Susan Swensen | Ithaca College (original) (raw)

Papers by Susan Swensen

Frontiers in plant science, Jan 25, 2024

Introduction: Scaevola taccada and Scaevola plumieri co-occur on shorelines of the Caribbean. Sca... more Introduction: Scaevola taccada and Scaevola plumieri co-occur on shorelines of the Caribbean. Scaevola taccada is introduced in this habitat and directly competes with native dune vegetation, including S. plumieri, a species listed as locally endangered and threatened in Caribbean locations. This study addresses whether the invasive S. taccada also impacts the native S. plumieri indirectly by competing for pollinators and represents the first comparative study of insect visitation between these species. Methods: Insect visitation rates were measured at sites where species co-occur and where only the native occurs. Where species cooccur, insect visitors were captured, identified and analyzed for the pollen they carry. Pollen found on open-pollinated flowers was analyzed to assess pollen movement between the two species. We also compared floral nectar from each species by measuring volume, sugar content, and presence and proportions of amine group containing constituents (AGCCs). Results: Our results demonstrate that both species share insect visitors providing the context for possible pollinator competition, yet significant differences in visitation frequency were not found. We found evidence of asymmetrical heterospecific pollen deposition in the native species, suggesting a possible reproductive impact. Insect visitation rates for the native were not significantly different between invaded and uninvaded sites, suggesting that the invasive S. taccada does not limit pollinator visits to S. plumieri. Comparisons of nectar rewards from the invasive and the native reveal similar volumes and sugar concentrations, but significant differences in some amine group containing constituents that may enhance pollinator attraction. Conclusion: Our analysis finds no evidence for pollination competition and therefore S. taccada's main impacts on S. plumieri are through competitive displacement and possibly through reproductive impacts as a consequence of heterospecific pollen deposition.

Conservation Biology, Apr 1, 1995

Isozyme, randomly amplified polymorphic DNA, and ribosomal DNA analyses were used to evaluate the... more Isozyme, randomly amplified polymorphic DNA, and ribosomal DNA analyses were used to evaluate the genetic distinctness and diversity of the endangered island endemic Malacothamnus fasciculatus var. nesioticus (Santa Cruz Island bush mallow). Analysis of amplified DNA profiles and electrophoretic data indicates that var. nesioticus is genetically distinct from other varieties within the species, No isozyme or amplified DNA variation was detected among individuals of nesioticus populations, but restriction site analysis of ribosomal DNA revealed the presence of three closely related genotypes within one of the nesioticus populations. Apparent clonal structuring was found in both nesioticus populations and in one mainland population, var. nuttallii. Results from these analyses provide the background necessay for the design of consmation efforts with recovey goals that insure the long-term survival of Malacothamnus fasciculatus var. nesioticus. Anilisis genetic0 de Malacothamnus fasciculatus (Nutt.) Greene var. nesioticus (Rob.) Kearn. (Malvaceae), una especie endernica a islas y en peligro de extincion Resumen: Se zcsaron datos de isoenzimas, perfiles depolimorfismos de ADN amplificados a1 azary analisis de ADN ribozomico para evaluar la singularidad y diversidad genetica de Malacothamnus fasciculatus vat nesioticus, una especie endemica en islas y enpeligro de extincion. El analisis deperfiles de ADN amplificados y datos electrofore'ticos indican que la variedad nesioticus es geneticamente distinta de otras variedades dentro de la misma especie. No se encontro ninguna variation de isoenzimas o ADiV amplificado entre 10s individuos de una misma poblacion de nesioticus, pero el analisis de enzimas de restriccion de iiDN ribozomico revelo lapresencia de tres genotipos estrechamente relacionados dentro de una de las poblaciones de nesioticus. Se encontro una estructuracion clonal aparente tanto en poblaciones de nesioticus como en una poblacion continental correspondiente a la variedad nuttallii. Los resultados de estos analisis proporcionan la infomzacion necesaria para disenar 10s esfuerzos de conservation con metas a la recuperacidn que aseguren la supewivencia a largo plazo de Malacothamnus fasciculatus var. nesioticus.

American Journal of Botany, Nov 1, 1996

According to morphologically based classification systems, actinorhizal plants, engaged in nitrog... more According to morphologically based classification systems, actinorhizal plants, engaged in nitrogen-fixing symbioses with Frankia bacteria, are considered to be only distantly related. However, recent phylogenetic analyses of seed plants based on chloroplast rbcL gene sequences have suggested closer relationships among actinorhizal plants. A more thorough sampling of chloroplast rbcL gene sequences from actinorhizal plants and their nonsymbiotic close relatives was conducted in an effort to better understand the phylogenetic relationships of these plants, and ultimately, to assess the homology of the different actinorhizal symbioses. Sequence data from 70 taxa were analyzed using parsimony analysis. Strict consensus trees based on 24 equally parsimonious trees revealed evolutionary divergence between groups of actinorhizal species suggesting that not all symbioses are homologous. The arrangement of actinorhizal species, interspersed with nonactinorhizal taxa, is suggestive of multiple origins of the actinorhizal symbiosis. Morphological and anatomical characteristics of nodules from different actinorhizal hosts were mapped onto the rbcL-based consensus tree to further assess homology among rbcL-based actinorhizal groups. The morphological and anatomical features provide additional support for the rbcL-based groupings, and thus, together, suggest that actinorhizal symbioses have originated more than once in evolutionary history.

Edinburgh Journal of Botany, Aug 18, 2022

A new cane-like begonia species, Begonia embera Jara & D.Franco, is described and illustrated. Mo... more A new cane-like begonia species, Begonia embera Jara & D.Franco, is described and illustrated. Morphological and molecular evidence suggest that it belongs to Begonia sect. Ruizopavonia. This species has been collected only in the Chocó Department, Colombia, growing by streams that flow into the Atrato river. We discuss its phylogenetic relationships, provide illustrations, and present the findings of an assessment of its conservation status.

Springer eBooks, Oct 5, 2007

Systematic Botany, Apr 1, 1998

... Revisited: Monophyly and the Sequence of Breeding System Evolution Susan M. Swensen1, Jennife... more ... Revisited: Monophyly and the Sequence of Breeding System Evolution Susan M. Swensen1, Jennifer N. Luthi, and Loren H. Rieseberg ... with organismal phylogeny and thus may lead to inaccurate biological conclusions (Avise 1989; Rieseberg and Soleis 1991; Doyle 1992). ...

American Journal of Botany, Jun 1, 2004

Kew Bulletin, 1997

Page 1. Taxonomic affinities of Medusagyne oppositifolia (Medusagynaceae) MICHAEL F. FAY', S... more Page 1. Taxonomic affinities of Medusagyne oppositifolia (Medusagynaceae) MICHAEL F. FAY', SUSAN M. SWENSEN2 & MARK W. CHASE Summary: Medusagyne oppositifolia Baker is the sole member of Medusagynaceae Engl. ...

Systematic Botany, Oct 1, 1996

Kew Bulletin, 2002

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact

Systematic Botany, Apr 1, 2006

Carolina Digital Repository (University of North Carolina at Chapel Hill), 1993

We present the results of two exploratory parsimony analyses of DNA sequences from 475 and 499 sp... more We present the results of two exploratory parsimony analyses of DNA sequences from 475 and 499 species of seed plants, respectively, representing all major taxonomic groups. The data are exclusively from the chloroplast gene rbcL, which codes for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO or RuBPCase). We used two different state-transformation assumptions resulting in two sets of cladograms: (i) equal-weighting for the 499-taxon analysis; and (ii) a procedure that differentially weights transversions over transitions within characters and codon positions among characters for the 475-taxon analysis. The degree of congruence between these results and other molecular, as well as morphological, cladistic studies indicates that rbcL sequence variation contains historical evidence appropriate for phylogenetic analysis at this taxonomic level of sampling. Because the topologies presented are necessarily approximate and cannot be evaluated adequately for internal support, these results should be assessed from the perspective of their predictive value and used to direct future studies, both molecular and morphological. In both analyses, the three genera of Gnetales are placed together as the sister group of the flowering plants, and the anomalous aquatic Ceratophyllum (Ceratophyllaceae) is sister to all other flowering plants. Several major lineages identified correspond well with at least some recent taxonomic schemes for angiosperms, particularly those of Dahlgren and Thorne. The basalmost clades within the angiosperms are orders of the apparently polyphyletic subclass Magnoliidae sensu Cronquist. The most conspicuous feature of the topology is that the major division is not monocot versus dicot, but rather one correlated with general pollen type: uniaperturate versus triaperturate. The Dilleniidae and Hamamelidae are the only subclasses that are grossly polyphyletic; an examination of the latter is presented as an example of the use of these broad analyses to focus more restricted studies. A broadly circumscribed Rosidae is paraphyletic to Asteridae and Dilleniidae. Subclass Caryophyllidae is monophyletic and derived from within Rosidae in the 475-taxon analysis but is sister to a group composed of broadly delineated Asteridae and Rosidae in the 499-taxon study.

Scaevola plumieri (Goodeniaceae), a species of coastal shrub, is native to the Caribbean Islands,... more Scaevola plumieri (Goodeniaceae), a species of coastal shrub, is native to the Caribbean Islands, Florida, and South Africa. Scaevola taccada, a congener native to the Indopacific, was introduced to the Caribbean in the 1970s and was first recorded in Vieques, Puerto Rico in 2002 (Breckon, 2007). S. taccada has been reported to encroach upon and displace S. plumieri and other native species in the Bahamas and the Cayman Islands. S. plumieri is now listed as critically endangered in many Caribbean locations, like the Cayman Islands, and considered threatened in other locations (Cottam, 2009).

Edinburgh Journal of Botany

Sustainability: The Journal of Record, 2010

Different approaches to delivering sustainability education are being employed at colleges and un... more Different approaches to delivering sustainability education are being employed at colleges and universities across the United States and Canada. For the 2009 Greening the Campus VIII conference, co-sponsored by Ball State and the Association for the Advancement of Sustainability in Higher Education (AASHE), Ithaca College representatives assembled a panel of faculty from different institutions to discuss differing approaches to sustainability education. These experienced educators also expressed their thoughts about how the emerging academic discipline of sustainability may help to better prepare future leaders to tackle global-scale challenges. Following that presentation, these educators reflected further on a number of the questions addressed by panelists during the presentation. Their insights are shared below.