The "law of constant extinction," proposed by Van Valen, states that long and short-lived taxa have equal chances of going extinct. This pattern of age-independent extinction was originally inferred using the fossil record of several different taxa and relied on survivorship curves built from the literal reading of the fossil record. Van Valen's seminal work was mostly done at higher taxonomic levels, hence its prevalence at the species level could not be directly inferred. The surprisingly few subsequent studies done at the species level have challenged the prevalence of age-independent extinction, but those have, for the most part, failed to explicitly incorporate inherent biases of the fossil record. Using a recent Bayesian framework that accounts for several of those biases, including the fact that very short-living lineages might never make to the record itself, we showed that Ruminantia species present age-dependent extinction, where extinction probability decreases with species age. An analysis at the genus level suggested ageindependent extinction but further examination suggested that the pattern might be more complex than previously reported by Van Valen. Our results indicate that different taxonomic levels may present different extinction regimes, which could justify the development of new macroevolutionary theory and methods.
Simulations are powerful tools for investigating evolutionary questions. Statistical methods for the analysis of diversification and fossil sampling rates require extensive testing through simulation. Simulations also aid in the investigation of evolutionary dynamics that lack analytical solutions, besides model adequacy tests. Flexible simulation of fossil records and phylogenies is a necessary tool to fully investigate diversity through time.
paleobuddy is an R package that aims to fill several gaps between current simulators by providing a more general framework, with flexible, robust and independent simulations of birth–death processes, fossil records and phylogenetic trees, while allowing for straightforward implementation of novel scenarios.
Here we describe the main algorithms involved in paleobuddy simulations, give a summary of the capabilities of the package in terms of evolutionary scenarios and visualization and illustrate a paleobuddy workflow.
paleobuddy expands the available parameter space to investigate complex inference models. Given that it allows for simulations of phylogenies (complete, reconstructed or ultrametric) and fossil records from the same underlying birth–death simulations, it can increase our understanding about the differences in palaeontological and neontological approaches, and consequently expand our capacity of analysing a combination of evidence from extinct and extant species. Finally, the focus on birth–death simulations with budding speciation events allows for more generality in the diversification processes considered, expanding the flexibility and capabilities of simulation in the field.
O presente trabalho se propõe a verificar de que modo a orientação de uma edificação rural influe na carga térmica radiante (radiação solar) interceptada pela mesma. Duas situações freqüentemente encontradas na prática são examinadas: a orientação Norte-Sul e a Leste-Oeste. Para determinar a carga térmica radiante, de importância nos problemas deventilação e refrigeração, é adotado um modelo de construção a título de exemplo, sendo que as relações aqui propostas são aplicáveis a qualquer modelo de construção desejado. Os resultados mostraram quea carga térmica radiante da exposição Leste-Oeste chega a ser 74% da carga na exposição Norte-Sul.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.