Sökning: "macroevolution"
Hittade 5 avhandlingar innehållade ordet macroevolution.
1. 100 million years of shark macroevolution : A morphometric dive into tooth shape diversity
Sammanfattning : Few vertebrate clades exhibit the evolutionary longevity and versatility of sharks, which constitute nearly half of all current chondrichthyan biodiversity and represent an ecological diversity of mid-to-apex trophic-level predators in both marine and freshwater environments. The rich fossil record of shark teeth from Mesozoic and Cenozoic rocks also makes the group amenable to large-scale quantitative analyses. LÄS MER
2. Stochastic Models in Phylogenetic Comparative Methods: Analytical Properties and Parameter Estimation
Sammanfattning : Phylogenetic comparative methods are well established tools for using inter-species variation to analyse phenotypic evolution and adaptation. They are generally hampered, however, by predominantly univariate approaches and failure to include uncertainty and measurement error in the phylogeny as well as the measured traits. LÄS MER
3. The tempo and mode of evolution : a neontological reappraisal
Sammanfattning : The theory of “punctuated equilibrium” suggests that species evolve rapidly during or immediately upon speciation, “punctuating” long periods of little or no morphological evolution. Here I confirm that body size differences within clades of birds and mammals are best explained using a model of punctuated evolution. LÄS MER
4. Phylogeny and macroevolution in Isoetes (Isoetales)
Sammanfattning : This thesis has focused on the evolutionary history of Isoetes (Isoetales, Lycopsida), its phylogeny, megaspore morphology and evolutionary path through deep time. With a broadened sampling of species to include more of the worldwide diversity of the genus compared to previous work an unexpected sister to the rest of the genus was found. LÄS MER
5. Unlocking the hidden diversity of organic-walled microfossils from the early Cambrian of North Greenland
Sammanfattning : The early Cambrian Buen Formation of North Greenland is celebrated for hosting one of the oldest Cambrian Burgess Shale-type deposits known to date – the Sirius Passet Lagerstätte. Further south in a shallower shelf facies belt, the Buen Formation yielded organic-walled microfossils (OWMs) that were originally described with a focus on acritarchs. LÄS MER