Biodiversity and biogeography of marine green algae of the Republic of Panama

Increases in known green algal diversity of over 150% are documented for both the Caribbean and Pacific green algal floras of the Republic of Panama. The increase in diversity is attributed to historical understudy, the use of SCUBA diving to access subtidal zones and to making collections over an extended period of time across diverse habitats. The Caribbean green algal flora harbors greater diversity than the Pacific flora at nearly all taxonomic levels. Species diversity was nearly two-fold greater on the Caribbean shore, but most of this discrepancy was represented by a single family of green algae that inhabit sandy environments which are far less common on the Pacific coast. Approximately 14% of the green algal flora is common to both coasts.; An intraspecific phylogenetic study of one such species, Phyllodictyon anastomosans (Harvey) Kraft et M. J. Wynne, based on ITS rDNA sequences revealed an historical imprint related to the emergence of the Central American Isthmus 3.5–3.1 Ma. The underlying vicariant pattern was obscured by numerous instances of recent trans-oceanic and trans-isthmian dispersal and one instance of an historical dispersal event that may have occurred via a putative shallow water breach of the isthmus approximately 2.3–2.0 Ma. DNA sequences also provided an independent evaluation of species concepts which were shown to be ambiguous. The lack of obvious morphological characters and the overlap of morphological character states among all taxa used in the study confirmed previous work indicating that species and generic boundaries among Boodlea, Phyllodictyon, Cladophoropsis and Struveopsis are poorly defined.; In a follow-up investigation using sequences of the more highly conserved SSU rDNA, poor species, genus and even family boundaries among these genera and others in the Cladophorales-Siphonocladales complex were confirmed. Numerous cases of generic and familial non-monophyly support the recognition of a single family, the Cladophoraceae, in a monotypic order, Cladophorales.; Finally, a molecular systematic treatment of the genus Caulerpa provided the opportunity to evaluate a intra-generic diversity in another Order of green algae using an alternative molecular marker, tufA. Morphological taxonomic concepts were not necessarily concordant with phylogenetic concepts as inferred from comparative DNA sequence analyses in Caulerpa or any of the green algae considered in these studies. All together my dissertation research has revealed an extraordinarily rich marine flora in a poorly studied area that underscores the importance of thorough taxonomic treatments for assessing evolutionary and biogeographic patterns in marine macroalgae.