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.

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.

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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.

Explaining broad molecular, phenotypic, and species biodiversity patterns necessitates a unifying framework spanning multiple evolutionary scales. We argue here that, although substantial effort has been made to reconcile microevolution and macroevolution, much work remains to identify the links between biological processes at play. We highlight four major questions of evolutionary biology whose solutions require conceptual bridges between micro and macroevolution. We review potential avenues for future research to establish how mechanisms at one scale (drift, mutation, migration, selection) translate to processes at the other (speciation, extinction, biogeographic dispersal) and vice versa. We propose ways in which current comparative methods to infer molecular evolution, phenotypic evolution and species diversification could be improved to specifically address those questions. We conclude that researchers are in a better position than ever before to build a synthesis to understand how microevolutionary dynamics unfold over millions of years.