Abstract Detail

Morphospaces, Morphometrics, and Phylogenetics

Jolles, Diana [1], Johnson, Melissa [1], Stoughton, Thomas [1], Roberts, Julian [2].

Hypothesis testing in circumscription-resistant lineages: morphometric methods for estimating patterns of floral evolution in species complexes.

Many groups of closely related taxa retain similar floral morphology long after genetic divergence has occurred, making taxonomic identification of plants difficult. However, distinguishing among these closely related taxa is critical for better understanding their past, present, and future evolutionary trajectories. In these tricky cases, morphological differences associated with genetically distinct taxa may instead be manifest in vegetative structures, but these are thought by some to be more sensitive to environmental variation and therefore less reliable. In this study, we argue that careful study of floral morphology can be used to detect subtle differences among genetic lineages, providing invaluable clues about the mechanisms of reproductive isolation near the species boundary. When genetic data are available for circumscribing distinct lineages within species complexes, careful observation and statistical analyses of floral structures can yield at least two types of information: (1) genetically structured differences in floral shape, and (2) patterns of floral morphology that might lead to hypotheses about evolutionary mechanisms of gene flow, reproductive isolation, and speciation. Using three different species complexes, we demonstrate how analyses of continuous variation in floral traits may be used to differentiate gene pools in groups with remarkably similar floral morphology. We studied the North American Pyrola picta (Ericaceae) and Claytonia lanceolata (Montiaceae) species complexes, and Pacific Island Cyrtandra (Gesneriaceae), groups for which both floral morphology and patterns of gene flow are poorly understood. Here, we demonstrate a variety of methods for extracting and statistically analyzing shape. These methods were used to characterize the subtle floral variation exhibited among taxa in each group and each finding was put into geographic and genetic context. In each case study, the interplay between floral variation and spatial aspects of gene flow are quite different. Morphometric techniques are invaluable for understanding floral variation and evolution in groups of closely related species.

1 - Rancho Santa Ana Botanic Garden, 1500 North College Avenue, Claremont, California, 91711, USA
2 - Pitzer College, 1050 North Mills Avenue, Claremont, California, 91711, USA

Keywords:
Cyrtandra
Pyrola
Claytonia
floral morphology
morphometry
species complex
speciation.

Presentation Type: Symposium Presentation
Session: SY06
Location: Salon 10/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 3:45 PM
Number: SY06006
Abstract ID:1091
Candidate for Awards:None