustly supported clades. Although some of these unite to form larger, well-supported lineages, the backbone of our phylogeny has several short branches and generally weak support, making it difficult to accurately assess deep relationships. Our maximum likelihood-based ancestral character state reconstructions of leaf blade architecture reveal remarkable convergent evolution across multiple clades for nearly all leaf forms. A single unique synapomorphy—leaves once-pinnate, usually with prolonged rooting tips—defines the philippense clade. Although a rare occurrence in Adiantum, simple leaves occur in three distinct clades (davidii, philippense, peruvianum). Most taxa have leaves that are more than once-pinnate, and only a few of these (in the formosum and pedatum clades) exhibit the distinct pseudopedate form. Distributional ranges for each of the terminal taxa show that most species (75%) are restricted to only one of six major biogeographical regions. Forty-eight of our sampled species (nearly one-third) are endemic to South America.Item Open Access Convergent evolution in lemur environmental niches(Journal of Biogeography, 2020-04-01) Herrera, JPAim: To test the hypothesis that adaptive convergent evolution of climate niches occurred in multiple independent lemur lineages. Location: Madagascar. Taxon: Lemurs. Methods: I collected climate and altitude data from WorldClim and summarized the niches of almost all living lemurs (83 species) into phylogenetically controlled principal components. To test for convergent evolution, I searched for multiple, similar climate optima using multi-peak Ornstein–Uhlenbeck models (surface, l1-ou, bayou). I compared the observed level of climate convergence to that simulated under neutral and single-optimum models. To test if behavioural or morphological traits were related to climate niches, I used phylogenetic regressions with activity pattern, diet, and body size. Results: From an ancestral niche with high rainfall and low seasonality, four lemur lineages independently converged on climate niche optima characterized by high temperatures and low rainfall, supporting adaptive evolution in southwest deciduous and arid habitats. The observed level of convergence was more frequent than expected under Brownian motion and single-optimum simulations, which illustrates that the results are likely not a result of stochastic evolution over long time periods. Nocturnal and cathemeral activity patterns were common among lineages in the arid climate niche. Conclusion: Lemur climate niche evolution demonstrated that convergence explains the distribution of four independent clades in hot, arid environments of southwest Madagascar. The timing of these convergent shifts coincided with the origination of modern arid-adapted plant genera, some of which are important lemur food sources. These communities have high endemicity and are especially threatened by habitat loss. Arid environments are arenas in which convergent evolution is predicted to occur frequently.Item Open Access Origins of the endemic scaly tree ferns on the galápagos and Cocos Islands(International Journal of Plant Sciences, 2015-11-01) Kao, T; Pryer, KM; Turner, MD; White, RA; Korall, P© 2015 by The University of Chicago. All rights reserved. Premise of research. Successful long-distance dispersal is rarely observed in scaly tree ferns (Cyatheaceae). Nevertheless, recent molecular evidence has suggested that the four endemic scaly tree ferns on the Galápagos Archipelago (Cyathea weatherbyana) and Cocos Island (Cyathea alfonsiana, Cyathea nesiotica, and Cyathea notabilis), two oceanic island groups west of Central and northern South America, probably each originated from different mainland America ancestors. However, the phylogenetic relationships inferred among these endemics and their mainland relatives have been unclear. This study is aimed at better resolving the relationships and tracing the origins of these island endemics. Methodology. Five plastid regions from 35 Cyathea species were analyzed to reconstruct phylogenetic relationships using parsimony, likelihood, and Bayesian approaches. We also estimated divergence times of these species, and our chronogram was used to reconstruct their biogeographical range history. Pivotal results. Our well-resolved phylogenetic tree of Cyathea, which is in agreement with previous studies, shows that when the four Galápagos and Cocos endemics are included, they each belong to separate subclades. Our biogeographical study suggests that the four endemics originated from independent colonization events from mainland America and that there was no dispersal of Cyathea between the island groups. We reveal more detailed relationships among the endemics and their respective close mainland relatives; some of these relationships differ from previous studies. Our findings are corroborated by new morphological data from ongoing stem anatomy studies. Conclusions. The four scaly tree ferns endemic to the Galápagos and Cocos Islands each did indeed originate as independent colonization events from separate sources in mainland America, and their closest relatives are identified here.Item Open Access The paraphyly of Osmunda is confirmed by phylogenetic analyses of seven plastid loci(Systematic Botany, 2008-03-01) Metzgar, JS; Skog, JE; Zimmer, EA; Pryer, KMTo resolve phylogenetic relationships among all genera and subgenera in Osmundaceae, we analyzed over 8,500 characters of DNA sequence data from seven plastid loci (atpA, rbcL, rbcL-accD, rbcL-atpB, rps4-trnS, trnG-trnR, and trnL-trnF). Our results confirm those from earlier anatomical and single-gene (rbcL) studies that suggested Osmunda s.l. is paraphyletic. Osmunda cinnamomea is sister to the remainder of Osmundaceae (Leptopteris, Todea, and Osmunda s.s.). We support the recognition of a monotypic fourth genus, Osmundastrum, to reflect these results. We also resolve subgeneric relationships within Osmunda s.s. and find that subg. Claytosmunda is strongly supported as sister to the rest of Osmunda. A stable, well-supported classification for extant Osmundaceae is proposed, along with a key to all genera and subgenera. © Copyright 2008 by the American Society of Plant Taxonomists.