Diversification Scenarios Research Articles

Tracing the propagation of disruptions in supply chain scenarios: A case study of photovoltaics diversification

Diversifying supply chains through reshoring and friendshoring is increasingly proposed as a key strategy for supply security and resilience. Quantitative analyses characterizing to what extend diversification shield countries from supply disruptions remain however scarce. In this paper, we present a methodology to assess the supply risk exposure of countries in different supply diversification scenarios – business-as-usual, reshoring, friendshoring. For each scenario, the propagation of three types of upstream disruptions – supply shortage, export restriction, bilateral trade conflict – is simulated. A fragility ratio metric is introduced to quantify the potential downstream shortages caused by these disruptions. A novel friendshoring modelling approach is also proposed. It consists in determining risk-optimized trade relations based on criteria such as supply concentration and UN voting similarity.The Python-based model is tested on the case of diversified photovoltaics supply chains, e.g., if the US, EU, and India increase domestic production from polysilicon to module. Beyond building up manufacturing capacities, choosing between vertical integration and trade is highly determinant in risk exposure. Each diversification scenario shows pros and cons depending on the country and process considered.Overall, this paper underlines the need for supply risk research to nuance diversification recommendations. It would be particularly helpful to improve indicators accounting for a region's technical and economic ability to supply a given product, and to realistically model the challenges of reshoring.

A Diffusion-Based Approach for Simulating Forward-in-Time State-Dependent Speciation and Extinction Dynamics.

We establish a general framework using a diffusion approximation to simulate forward-in-time state counts or frequencies for cladogenetic state-dependent speciation-extinction (ClaSSE) models. We apply the framework to various two- and three-region geographic-state speciation-extinction (GeoSSE) models. We show that the species range state dynamics simulated under tree-based and diffusion-based processes are comparable. We derive a method to infer rate parameters that are compatible with given observed stationary state frequencies and obtain an analytical result to compute stationary state frequencies for a given set of rate parameters. We also describe a procedure to find the time to reach the stationary frequencies of a ClaSSE model using our diffusion-based approach, which we demonstrate using a worked example for a two-region GeoSSE model. Finally, we discuss how the diffusion framework can be applied to formalize relationships between evolutionary patterns and processes under state-dependent diversification scenarios.

An agent-based modelling approach to wave-like diversification of language families

Abstract In contrast to phylogenetic tree inference, wave model approaches are often regarded as difficult to computationally implement for inference of language relatedness. This paper proposes a basic framework for the computational modelling of wave-like diversification in language families and explains the model type of agent-based models for linguistic data. The approach is based on agent-based simulations which allow for the detailed simulation of speaker interactions within speech communities. The proposed framework operates by simulating a large number of possible diversification situations with different parameter settings and selecting those runs that yield a good fit to the linguistic data of the geographical spread of different languages. The model can be fed with the geographical extent of languages and their known innovations in order to computationally reconstruct the most likely diversification scenarios of these languages under the wave model.

Phylogenetic Insights into Diversification

Species diversification—the balance between speciation and extinction—is fundamental to our understanding of how species richness varies in space and time and throughout the Tree of Life. Phylogenetic approaches provide insights into species diversification by enabling support for alternative diversification scenarios to be compared and speciation and extinction rates to be estimated. Here, we review the current toolkit available for conducting such analyses. We first highlight how modeling efforts over the past decade have fostered a notable transition from overly simplistic evolutionary scenarios to a more nuanced understanding of how and why diversification rates vary through time and across lineages. Using the latitudinal diversity gradient as a case study, we then illustrate the impact that modeling choices can have on the results obtained. Finally, we review recent progress in two areas that are still lagging behind: phylogenetic insights into microbial diversification and the speciation process.

Exploring the Distribution of Phylogenetic Networks Generated Under a Birth-Death-Hybridization Process

Gene-flow processes such as hybridization and introgression play important roles in shaping diversity across the tree of life. Recent studies extending birth-death models have made it possible to investigate patterns of reticulation in a macroevolutionary context. These models allow for different macroevolutionary patterns of gene flow events that can either add, maintain, or remove lineages—with the gene flow itself possibly being dependent on the relatedness between species—thus creating complex diversification scenarios. Further, many reticulate phylogenetic inference methods assume specific reticulation structures or phylogenies belonging to certain network classes. However, the distributions of phylogenetic networks under reticulate birth-death processes are poorly characterized, and it is unknown whether they violate common methodological assumptions. We use simulation techniques to explore phylogenetic network space under a birth-death-hybridization process where the hybridization rate can have a linear dependence on genetic distance. Specifically, we measured the number of lineages through time and role of hybridization in diversification along with the proportion of phylogenetic networks that belong to commonly used network classes (e.g., tree-child, tree-based, or level-1 networks). We find that the growth of phylogenetic networks and class membership are largely affected by assumptions about macroevolutionary patterns of gene flow. In accordance with previous studies, a lower proportion of networks belonged to these classes based on type and density of reticulate events. However, under a birth-death-hybridization process, these factors form an antagonistic relationship; the type of reticulation events that cause high membership proportions also lead to the highest reticulation density, consequently lowering the overall proportion of phylogenies in some classes. Further, we observed that genetic distance–dependent gene flow and incomplete sampling increase the proportion of class membership, primarily due to having fewer reticulate events. Our results can inform studies if their biological expectations of gene flow are associated with evolutionary histories that satisfy the assumptions of current methodology and aid in finding phylogenetic classes that are relevant for methods development.

Cost benefit analysis of diversified farming systems across Europe: Incorporating non-market benefits of ecosystem services

Crop diversification can enhance farm economic sustainability while reducing the negative impact on the environment and ecosystem services related. Despite the market and non-market benefits of crop diversification, monocropping is a widely used dominant practice in Europe. In this context, this works aims to assess the overall economic impact of several crop diversification systems across Europe and compared it to the monocropping system. For this purpose, an economic valuation by integrating market and non-market values for eight case studies distributed across three different European pedoclimatic regions (Southern Mediterranean, Northern Mediterranean and Boreal) is proposed. The economic valuation was conducted both in the short and medium-long term. For the short-term we conducted a social gross margin analysis, while for the medium-long term a cost-benefit analysis is developed. The results show an improvement in social gross margins for most of the diversification scenarios assessed when environmental and socio-cultural benefits are considered in the short-term. In the medium and long-term the transformation of cropping towards a more diversified agriculture is encouraged by greater economic benefits. These results provide a first insight in global economic performance of diversified cropping systems, whose main contribution relies on the integration of market and non-market values of ecosystem services from crop diversification. They are expected to be useful for guiding policy makers to promote crop diversification practices as a key instrument for building resilience in farming systems for an adaptive management to climate change.

Environmental impact of grass-based cattle farms: A life cycle assessment of nature-based diversification scenarios

Diversification is widely considered to positively influence the environmental sustainability of livestock farming. Multiple options exist to diversify cattle farms, but few have been examined at a systems level for grass-based livestock farms. Three nature-based diversification options recommended for livestock farms were examined in this study: mixed grass–white clover swards (GWC), organic farming (OFS) and agroforestry (AGF). They were applied on dairy and suckler calf-to-beef farming systems common in the Republic of Ireland. Both of these bovine systems were evaluated over a 3-year period (2017–2019) and were nationally representative. The environmental impact and resource use of dairy and suckler calf-to-beef systems were modelled using life cycle assessment (LCA). The system boundary of the LCA model extended from the extraction of raw materials to the sale of milk and cattle from the farm, i.e. cradle to farm-gate. Six of the major environmental impacts of cattle farming were simulated; global warming potential (GWP), non-renewable energy (NRE) depletion, land occupation (LO), acidification potential (ACP), freshwater and marine eutrophication potential (FEP and MEP). Impacts were scaled to the following functional units: land area, fat and protein corrected milk (FPCM) for dairy and carcass weight (CW) for beef. The result illustrated that GWC swards reduced the GWP of milk production by 9% and cut the GWP of beef LW by 3%. Per unit of product, this strategy decreased ACP by 4%–5%, NRE depletion by 13%–19% and LO by 6%–7%. However, it increased MEP by 5%–12% due to clover fixing more N than it replaced. Cattle farms based on GWC were more productive than conventional farms, but tended to increase impacts per hectare. Organic farming had the lowest environmental impacts per unit of land and reduced GWP and NRE depletion. Without carbon sequestration, organic farming had the opposite effect on GWP of FPCM and increased ACP and MEP per product unit. Declines in productivity in organic systems led to the rise in these impacts per unit of product and increases in LO relative to conventional systems. Partial conversion (10%–20%) of grassland to silvopasture decreased milk and beef output, and slightly improved environmental performance. Carbon sequestration was greater in silvopasture than in grassland, albeit LCA models struggle to accurately quantify the influence of management change on this process. This issue can be overcome through more field and modelling research on sequestration. Further research is also required on combining diversification options to optimise the environmental sustainability of cattle farming.

The Himalayan uplift and evolution of aquatic biodiversity across Asia: Snowtrout (Cyprininae: Schizothorax) as a test case.

Global biodiversity hotspots are often remote, tectonically active areas undergoing climatic fluctuations, such as the Himalaya Mountains and neighboring Qinghai-Tibetan Plateau (QTP). They provide biogeographic templates upon which endemic biodiversity can be mapped to infer diversification scenarios. Yet, this process can be somewhat opaque for the Himalaya, given substantial data gaps separating eastern and western regions. To help clarify, we evaluated phylogeographic and phylogenetic hypotheses for a widespread fish (Snowtrout: Cyprininae; Schizothorax) by sequencing 1,140 base pair of mtDNA cytochrome-b (cytb) from Central Himalaya samples (Nepal: N = 53; Bhutan: N = 19), augmented with 68 GenBank sequences (N = 60 Schizothorax/N = 8 outgroups). Genealogical relationships (N = 132) were analyzed via maximum likelihood (ML), Bayesian (BA), and haplotype network clustering, with clade divergence estimated via TimeTree. Snowtrout seemingly originated in Central Asia, dispersed across the QTP, then into Bhutan via southward-flowing tributaries of the east-flowing Yarlung-Tsangpo River (YLTR). Headwaters of five large Asian rivers provided dispersal corridors from Central into eastern/southeastern Asia. South of the Himalaya, the YLTR transitions into the Brahmaputra River, facilitating successive westward colonization of Himalayan drainages first in Bhutan, then Nepal, followed by far-western drainages subsequently captured by the (now) westward-flowing Indus River. Two distinct Bhutanese phylogenetic groups were recovered: Bhutan-1 (with three subclades) seemingly represents southward dispersal from the QTP; Bhutan-2 apparently illustrates northward colonization from the Lower Brahmaputra. The close phylogenetic/phylogeographic relationships between the Indus River (Pakistan) and western tributaries of the Upper Ganges (India/Nepal) potentially implicate an historic, now disjunct connection. Greater species-divergences occurred across rather than within-basins, suggesting vicariance as a driver. The Himalaya is a component of the Earth's largest glacial reservoir (i.e., the "third-pole") separate from the Arctic/Antarctic. Its unique aquatic biodiversity must be defined and conserved through broad, trans-national collaborations. Our study provides an initial baseline for this process.

A framework for the assessment of farm diversification options in broadacre agriculture

CONTEXTThe economic and environmental sustainability of farming systems is under increased pressure from extreme climate variability and market volatility. The diversification of large-scale farms can increase profits, resilience, and deliver sustainability outputs. OBJECTIVETo (a) propose a farm diversification framework specifically designed for large-scale commercial farms; and (b) demonstrate its application to assess the benefits and trade-offs associated with alternative diversification options for a case-study farm in Northern Queensland, Australia. METHODSA literature review and discussions with large-scale commercial farmers, a Natural Resource Management NGO, and a regional council were used to co-design our framework. The framework was then used to guide discussions with a case-study farmer and conduct a participatory modelling exercise on alternative cropping-based diversification scenarios. We used a simulation model to produce quantitative information on the present and co-designed alternative scenarios, to iteratively inform discussions with the participating case-study farmer. The simulated scenarios included (i) the current system of dryland (non-irrigated) monocropping of cotton, (ii) a dryland cotton-maize rotation, (iii) an irrigated cotton-maize rotation, and (iv) an irrigated maize-mungbean-cotton rotation. The benefits and trade-offs of each scenario were assessed across five performance measures: downside risk, profit, water-use efficiency, ground cover and, from the discussion with the participating farmer, the skills needed to de-risk the diversification process. RESULTSResults from the co-designed scenarios showed that adding dryland maize as a rotation crop can reduce downside risks by 12.5% and increase fractional ground cover by more than two-fold, i.e., from 20% to >40%, compared to the current system. The use of irrigation in the cropping system increased the median gross margin by $2000 ha−1 and reduced downside risks to zero. The water-use efficiencies of the proposed irrigated scenarios were similar. Farmers reported that developing skills in irrigated cropping could increase their capacity to dynamically chose more profitable crops to sow with certainty of higher returns, but it would require up-front investments in terms of money and time. SIGNIFICANCEOur proposed framework can be used to assess benefits and trade-offs of alternative farm diversification options across a range of performance dimensions (risk; profit; resource-use efficiency; skills). These assessments will ensure that the co-designed options are evaluated across multiple dimensions, all within the local context of the study and farmers' preference(s) and circumstances. The use of a co-design approach can be expected to increase learnings for all those involved and increase the chances of practice change and adoption.

New insights into Silurian–Devonian palaeophytogeography

The Silurian–Devonian plant radiation was an event triggered by the progressive colonization of subaerial habitats. Nevertheless, it is still unclear whether this radiation was globally uniform or whether alternative diversification scenarios emerged depending on the geographical context. Here, we report on early land plant diversity patterns across different previously defined palaeogeographical units (i.e., Laurussia, Siberia, Kazakhstania, NE, NW and South Gondwana). Results reveal apparent diachronous events of diversification and extinction partly resulting from uneven sampling effort, especially in Gondwana. Global diversity patterns are most similar to the Laurussian curve suggesting that the observed global dynamics are mostly controlled by the historically best-sampled continents. Nevertheless, changes in floral composition through time become less prone to sampling biases, and reveal geographical disparities that indicate a non-random distribution of the Silurian–Devonian vegetation. Consequently, we further performed a set of multivariate analyses to revisit the palaeophytogeographical signal through four time-intervals (i.e., Silurian–Lochkovian, Pragian–Emsian, Middle and Late Devonian), which revealed that spatial differentiation of vegetation was mainly controlled by climatic conditions and to a lesser extent geographical barriers. Most importantly, we find the maximum provincialism during cooler periods such as during the Silurian–Lochkovian and Middle Devonian, whilst warmer periods (Pragian–Emsian and Late Devonian) coincided with increased cosmopolitanism among early land plants.

Management diversification increases habitat availability for multiple biodiversity indicator species in production forests

ContextForest biodiversity is closely linked to habitat heterogeneity, while forestry actions often cause habitat homogenization. Alternative approaches to even-aged management were developed to restore habitat heterogeneity at the stand level, but how their application could promote habitat diversity at landscape scale remains uncertain.ObjectivesWe tested the potential benefit of diversifying management regimes to increase landscape-level heterogeneity. We hypothesize that different styles of forest management would create a diverse mosaic of forest habitats that would in turn benefit species with various habitat requirements.MethodsForest stands were simulated under business-as-usual management, set-aside (no management) and 12 alternative management regimes. We created virtual landscapes following diversification scenarios to (i) compare the individual performance of management regimes (no diversification), and (ii) test for the management diversification hypothesis at different levels of set-aside. For each virtual landscape, we evaluated habitat availability of six biodiversity indicator species, multispecies habitat availability, and economic values of production.ResultsEach indicator species responded differently to management regimes, with no single regime being optimal for all species at the same time. Management diversification led to a 30% gain in multispecies habitat availability, relative to business-as-usual management. By selecting a subset of five alternative management regimes with high potential for biodiversity, gains can reach 50%.ConclusionsVarious alternative management regimes offer diverse habitats for different biodiversity indicator species. Management diversification can yield large gains in multispecies habitat availability with no or low economic cost, providing a potential cost-effective biodiversity tool if the management regimes are thoughtfully selected.

Pulled Diversification Rates, Lineages-Through-Time Plots, and Modern Macroevolutionary Modeling.

Estimating time-dependent rates of speciation and extinction from dated phylogenetic trees of extant species (timetrees), and determining how and why they vary, is key to understanding how ecological and evolutionary processes shape biodiversity. Due to an increasing availability of phylogenetic trees, a growing number of process-based methods relying on the birth–death model have been developed in the last decade to address a variety of questions in macroevolution. However, this methodological progress has regularly been criticized such that one may wonder how reliable the estimations of speciation and extinction rates are. In particular, using lineages-through-time (LTT) plots, a recent study has shown that there are an infinite number of equally likely diversification scenarios that can generate any timetree. This has led to questioning whether or not diversification rates should be estimated at all. Here, we summarize, clarify, and highlight technical considerations on recent findings regarding the capacity of models to disentangle diversification histories. Using simulations, we illustrate the characteristics of newly proposed “pulled rates” and their utility. We recognize that the recent findings are a step forward in understanding the behavior of macroevolutionary modeling, but they in no way suggest we should abandon diversification modeling altogether. On the contrary, the study of macroevolution using phylogenetic trees has never been more exciting and promising than today. We still face important limitations in regard to data availability and methods, but by acknowledging them we can better target our joint efforts as a scientific community. [Birth–death models; extinction; phylogenetics; speciation.]

Diversification in session-based news recommender systems

Recommender systems are widely applied in digital platforms such as news websites to personalize services based on user preferences. In news websites most of users are anonymous and the only available data is sequences of items in anonymous sessions. Due to this, typical collaborative filtering methods, which are highly applied in many applications, are not effective in news recommendations. In this context, session-based recommenders are able to recommend next items given the sequence of previous items in the active session. Neighborhood-based session-based recommenders has been shown to be highly effective compared to more sophisticated approaches. In this study we propose scenarios to make these session-based recommender systems diversity-aware and to address the filter bubble phenomenon. The filter bubble phenomenon is a common concern in news recommendation systems and it occurs when the system narrows the information and deprives users of diverse information. The results of applying the proposed scenarios show that these diversification scenarios improve the diversity measures in these session-based recommender systems based on four news datasets.

Why extinction estimates from extant phylogenies are so often zero

Time-calibrated phylogenies of extant species ("extant timetrees") are widely used to estimate historical speciation and extinction rates by fitting stochastic birth-death models.1 These approaches have long been controversial, as many phylogenetic studies report zero extinction in many taxa, contradicting the high extinction rates seen in the fossil record and the fact that the majority of species ever to have existed are now extinct.2-9 To date, the causes of this discrepancy remain unresolved. Here, we provide a novel and simple explanation for these "zero-inflated" extinction estimates, based on the recent discovery that there exist many alternative "congruent" diversification scenarios that cannot be distinguished based solely on extant timetrees.10 Due to such congruencies, estimation methods tend to converge to some scenario congruent to (i.e., statistically indistinguishable from) the true diversification scenario, but not necessarily to the true diversification scenario itself. This congruent scenario may exhibit negative extinction rates, a biologically meaningless but mathematically feasible situation, in which case estimators will tend to stick to the boundary of zero extinction. Based on this explanation, we make multiple testable predictions, which we confirm using analyses of simulated trees and 121 empirical trees. In contrast to other proposed mechanisms for erroneous extinction rate estimates,5,11-14 our proposed mechanism specifically explains the zero inflation of previous extinction rate estimates in the absence of detectable model violations, even for large trees. Not only do our results likely resolve a long-standing mystery in phylogenetics, they demonstrate that model congruencies can have severe consequences in practice.

Quaternary climatic fluctuations influence the demographic history of two species of sky-island endemic amphibians in the Neotropics

We evaluated the role of Quaternary climatic fluctuations on the demographic history and population structure of amphibian species endemic to the ‘campo rupestre’ in the Neotropics, evaluating their distributional shifts, demographic changes, and lineage formation from the end of Pleistocene to present. We chose two anurans endemic to the high-elevation ‘campo rupestre’ in the Espinhaço Range (ER) in northeastern and southeastern Brazil (Bokermannohyla alvarengai and Bokermannohyla oxente), as models to test the role of Quaternary climatic fluctuations over their distribution range in this region. We collected tissue samples throughout their distribution range and used statistical phylogeography to examine processes of divergence and population demography. We generated spatial–temporal reconstructions using Bayesian inference in a coalescent framework in combination with hind-cast projections of species distribution models (SDMs). We also used the results and literature information to test alternative diversification scenarios via approximate Bayesian computation (ABC). Our results show that Quaternary climatic fluctuations influenced the geographic ranges of both species showing population expansion during the last glacial maximum (LGM) and range contraction during interglacial periods, as inferred from selected ABC models and from past projections of SDMs. We recovered Pleistocene diversification for both species occuring in distinctly unique periods for each taxon. An older and range-restricted lineage was recovered in a geographically isolated geological massif, deserving conservation and further taxonomic study. The diversification and distribution of these amphibian species endemic to the Neotropical ‘campo rupestre’ were influenced by Quaternary climatic fluctuations. The expansion of cold adapted species restricted to higher elevations during glacial periods and their concomitant retraction during interglacial periods may have been crucial for producing patterns of species richness and endemism along elevation gradients in tropical and subtropical domains. Such processes may influence the evolution of the biota distributed in heterogeneous landscapes with varied topography.

A Total-Group Phylogenetic Metatree for Cetacea and the Importance of Fossil Data in Diversification Analyses.

Phylogenetic trees provide a powerful framework for testing macroevolutionary hypotheses, but it is becoming increasingly apparent that inferences derived from extant species alone can be highly misleading. Trees incorporating living and extinct taxa are needed to address fundamental questions about the origins of diversity and disparity but it has proved challenging to generate robust, species-rich phylogenies that include large numbers of fossil taxa. As a result, most studies of diversification dynamics continue to rely on molecular phylogenies. Here, we extend and apply a recently developed meta-analytic approach for synthesizing previously published phylogenetic studies to infer a well-resolved set of species level, time-scaled phylogenetic hypotheses for extinct and extant cetaceans (whales, dolphins, and allies). Our trees extend sampling from the $\sim 90$ extant species to over 500 living and extinct species, and therefore allow for more robust inference of macroevolutionary dynamics. While the diversification scenarios, we recover are broadly concordant with those inferred from molecular phylogenies they differ in critical ways, notably in the relative contributions of extinction and speciation rate shifts in driving rapid radiations. The metatree approach provides the most immediate route for generating higher level phylogenies of extinct taxa and opens the door to re-evaluation of macroevolutionary hypotheses derived only from extant taxa.[Extinction; macroevolution; matrix representation with parsimony; morphology; supertree.].

Locally adaptive Bayesian birth-death model successfully detects slow and rapid rate shifts.

Birth-death processes have given biologists a model-based framework to answer questions about changes in the birth and death rates of lineages in a phylogenetic tree. Therefore birth-death models are central to macroevolutionary as well as phylodynamic analyses. Early approaches to studying temporal variation in birth and death rates using birth-death models faced difficulties due to the restrictive choices of birth and death rate curves through time. Sufficiently flexible time-varying birth-death models are still lacking. We use a piecewise-constant birth-death model, combined with both Gaussian Markov random field (GMRF) and horseshoe Markov random field (HSMRF) prior distributions, to approximate arbitrary changes in birth rate through time. We implement these models in the widely used statistical phylogenetic software platform RevBayes, allowing us to jointly estimate birth-death process parameters, phylogeny, and nuisance parameters in a Bayesian framework. We test both GMRF-based and HSMRF-based models on a variety of simulated diversification scenarios, and then apply them to both a macroevolutionary and an epidemiological dataset. We find that both models are capable of inferring variable birth rates and correctly rejecting variable models in favor of effectively constant models. In general the HSMRF-based model has higher precision than its GMRF counterpart, with little to no loss of accuracy. Applied to a macroevolutionary dataset of the Australian gecko family Pygopodidae (where birth rates are interpretable as speciation rates), the GMRF-based model detects a slow decrease whereas the HSMRF-based model detects a rapid speciation-rate decrease in the last 12 million years. Applied to an infectious disease phylodynamic dataset of sequences from HIV subtype A in Russia and Ukraine (where birth rates are interpretable as the rate of accumulation of new infections), our models detect a strongly elevated rate of infection in the 1990s.

Impacts of climate change policies worldwide on the Russian economy

ABSTRACT Because the Russian economy relies heavily on exports of fossil fuels, the primary source of human-induced greenhouse gas (GHG) emissions, it may be adversely impacted by Paris Agreement-based climate policies that target reductions in GHG emissions. Applying the MIT Economic Projection and Policy Analysis (EPPA) model to assess the impacts on the Russian economy of the efforts of the main importers of Russian fossil fuels to follow the global goals of the Paris Agreement, we project that climate-related actions outside of Russia will lower the country's GDP growth rate by about one-half of a percentage point. The Paris Agreement is also expected to raise Russia's risks of facing market barriers for its exports of energy-intensive goods, and of falling behind in the development of low-carbon energy technologies that most of the world is increasingly adopting. Key policy insights Regardless of its domestic emissions reduction efforts, Russia will not be able to sustain its current trajectory of fossil fuel export-based development due to climate policies worldwide. To address the challenge of climate-related energy transition, Russia needs a new comprehensive development strategy that accounts for the post-Paris Agreement global energy landscape. The key elements of such a strategy include diversification of the economy, moving to low-carbon energy sources, and investing in human capital development. Our diversification scenarios show that redistribution of income from the energy sector to the development of human capital would benefit the economy. The largest impact of investment re-orientation from the fossil fuel sector would be on manufacturing, services, agriculture and food production.

Extant timetrees are consistent with a myriad of diversification histories.

Time-calibrated phylogenies of extant species (referred to here as 'extant timetrees') are widely used for estimating diversification dynamics1. However, there has been considerable debate surrounding the reliability of these inferences2-5 and, to date, this critical question remains unresolved. Here we clarify the precise information that can be extracted from extant timetrees under the generalized birth-death model, which underlies most existing methods of estimation. We prove that, for any diversification scenario, there exists an infinite number of alternative diversification scenarios that are equally likely to have generated any given extant timetree. These 'congruent' scenarios cannot possibly be distinguished using extant timetrees alone, even in the presence of infinite data. Importantly, congruent diversification scenarios can exhibit markedly different and yet similarly plausible dynamics, which suggests that many previous studies may have over-interpreted phylogenetic evidence. We introduce identifiable and easily interpretable variables that contain all available information about past diversification dynamics, and demonstrate that these can be estimated from extant timetrees. We suggest that measuring and modelling these identifiable variables offers a more robust way to study historical diversification dynamics. Our findings also make it clear that palaeontological data will continue to be crucial for answering some macroevolutionary questions.

Species Selection Regime and Phylogenetic Tree Shape.

Species selection, the effect of heritable traits in generating between-lineage diversification rate differences, provides a valuable conceptual framework for understanding the relationship between traits, diversification, and phylogenetic tree shape. An important challenge, however, is that the nature of real diversification landscapes-curves or surfaces which describe the propensity of species-level lineages to diversify as a function of one or more traits-remains poorly understood. Here, we present a novel, time-stratified extension of the QuaSSE model in which speciation/extinction rate is specified as a static or temporally shifting Gaussian or skewed-Gaussian function of the diversification trait. We then use simulations to show that the generally imbalanced nature of real phylogenetic trees, as well as their generally greater than expected frequency of deep branching events, are typical outcomes when diversification is treated as a dynamic, trait-dependent process. Focusing on four basic models (Gaussian-speciation with and without background extinction; skewed-speciation; Gaussian-extinction), we also show that particular features of the species selection regime produce distinct tree shape signatures and that, consequently, a combination of tree shape metrics has the potential to reveal the species selection regime under which a particular lineage diversified. We evaluate this idea empirically by comparing the phylogenetic trees of plant lineages diversifying within climatically and geologically stable environments of the Greater Cape Floristic Region, with those of lineages diversifying in environments that have experienced major change through the Late Miocene-Pliocene. Consistent with our expectations, the trees of lineages diversifying in a dynamic context are less balanced, show a greater concentration of branching events close to the present, and display stronger diversification rate-trait correlations. We suggest that species selection plays an important role in shaping phylogenetic trees but recognize the need for an explicit probabilistic framework within which to assess the likelihoods of alternative diversification scenarios as explanations of a particular tree shape. [Cape flora; diversification landscape; environmental change; gamma statistic; species selection; time-stratified QuaSSE model; trait-dependent diversification; tree imbalance.].