Browsing by Subject "PHYLOGENY"

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    A revised generic classification of vittarioid ferns (Pteridaceae) based on molecular, micromorphological, and geographic data
    (Taxon, 2016-08-01) Schuettpelz, E; Chen, C; Kessler, M; Pinson, JB; Johnson, G; Davila, A; Cochran, AT; Huiet, L; Pryer, KM
    © International Association for Plant Taxonomy (IAPT) 2016. Vittarioid ferns compose a well-supported clade of 100-130 species of highly simplified epiphytes in the family Pteridaceae. Generic circumscriptions within the vittarioid clade were among the first in ferns to be evaluated and revised based on molecular phylogenetic data. Initial analyses of rbcL sequences revealed strong geographic structure and demonstrated that the two largest vittarioid genera, as then defined, each had phylogenetically distinct American and Old World components. The results of subsequent studies that included as many as 36 individuals of 33 species, but still relied on a single gene, were generally consistent with the early findings. Here, we build upon the previous datasets, incorporating many more samples (138 individuals representing 72 species) and additional plastid markers (atpA, chlN, rbcL, rpoA). Analysis of our larger dataset serves to better characterize known lineages, reveals new lineages, and ultimately uncovers an underlying geographic signal that is even stronger than was previously appreciated. In our revised generic classification, we recognize a total of eleven vittarioid genera. Each genus, including the new genus Antrophyopsis (Benedict) Schuettp., stat. nov., is readily diagnosable based on morphology, with micromorphological characters related to soral paraphyses and spores complementing more obvious features such as venation and the distribution of sporangia. A key to the currently recognized vittarioid genera, brief generic descriptions, and five new species combinations are provided.
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    Are there too many fern genera?
    (Taxon, 2018-06-01) Schuettpelz, E; Rouhan, G; Pryer, KM; Rothfels, CJ; Prado, J; Sundue, MA; Windham, MD; Moran, RC; Smith, AR
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    Baja: A New Monospecific Genus Segregated from Cheilanthes s. l. (Pteridaceae)
    (Systematic Botany, 2019-09-06) George, LO; Pryer, KM; Kao, T; Huiet, L; Windham, MD
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    Comparative morphology of reproductive structures in heterosporous water ferns and a reevaluation of the sporocarp
    (International Journal of Plant Sciences, 2006-07-01) Nagalingum, NS; Schneider, H; Pryer, KM
    Heterosporous water ferns (Marsileaceae and Salviniaceae) are the only extant group of plants to have evolved heterospory since the Paleozoic. These ferns possess unusual reproductive structures traditionally termed "sporocarps." Using an evolutionary framework, we critically examine the complex homology issues pertaining to these structures. Comparative morphological study reveals that all heterosporous ferns bear indusiate sori on a branched, nonlaminate structure that we refer to as the sorophore; this expanded definition highlights homology previously obscured by the use of different terms. By using a homology-based concept, we aim to discontinue the use of historically and functionally based morphological terminology. We recognize the sorophore envelope as a structure that surrounds the sorophore and sori. The sorophore envelope is present in Marsileaceae as a sclerenchymatous sporocarp wall and in Azolla as a parenchymatous layer, but it is absent in Salvinia. Both homology assessments and phylogenetic character-state reconstructions using the Cretaceous fossil Hydropteris are consistent with a single origin of the sorophore envelope in heterosporous ferns. Consequently, we restrict the term "sporocarp" to a sorophore envelope and all it contains. Traditional usage of "sporocarp" is misleading because it implies homology for nonhomologous structures, and structures historically called sporocarps in Salviniaceae are more appropriately referred to as sori. © 2006 by The University of Chicago. All rights reserved.
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    Convergent evolution in lemur environmental niches
    (Journal of Biogeography, 2020-04-01) Herrera, JP
    Aim: 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.
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    Marsileaceae sporocarps and spores from the late cretaceous of Georgia, U.S.A.
    (International Journal of Plant Sciences, 2000-01-01) Lupia, R; Schneider, H; Moeser, GM; Pryer, KM; Crane, PR
    A new species provisionally assigned to the extant genus Regnellidium Lindm. (Regnellidium upatoiensis sp. nov.) is established for isolated sporocarps assignable to the heterosporous water fern family Marsileaceae. Three sporocarps and hundreds of dispersed megaspores were recovered from unconsolidated clays and silts of the Eutaw Formation (Santonian, Late Cretaceous) along Upatoi Creek, Georgia, U.S.A. The sporocarps are ellipsoidal and flattened, contain both megasporangia and microsporangia, and possess a two-layered wall - an outer sclerenchymatous layer and an inner parenchymatous layer. In situ megaspores are spheroidal, with two distinct wall layers - an exine, differentiated into two layers, and an outer ornamented perine also differentiated into two layers. The megaspores also possess an acrolamella consisting of six (five to seven) triangular lobes that are twisted. In situ microspores are trilete and spheroidal, with a strongly rugulate perine, and show modification of the perine over the laesura to form an acrolamella. Comparison of the fossil sporocarps with those of four extant species of Marsileaceae reveal marked similarity with Regnellidium diphyllum Lindm., particularly in megaspore and microspore morphology. If found dispersed, the in situ megaspores would be assigned to Molaspora lobata (Dijkstra) Hall and the microspores to Crybelosporites Dettmann based on their size, shape, and ornamentation. Regnellidium upatoiensis sp. nov. extends the stratigraphic range of the genus back to the Santonian, nearly contemporaneous with the first evidence of Marsilea, and implies that the diversification of the Marsileaceae into its extant lineages occurred in the mid-Cretaceous.
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    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.
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    Rediscovery of Polypodium calirhiza (Polypodiaceae) in Mexico
    (Brittonia, 2014) Sigel, EM; Windham, MD; Smith, AR; Dyer, RJ; Pryer, KM
    This study addresses reported discrepancies regarding the occurrence of Polypodium calirhiza in Mexico. The original paper describing this taxon cited collections from Mexico, but the species was omitted from the recent Pteridophytes of Mexico. Originally treated as a tetraploid cytotype of P. californicum, P. calirhiza now is hypothesized to have arisen through hybridization between P. glycyrrhiza and P. californicum. The tetraploid can be difficult to distinguish from either of its putative parents, but especially so from P. californicum. Our analyses show that a combination of spore length and abaxial rachis scale morphology consistently distinguishes P. calirhiza from P. californicum, and we confirm that both species occur in Mexico. Although occasionally found growing together in the United States, the two species are strongly allopatric in Mexico: P. californicum is restricted to coastal regions of the Baja California peninsula and neighboring Pacific islands, whereas P. calirhiza grows at high elevations in central and southern Mexico. The occurrence of P. calirhiza in Oaxaca, Mexico, marks the southernmost extent of the P. vulgare complex in the Western Hemisphere. © 2014 The New York Botanical Garden.
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    Revealing a cryptic fern distribution through DNA sequencing: Pityrogramma trifoliata in the Western Andes of Peru
    (American Fern Journal, 2013-01-01) León, B; Rothfels, CJ; Arakaki, M; Young, KR; Pryer, KM
    Fern identification usually requires the use of mature sporophytes, since attempts to identify juveniles using morphological traits often provides unsatisfactory results. Here we examined young sporophytes found among boulders in a river basin of a xeric valley in central Peru. Attempts to identify these sporophytes first pointed to four different genera, two in Pteridaceae (Anogramma and Pityrogramma), and the others in Aspleniaceae (Asplenium) and Cystopteridaceae (Cystopteris). Here, we resolved this puzzle combining morphology and sequences of DNA (rbcL and trnG-R) that point to Pityrogramma trifoliata of Pteridaceae.
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    Structure and function of spores in the aquatic heterosporous fern family Marsileaceae
    (International Journal of Plant Sciences, 2002-01-01) Schneider, H; Pryer, KM
    Spores of the aquatic heterosporous fern family Marsileaceae differ markedly from spores of Salviniaceae, the only other family of heterosporous ferns and sister group to Marsileaceae, and from spores of all homosporous ferns. The marsileaceous outer spore wall (perine) is modified above the aperture into a structure, the acrolamella, and the perine and acrolamella are further modified into a remarkable gelatinous layer that envelops the spore. Observations with light and scanning electron microscopy indicate that the three living marsileaceous fern genera (Marsilea, Pilularia, and Regnellidium) each have distinctive spores, particularly with regard to the perine and acrolamella. Several spore characters support a division of Marsilea into two groups. Spore character evolution is discussed in the context of developmental and possible functional aspects. The gelatinous perine layer acts as a flexible, floating organ that envelops the spores only for a short time and appears to be an adaptation of marsileaceous ferns to amphibious habitats. The gelatinous nature of the perine layer is likely the result of acidic polysaccharide components in the spore wall that have hydrogel (swelling and shrinking) properties. Megaspores floating at the water/air interface form a concave meniscus, at the center of which is the gelatinous acrolamella that encloses a "sperm lake". This meniscus creates a vortex-like effect that serves as a trap for free-swimming sperm cells, propelling them into the sperm lake.