Author: Hannah-Maria R. BramePublisher:
ISBN:
Category : Invertebrates, Fossil
Languages : en
Pages :
Book Description
Are Cincinnatian (Late Ordovician) Niche Stability Responses to Variable Environmental Changes Congruent Across Clades, Taxonomic Scales, and Through Time?
Author: Hannah-Maria R. BramePublisher:
ISBN:
Category : Invertebrates, Fossil
Languages : en
Pages :
Book Description
How Do Ecological Niches Evolve During Late Ordovician Environmental Change?
Author: Ceara K.Q. PurcellPublisher:
ISBN:
Category : Brachiopoda, Fossil
Languages : en
Pages : 176
Book Description
The Ordovician Period is characterized by dramatic abiotic and biotic environmental alterations, particularly during the Late Ordovician epoch. Climatic shifts and sea level change were common throughout the Late Ordovician, and the Taconic Orogeny locally deformed the eastern margin of Laurentia and altered sedimentation regimes. This interval is also characterized by changes in diversity and dispersal among marine faunas. Towards the end of the Late Ordovician, the Richmondian Invasion, a regional species invasion, introduced new competitive biotic interactions among shallow marine species. These environmental alterations impacted the taxa present at the time by affecting the habitat structure. The distribution of ancient and modern taxa alike are either directly or indirectly influenced by the environmental variables around them, and their occupation of this ecospace, or niche, is classically interpreted to reflect this relationship. Modern ecological studies that utilize niche concepts, including conservation ecology, are frequently based on the assumption that species will maintain their niche, referred to as niche stability. However, modern studies lack the long-term record necessary to assess this assumption.
Diagnosis and Prediction of Variations in the Environmental Distributions of Marine Fossil Taxa Across Space and Time
Author: Andrew A. ZaffosPublisher:
ISBN:
Category :
Languages : en
Pages : 358
Book Description
The distribution of taxa across time and space is controlled by each taxon's responses to a potentially infinite number of different environmental and biological stimuli. Broader regional patterns of taxonomic distribution, however, are primarily controlled by only a few key environmental variables. The response of taxa to any single environmental variable, determined to be of ecological importance, can be modeled as a Gaussian curve, along which taxa symmetrically rise and fall in abundance in tandem with environmental changes. This "unimodal response curve model" can be used to evaluate a number of prominent hypotheses in community ecology and paleobiology. In this dissertation, such a model is used to understand: patterns of immigration, emigration, extinction, and origination along the global latitudinal gradient throughout the Cenozoic Era (65 mya-Present); patterns of ecological stability playing out over millions of years in the Middle Devonian (Givetian, ~387-382 mya) strata of the northern Appalachian basin; and the impact of geologic preservation and faunal turnover on perceptions of ecological stability between two different ancient marine basins, the Middle Devonian upper Hamilton Group of the northern Appalachian basin and the Upper Ordovician (Cincinnatian, ~454-444 mya) type-Cincinnatian Series of the Cincinnati Arch. Collectively, across all study areas, there is a confluence of evidence for a ubiquitous pattern of conservatism at all scales investigated, with a greater tendency towards smaller changes in the shape and size of response curves than larger ones over timescales ranging from hundreds of thousands to tens of millions of years.
Community Ecology, Stable Isotope Ecology, and Taxonomy of Small Mammal Fossils from Rancho La Brea, Los Angeles, CA
Author: Nathaniel S. FoxPublisher:
ISBN:
Category :
Languages : en
Pages : 636
Book Description
Contemporary species are undergoing population declines and extinction at rates unprecedented in recorded history. These ongoing global biodiversity losses are largely caused by human overpopulation and other anthropogenic impacts on the environment such as natural habitat destruction driven by urbanization, deforestation, agriculture, pollution, overconsumption of natural resources, and climate change. Understanding how species are influenced by - and respond to - various changes in their environment is critical for predicting and mitigating future biodiversity loss. These predictions are challenging, however, because humans have been heavily modifying ecosystems for centuries - well before the advent of modern ecology as a field of study. Disentangling species responses to naturally occurring changes in their environment versus anthropogenic changes is thus extremely challenging. Paleoecological studies of fossil organisms can help establish the baseline responses of biota to natural environmental changes at times before humans dominated terrestrial ecosystems. However, these studies have their own set of challenges. For example, it can be difficult to determine how representative a preserved fossil community is of the original living community because the fossil record is inherently incomplete and often biased. It is also difficult to quantify species-specific responses to environmental change if the identity of species is unknown or imprecise; and due to the fragmentary nature of the fossil record, it can be difficult to identify isolated elements to species. The incompleteness of the fossil record does not only apply to the organisms preserved, but also to the environmental data documenting the contexts in which they operated while alive and during preservation. Most paleontological assemblages are affected by time-averaging and incomplete depositional sequences to some degree. Depending on the severity of time averaging, and the resolution of data collected, these temporal gaps can erase fine-scale and geologically rapid events that are important for understanding ecological patterns and processes. These unique opportunities and challenges of working with paleoecological data are what motivate my research. Within the scope of my dissertation, my goals are twofold. Foremost, I strive to quantify long-term biotic composition, diversity, and trait changes in response to pre-anthropogenic environmental change at population and community levels to establish baselines of organismal responses to natural ecosystem perturbations. However, to accomplish this, it is first necessary to quantify the strengths and limitations of paleontological data in these systems and maximize data resolution to mitigate erroneous interpretations. The main data types I focus on improving here are those of taxonomic fidelity and age control. The first three chapters of my dissertation focus on the former, using morphometric techniques to improve identification accuracy of closely related and morphologically similar species, thus extending paleoecological data resolution from genus to species for several taxa. The last two chapters of my dissertation focus on the latter, examining paleoecological data at various levels of temporal precision using a combination of radiocarbon-dated and time-averaged data to determine how analytical results and conclusions are affected by time-averaging. Once these limitations have been quantified and mitigated to the extent possible, I determine how the focal taxa of my study system were impacted by long-term environmental changes using multidisciplinary approaches. Chapter 3 focuses on intraspecific phenotypic responses to climate change using geometric morphometrics, Chapter 4 evaluates long-term changes in biotic community structure using diversity and trait metrics, and Chapter 5 quantifies the relative impacts of climate and biotic interactions on species niches over the last 50,000 years using stable isotope analysis. My study system for addressing all these topics is Rancho La Brea (RLB), a world renowned late Quaternary paleontological locality in Los Angeles, California, USA. I specifically examine the small mammals (e.g., rodents, lagomorphs, and soricomorphs) of this locality because they are ubiquitous across most Quaternary fossil assemblages, thus facilitating large sample sizes. In addition, small mammals are generally short lived and confined to small home ranges, so I am relatively certain that the paleoecological signals I track within samples are local and geologically instantaneous rather than substantially spatially or temporally averaged. Results of the three taxonomic studies indicate that, although closely related and speciose small mammals are difficult to differentiate due to morphological variation and overlap, they can be identified to species with relatively good accuracy, usually> 80%, using quantitative techniques including morphometric and geometric morphometric measurements and statistical grouping analyses (Chapters 1-3). However, results can deviate considerably if data acquisition processes are not standardized. For example, geometric morphometric data collected by different personnel and, to a lesser extent, with different instruments can generate substantially different classification statistics (Chapter 2). It is therefore recommended that data acquisition procedures are standardized as much as possible to facilitate analytical replicability. Comparisons of time-averaged trait datasets (Chapters 4 and 5) to those with good age control (Chapter 5) further show that much information can be lost from geologically rapid events when data is time-averaged or time-binned versus continuous data. Such loss of information can then result in profoundly different interpretations regarding the probable drivers of observed paleoecological patterns (Chapter 5). With these insights and limitations in mind, I show that local environments of RLB during the last glacial period (specifically Marine Isotope Stage (MIS) 3, ~60,000 to 29,000 years BP) were generally similar to that of the Los Angeles Basin today based on overall similarities between contemporary and fossil small mammal faunas (Chapter 4). Changes in taxonomic abundances and trait diversity among deposits of different mean ages suggest that the small mammal communities of RLB were responding to slight or moderate changes in temperature and precipitation during that time (Chapter 4). Unfortunately, precise information on the timing and pattern of environmental changes cannot be discerned at the community level due to the time-averaged nature of the deposits and faunas examined, combined with the variable climates during MIS 3. By subsequently examining the isotopic niches of individually-dated specimens, however, it becomes clear that geologically rapid environmental changes were occurring at RLB throughout the late Quaternary that largely reflect regional climate patterns (Chapter 5). Further, the isotopic niches of small mammals appear to be shaped more strongly by those climatic oscillations than by biotic interactions over the last 50,000 years. Insights on the paleoenvironments of RLB (Chapter 4) and climatic changes that likely occurred there during the late Quaternary (Chapter 5) have significant implications for studies of other RLB biota in that species responses to changing environments can be better contextualized now that those changes are better understood. In a broader context, my work quantifying geometric morphometric error (Chapter 2) and time-averaging error (Chapter 5) may facilitate best practices protocols for similar study systems. Finally, my taxonomic identification protocols for lagomorphs (Chapter 1) and woodrats (Chapter 3) should be useful for other small mammal studies because lagomorph remains are common at most late Quaternary sites and woodrat species are good indicators of paleoecological conditions and change.
Fritz Höger
Author: The Great Ordovician Biodiversification Event
Author: Barry D. WebbyPublisher: Columbia University Press
ISBN: 0231501633
Category : Science
Languages : en
Pages : 497
Book Description
Two of the greatest evolutionary events in the history of life on Earth occurred during Early Paleozoic time. The first was the Cambrian explosion of skeletonized marine animals about 540 million years ago. The second was the "Great Ordovician Biodiversification Event," which is the focus of this book. During the 46-million-year Ordovician Period (489–443 m.y.), a bewildering array of adaptive radiations of "Paleozoic- and Modern-type" biotas appeared in marine habitats, the first animals (arthropods) walked on land, and the first non-vascular bryophyte-like plants (based on their cryptospore record) colonized terrestrial areas with damp environments. This book represents a compilation by a large team of Ordovician specialists from around the world, who have enthusiastically cooperated to produce this first globally orientated, internationally sponsored IGCP (International Geological Correlation Program) project on Ordovician biotas. The major part is an assembly of genus- and species-level diversity data for the many Ordovician fossil groups. The book also presents an evaluation of how each group diversified through Ordovician time, with assessments of patterns of change and rates of origination and extinction. As such, it will become the standard work and data source for biotic studies on the Ordovician Period.
Cyanobacterial Harmful Algal Blooms: State of the Science and Research Needs
Author: H. Kenneth HudnellPublisher: Springer Science & Business Media
ISBN: 0387758658
Category : Medical
Languages : en
Pages : 955
Book Description
With the ever-increasing incidence of harmful cyanobacterial algal blooms, this monograph has added urgency and will be essential reading for all sorts of researchers, from neuroscientists to cancer research specialists. The volume contains the proceedings of the 2005 International Symposium on Cyanobacterial Harmful Algal Blooms, and has been edited by H. Kenneth Hudnell, of the US Environmental Protection Agency. It contains much of the most recent research into the subject.
An Introduction to Population Ecology
Author: George Evelyn HutchinsonPublisher:
ISBN:
Category : Biotic communities.
Languages : en
Pages : 260
Book Description
Discusses how to construct mathematical models of populations, the changing proportions of individuals of various ages, birthrate, the ecological niche, and population interaction in this technical introduction to population ecology
Paleontology in Ecology and Conservation
Author: Julien LouysPublisher: Springer Science & Business Media
ISBN: 3642250386
Category : Science
Languages : en
Pages : 277
Book Description
The fossil record contains unique long-term insights into how ecosystems form and function which cannot be determined simply by examining modern systems. It also provides a record of endangered species through time, which allow us to make conservation decisions based on thousands to millions of years of information. The aim of this book is to demonstrate how palaeontological data has been or could be incorporated into ecological or conservation scientific studies. This book will be written by palaeontologists for modern ecologists and conservation scientists. Manuscripts will fall into one (or a combination) of four broad categories: case studies, review articles, practical considerations and future directions. This book will serve as both a ‘how to guide’ and provide the current state of knowledge for this type of research. It will highlight the unique and critical insights that can be gained by the inclusion of palaeontological data into modern ecological or conservation studies.
Ordovician of the World
Author: Diego García-Bellido CapdevilaPublisher: IGME
ISBN: 9788478408573
Category : Geology, Stratigraphic
Languages : en
Pages : 692
Book Description