Topic
Pyxidanthera
About: Pyxidanthera is a research topic. Over the lifetime, 3 publications have been published within this topic receiving 40 citations.
Papers
TL;DR: In this paper, the taxonomy and phylogeography of Pyxidanthera using morphological data, cpDNA sequences, and amplified fragment length polymorphism markers are investigated.
Abstract: The general phylogeographical paradigm for eastern North America (ENA) is that many plant and animal species retreated into southern refugia during the last glacial period, then expanded northward after the last glacial maximum (LGM). However, some taxa of the Gulf and Atlantic Coastal Plain (GACP) demonstrate complex yet recurrent distributional patterns that cannot be explained by this model. For example, eight co-occurring endemic plant taxa with ranges from New York to South Carolina exhibit a large disjunction separating northern and southern populations by >300 km. Pyxidanthera (Diapensiaceae), a plant genus that exhibits this pattern, consists of two taxa recognized as either species or varieties. We investigated the taxonomy and phylogeography of Pyxidanthera using morphological data, cpDNA sequences, and amplified fragment length polymorphism markers. Morphological characters thought to be important in distinguishing Pyxidanthera barbulata and P. brevifolia demonstrate substantial overlap with no clear discontinuities. Genetic differentiation is minimal and diversity estimates for northern and southern populations of Pxyidanthera are similar, with no decrease in rare alleles in northern populations. In addition, the northern populations harbour several unique cpDNA haplotypes. Pyxidanthera appears to consist of one morphologically variable species that persisted in or near its present range at least through the latter Pleistocene, while the vicariance of the northern and southern populations may be comparatively recent. This work demonstrates that the refugial paradigm is not always appropriate and GACP endemic plants, in particular, may exhibit phylogeographical patterns qualitatively different from those of other ENA plant species.
17 citations
TL;DR: Morphological and ecological studies of seven populations ofPyxidanthera barbulata Michx.
Abstract: Morphological and ecological studies of seven populations ofPyxidanthera barbulata Michx. in North and South Carolina indicate that the variation among populations is clinal and associated with differences in soil moisture retaining capacity and other environmental parameters. Breeding experiments show that the morphologically extreme populations are interfertile.Pyxidanthera brevifolia Wells (=P. barbulata var.brevifolia (Wells) Ahles) is therefore rejected as a later taxonomic synonym. An evolutionary history of the genus is proposed.
10 citations
TL;DR: It is proposed that the two endemic species of the longleaf pine-wiregrass ecosystem of the southeastern USA may be remnants from a past vegetation assemblage that experienced less frequent fire and thus may be adapted to longer fire-return intervals compared to other species currently in the ecosystem.
Abstract: Fire can have dramatic effects on the vital rates of plant species and has been used successfully for management in a number of ecosystems. However, the demographic response of species to fire in fire-dependent ecosystems is variable, making it important to study the effects of fire on rare and threatened species. We quantified the effects of fire on Astragalus michauxii and Pyxidanthera brevifolia, two rare endemics of the longleaf pine-wiregrass ecosystem of the southeastern USA, by means of periodic matrix models to project the effect of fire frequency on population growth. In contrast to many species in the longleaf pine-wiregrass ecosystem, fire had short-term negative effects on both species, causing reductions in survival, size, flowering, and fruit production. Relative to the three-year fire intervals to which the study populations are currently exposed, more frequent burning is projected to cause population decline, with the most dramatic effects under annual burning. Although the current longleaf pine-wiregrass ecosystem is fire dependent and has experienced frequent fire for at least several thousand years, we propose that the two endemic species may be remnants from a past vegetation assemblage that experienced less frequent fire and thus may be adapted to longer fire-return intervals compared to other species currently in the ecosystem. Despite the short-term negative effects of fire on the vital rates of these species, longer-term benefits such as reduction of woody encroachment and litter removal may be important for the ultimate success of the species.
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2012 | 1 |
| 2010 | 1 |
| 1975 | 1 |