Assessing the Climate Change Vulnerability of Ecosystem Types of the Southwestern U.S.

Climate change is challenging scientists and decision-makers to understand the complexities of climate change and to predict the related effects at scales relevant to environmental policy and the management of ecosystem services. Extraordinary change in climate, and the ensuing impacts to ecosystem services, are widely anticipated for the southwestern United States. Predicting the vulnerability of Southwest ecosystems and their components has been a priority of natural resource organizations over the past decade. Supplementing vulnerability assessments in the region with geospatial inputs of high thematic and spatial detail has become vital for supporting local analyses, planning, and decisions. In this context has come the opportunity to build upon a framework of major ecosystem types of the Southwest and to assess vulnerability to climate change for each type. Herein are presented three studies that set the backdrop for vulnerability assessment, detail a novel correlative modeling procedure to predict the location and the magnitude of vulnerability to familiar vegetation patterns, and then explore applications of the resulting geospatial vulnerability surface: 1) considerations for evaluating or designing a vulnerability assessment; 2) an overview of the vegetation and climate of major ecosystem types, and 3) a climate change vulnerability assessment for all major ecosystem types of the Southwest. This work has resulted in a regionwide vulnerability surface of greater extent and higher spatial and thematic resolution than previous modeling efforts, giving local managers information on the location and degree of climate risk to vegetation resources

Heteromorphisme floral chez <i>Dais cotinifolia</i> L. (<i>Thymelaeaceae</i>) : un cas possible d'hétérophyllie.

Un hétéromorphisme floral est signalé chez Dais cotinifolia L. (Thymelaeaceae), associé une suite inhabituelle de caractères secondaires. Les styles des fleurs apétales présentent trois morphologies différentes. Dans la forme style moyen, les étamines du verticille supérieur sont de longueurs moyennes plutôt que longues, comme celles d\u27autres espèces tristyles. La morphologie des papilles stigmatiques ainsi que l\u27ornementation du pollen varient entre les trois formes de style, mais la taille du pollen reste constante. Le périanthe de la forme style moyen est notamment plus court que chez les formes style long ou court. Cette suite inhabituelle de caractères dans une espèce apparemment tristyle élargit la gamme d\u27hétéromorphisme floral actuellement acceptée. Il est aussi évident qu\u27une étude plus complète est souhaitable pour les Thymelaeaceae tropicales (ainsi que pour l\u27ensemble des angiospermes tropicaux).Floral heteromorphism is reported in Dais cotinifolia L. (Thymelaeaceae) and is associated with an unusual array of ancillary features. The apetalous flowers have three different style morphologies. The upper whorl of stamens in the mid style morph are mid-length, instead of having a whorl of long stamens, as in other tristylous species. There are differences in the morphology of the stigmatic papillae and pollen sculpturing among the three style morphs, however, there is no difference in pollen size. The perianth in the mid style morph is significantly shorter than the perianth in the short and long style morphs. This unusual array of features in what appears to be a tristylous species suggest that floral heteromorphism may be more variable than previously thought. It is also apparent that a more complete survey of tropical Thymelaeaceae (and tropical angiosperms in general) for floral heteromorphism is needed

Comparative Pollen Morphology of Brachylena, Tarchananthus and Two Species of Tubulifloridites (Asteraceae) From the Eocene, Knysna Lignite of South Africa

Two fossil taxa Tubulifloridites antipodica and T. viteauensis recovered from the Eocene Knysna Lignite of South Africa were examined with scanning (SEM) and transmission electron microscopy (TEM). The details of their sculpturing and wall structure are similar to the same species of fossil dispersed pollen taxa recovered from southwestern Africa and South America. Fifteen species of the woody South African taxa, Brachylaena (9 species) and Tarchonanthus (6 species) were investigated with SEM and TEM. All of the taxa are tricolporate, spherical to slightly prolate, microechinate to echinate and have a bilayered columellate infrastructure, except B. ilicifolia, which has a single columellate infrastructural level with the granularization of the outer portion of the infrastructural layer or the inner layer of the tectum. There is a similar distribution of plesiomorphic and derived pollen characters in a number of aster subfamilies and tribes suggesting a similar evolutionary progression of pollen, and pollen wall character evolution was occurring synchronously in a variety of aster subfamilies during the middle Tertiary and that these unique pollen features may be important to the evolution and diversification of the Asteraceae

Leaf Anatomy of Orcuttieae (Poaceae: Chloridoideae): More Evidence of C 4 Photosynthesis without Kranz Anatomy

Volume: 55Start Page: 143End Page: 15

Sphaeromeria, a genus closer to Artemisia than to Tanacetum (Asteraceae: Anthemideae)

A new species,Sphaeromeria ruthiae, from Zion National Park, and three new combinations,S. martirensis,S. compacta, andS. potentilloides var.nitrophila, are presented. Morphological and anatomical evidence is used to support the recognition ofSphaeromeria as distinct fromTanacetum

Genetic diversity in Asteraceae endemic to oceanic islands: Baker’s Law and polyploidy

When considering the two factors ploidy and breeding system of ancestral colonizers together from the fi ve archipelagos, two things are most evident. First, the Canary Islands are exceptional because of the frequency of diploid colonizers compared to the other island groups. The hypothesis advanced to explain this is the much closer proximity of the Canaries to a continental source area than the other island systems; thus, multiple early introductions may have reduced the selective advantage of the greater genetic diversity aff orded the single polyploid propagules dispersed to more remote archipelagos. The other notable observation is the greater frequencyof SC ancestors for Hawaii relative to the other island systems. It is tempting to suggest that the higher frequency of SC colonizers in Hawaii is due to the greater distance to source areas; however, the most spectacular radiation in Hawaii, the silversword alliance, originated from SI or PSF ancestors. An equally large radiation in Hawaii, but perhaps not as spectacular in terms of ecological and morphological diversity as the silverswords, is Bidens where the thirty species originated from a SC ancestor. Bidens in Hawaii is a high polyploid, so a single ancestor colonist could have carried extensive diversity to the island. Although species of Bidens are SC, there has been evolution of sexual expression in the lineage, including factors that promote outcrossing, with the net result that species exhibit a mixed mating system. One of the lineages that seems to “break the rules” for Hawaii, and indeed for the other four archipelagos, is Tetramolopium. The colonizing ancestor of this ecologically and morphologically diverse lineage was both SC and diploid . The progenitor of Hawaiian Tetramolopium is from New Guinea and possible dispersal mechanisms are birds and wind; the pappus and glandular trichomes on the fruits could facilitate adherence to the feathers and feet of birds. Though highly speculative, it is suggested that there may have been multiple fruits in a single dispersal event, and Tetramolopium evolved from more than a single colonizer. Tetramolopium is an illustration of the limitation of attempting to interpret the genetic diversity of colonizers with only two variables of ploidy and breeding system. While the dispersal agent of Asteraceae isnormally the individual fruit, this does not mean that single dispersal events involve only one fruit, as was admitted by Baker (1967). However, an important point with regard to Tetramolopium, and other lineages originating from SC colonizers, is that if a single dispersalevent included more than one fruit from the same selfi ng population, then the multiple fruits may not collectively contain signifi cantly more genetic diversity than a single fruit. In contrast to multiple propagules from selfi ng source populations, dispersal of multiple fruits in a single event from an outcrossing source population would enhance genetic diversity in a founding population relative to a single propagule. This may explain why the colonizing ancestors of so many island lineages were SI (or more likely PSF) regardless of whether there was one or multiple propagules in a single dispersal event. Despite the limitations of considering only the two variables of ploidy and breedingsystem, observations for the fi ve archipelagos show that both polyploidy and SI accompanied by PSF are common attributes of successful lineages. It seems reasonable to hypothesize that these two factors, both alone or in concert, provide colonizers with the requisite diversity necessaryfor radiation and speciation in an archipelago. There are plausible hypotheses to explain the two notable exceptions to the above generalizations, the paucity of polyploidy in the Canary Islands and SC colonizers in Hawaii.Fil: Crawford, Daniel J.. University of Kansas; Estados UnidosFil: Lowrey, Timothy K.. University of California; Estados UnidosFil: Anderson, Gregory J.. University of Connecticut; Estados UnidosFil: Bernardello, Gabriel Luis Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Santos-Guerra, Arnoldo. Jardín Botánico de Puerto de la Cruz; EspañaFil: Stuessy, Tod F.. University of Texas at Austin; Estados Unido