@inproceedings{Rohlf:2005:VPE,
| title | = | "Visualizing primate evolution: reification of a statistical model", |
| booktitle | = | "Classification Society of North
America 2005 meeting", |
| author | = | "F.
James Rohlf AND Nina
Amenta AND Eric
Delson AND David
F. Wiley AND Will
Harcourt-Smith AND Steven
Frost AND Alfred
L. Rosenberger AND Dan
A. Alcantara AND Lissa
Tallman ", |
| year | = | "2005", |
| pages | = | "62", |
| location | = | "Washington University in St. Louis", |
| eventtime | = | "June 8-12", |
| abstract | = | "Evolutionary biologists are often concerned with identifying intermediate shapes in
an evolutionary sequence or inferring, in a rigorous way, what a hypothetical ancestor
might have looked like. Consider the past 150 years during which time scientists have
pondered how the first members of the human lineage might have looked - after departing
phylogenetically from an African ape ancestor. We are developing a set of tools to address
this matter: how to mathematically constrain and visualize shape transformation based on
knowledge from phylogenetics. As a case study we examine the evolution of Old World
monkeys.
The locations of biological landmarks were identified on laser surface scans (LSS) of the
skulls of five extant species of Old World monkey (Family Cercopithecidae). In addition,
semi-landmark points were located to capture additional shape information along surfaces
between the landmarks. The locations of the semilandmark points were slightly adjusted
to minimize difierences in shape resulting from arbitrary difierences in the spacing of the
semi-landmarks. Generalized Procrustes analysis was then used to align the configurations
of landmarks and to project each specimen into a multivariate space that is tangent to
Kendall's shape space. This allows variation among shapes to be analyzed using conventional
multivariate methods. A phylogeny was imbedded in this space so that the squared
length of the implied trajectory was minimized. Points along this trajectory were then
projected back into the physical space of the organism and visualized as 3-dimensional representations
of the surfaces of hypothetical skulls which are estimates of ancestral forms
along the evolutionary trajectories. The 3-dimensional representations are produced by
warping all of the original surface scans so that their landmark points coincide with the
landmark configuration corresponding to the point of the trajectory, and then merging the
surface scans into a single surface.
These methods can also be extended to allow the visualization of shape variation implied
by other types of multivariate analysis such as multivariate multiple regression and related
methods.", |
