Article

Developmental Dynamics and G-Matrices: Can Morphometric Spaces be Used to Model Phenotypic Evolution?

Indiana University Department of Geological Sciences 1001 E 10th Street Bloomington IN 47405 USA; Indiana University Department of Biology Bloomington IN USA; Indiana University Department of Anthropology Bloomington IN USA
Evolutionary Biology (impact factor: 3.61). 04/2012; 35(2):83-96. DOI:10.1007/s11692-008-9020-0 pp.83-96

ABSTRACT Modern morphometrics, especially geometric morphometrics, is a powerful tool for modeling the evolution and development of
the phenotype. Complicated morphological transformations can be simulated by using standard evolutionary genetic equations
for processes such as selection and drift in the same morphospaces that are used for empirical morphometric studies. Such
applications appear to be consistent with the theory of quantitative evolution of the phenotype. Nevertheless, concerns exist
whether simulations of phenotypic changes directly in morphospaces is realistic because trajectories traced in such spaces
describe continuous gradations in the phenotype and because the gain and loss of structures is often impossible because morphospaces
are necessarily constructed from variables shared in common by all the phenotypes being considered. Competing models of phenotypic
change emphasize morphological discontinuity and novelty. Recently developed models of phenotypic evolution that introduce
a “phenotypic landscape” between evolutionary genetic constructs like the adaptive landscape and morphospace may correct this
shortcoming.

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    Article: A computational model of teeth and the developmental origins of morphological variation.
    Isaac Salazar-Ciudad, Jukka Jernvall
    [show abstract] [hide abstract]
    ABSTRACT: The relationship between the genotype and the phenotype, or the genotype-phenotype map, is generally approached with the tools of multivariate quantitative genetics and morphometrics. Whereas studies of development and mathematical models of development may offer new insights into the genotype-phenotype map, the challenge is to make them useful at the level of microevolution. Here we report a computational model of mammalian tooth development that combines parameters of genetic and cellular interactions to produce a three-dimensional tooth from a simple tooth primordia. We systematically tinkered with each of the model parameters to generate phenotypic variation and used geometric morphometric analyses to identify, or developmentally ordinate, parameters best explaining population-level variation of real teeth. To model the full range of developmentally possible morphologies, we used a population sample of ringed seals (Phoca hispida ladogensis). Seal dentitions show a high degree of variation, typically linked to the lack of exact occlusion. Our model suggests that despite the complexity of development and teeth, there may be a simple basis for dental variation. Changes in single parameters regulating signalling during cusp development may explain shape variation among individuals, whereas a parameter regulating epithelial growth may explain serial, tooth-to-tooth variation along the jaw. Our study provides a step towards integrating the genotype, development and the phenotype.
    Nature 03/2010; 464(7288):583-6. · 36.28 Impact Factor
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Keywords

adaptive landscape
 
Competing models
 
Complicated morphological transformations
 
concerns
 
empirical morphometric studies
 
evolutionary genetic constructs
 
geometric morphometrics
 
models
 
Modern morphometrics
 
morphological discontinuity
 
phenotype
 
phenotypes
 
phenotypic changes
 
phenotypic evolution
 
quantitative evolution
 
shortcoming
 
standard evolutionary genetic equations
 
trajectories traced
 
variables
 
“phenotypic landscape”
 

P David Polly