Multiphasic Allometric Analyses of the Felidae: Addressing Variation and Covariation in Endangered and Extinct Populations

Biological studies require consideration of variation and covariation within populations. Allometry is the covariation of shape change accompanying size change. While allometric relationships have been studied intensively for nearly a century, most of them have only been examined with monophasic regression equations. Increasing sizes of museum collections and improved computer power allow for higher resolution analyses of allometric analyses that can account for different allometric relationships in different size ranges within the same populations. Referred to as multiphasic allometric relationships, these complex allometries are used in this dissertation to examine broad-scale evolutionary patterns, small-scale species comparisons, and single-species life history.;In Chapter 2, I determined the relative frequency of different types of allometric change over evolutionary time. Strong theoretical arguments have been made that the incidence of slope change should be less frequent than the incidence of elevation shift, which in turn should be less frequent than elongation or truncation of an allometric relationship (shift along slope). However, few studies have analyzed allometric patterns across related species to determine if these frequency expectations are borne out. Comparison of the frequencies of these different types of allometric change indicates that these assumptions are met with 38-45% of comparisons showing slope change, 70-75% of comparisons showing elevation shift, and 87-91% showing shift along slope. Slope changes showed a strong correlation with phylogenetic distance (Spearman rs, and Kendall's τ exhibit p<0.001 for all analyses), indicating that more distantly related taxa are more likely to have altered the slopes of their allometric relationships. Neither elevation shift nor shift along slope showed such robust correlations, indicating that such changes are so common at this time scale that reversals swamp the phylogenetic signal. Multiphasic allometric analyses did not yield different results from traditional monophasic analyses in these studies. Sampling may not have been intense enough to provide the resolution needed to discern multiphasic relationships in many of the taxa. Only 20% of measurements exhibited multiphasic relationships, primarily in the best sampled and least damaged taxa.;In Chapter 3, species status of a fossil taxon was examined using multiphasic allometric analyses. The American Lion is a taxon found in the Americas that has been variably described as its own species (P. atrox) or a subspecies of the modern lion (P. l. atrox). Several cranial and mandibular characteristics have been used to argue for species status of this specimen, but no examination of the differences between modern lions and American Lions accounts for the larger size of the American Lion. Multiphasic allometric analyses found that most of the characters differentiated as described. However, braincase width and facial length did not exhibit differences independent of the change in body size, invalidating their use as arguments for species status. Orbit size may exhibit too much non-allometric variation to be informative.;In Chapter 4, patterns of growth discovered by multiphasic allometric analyses are linked to life history in extant P. leo. Braincase width in subadult lions exhibited an increase in allometric slope at 15-17 months, shortly before forcible eviction from their natal pride. The differences between these slopes were significant (Fs; p<0.005 for all). This late increase in braincase width is interpreted as a girding of the origination sites of the temporalis muscles to enhance bite strength. Eviction from the natal pride means that they will be hunting without the aid of adults. Subadults also have to defend themselves during the eviction from conspecific attacks. Increased bite strength anticipating this hostility allows a greater chance of survival during this time of high mortality. Interestingly, males experience greater hostility during this period than females and exhibit rate hypermorphosis to attain larger size while maintaining the same allometric growth pattern. (Abstract shortened by UMI.).