Kylie Bucalo

Date of Award

2016

Type

Thesis

Major

Master of Science

Department

Biology

Abstract

DNA barcoding is a molecular based technique used to separate and identify individual species. Here we establish a DNA Barcode library for the orchid flora of an Andean cloud forest in Northwestern Ecuador. The library contains 135 matK and 136 rbcL DNA Barcodes representing over 33 Orchidaceae genera. Sequence analysis shows percent species resolution was higher for matK (98.8%) than rbcL (70.24%), with a large portion of the unresolved species for the rbcL loci coming from taxonomically complex genera in the subtribe Pleurothallidinae. Neighbor Joining (NJ) trees revealed that the orchid flora of Siempre Verde is divided taxonomically into two large monophyletic clades at the sub family level; Orchidoideae and Epidendroideae. Sequences within Orchidoideae presented with high bootstrap support across all NJ trees (matK, rbcL and matK+rbcL), indicating species within the clade are well resolved. Resolution for sequences within sub family Epidendroideae varied depending on taxonomic clade and loci used. Overall the matK NJ tree outperformed the rbcL NJ tree by delivering monophyletic clades at the subfamily, tribe, and subtribe level with higher bootstrap values, separating a higher number of congeners, particularly those in taxonomically complex genera such as Pleurothallis, Stelis, and Lepanthes. Estimates of evolutionary divergence showed a very low level of intraspecific variation in DNA Barcodes of target cryptic species Oncidium heteranthum, acknowledging that floral traits in Oncidium are often highly plastic, and not indicative of species lines.

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