This chapter details the geography and ecology of the Mesozoic period. It explains that the Mesozoic period was a time of major diversification and radiation, leading to large-scale changes in flora and fauna by the end of the era. In Mesozoic oceans, neoselachians diversified, while the total diversity of tetrapods changed relatively slowly. Meanwhile, lissamphibians evolved and the two major lineages of amniotes diversified into Synapsida and Sauropsida. The chapter highlights how the era's history of extinction events opened the way for a new faunal balance in the Cenozoic period. Most Mesozoic extinction events resulted from intense episodes of volcanic activity accompanying collisions and splitting of continents as Pangaea formed and later ruptured.
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Chapter
Geography and Ecology of the Mesozoic
Chapter
Defining Conservation Biology
This chapter provides a background of conservation biology. Human activities are causing the extinction of thousands of species both locally and globally, with threats to species and ecosystems accelerating due to human population growth and the associated demands for resources. Conservation biology is a field that combines basic and applied disciplines with three goals: to describe the full range of biodiversity on Earth; to understand human impact on biodiversity; and to develop practical approaches for preventing species extinctions, maintaining genetic diversity, and protecting and restoring ecosystems. It rests on a number of underlying assumptions that are accepted by most professionals in the discipline: biodiversity has value in and of itself; extinction from human causes should be prevented; diversity at multiple levels should be preserved; science plays a critical role, and scientists must collaborate with nonscientists to achieve their goals. Ultimately, the conservation of biodiversity has become an international undertaking.
Chapter
Speciation and Extinction
This chapter examines the processes of speciation and extinction. It shows that dispersal has highly influenced processes of evolution and extinction. It argues that it has a strong geographic context. If the rate of extinction exceeds the rate of speciation, the group diversity decreases, and all or nearly all of its representatives go extinct. Essentially, the living and extinct organisms on Earth have been produced through repeated cycles of rapid bursts of speciation following an abrupt mass extinction with the underlying dynamics of the Earth's geographic, geological, and climatic templates. The chapter also covers the notions of macroevolution and microevolution identifying changes of contrasting magnitudes and scales of time in line with the change of species level.
Book
Mark V. Lomolino, Brett R. Riddle, and Robert J. Whittaker
Biogeography, which is in its fifth edition, provides an explanation of how geographic variation across terrestrial and marine environments has influenced the fundamental processes of immigration, extinction, and evolution to shape species distributions and nearly all patterns of biological diversity. This edition builds on the strengths of previous editions to illustrate general patterns and processes using examples from a broad diversity of life forms, time periods, and aquatic and terrestrial ecosystems.
Chapter
Turtles
This chapter notes the unique structure of turtles. The unique body form of turtles makes them immediately recognizable, but their anatomical rearrangements have obscured morphological characteristics which are used to determine evolutionary affinities among other vertebrates. The shells of different turtle species reveal their habitat and lifestyle of living in terrestrial, freshwater and marine environments. The chapter discusses the form, diversity, social behavior, reproduction, and migration of turtles. It then acknowledges how more than half of the extant species of turtles are facing extinction as they are not safe from humans even though they are relatively safe from natural predators.
Chapter
Therians
This chapter tackles the evolutionary history of Theria and its two clades, Marsupalia and Eutheria. Therians are viviparous amniotes which give birth to young after a period of internal gestation. Although most therians are terrestrial, there are also therians with burrowing, aquatic, and flying forms. Thus, the evolution of these different ways of life led to corresponding diversity in anatomy, body size, and ecology, as well as many striking cases of convergent evolution. The chapter considers the diversity of Metatheria and Eutheria in relation to the key elements of therian reproductive biology and specializations for feeding and locomotion. It notes how mammals front extinction risk at the hands of humans, which includes habitat loss and the introduction of alien species.
Book
An Introduction to Conservation Biology provides up-to-date perspectives on high-profile issues such as sustainable development, global warming, and strategies to save species on the verge of extinction. The book focuses on biological diversity and its value; threats to biological diversity; conservation at the population and species levels; protecting, managing, and restoring ecosystems; and sustainable development. Each chapter is illustrated with diverse examples from the current literature. Throughout, the text maintains a focus on the active role that scientists, local people, conservation organizations, government, and the general public play in protecting biodiversity, even while providing for human needs. The last chapter, crucially, looks at presenting an agenda for the future.
Chapter
Biodiversity and Conservation of the Ocean
This chapter looks at the notion of biodiversity and the conservation of the ocean. It explores patterns of biological diversity from the broader perspectives of evolution, extinction, and biogeography. Regional variation in geography and climate influences the origin of species, and also the degree of geographic structuring of the world into assemblages of species. The chapter then elaborates on factors of diversity, speciation, extinction, and biography in the ocean. It explains how many marine invasions are facilitated by human transport, referencing the subsequent local extinctions and homogenization of marine biot after the introduction of new species. Thus, conservation genetics play a role in identifying both species and genetically distinct populations.
Chapter
Climate Change and Other Threats to Biodiversity
This chapter addresses the other four major threats to biodiversity: climate change, overexploitation, invasive species, and disease. Global climate change, including warmer temperatures and changing precipitation patterns, is already occurring because of the large amounts of carbon dioxide and other greenhouse gases produced by the burning of fossil fuels and deforestation. Meanwhile, overexploitation is driving many species to extinction and can consequently undermine entire ecosystems. It is the result of increasingly efficient methods of harvesting and marketing, increasing demand for products, and increased access to remote areas. Humans have deliberately and accidentally moved thousands of species to new regions of the world. Some of these nonnative species have become invasive, greatly increasing their numbers at the expense of native species. Ultimately, species may be threatened by a combination of factors, all of which must be addressed in a comprehensive conservation plan.
Chapter
Extinction Risk
This chapter evaluates the problem of extinction. Many species are currently on the brink of extinction due to increasing human activity; this is well documented in the well-studied groups of birds, mammals, and amphibians. Island species have had a higher rate of extinction than mainland species, due to small population sizes and less previous exposure to humans and mainland species. The island biogeography model is used to predict the numbers of species that will persist in new protected areas and the numbers that will go extinct elsewhere due to habitat destruction and other human activities. Those species that are most vulnerable to extinction have particular features, including a narrow range, one or only a few populations, small population size, declining population size, and economic value to humans that leads to overexploitation. Small populations are vulnerable to further declines in size and eventual extinction due to genetic, demographic, and environmental factors.
Chapter
The History of Life
This chapter explores the history of life by studying fossils. Fossils provide direct
evidence of events of extinction, diversification, and the movement of continents and
climate that affected species. Moreover, evidence from living organisms indicates that all
living things are descended from a single common ancestor. The chapter then details the
history of the Cenozoic era, Mesozoic era, Paleozic era, and Precambrian era. It explains
how the most devastating mass extinction at the end of the Permian resulted in the massive
alteration of the taxonomic composition of the Earth's biota. Human population growth
and technology also had an accelerating impact on biological diversity and major
extinction.
Chapter
Conservation, Ecology, and Science
This chapter discusses the relationship between conservation, ecology, and science. The big problem facing human beings, and all other organisms on the planet, is that the ecological footprint of humans—the area of biologically productive land needed per person per year to sustain their lifestyles—exceeds the ability of the Earth to support it. This environmental crisis will drive many species to extinction. The extent to which these extinctions matter depends on what the species actually do in ecosystems. The chapter then looks at the importance of biodiversity. Apart from dealing with living evolving organisms that are individually different, there are other important aspects of ecology (and hence conservation) as a science. Some of these are: that it involves the hierarchical structure of nature; that it involves huge changes of scale; and that there are many different kinds of explanations for the same thing.
Chapter
Rarity and Extinction
This chapter examines the consequences of changes in the size of a patch of suitable habitat. Reductions in island or habitat area lead to extinction of some of the populations because of the reduced resources and increased isolation. Meanwhile, habitat fragmentation leads to an extinction debt because it takes time for populations to die out. Creating corridors between isolated patches can help prevent some extinctions, but they cannot abolish them entirely. Setting aside nature reserves for conservation is obviously a good thing to do, but it will also not be enough as the reserves become isolated patches of natural habitat in a sea of man-made agricultural or urban landscapes. Ultimately, a landscape approach to conservation is needed for it to be successful.
Chapter
What Processes Create Ecological Communities?
This chapter focuses on four processes at work in ecological communities. These are selective forces (competition, predation, and coevolution) that modify the characteristics of populations and species, and/or determine their presence in a community; ecological drift, i.e. random chance that affects small populations in particular, that might lead to extinction or immigration events; speciation; and dispersal. On the large scale, the relative importance of these processes is not the same as on the small scale. The species richness of local communities depends on large-scale species richness via the processes of dispersal, and abiotic and biotic filtering. The chapter then considers the idea of the 'balance of Nature'.
Chapter
Introducing Evolution
This chapter introduces the theory of evolution, which sparked concepts of competition, struggle, uncertainty, and random chance before it became the major unifying principle of biological sciences. The crucial concept of species is constantly referred to in discussions around this theory. Selection is the driver behind the evolution of species, while natural selection leads to the speciation and extinction of species. The chapter lists the different types of selection: stabilizing selection, sexual selection, disruptive selection, and directional selection. It also highlights the foundational works of Charles Darwin and Gregor Mendel establishing the field of evolution. The birth and death of species, through these works, came to be understood as central to the evolution of life on Earth.
Chapter
The Birth and Death of Species
This chapter focuses on the birth and death of species, which has been referred to be the nature of evolution. It also notes the modern classification system based on Linnaeus' Systema Naturae, a framework featuring genus and kingdoms of species. The chapter also notes how reproduction isolation is required for speciation. Genetic isolation is the result of a physical or geographical barrier to gene flow during the process of allopatric speciation. Sympatric speciation is involved in the emergence of hybrids, especially among plant species. Extinction, the chapter explains, is an essential part of evolution as new niches and set of speciation take over.
Chapter
What is the future of biodiversity?
This chapter examines extinction and biodiversity loss. Extinction is one of the key processes that have shaped the history of life and the development of biodiversity. Currently, species declines and extinctions appear to be happening much more rapidly than at any time in geological history as a result of the way human activity is modifying the world's natural systems. There is widespread international consensus that action is needed to prevent further extinctions and mitigate ongoing loss of biodiversity. To develop effective strategies for conservation, we need to understand how biodiversity is distributed (phylogenetically and spatially), we need objective methods to quantify the speed and extent of biodiversity loss, and we need an understanding of the processes that cause the loss of biodiversity. In developing this kind of big-picture view of conservation, we can make use of some of the tools and knowledge gained from the study of macroevolution and macroecology.
Chapter
Conservation genetics
The chapter looks into conservation genetics as a method used to mitigate extinction. It explains how molecular genetics is used in conservation biology. Molecular systemics are great assets in wildlife forensic investigations. PCR technology enables genetic studies to be conducted on rare species. The chapter notes careful evaluation is needed as neutral estimates of genetic diversity sometimes differ from measures of adaptive variation. Next, the chapter explores the basis and impact of inbreeding and captive breeding in relation to the genetic load of smaller populations. The chapter expounds on the concept of plant and animal conservations as well. De-extinction, meanwhile, is regarded as only a movie concept.
Chapter
The Evidence for Evolution
This chapter provides an overview of the science of evolution, which explains how the vast diversity of living things is governed by a few simple natural principles. The outward diversity of animals and plants is based on a very restricted range of materials, body plans, power sources, and instructions, relative to those we use in everyday life. Evolution is modification through descent. All organisms are similar, not because they have been perfectly engineered, but rather because they all descend from the same common ancestor. The chapter is concerned mainly with descent—how we know that the diversity of living forms springs from a single root. The chapter then introduces the concepts of extinction, adaptation, development, sex, and diversity.
Chapter
The Origin of Species
This chapter assesses how lineages that acquire new genes evolve into new species. Lineages always tend to change because they adapt to new conditions of growth or evolve different ways of mating. In time, they may become sufficiently different from their ancestor to be recognized as a distinct species. The chapter then looks at how diversification is the natural tendency of lineages; how populations that are permanently separated may diverge through drift or selection; and how divergent selection leads to more or less strongly marked varieties. It also considers how species are recognized when ecologically distinctive forms become sexually isolated; how rapid speciation gives rise to swarms of sister species; and how diversity is the dynamic equilibrium between the origin and extinction of species.
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