Chromosome study of the fern genus Cyrtomium (Dryopteridaceae)

Cyrtomium (Dryopteridaceae) is an Asiatic genus comprising about 40 species characterized by having anastomosing veins that form areolae with included veinlets. Twelve chromosome counts representing 11 taxa were made in the present study. The chromosome numbers of six species endemic to China are reported for the first time: C. uniseriale , 2 n  = 164; C. guizhouense , 2 n  = 82; C. shingianum , n  = 82, 2 n  =  c .164; C. chingianum , 2 n  = 164; C. urophyllum , 2 n  = 82 and C. aequibasis , 2 n  = 123. The results were used to show that (1) C. uniseriale should be reduced to varietal status under C. balansae ; (2) subseries Balansana is not closely related to any other Cyrtomium species and should be separated from Cyrtomium ; and (3) C. guizhouense and C. lonchitoides are basal groups when subseries Balansana is not considered. These results were also supported by morphology. A high level of differentiation is a distinct characteristic in Cyrtomium . The genus has two reproductive types: sexual and apogamous. Sexual species are distributed mostly in China. Southwestern China is a modern diversity centre of Cyrtomium , with 80.6% of known species occurring there. Many species are endemic, most of which are sexual tetraploids or apogamous triploids. Both the apogamous reproductive type and polyploid species are adaptions to limestone habitats.  © 2006 The Linnean Society of London, Botanical Journal of the Linnean Society , 2006, 150 , 221–228.     

Notes on the genus Polystichum (Dryopteridaceae) in Bolivia, with descriptions of ten new species

We describe ten new species ofPolystichum (Dryopteridaceae, Pteridophyta) from Bolivia, provide brief notes on the other eleven species of the genus in the country, and present a key to all species, New species are:P. albomarginatum, P. amboroense, P. bachii, P. chaparensis, P. congestum, P. giganteum, P. lepidotum, P. paramicola, P. rufum, andP. solomonii.     

Gametophyte development and reproduction of the Asian fern Polystichum polyblepharum (Roem. ex Kunze) C. Presl (Dryopteridaceae,Polypodiopsida)

Abstract

The gametophytic generation of Polystichum polyblepharum (Dryopteridaceae), including spore germination, morphological development of the gametophytes, major vegetative features and reproduction strategies, was studied. Spore germination was of the Vittaria model and the developmental pattern was of the Aspidium model. Adult gametophytes were cordate and hairy, with unicellular hairs located at the margins and at the prothallus surface. The marginal ones were secretory. The gametophytes produced archegonia located in the central area between the notch and the rhizoids, but antheridia were never detected. Archegonia were of the normal type described for leptosporangiate ferns. Apogamous sporophytes appeared from a cellular outgrowth developed just under the apical notch. Initially, the outgrowth appeared completely surrounded by glandular hairs and scales, which persisted throughout the subsequent stages of leaf development.     

New species in the fern genus Dryopteris (Dryopteridaceae) from the islands in the Gulf of Guinea (West Africa)

Three new species of Dryopteris, D. cicatricata J.P. Roux and D. caperata J.P. Roux from São Tomé and D. aurantiaca J.P. Roux from Annobón are described. All three taxa appear to be local endemics. A key to the Dryopteris species occurring on the islands in the Gulf of Guinea is provided.     

Origin of Hawaiian Polystichum (Dryopteridaceae) in the context of a world phylogeny

A genus-wide molecular phylogeny for Polystichum and allied genera (Dryopteridaceae) was reconstructed to address the biogeographic origin and evolution of the three Hawaiian Polystichum species, all endemic there. The analysis was based on the cpDNA sequences rbcL and the trnL-F spacer from a taxonomically and geographically diverse sample. Parsimony and Bayesian phylogenetic analyses of the combined data support a monophyletic Polystichum and corroborate recent hypotheses as to membership and sequence of origin of the major groups within the genus. The Hawaiian Polystichum species are polyphyletic; two separate lineages appear to have arrived independently from the Old World. The provenance of the diploid Polystichum hillebrandii is continental eastern Asia, while the source of the polyploid lineage comprising tetraploid P. haleakalense and octoploid P. bonseyi is likely continental Asia. From our results, the origin of the Hawaiian species of Polystichum, like many Hawaiian fern genera with several species, is the result of multiple migrations to the islands, rather than single migrations yielding nearly all the local diversity as in the angiosperms. This emerging pattern provides a modern test of the premise that propagule vagility has a central role in determining pattern of evolution.     

A new species of Polystichum (Pteridophyta: Dryopteridaceae) from South Africa

A new Polystichum (Pteridophyta: Dryopteridaceae) species, P. incongruum J.P.Roux sp. nov. from the Western and Eastern Cape Provinces from Soudi Africa is described. This variable species is related to P. pungens (Kaulf.) C.Presl but differs from it in pinnule morphology, the frequent occurrence of glandular cells along the sporangium stalk, the (more rare) occurrence of clavate unicellular glands along the indusium margin and a chromosome number of 2 n = 164.     

The evolutionary origin and diversification of feathers

Progress on the evolutionary origin and diversification of feathers has been hampered by conceptual problems and by the lack of plesiomorphic feather fossils. Recently, both of these limitations have been overcome by the proposal of the developmental theory of the origin of feathers, and the discovery of primitive feather fossils on nonavian theropod dinosaurs. The conceptual problems of previous theories of the origin of feathers are reviewed, and the alternative developmental theory is presented and discussed. The developmental theory proposes that feathers evolved through a series of evolutionary novelties in developmental mechanisms of the follicle and feather germ. The discovery of primitive and derived fossil feathers on a diversity of coelurosaurian theropod dinosaurs documents that feathers evolved and diversified in nonavian theropods before the origin of birds and before the origin of flight. The morphologies of these primitive feathers are congruent with the predictions of the developmental theory. Alternatives to the theropod origin of feathers are critique and rejected. Hypotheses for the initial function of feathers are reviewed. The aerodynamic theory of feather origins is falsified, but many other functions remain developmentally and phylogenetically plausible. Whatever their function, feathers evolved by selection for a follicle that would grow an emergent tubular appendage. Feathers are inherently tubular structures. The homology of feathers and scales is weakly supported. Feathers are composed of a suite of evolutionary novelties that evolved by the duplication, hierarchical organization, interaction, dissociation, and differentiation of morphological modules. The unique capacity for modular subdivision of the tubular feather follicle and germ has fostered the evolution of numerous innovations that characterize feathers. The evolution of feather keratin and the molecular basis of feather development are also discussed.     

Out-of-Africa origin and dispersal-mediated diversification of the butterfly genus Junonia (Nymphalidae: Nymphalinae)

The relative importance of dispersal and vicariance in the diversification of taxa has been much debated. Within butterflies, a few studies published so far have demonstrated vicariant patterns at the global level. We studied the historical biogeography of the genus Junonia (Nymphalidae: Nymphalinae) at the intercontinental level based on a molecular phylogeny. The genus is distributed over all major biogeographical regions of the world except the Palaearctic. We found dispersal to be the dominant process in the diversification of the genus. The genus originated and started diversifying in Africa about 20 Ma and soon after dispersed into Asia possibly through the Arabian Peninsula. From Asia, there were dispersals into Africa and Australasia, all around 5 Ma. The origin of the New World species is ambiguous; the ancestral may have dispersed from Asia via the Beringian Strait or from Africa over the Atlantic, about 3 Ma. We found no evidence for vicariance at the intercontinental scale. We argue that dispersal is as important as vicariance, if not more, in the global diversification of butterflies.     

Evidence of genetic segregation in the apogamous fern species Cyrtomium fortunei (Dryopteridaceae)

In apogamous ferns, all offspring from a parent are expected to be clonal. However, apogamous 'species' frequently demonstrate a large amount of morphological and genetic variations. Cyrtomium fortunei composed of four varieties (C. fortunei var. fortunei, var. clivicola, var. intermedium, and var. atropunctatum), is all reported to be apogamous triploids, but demonstrates large and continuous morphological variation. In previous studies, we showed that considerable genetic diversity was observed in many local populations of the apogamous fern 'species'. We hypothesized that genetic segregation has occurred, because neither sexual type nor intraspecific polyploidy have been observed in C. fortunei in Japan. Of 732 progeny examined (250 gametophytes and 482 sporophytes), obtained from a parental sporophyte whose pgiC genotype was estimated as aab, 11 (4.4%) gametophytes and 8 (1.7%) sporophytes showed a different genotype (aaa) from that of the parent sporophyte. We showed that genetic segregation occurs in apogamous C. fortunei in relatively high frequency. Moreover, we could first show that the segregation frequency in gametophytes is significantly higher than that in sporophytes of the next generation (χ (2)?=?4.90, P?=?0.027). It may suggest the existence of deleterious genes, which are expressed during the morphogenesis and growth of sporophytes.     

Pathological evaluation of Polystichum squarrosum (D. Don) fern in laboratory rats

Polystichum squarrosum fern fed (30% w/w) rats showed moderate mortality, decrease in body weight, less body fat and splenomegaly. On post-mortem examination, significant gross lesions were not seen in sacrificed animals. Histopathologically, Polystichum fed rats showed dilated Virchow Robin's space in brain, mild to moderate vascular changes likeoedema, engorgement of blood vessels and haemorrhages in most of the visceral organs, interstitial pneumonia in lungs, focal necrosis and generalised vacuolative degenerative changes in liver, more haemosiderin deposition and presence of higher number of megakaryocytes in spleen, shrunken glomeruli, more peri-glomerular space and more number of glomeruli per microscopic field in kidneys, focal hyperplasia of urinary bladder and moderate to marked depletion of germinal epithelium and spermatids in seminiferous tubules of testes. Pathologically, progressive changes were observed only in liver, urinary bladder and testes on 180 days post feeding (DPF). One fern fed rat sacrificed on 135 DPF showed hepatic tumour which was diagnosed as hepatocellular carcinoma. The results showed that P. squarrosum produced almost comparable pathological changes/preneoplastic lesions as reported in bracken fern fed animals. Long term exposure studies (i.e. 2 yrs) are desired.     

Hydraulic properties of fern sporophytes: Consequences for ecological and evolutionary diversification

? Premise of the study: Ferns are an important component of both tropical and temperate forests; yet, our understanding of the water relations of their sporophyte generation is limited. Indeed, to date there has been no large scale survey that attempts to clarify how ferns fit into current ideas of plant water relations. This study examines several tropical ferns with the goal of understanding how these characters vary between species from various habitats and across life forms ? Methods: We measured stipe hydraulic conductivity, water potential, and vulnerability to cavitation along with photosynthetic variables and leaf allometry of 21 species from 14 genera to identify physiological trait assemblages across taxa. ? Key results: Epiphytic ferns have significantly lower hydraulic conductivity and a vascular system more resistant to cavitation (i.e., higher P(50) values). They reached lower mid-day water potentials and produced leaves with reduced stipe lengths and reduced laminar area relative to terrestrial species. Xylem specific hydraulic conductivity (K(S)) was correlated with the mean hydraulic diameter of tracheids in terrestrial species, but not in epiphytes. There was no evidence of safety-efficiency trade-offs in any group. ? Conclusions: When compared across life forms, our data shed light on physiological mechanisms that may have allowed for terrestrial ferns to move into the epiphytic habit. When compared across a diverse assemblage of terrestrial plants, we find that resistance to water flow in fern stipes is significantly higher than that recorded from the stems of seed plants.     

Ecological and evolutionary diversification of the seed beetle genus Stator (Coleoptera: Chrysomelidae: Bruchinae)

Ehrlich and Raven's (1964) hypothesis on coevolution has stimulated numerous phylogenetic studies that focus on the effects of plant defensive chemistry as the main ecological axis of phytophagous insect diversification. However, other ecological features affect host use and diet breadth and they may have very different consequences for insect evolution. In this paper, we present a phylogenetic study based on DNA sequences from mitochondrial and protein-coding genes of species in the seed beetle genus Stator, which collectively show considerable interspecific variation in host affiliation, diet breadth, and the dispersal stage of the seeds that they attack. We used comparative analyses to examine transitions in these three axes of resource use. We argue that these analyses show that diet breadth evolution is dependent upon colonizing novel hosts that are closely or distantly related to the ancestral host, and that oviposition substrate affects the evolution of host-plant affiliation, the evolution of dietary specialization, and the degree to which host plants are shared between species. The results of this study show that diversification is structured by interactions between different selective pressures and along multiple ecological axes.     

The morphology and cytology of a new Polystichum (Pteridophyta: Dryopteridaceae) hybrid from South Africa

A new Polystichum (Pteridophyta: Dryopteridaceae) hybrid, P. x saltum is described. Several micromorphological characters are anomalous in their being a summation of the character states of the progenitors rather than being intermediate or closer to one of the parent species. The putative parents of this sterile hybrid are P. transvaalen.se and P. wilsonii , both sexual tetraploids (2 n = 164). Polystichum x saltum also has a somatic chromosome number of 2 n = 164, but meiosis yields univalents and bivalents.     

The genus Cyrtomium (Pteridophyta: Dryopteridaceae) in Africa and Madagascar

The fern genus Cyrtomium (Dryopteridaceae) in Africa and Madagascar is reviewed. Until now, a single Cyrtomium species ascribed to either C. caryotideum or C. micropterum (the latter often considered to be a variety of the former) was recognized for the region. This study shows that three Cyrtomium species occur in the region. One, C. falcatum, is not native to the African or Madagascan region, but has become naturalized in various parts of South Africa and Réunion. Two, formerly considered as a single taxon and confused with C. caryotideum and Indian forms thereof, are described as new – C. luctuosum from Madagascar, East, West and South Africa and C. pseudocaryotideum from South Africa. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 167 , 449–465.