RUI: The Meaning of Morphology: Source Hierarchy for Phenotypic Variation of Skeletal Hard Parts (Bryozoa)

Appalachian State University, Boone NC

Investigators

Abstract

The Meaning of Morphology: Source Hierarchy of Phenotypic Variation of Skeletal Hard Parts (Bryozoa) Steven J. Hageman EAR-0073648 Criteria for the recognition of fossil species are based largely on preservable hard parts of the ancient organism. This is in contrast to the classification of living species, which in addition to skeletal hard parts, may include data from their soft tissue, behavior, biochemical and genetic composition. Uncertainty about the relationships between genetic characteristics of an organism relative to its morphological characteristics can raise questions about the biological significance of fossil species. Because paleontology had the ability to document change through deep time, it has a significant contribution to make toward answering fundamental questions of evolutionary biology. These can not be addressed with confidence however, until we can document the relative importance of the genetic versus environmental components of variation in the skeletal hard parts of organisms. In addition, little is known about how differences in the scale and magnitude of environmental variation may affect skeletal hard part morphologies (i.e., microscale spatial variation within an environmental setting could induce more morphological change than between two similar settings many kilometers apart, or vice versa). By measuring features on the skeleton of modern colonial marine invertebrate organisms (Bryozoa) that are grown as clonal replicates in controlled laboratory experiments, the variation in the skeletal hard parts can be separated mathematically into their genetic and environmental sources. This is a natural system analogous to cloning hundreds of sheep and growing sets of identical clones in different environments to determine the environment's influence on their final morphology. Researchers at Gatty Marine Laboratory, Scotland have already grown clonal replicates of genetically different colonies of the intertidal bryozoan Electra pilosa under several controlled environmental conditions. This project will separate genetic from environmental variation in these specimens. In the second part of this study, specimens will be collected from the wild from environments that have been hierarchically subdivided in order to determine whether signals can be differentiated in a real world example. Results from this study will have broader applicability to the fields of evolutionary biology, biostratigraphy, biogeography, and relationships among fossil lineages.