Islands do not make up a large area of land on the globe, but they do contain a disproportionate number of endemic species because of their isolation from mainland ancestors. It now appears that the global decline in amphibian species recognized in the s is, in some part, caused by the fungus Batrachochytrium dendrobatidis , which causes the disease chytridiomycosis. There is evidence that the fungus, native to Africa, may have been spread throughout the world by transport of a commonly-used laboratory and pet species: the African clawed toad Xenopus laevis.
It may well be that biologists themselves are responsible for spreading this disease worldwide. The North American bullfrog, Rana catesbeiana , which has also been widely introduced as a food animal, but which easily escapes captivity, survives most infections of Batrachochytriumdendrobatidis and can act as a reservoir for the disease.
The global warming trend is recognized as a major biodiversity threat, especially when combined with other threats such as habitat loss. Climate change, specifically, the anthropogenic caused by humans warming trend presently underway, is recognized as a major extinction threat, particularly when combined with other threats such as habitat loss.
Scientists disagree about the probable magnitude of the effects, with extinction rate estimates ranging from 15 percent to 40 percent of species by Scientists do agree, however, that climate change will alter regional climates, including rainfall and snowfall patterns, making habitats less hospitable to the species living in them. Grizzly-polar bear hybrid : Since , grizzly bears Ursus arctos horribilis have been spotted farther north than their historic range, a possible consequence of climate change.
As a result, grizzly bear habitat now overlaps polar bear Ursus maritimus habitat. The two kinds of bears, which are capable of mating and producing viable offspring, are considered separate species as historically they lived in different habitats and never met. However, in a hunter shot a wild grizzly-polar bear hybrid known as a grolar bear, the first wild hybrid ever found. The warming trend will shift colder climates toward the north and south poles, forcing species to move with their adapted climate norms while facing habitat gaps along the way.
The shifting ranges will impose new competitive regimes on species as they find themselves in contact with other species not present in their historic range. One such unexpected species contact is between polar bears and grizzly bears.
Previously, these two species had separate ranges. Now, with their ranges are overlapping, there are documented cases of these two species mating and producing viable offspring. Many contemporary mismatches to shifts in resource availability and timing have recently been documented. Range shifts are already being observed. The same study suggests that the optimal shift based on warming trends was double that distance, suggesting that the populations are not moving quickly enough.
Range shifts have also been observed in plants, butterflies, other insects, freshwater fishes, reptiles, and mammals. Climate gradients will also move up mountains, eventually crowding species higher in altitude and eliminating the habitat for those species adapted to the highest elevations.
Some climates will completely disappear. The rate of warming appears to be accelerated in the arctic, which is recognized as a serious threat to polar bear populations that require sea ice to hunt seals during the winter months; seals are the only source of protein available to polar bears. A trend to decreasing sea ice coverage has occurred since observations began in the mid-twentieth century. The rate of decline observed in recent years is far greater than previously predicted by climate models.
Finally, global warming will raise ocean levels due to glacial melt and the greater volume of warmer water. Shorelines will be inundated, reducing island size, which will have an effect on many species; a number of islands will disappear entirely. Additionally, the gradual melting and subsequent refreezing of the poles, glaciers, and higher elevation mountains, a cycle that has provided freshwater to environments for centuries, will also be jeopardized.
This could result in an overabundance of salt water and a shortage of fresh water. Privacy Policy. Skip to main content. Conservation Biology and Biodiversity. Search for:. Threats to Biodiversity. Habitat Loss and Sustainability Through increased adoption of sustainable practices, we can reduce habitat loss and its consequences.
Learning Objectives Describe the effects of habitat loss to biodiversity and concept of sustainability. Key Takeaways Key Points Habitat destruction renders entire habitats functionally unable to support the species present; biodiversity is reduced in this process when existing organisms in the habitat are displaced or destroyed. Clearing areas for agricultural purposes is the main cause of habitat destruction; other principal causes include mining, logging, and urban sprawl.
The primary cause of species extinction worldwide is habitat destruction. Sustainability is a term that describes how biological systems remain diverse and productive over time, creating the potential for long-term maintenance of human well-being. Reducing negative human impact requires three concepts: environmental management, management of human consumption of resources, and awareness of cultural and political concerns to increase sustainability.
Key Terms sustainability : Configuring society so that each person can meet their own needs and greatest potential, while preserving biodiversity and natural ecosystems, and planning for future generations to maintain this potential. Overharvesting Overharvesting threatens biodiversity by degrading ecosystems and eliminating species of plants, animals, and other organisms.
Learning Objectives Explain why overharvesting is a threat to biodiversity. Key Takeaways Key Points Until recently, human populations harvested resources in limited quantities. Today, new methods of harvest and capture contribute to overharvesting and overexploitation. Overharvesting stems from several factors, including an exponential increase in the human population, expanding markets, increasing demand, and improved access and techniques for capture.
Overharvesting natural resources for extended periods of time depletes these resources until they cannot recover within a short period of time; some may never recover. Overharvesting is one of five primary activities threatening global biodiversity; others include pollution, introduced species, habitat fragmentation, and habitat destruction.
Sci Rep Bioscience — Thompson PL, Rayfield B, Gonzalez A Loss of habitat and connectivity erodes species diversity, ecosystem functioning, and stability in metacommunity networks. PLoS Biol — CAS Google Scholar. Wardle DA The influence of island area on ecosystem properties. Wardle DA Do experiments exploring plant diversity-ecosystem functioning relationships inform how biodiversity loss impacts natural ecosystems?
Front Ecol Environ — Wardle DA, Zackrisson O Effects of species and functional group loss on island ecosystem properties. Wu JG Ecological dynamics in fragmented landscapes. Wu J a Landscape sustainability science: ecosystem services and human well-being in changing landscapes. Wu J b Key concepts and research topics in landscape ecology revisited: 30 years after the Allerton Park workshop. Wu J, Loucks OL From balance of nature to hierarchical patch dynamics: a paradigm shift in ecology.
Q Rev Biol — Download references. You can also search for this author in PubMed Google Scholar. Correspondence to Mingjian Yu. Reprints and Permissions. Liu, J. How does habitat fragmentation affect the biodiversity and ecosystem functioning relationship?. Landscape Ecol 33, — Download citation. Received : 28 September Accepted : 07 February Published : 15 February Issue Date : March Anyone you share the following link with will be able to read this content:.
Sorry, a shareable link is not currently available for this article. Provided by the Springer Nature SharedIt content-sharing initiative. Skip to main content. Search SpringerLink Search. Abstract Context The relationship between biodiversity and ecosystem functioning BEF has been a central topic in ecology for more than 20 years.
Objectives To develop a framework that connects habitat fragmentation to the BEF relationship from a landscape perspective. Methods We reviewed the literature on habitat fragmentation, BEF, and related fields, and developed a framework to analyze how habitat fragmentation affects the BEF relationship through altering biodiversity, environmental conditions, and both, based on the pattern-process-scale perspective in landscape ecology.
Results Our synthesis of the literature suggests that habitat fragmentation can alter BEF relationship through several processes. Conclusions Habitat fragmentation can affect the BEF relationship directly by altering community composition, as well as indirectly by changing environmental conditions within and among habitat patches on both local and landscape levels.
Landscape Ecol — Article Google Scholar Huston MA Hidden treatments in ecological experiments: re-evalutating the ecosystem function of biodiverstiy.
Divers Distrib — Article Google Scholar Loreau M Linking biodiversity and ecosystems: towards a unifying ecological theory. Increasing food production is a major agent for the conversion of natural habitat into agricultural land. Why is it happening? Forest loss and degradation is mostly caused by the expansion of agricultural land, intensive harvesting of timber, wood for fuel and other forest products, as well as overgrazing.
High land conversion rates The net loss in global forest area during the s was about 94 million ha equivalent to 2. Around half of the world's original forests have disappeared, and they are still being removed at a rate 10x higher than any possible level of regrowth.
As tropical forests contain at least half the Earth's species, the clearance of some 17 million hectares each year is a dramatic loss. Coastal and marine areas Human impact on terrestrial and marine natural resources results in marine and coastal degradation. Population growth, urbanization, industrialization and tourism are all factors. Poverty, consumption and land-use patterns contribute to the degradation of marine habitats and to the destruction of the species that rely on them to survive.
Great Barrier Reef Marine Park, Australia, is a network of fully protected areas within a larger protected area, designed to protect all habitats in the region.
Although recent government figures in Brazil show a reduction in the rate of deforestation this year in the Amazon, burning rainforest to create pastureland for ranching and other agricultural activities continues. Amazon, Brazil. Palm oil plantations in the tropical regions of Africa, Latin America, and Asia have led the large scale destruction of important habitat for many species.
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