For centuries, biologists have been captivated by the vast disparity in species richness between different groups of organisms. Variation in diversity is widely attributed to differences between groups in how fast they speciate or go extinct. Such macroevolutionary rates have been estimated for thousands of groups and have been correlated with an incredible variety of organismal traits. Here we analyze a large collection of phylogenetic trees and fossil time series and describe a hidden generality among these seemingly idiosyncratic results: speciation and extinction rates follow a scaling law in which both depend on the age of the group in which they are measured, with the fastest rates in the youngest clades. Using a series of simulations and sensitivity analyses, we demonstrate that the time dependency is unlikely to be a result of simple statistical artifacts. As such, this time scaling is likely a genuine feature of the tree of life, hinting that the dynamics of biodiversity over deep time may be driven in part by surprisingly simple and general principles.

Evolutionary rates play a central role in connecting micro- and macroevolution. All evolutionary rate estimates, including rates of molecular evolution, trait evolution, and lineage diversification, share a similar scaling pattern with time: The highest rates are those measured over the shortest time interval. This creates a disconnect between micro- and macroevolution, although the pattern is the opposite of what some might expect: Patterns of change over short timescales predict that evolution has tremendous potential to create variation and that potential is barely tapped by macroevolution. In this review, we discuss this shared scaling pattern across evolutionary rates. We break down possible explanations for scaling into two categories, estimation error and model misspecification, and discuss how both apply to each type of rate. We also discuss the consequences of this ubiquitous pattern, which can lead to unexpected results when comparing rates over different timescales. Finally, after addressing purely statistical concerns, we explore a few possibilities for a shared unifying explanation across the three types of rates that results from a failure to fully understand and account for how biological processes scale over time. Expected final online publication date for the Annual Review of Ecology, Evolution, and Systematics, Volume 52 is November 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

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Highlights• AGB stocks of terra firme and flooded forests depend on the number of large trees• Tree species diversity is not correlated to AGB in seasonally flooded forests • Conservation of seed disperser animals enhances the conservation of AGB stocks 3 AbstractThe conservation of tropical forests has become an important mechanism for the mitigation of the negative effects of climate change. Countries located in the Neotropical region, Central and South America, are aiming to understand the drivers of carbon stocks of their forests to build a better capacity for forest management. In this study, we calculated Above Ground Biomass -AGB stocks for 32 (1ha) vegetation plots of forests classified as terra firme and seasonally flooded, and evaluated the effect of basin location, structural and environmental variables on the magnitude of AGB stocks. We report that variation among river basins results from the effects of fragmentation and soil fertility. The most important variable, determining the magnitude of AGB stocks in lowland forests in the region is the number of large trees per hectare. Seasonally flooded forests should be studied and managed separately from terra firme forests as these behave differently in the relationship between tree species diversity and AGB stocks. We found that the proportions of endozoochoric and synzoochoric tree species are important variables for the magnitude of AGB stocks in these forests. We present the first account on the drivers of AGB stocks in Northwestern South America and show that environmental characteristics of forests, such as flooding and fragmentation should be taking in to account to determine the variation on AGB stocks among forests in this region.

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Numerous phylogenetic studies reported the existence of a pervasive scaling relationship between the ages of extant eukaryotic clades and their estimated diversification rates. The causes of this age-rate-scaling (ARS), whether biological and/or artifactual, remain unresolved. Here we fit diversification models to thousands of eukaryotic time-calibrated phylogenies to explore multiple potential causes of the ARS including parameter non-identifiability, model inadequacy, biases in taxonomic practice, and an important and ubiquitous form of sampling bias-preferentially analyzing larger extant clades. We distinguish between two mechanism by which such sampling biases can cause an ARS: First, by favoring clades that happen to be unusually large merely by chance (i.e., due to the stochastic nature of the cladogenic process), thus leading to rate overestimation, and second, by favoring clades that have truly higher diversification rates. We find that, of the proposed explanations, only sampling biases are likely to contribute to the observed ARS. We develop methods for fully correcting for sampling bias mechanism 1, and find that despite these corrections a substantial ARS remains. We then confirm using simulations that preferring trees with truly higher rates (mechanism 2) likely explains this residual ARS. Since we do not have a completely unbiased sample of clades, including extinct ones, for phylogenetic analyses, it is difficult to demonstrate unambiguously that sampling biases are the sole cause of the ARS. Sampling biases are, however, a parsimonious and plausible explanation for this widely observed macroevolutionary pattern, and this has implications for how we interpret the distribution of diversification rate estimates in extant clades.

∙ Oilbirds (Steatornis caripensis) are specialized nocturnal frugivores that inhabit Neotropical forests and have the potential to play key ecological roles as seed dispersers. In this study, we focused on type and quantity of seeds dispersed by a population of Oilbirds in Cueva de Los Guácharos National Park (Colombia). We assessed temporal variation in diet composition, fruit nutrient composition and measured seed morphology. To do this, we used 5–10 seed traps in a cave from 2011 to 2016, conducting a 5‐day census 1–4 times each year. In 2015, we performed a census in all 12 months to document within year variation. We found seeds of 52 species (including 17 named species, 12 identified just to family, and 23 morphospecies). We found a clear dominance of Arecaceae and Lauraceae families. Intra‐annual variation in species richness reflects the fact that more biomass and higher seed numbers are deposited in the cave in periods of nesting (January–June), as well as during seasonal fruiting patterns in the region. Data on fruit contents from published literature indicated that oilbird diet includes a high representation of lipid‐rich fruits. Consumed seed size varied enormously (range: 0.01–5.99 g dry mass), the largest seeds being up to 29 mm wide and 54 mm long. Regurgitated seeds showed a negative allometric relationship between width and length. Overall, we found a diverse diet and that Oilbirds provide efficient seed dispersal in terms of seed quantity; however, many aspects of dispersal quality remain to be determined. Resumen ∙ Dieta de los Guácharos (Steatornis caripensis) en el parque nacional Cueva de Los Guácharos (Colombia): variación temporal en la cantidad de la dispersión y morfología de semillas Los guácharos (Steatornis caripensis) son aves nocturnas frugívoras especializadas que habitan bosques neotropicales y que tienen el potencial de desempeñar roles ecológicos claves como dispersoras de semillas. En este trabajo, estudiamos la dieta y la cantidad de semillas dispersadas por una población de guácharos en el Parque Nacional Natural Cueva de los Guácharos (Colombia). Para ello, evaluamos la variación temporal, comparamos la composición de lípidos y medimos la morfología de las semillas. De 2011 a 2016 dispusimos 5–10 trampas de semillas en la cueva principal del parque y llevamos a cabo censos de usualmente 5 días, 1–4 veces cada año. Adicionalmente, en 2015 hicimos censos mensuales durante todo el año. En la dieta de los guácharos encontramos semillas de 52 especies de plantas (incluyendo 17 especies, 12 taxones identificados hasta familia y 23 morfoespecies), en las cuales se reflejó una clara dominancia de las familias Arecaceae y Lauraceae. La variación intranual en la riqueza de especies de las semillas depositadas en la cueva mostró que en los periodos de anidación de los guácharos (enero a junio) se presentó el mayor número de semillas y la mayor biomasa, además una alta riqueza de especies en el primer semestre es coherente con los patrones de fructificación en la región. La dieta del guácharo incluyó una alta representación de frutos ricos en lípidos, lo cual fue inferido de la literatura publicada. Los tamaños de las semillas dispersadas variaron enormemente (peso seco entre 0.01 y 5.99 g), siendo las semillas más grandes de 29 mm de ancho y 54 mm de largo. Las semillas que fueron dispersadas mostraron una relación alométrica negativa entre el ancho y el largo. Aunque, nosotros reportamos que los guácharos tienen una dieta diversa y proveen una eficiente dispersión de semillas en términos de la cantidad, aún deben determinarse muchos aspectos de la calidad de la dispersión.

Abstract. Wood density, or more precisely, wood specific gravity, is an important parameter when estimating aboveground biomass, which has become a central tool for the management and conservation of forests around the world. When using biomass allometric equations for tropical forests, researchers are often required to assume phylogenetic trait conservatism, which allows us to assign genus-and family-level wood specific gravity mean values, to many woody species. The lack of information on this trait for many Neotropical plant species has led to an imprecise estimation of the biomass stored in Neotropical forests. The data presented here has information of woody tissue specific gravity from 2,602 individual stems for 386 species, including trees, lianas, and hemi-epiphytes of lowland tropical forests in Colombia. This data set was produced by us collecting wood cores from woody species in five localities in the Orinoco and Magdalena Basins in Colombia. We found lower mean specific gravity values in várzea than in terra firme and igapó.