Biology subjects

Burger, J. R.

Publications and source records attributed to Burger, J. R..

6 recordsLinked to original sources

bioRxiv2026

Defusing the consumption bomb

For decades, the "population bomb" has dominated environmental discourse, arguing that high fertility rates -especially in the low income countries- drive global environmental problems. However, current trajectories show global declines in population growth rates, especially in higher development index (HDI) nations, which have the highest consumption. Here we showcase evidence for a paradigm shift from the "population bomb" to a "consumption bomb" narrative of the Anthropocene emphasizing the central role of increases in per capita energy use and CO2 production, modulated by current standard metrics for development and affluence, in transforming the Earth system. Defusing and manoaging the consumption bomb requires rethinking economic growth and wellbeing metrics, reallocating resources toward global change retribution and mitigation, especially in low HDI countries, and transitioning from continually-increasing energy expenditures, especially from fossil fuels, toward more equitable and ecologically resilient ways of living. A new sustainability science must move beyond population counts to confront the biophysical and energetic consequences of the changing cultural, economic, and technological systems that sustain ever-growing demands on Earths life-support systems.

ecology↗

bioRxiv2026

Patchy distribution of a Madrean Sky Island squirrel shaped by historical habitat configuration

Sky islands, mountain-top forests isolated by surrounding lowlands, offer unique opportunities to test how past and present landscapes shape species distributions. We examined the distribution of the Arizona gray squirrel (Sciurus arizonensis) across the Madrean Archipelago to test the constraint-based dynamic island biogeography (C-DIB) model, which posits that current occupancy in the sky islands reflects historical habitat size and connectivity. Using verified specimen records, we modeled climatically suitable habitats across four time periods: the Last Glacial Maximum (LGM), Mid-Holocene (MH), Present, and Future. For each mountain, we quantified suitable habitat area and estimated least-cost dispersal distances to assess both persistence and colonization potential. Our results suggest that species presence is best explained by LGM habitat metrics, which marginally outperformed models based on current conditions. Mountains that were large or well-connected during the LGM continue to support S. arizonensis, whereas historically isolated ranges remain unoccupied despite suitable contemporary habitat. These findings indicate a legacy of Pleistocene connectivity and reveal patterns of distributional disequilibrium. Furthermore, climatically suitable habitat for S. arizonensis has shifted both elevationally and geographically through time, reflecting long-term responses to climatic change. Together, these results emphasize the importance of protecting historically connected refugia, restoring riparian corridors that facilitate dispersal, and developing mountain range-specific management strategies that account for elevational shifts and potential downslope habitat recovery under future climate scenarios.

ecology↗

bioRxiv2020

Universal rules of life: metabolic rates, biological times and the equal fitness paradigm

Here we review and extend the equal fitness paradigm (EFP) as an important step in developing and testing a synthetic theory of ecology and evolution based on energy and metabolism. The EFP states that all organisms are equally fit at steady state, because they allocate the same quantity of energy, ~22.4 kJ/g/generation to production of offspring. On the one hand, the EFP may seem tautological, because equal fitness is necessary for the origin and persistence of biodiversity. On the other hand, the EFP reflects universal laws of life: how biological metabolism - the uptake, transformation and allocation of energy - links ecological and evolutionary patterns and processes across levels of organization from: i) structure and function of individual organisms, ii) life history and dynamics of populations, iii) interactions and coevolution of species in ecosystems. The physics and biology of metabolism have facilitated the evolution of millions of species with idiosyncratic anatomy, physiology, behavior and ecology but also with many shared traits and tradeoffs that reflect the single origin and universal rules of life.

ecology↗

bioRxiv2020

Areas of global importance for terrestrial biodiversity, carbon, and water

Summary paragraphTo meet the ambitious objectives of biodiversity and climate conventions, countries and the international community require clarity on how these objectives can be operationalized spatially, and multiple targets be pursued concurrently1. To support governments and political conventions, spatial guidance is needed to identify which areas should be managed for conservation to generate the greatest synergies between biodiversity and natures contribution to people (NCP). Here we present results from a joint optimization that maximizes improvements in species conservation status, carbon retention and water provisioning and rank terrestrial conservation priorities globally. We found that, selecting the top-ranked 30% (respectively 50%) of areas would conserve 62.4% (86.8%) of the estimated total carbon stock and 67.8% (90.7%) of all clean water provisioning, in addition to improving the conservation status for 69.7% (83.8%) of all species considered. If priority was given to biodiversity only, managing 30% of optimally located land area for conservation may be sufficient to improve the conservation status of 86.3% of plant and vertebrate species on Earth. Our results provide a global baseline on where land could be managed for conservation. We discuss how such a spatial prioritisation framework can support the implementation of the biodiversity and climate conventions.

ecology↗

bioRxiv2020

Metabolic life tables: the sockeye salmon example

O_LIA metabolic life table (MLT) is a combination of energy budget and life table that quantifies metabolism and life history over an entire life cycle. It provides a conceptual framework for integrating data on physiology, demography and ecology that are usually the subject of discipline- and taxon-specific studies. C_LIO_LIOur MLT for sockeye salmon revives John Bretts classic data on metabolism, growth, survival and reproduction to provide a synthetic analysis of metabolic performance and its life history consequences. C_LIO_LIThe MLT quantifies the energy budget of an average female over her life cycle. The early stages in fresh water have low rates of growth and mortality. Then juveniles enter the ocean, feed voraciously, grow rapidly, and accumulate a store of biomass; More than 98% of the total lifetime assimilation and growth occurs in the ocean. Maturing adults stop feeding, return to fresh water, expend stored body energy to fuel migration and reproduction, and leave a clutch of eggs and a depleted carcass. C_LIO_LIThe MLT also quantifies the energetic contribution of salmon to freshwater and marine ecosystems. Salmon are very efficient: of the food energy in their zooplankton prey, 47% is expended on respiration to fuel activity, 23% is allocated to growth and reproduction to produce biomass, and 30% is excreted in feces. Although 96% of lifetime biomass production occurs in the ocean, about 29% is transported into fresh water in the bodies of maturing adults, where their carcasses and gametes provide an important "marine subsidy" to the energy and nutrient budgets of freshwater and terrestrial ecosystems. C_LIO_LIThe MLT highlights some features of the salmon metabolism - variation in rates of assimilation, respiration and production with body size and temperature - that are qualitatively similar to other ectotherms and predictions of metabolic theory. But because of the unusual physiology, life history, ecosystem impacts and socio-economic importance of wild-caught salmon, reanalyzing Bretts data in the context of a MLT has additional broad applications for basic and applied ecology. C_LI

ecology↗

bioRxiv2018

A constraint-based model reveals hysteresis in island biogeography

AimWe present a Constraint-based Model of Dynamic Island Biogeography (C-DIB) that predicts how species functional traits interact with dynamic environments to determine the candidate species available for local community assembly on real and habitat islands through time.\n\nLocationReal and habitat islands globally.\n\nMethodsWe develop the C-DIB model concept, synthesize the relevant literature, and present a toolkit for evaluating model predictions for a wide variety of \"island\" systems and taxa.\n\nResultsThe C-DIB model reveals that as islands cycle between phases of increasing or decreasing size and connectivity to a source pool, the dominant process driving species presence or absence switches between colonization and extinction. Both processes are mediated by interactions between organismal traits and environmental constraints. Colonization probability is predicted by a species ability to cross the intervening matrix between a population source and the island; population persistence (or extinction) is predicted by the minimum spatial requirements to sustain an isolated population. The non-random distributions of mammals on islands of the Sunda Shelf and Great Basin \"sky islands\" provide example study systems for evaluating the C-DIB model.\n\nMain conclusionsBecause different suites of traits impose constraints on the processes of colonization and extinction, similar environmental conditions can host different candidate species despite the same predicted richness. Thus, the model exemplifies the specific yet underappreciated role of hysteresis -the dependency of outcomes not only on the current system state -but also the historical contingency of environmental change in affecting populations and communities in insular systems.

ecology↗