Extinction in the context of "Trinidad piping guan"

An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp fall in the diversity and abundance of multicellular organisms. It occurs when the rate of extinction increases with respect to the background extinction rate and the rate of speciation.

Estimates of the number of major mass extinctions in the last 540 million years range from as few as five to more than twenty. These differences stem from disagreement as to what constitutes a "major" extinction event, and the data chosen to measure past diversity.

Paleontology or palaeontology is the scientific study of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geologic time, and assess the interactions between prehistoric organisms and their natural environment. While paleontological observations are known from at least the 6th century BC, the foundation of paleontology as a science dates back to the work of Georges Cuvier in 1796. Cuvier demonstrated evidence for the concept of extinction and how the life of the past was not necessarily the same as that of the present. The field developed rapidly over the course of the following decades, and the French word paléontologie was introduced for the study in 1822, which was derived from the Ancient Greek word for 'ancient' and words describing relatedness and a field of study. Further advances in the field accompanied the work of Charles Darwin who popularized the concept of evolution. Together, evolution and extinction can be understood as complementary processes that shaped the history of life.

Paleontology overlaps the most with the fields of geology and biology. It draws on technology and analysis of a wide range of sciences to apply them to the study of life and environments of the past, particularly for the subdisciplines of paleobiology and paleoecology that are analogous to biology and ecology. Paleontology also contributes to other sciences, being utilized for biostratigraphy to reconstruct the geologic time scale of Earth, or in studies on extinction to establish both external and internal factors that can lead to the disappearance of a species. Much of the history of life is now better understood because of advances in paleontology and the increase in interdisciplinary studies. Several improvements in understanding have occurred from the introduction of theoretical analysis to paleontology in the 1950s and 1960s which led to the rise of more focused fields of paleontology that assess the changing geography and climate of Earth, the phylogenetic relationships between different species, and the analysis of how fossilization occurs and what biases can impact the quality of the fossil record.

Biodiversity loss happens when species disappear completely from Earth (extinction) or when there is a decrease or disappearance of species in a specific area. Biodiversity loss means that there is a reduction in biological diversity in a given area. The decrease can be temporary or permanent. It is temporary if the damage that led to the loss is reversible in time, for example through ecological restoration. If this is not possible, then the decrease is permanent. The cause of most of the biodiversity loss is, generally speaking, human activities that push the planetary boundaries too far. These activities include habitat destruction (for example deforestation) and land use intensification (for example monoculture farming). Further problem areas are air and water pollution (including nutrient pollution), over-exploitation, invasive species and climate change.

Many scientists, along with the Global Assessment Report on Biodiversity and Ecosystem Services, say that the main reason for biodiversity loss is a growing human population because this leads to human overpopulation and excessive consumption. Others disagree, saying that loss of habitat is caused mainly by "the growth of commodities for export" and that population has very little to do with overall consumption. More important are wealth disparities between and within countries. In any case, all contemporary biodiversity loss has been attributed to human activities.

Environmental degradation is the deterioration of the environment through depletion of resources such as quality of air, water and soil; the destruction of ecosystems; habitat destruction; the extinction of wildlife; and pollution. It is defined as any change or disturbance to the environment perceived to be deleterious or undesirable. The environmental degradation process amplifies the impact of environmental issues which leave lasting impacts on the environment.

Environmental degradation is one of the ten threats officially cautioned by the High-level Panel on Threats, Challenges and Change of the United Nations. The United Nations International Strategy for Disaster Reduction defines environmental degradation as "the reduction of the capacity of the environment to meet social and ecological objectives, and needs".

Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, the Cape sugarbird (Promerops cafer) is found exclusively in southwestern South Africa and is therefore said to be endemic to that particular part of the world. An endemic species can also be referred to as an endemism or, in scientific literature, as an endemite.

Endemism is an important concept in conservation biology for measuring biodiversity in a particular place and evaluating the risk of extinction for species. Endemism is also of interest in evolutionary biology, because it provides clues about how changes in the environment cause species to undergo range shifts (potentially expanding their range into a larger area or becoming extirpated from an area they once lived), go extinct, or diversify into more species.

The history of biology traces the study of the living world from ancient to modern times. Although the concept of biology as a single coherent field arose in the 19th century, the biological sciences emerged from traditions of medicine and natural history reaching back to Ayurveda, ancient Egyptian medicine and the works of Aristotle, Theophrastus and Galen in the ancient Greco-Roman world. This ancient work was further developed in the Middle Ages by Muslim physicians and scholars such as Avicenna. During the European Renaissance and early modern period, biological thought was revolutionized in Europe by a renewed interest in empiricism and the discovery of many novel organisms. Prominent in this movement were Vesalius and Harvey, who used experimentation and careful observation in physiology, and naturalists such as Linnaeus and Buffon who began to classify the diversity of life and the fossil record, as well as the development and behavior of organisms. Antonie van Leeuwenhoek revealed by means of microscopy the previously unknown world of microorganisms, laying the groundwork for cell theory. The growing importance of natural theology, partly a response to the rise of mechanical philosophy, encouraged the growth of natural history (although it entrenched the argument from design).

Over the 18th and 19th centuries, biological sciences such as botany and zoology became increasingly professional scientific disciplines. Lavoisier and other physical scientists began to connect the animate and inanimate worlds through physics and chemistry. Explorer-naturalists such as Alexander von Humboldt investigated the interaction between organisms and their environment, and the ways this relationship depends on geography—laying the foundations for biogeography, ecology and ethology. Naturalists began to reject essentialism and consider the importance of extinction and the mutability of species. Cell theory provided a new perspective on the fundamental basis of life. These developments, as well as the results from embryology and paleontology, were synthesized in Charles Darwin's theory of evolution by natural selection. The end of the 19th century saw the fall of spontaneous generation and the rise of the germ theory of disease, though the mechanism of inheritance remained a mystery.

The Anatidae are the biological family of water birds that includes ducks, geese, and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica. These birds are adapted for swimming, floating on the water surface, and, in some cases, diving in at least shallow water. The family contains around 174 species in 43 genera (the magpie goose is no longer considered to be part of the Anatidae and is now placed in its own family, Anseranatidae).

They are generally herbivorous and are monogamous breeders. A number of species undertake annual migrations. A few species have been domesticated for agriculture, and many others are hunted for food and recreation. Five species have become extinct since 1600, and many more are threatened with extinction.

Overfishing is the removal of aquatic animals — primarily fish — from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stocks), resulting in the species becoming increasingly underpopulated in that area. Excessive fishing practices can occur in water bodies of any sizes, from ponds, wetlands, rivers, lakes to seas and oceans, and can result in resource depletion, reduced biological growth rates and low biomass levels. Sustained overfishing, especially industrial-scale commercial fishing, can lead to critical depensation, where the fish population is no longer able to sustain itself, resulting in extirpation or even extinction of species. Some forms of overfishing, such as the overfishing of sharks, has led to the upset of entire marine ecosystems. Types of overfishing include growth overfishing, recruitment overfishing, and ecosystem overfishing. Overfishing not only causes negative impacts on biodiversity and ecosystem functioning, but also reduces fish production, which subsequently leads to negative social and economic consequences.

The ability of a fishery to recover from overfishing depends on whether its overall carrying capacity and the variety of ecological conditions are suitable for the recovery. Dramatic changes in species composition can result in an ecosystem shift, where other equilibrium energy flows involve species compositions different from those that had been present before the depletion of the original fish stock. For example, once trout have been overfished, carp might exploit the change in competitive equilibria and take over in a way that makes it impossible for the trout to re-establish a breeding population.

There are several plausible pathways that could lead to plant and animal species extinction from climate change. Every species has evolved to exist within a certain ecological niche, but climate change leads to changes of temperature and average weather patterns. These changes can push climatic conditions outside of the species' niche, and ultimately render it extinct. Normally, species faced with changing conditions can either adapt in place through microevolution or move to another habitat with suitable conditions. However, the speed of recent climate change is very fast. Due to this rapid change, for example cold-blooded animals (a category which includes amphibians, reptiles and all invertebrates) may struggle to find a suitable habitat within 50 km of their current location at the end of this century (for a mid-range scenario of future global warming).

Climate change also increases both the frequency and intensity of extreme weather events, which can directly wipe out regional populations of species. Those species occupying coastal and low-lying island habitats can also become extinct by sea level rise. This has already happened with Bramble Cay melomys in Australia. Finally, climate change has been linked with the increased prevalence and global spread of certain diseases affecting wildlife. This includes Batrachochytrium dendrobatidis, a fungus that is one of the main drivers of the worldwide decline in amphibian populations.

This page features lists of species and organisms that have become extinct. The reasons for extinction range from natural occurrences, such as shifts in the Earth's ecosystem or natural disasters, to human influences on nature by hunting and destruction of natural habitats.

A species is presumed to be extinct after surveys of its expected and historical habitat demonstrates an inability to locate an individual. Species which meet this criteria but are known to be kept in captivity are extinct in the wild. If a final specimen of a moribund species is found, it is an endling.