Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

The Theory of Island Biogeography

Bones of recent mammals in the Amboseli Basin, southern Kenya, exhibit distinctive weathering characteristics that can be related to the time since death and to the local conditions of temperature, humidity and soil chemistry. A categorization of weathering characteristics into six stages, recognizable on descriptive criteria, provides a basis for investigation of weathering rates and processes. The time necessary to achieve each successive weathering stage has been calibrated using known-age carcasses. Most bones decompose beyond recognition in 10 to 15 yr. Bones of animals under 100 kg and juveniles appear to weather more rapidly than bones of large animals or adults. Small-scale rather than widespread environmental factors seem to have greatest influence on weathering characteristics and rates. Bone weathering is potentially valuable as evidence for the period of time represented in recent or fossil bone assemblages, in- cluding those on archeological sites, and may also be an important tool in censusing populations of animals in modern ecosystems.

Taphonomic and Ecologic Information Form Bone Weathering

Geological atlas of western and central Europe

This review highlights the ubiquity of black carbon (BC) produced by incomplete combustion of plant material and fossil fuels in peats, soils, and lacustrine and marine sediments. We examine various definitions and analytical approaches and seek to provide a common language. BC represents a continuum from partly charred material to graphite and soot particles, with no general agreement on clear-cut boundaries. Formation of BC can occur in two fundamentally different ways. Volatiles recondense to highly graphitized soot-BC, whereas the solid residues form char-BC. Both forms of BC are relatively inert and are distributed globally by water and wind via fluvial and atmospheric transport. We summarize, chronologically, the ubiquity of BC in soils and sediments since Devonian times, differentiating between BC from vegetation fires and from fossil fuel combustion. BC has important implications for various biological, geochemical and environmental processes. As examples, BC may represent a significant sink in the global carbon cycle, affect the Earth's radiative heat balance, be a useful tracer for Earth's fire history, build up a significant fraction of carbon buried in soils and sediments, and carry organic pollutants. On land, BC seems to be abundant in dark-colored soils, affected by frequent vegetation burning and fossil fuel combustion, thus probably contributing to the highly stable aromatic components of soil organic matter. We discuss challenges for future research. Despite the great importance of BC, only limited progress has been made in calibrating analytical techniques. Progress in the quantification of BC is likely to come from systematic intercomparison using BCs from different sources and in different natural matrices. BC identification could benefit from isotopic and spectroscopic techniques applied at the bulk and molecular levels. The key to estimating BC stocks in soils and sediments is an understanding of the processes involved in BC degradation on a molecular level. A promising approach would be the combination of short-term laboratory experiments and long-term field trials.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1999GB001208

Black carbon in soils and sediments: Analysis, distribution, implications, and current challenges

The role of fossils in dating the tree of life has been misunderstood. Fossils can provide good "minimum" age estimates for branches in the tree, but "maximum" constraints on those ages are poorer. Current debates about which are the "best" fossil dates for calibration move to consideration of the most appropriate constraints on the ages of tree nodes. Because fossil-based dates are constraints, and because molecular evolution is not perfectly clock-like, analysts should use more rather than fewer dates, but there has to be a balance between many genes and few dates versus many dates and few genes. We provide "hard" minimum and "soft" maximum age constraints for 30 divergences among key genome model organisms; these should contribute to better understanding of the dating of the animal tree of life.

/pdf/paleontological-evidence-to-date-the-tree-of-life-5dhwbwgnyr.pdf

Paleontological Evidence to Date the Tree of Life

Abrupt collapse of the tropical rainforest biome (Coal Forests) drove rapid diversification of Carboniferous tetrapods (amphibians and reptiles) in Euramerica. This finding is based on analysis of global and alpha diversity databases in a precise geologic context. From Visean to Moscovian time, both diversity measures steadily increased, but following rainforest collapse in earliest Kasimovian time (ca. 305 Ma), tetrapod extinction rate peaked, alpha diversity imploded, and endemism developed for the first time. Analysis of ecological diversity shows that rainforest collapse was also accompanied by acquisition of new feeding strategies (predators, herbivores), consistent with tetrapod adaptation to the effects of habitat fragmentation and resource restriction. Effects on amphibians were particularly devastating, while amniotes (‘reptiles’) fared better, being ecologically adapted to the drier conditions that followed. Our results demonstrate, for the first time, that Coal Forest fragmentation influenced profoundly the ecology and evolution of terrestrial fauna in tropical Euramerica, and illustrate the tight coupling that existed between vegetation, climate, and trophic webs.

Rainforest collapse triggered Carboniferous tetrapod diversification in Euramerica

Cyclic changes in Pennsylvanian paleoclimate and effects on floristic dynamics in tropical Pangaea

Pennsylvanian tropical rain forests flourished during an icehouse climate mode. Although it is well established that Milankovitch-band glacial-interglacial rhythms caused marked synchronous changes in Pennsylvanian tropical climate and sea level, little is known of vegetation response to orbital forcing. This knowledge gap has now been addressed through sequence- stratigraphic analysis of megafloral and palynofloral assemblages within the Westphalian D–Cantabrian Sydney Mines Formation of eastern Canada. This succession was deposited in a low- accommodation setting where sequences can be attributed confidently to glacio-eustasy. Results show that long-lived, low-diversity peat mires dominated by lycopsids were initiated during deglaciation events, but were mostly drowned by rising sea level at maximum interglacial conditions. Only upland coniferopsid forests survived flooding without significant disturbance. Mid- to late interglacial phases witnessed delta-plain progradation and establishment of high-diversity, mineral-substrate rain forests containing lycopsids, sphenopsids, pteridosperms, cordaites, and tree ferns. Renewed glaciation resulted in sea-level fall, paleovalley incision, and the onset of climatic aridity. Glacial vegetation was dominated by cordaites, pteridosperms, and tree ferns; hydrophilic lycopsids and sphenopsids survived in paleovalley refugia. Findings clearly demonstrate the dynamic nature of Pennsylvanian tropical ecosystems and are timely given current debates about the impact of Quaternary glacial-interglacial rhythms on the biogeography of tropical rain forest.

Pennsylvanian tropical rain forests responded to glacial-interglacial rhythms

The idea that the Pennsylvanian tropical lowlands were temporally dominated by rainforest (i.e., the Coal Forest) is deeply ingrained in the literature. Here we challenge two centuries of research by suggesting that this concept is based on a taphonomic artifact, and that seasonally dry vegetation dominated instead. This controversial finding arises from the discovery of a new middle Pennsylvanian (Moscovian) fossil plant assemblage in southeast Illinois, United States. The assemblage, which contains xerophytic walchian conifers, occurs in channels incised into a calcic Vertisol below the Baker Coal. These plants grew on seasonally dry tropical lowlands inferred to have developed during a glacial phase. This xerophytic flora differs markedly from that of the typical clubmoss-dominated Coal Forest developed during deglaciation events. Although preserved only very rarely, we argue that such xerophytic floras were temporally as dominant, and perhaps more dominant, than the iconic Coal Forests, which are overrepresented in the fossil record due to taphonomic megabias. These findings require the iconography of Pennsylvanian tropical lowlands to be redrawn.

Incised channel fills containing conifers indicate that seasonally dry vegetation dominated Pennsylvanian tropical lowlands

Sequence stratigraphic analysis of Pennsylvanian coal-bearing strata suggests that glacial-interglacial fluctuations at high latitudes drove cyclic changes in tropical biomes. A literature review of plant assemblages in this paleoclimatic context suggests that coal forests dominated during humid interglacial phases, but were replaced by seasonally dry vegetation during glacial phases. After each glacial event, coal forests reassembled with largely the same species composition. This remarkable stasis implies that coal-forest refugia existed across the equatorial landscape during glacial phases, expanding to repopulate lowlands during and following deglaciation. One possibility is that refugia comprised small pockets of wetland forest strung out along valleys at some sites, but data are currently insufficient to test this hypothesis. The model presented here, if accepted, dramatically alters our understanding of the coal forests and helps explain aspects of their dynamics.

/pdf/what-happened-to-the-coal-forests-during-pennsylvanian-3pvvmgxu8r.pdf

Howard J. Falcon-Lang

Papers

Rainforest collapse triggered Carboniferous tetrapod diversification in Euramerica

Cyclic changes in Pennsylvanian paleoclimate and effects on floristic dynamics in tropical Pangaea

Pennsylvanian tropical rain forests responded to glacial-interglacial rhythms

Incised channel fills containing conifers indicate that seasonally dry vegetation dominated Pennsylvanian tropical lowlands

What happened to the coal forests during pennsylvanian glacial phases