Explore the new worlds of these alien species with this collection of resources. Biodiversity refers to the variety of organisms found in a particular habitat.
It is important to maintain biodiversity because we rely on it for ecosystem services, which fall into four main categories: provisioning, regulating, cultural, and supporting.
The earth provides these to us for free and they are critical to achieving a planet in balance. Use these resources to explore the diverse species that exist across the globe, and encourage your students to become good stewards of life on earth. An endangered species is a type of organism that is threatened by extinction. Species become endangered for two main reasons: loss of habitat and loss of genetic variation.
Join our community of educators and receive the latest information on National Geographic's resources for you and your students. Skip to content. Image polar bear The polar bear is the largest modern species of bear, and lives predominately on sea ice in the frigid Arctic, and can be found in the northern United States, Canada, Russia, Greenland, and Norway. Photograph by Rebecca R. Twitter Facebook Pinterest Google Classroom. Encyclopedic Entry Vocabulary. Media Credits The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit.
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Related Resources. Invasive Species. For example, the darker anubis fur that some hybrids have may overheat baboons in pure-yellow territory, which tends to be hotter, drier and more savannah-like compared with mountainous forests of pure-anubis land. If so, it suggests that hybridization between hominins may also have been useful in some environments and societies, but not others. Ackermann also researches baboons, but hers are dead.
An expert in skeletal anatomy, she got interested in hybridization in the early s while studying bones from baboons with known pedigrees. She hoped to find skeletal features that result from interbreeding in general, which could be used to spot hybrids among human fossils. It was a provocative goal, years before genetic methods would confirm hominin hybridization even took place.
Because she focuses on visible skeletal traits, Ackermann can potentially identify hybrid fossils spanning the more than 6 million-year history of hominins. Measuring skulls from yellow, anubis and hybrid baboons that had lived in captivity, she found that hybrids are not simply intermediates of the parent species.
They do, however, frequently have abnormalities such as extra or misaligned teeth. Ackermann found the same developmental quirks across diverse mammal groups such as wildebeests and gorillas. Then she applied her method to human ancestors. Anthropologists have long debated whether particular hominin fossils could represent hybrids, but usually based their arguments on the unfounded assumption that hybrids resemble intermediates, or averages, of their parents.
In a study, Ackermann used developmental anomalies to suggest hybrid candidates, such as ,year-old Neanderthals from Croatia with abnormal premolars and ,year-old modern humans from Israel with traits such as misaligned teeth and an asymmetric face. She also included a 35,year-old anatomically modern human skull from Romania. Ackermann and her colleagues want to know how common these development quirks are among hybrids, and whether they persist in subsequent generations.
Her colleagues at the University of Calgary bred several generations of mice from three subspecies and two species for the project. Offspring can resemble one parent or a blend — or take on forms unlike either parent.
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