Abstract Detail



Evolution, ecology, development, and conservation of carnivorous plants

Naczi, Robert [1].

Systematics and Biogeography of the Western Hemisphere Pitcher Plants (Sarraceniaceae).

The Sarraceniaceae include 35 species of pitcher plants native to portions of North America and northeastern South America.  Three genera comprise the family: Darlingtonia (1 sp.) of southwestern Oregon and northern California, Heliamphora (23 spp.) of the Guayana Highlands of Venezuela, Guyana, and Brazil, and Sarracenia (11 spp.) of eastern U.S.A. and Canada.  Mirroring these geographic disjunctions, the genera are sharply divergent morphologically, chromosomally, and molecularly.  In contrast, species within Heliamphora and Sarracenia are incompletely resolved and their relationships are poorly understood, despite several molecular phylogenetic analyses.  Divergence time estimates indicate speciation in these genera has been relatively recent.  Formidable obstacles stymie efforts to resolve phylogenetic relationships of the species and to reconstruct the biogeographic history of the genera and species.  Fossils are lacking, many of the morphologic characters (especially of pitchers) are unique to the family, few morphologic characters separate the species, interspecific hybridization is frequent, and little interspecific DNA sequence divergence exists.  Ongoing exploration for new morphologic characters has yielded important discoveries for phylogenetic analysis.  Though useful characters are few, these characters diagnose relationships among species in both Heliamphora and Sarracenia.  For example, in Heliamphora, morphology supports a clade comprised of H. collina, H. elongata, H. folliculata, H. heterodoxa, H. nutans, and H. purpurascens.  In Sarracenia, morphologic characters support S. purpurea and S. rosea as sister to the rest of Sarracenia.  In addition, morphologic characters place S. flava in a clade with S. minor.  Molecular phylogenies are contradictory for some of these relationships.  For biogeography, important evidence comes from pitcher-dwelling symbiotic mites of the genus Sarraceniopus (Histiostomatidae).  Relevant properties of the symbiosis include restriction of Sarraceniopus to Sarraceniaceae, presence of mites in all species of Darlingtonia and Sarracenia as well as all sampled species of Heliamphora, and relatively high host-specificity.  Because these mites have thin exoskeletons and desiccate relatively rapidly when they are outside of pitchers, they indicate vicariance is much more likely than long-distance dispersal in accounting for disjunctions among genera of Sarraceniaceae.


1 - The New York Botanical Garden, 2900 Southern Blvd., Bronx, NY, 10458-5126, USA

Keywords:
Sarraceniaceae
Darlingtonia
Heliamphora
Sarracenia.

Presentation Type: Colloquium Presentations
Number:
Abstract ID:653
Candidate for Awards:None


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