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from article Camel
Bactrian camel (Camelus bactrianus). (Photo courtesy of Brent Huffman, Ultimate Ungulate Images)
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from article Plant communication
Hillsides in central California covered by hard chaparral composed almost entirely of chemise shrubs. Chemise (also spelled chamise) produces allelopathic chemicals that, through plant communication, inhibit the germination of seeds and the…
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from article Soil
Soil supports plant growth. A pumpkin seed in nutritious soil sprouts and comes to life. (Credit: Redmal/Getty Images)
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from article Soil
A soil profile showing horizons. This particular soil belongs to the Dothan series of soils, which are very deep, well drained soils that form in thick beds of unconsolidated, medium- to fine-textured marine sediments. (Credit: John A. Kelley,…
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from article Soil
Erosion is an important concern of soil management. The soil along the river bank has eroded significantly, causing riparian trees to fall. (Credit: Hans Engbers, Shutterstock)
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from article Dendrochronology
Ring patterns showing complacent and sensitive ring series. (a) Climate has minimal effect on ring widths when trees have ample moisture every year. (b) Maximum ring-width variations occur on sites where growth is limited by factors that vary from…
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from article Dendrochronology
Core being taken from a tree with an increment borer. (Courtesy of Laboratory of Tree-Ring Research, University of Arizona)
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from article Dendrochronology
Chronology building. Chronologies are extended backward in time by matching patterns of wood samples whose ages overlap.
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from article Dendrochronology
Skeleton plot (top) from an idealized tree-ring sequence in a specimen (bottom). Ring widths are represented by vertical lines in inverse proportion; that is, tall lines represent narrow rings. An exceptionally wide ring is designated by the letter…
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from article Dendrochronology
Bristlecone pines, which attain ages of more than 4000 years, form the basis for the second longest chronology yet developed. (Courtesy of Laboratory of Tree-Ring Research, University of Arizona)
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from article Paleoindian
Location of some important North American Paleoindian sites during the late-Pleistocene Ice Age.
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from article Territoriality
The tiger (Panthera tigris) is highly territorial in its behavior. (Credit: Safique Hazarika Photography/Getty Images)
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from article Fossil primates
Representatives of living primate families. (Copyright © McGraw-Hill Education)
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from article Fossil primates
Carpolestes simpsoni, a 55.5-million-year-old plesiadapiform from Wyoming: (a) skeleton as recovered, laid out in approximate anatomical position; (b) reconstruction in life stance on a tree branch; elements in dark gray are known; (c) external…
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from article Fossil primates
Cranium of the omomyoid tarsiiform Teilhardina asiatica, from deposits dated approximately 55 MYA in China: (a) dorsal (top) view as found; (b) left lateral reconstruction. (Credit: Xijun Ni)
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from article Fossil primates
Anjohibe (Madagascar) specimen of Palaeopropithecus ingens (an extinct lemur), mounted in a probable habitat posture. (Credit: American Geological Institute)
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from article Fossil primates
Partly reconstructed skeleton (casts) of Paracolobus chemeroni, a 3.2-million-year-old colobine monkey from Kenya, on exhibit at the American Museum of Natural History in New York. (Credit: Eric Delson)
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from article Fossil primates
Reconstructed skeleton of Proconsul heseloni, an early hominoid (23–14 MYA) from East Africa. Known parts are shaded. (Credit: R. L. Ciochon and R. S. Corruccini)
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from article Ecological competition
The competitive exclusion principle can be prevented through resource partitioning and species coexistence. In this illustration, each warbler species prefers to feed at a different height and portion of the tree, thus reducing competition.…
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from article Biosphere
All environments capable of sustaining life above, on, and beneath the Earth's surface, as well as in the oceans, are contained in the biosphere. (Credit: National Aeronautics and Space Administration)
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from article Biosphere
The upper and lower limits of the biosphere are not sharply defined. However, most of the biosphere lies within the zone that is reached by sunlight and where liquid water exists. The mountains shown in this photograph are located in Torres del…
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from article Predator-prey interactions
A predatory panther chameleon (Furcifer pardalis) is preying upon a cricket. (Credit: Cathy Keifer/Shutterstock)
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from article Predator-prey interactions
Predator-prey interactions play important roles in explaining the population dynamics of many species. In this photograph, a cheetah (Acinonyx jubatus) is hunting a springbok (Antidorcas marsupialis) in Namibia. (Credit: Elana Erasmus/Shutterstock)
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from article Predator-prey interactions
Snowshoe hare populations (solid blue circles) and lynx populations (white squares) inferred from the numbers of pelts sold to the Hudson's Bay Company. (Credit: Based on data compiled by D. A. MacLuclich; copyright © McGraw-Hill Education)
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from article Food web
The trophic levels of a food chain, which is one particular route through a food web, are often separated into primary producers, primary consumers (herbivores), and secondary consumers. (Copyright © McGraw-Hill Education)
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from article Food web
In a food web, the energy that plants capture from the sun during photosynthesis may end up in the tissues of a hawk. It gets there via a sparrow that the hawk has eaten, the insects that were eaten by the sparrow, and the plants on which the…
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from article Biomass
Wood materials are common sources of biomass. They can be burned directly for energy or processed in industrial facilities to produce renewable biofuels. (Credit: alffoto/Getty Images)
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from article Biomass
Carbon cycle, showing conversion of solar energy to fuel and electricity. (Copyright © McGraw-Hill Education)
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from article Biomass
Methods of converting biomass to energy, fuels, and chemicals. (Copyright © McGraw-Hill Education)
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from article Invasive forest species
The emerald ash borer (Agrilus planipennis) is a destructive invasive forest species. Native to northeastern Asia, this wood-boring beetle has devastated large areas of forests in North America and Europe. (Credit: Benjamin Smith)
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from article Invasive forest species
Perennial vine legume kudzu (Pueraria montana) growing in California. (Copyright © California Department of Food and Agriculture)
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from article Fossil apes
Reconstructions and partial reconstructions of the craniums of fossil apes: (a) Proconsul, (b) Afropithecus, (c) Oreopithecus, (d) Ouranopithecus, (e) Sivapithecus, and (f) Ankarapithecus.
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from article Fossil apes
Cladogram of the evolutionary relationships of the key fossil and living apes. Broken lines indicate uncertain relationships.
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from article Plant
The kingdom Plantae contains a tremendous diversity of plants. The plants seen in the photograph are drought-tolerant varieties native to California and the Mediterranean region. (Credit: David Madison/Getty Images)
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from article Agroecosystem
A group of pigs at a pig breeding farm. (Credit: Shutterstock / DN1988)
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from article Agroecosystem
Glysophate-resistant Palmer pigweed growing uncontrolled in Roundup Ready soy beans. (Credit: Bill Barksdale / Design Pics/Getty Images)
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from article Population ecology
Relationship between prey and predator populations. The abundance curve (population density versus time) for the predator lags behind that of the prey. (Copyright © McGraw Hill)
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from article Population ecology
Carrying capacity is a measure of the largest number of individuals that can be sustained in a given space. The population reaches a stable equilibrium phase when the carrying capacity is approximately maintained. (Copyright © McGraw Hill)
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from article Guild
Guilds of granivorous rodents in three deserts in the southwest United States. Mean weight (in grams) of each species is plotted on the body mass axis. The body mass scale is logarithmic, so that equal spacing shows equal ratios. (After M. A. Bowers…
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from article Biodegradation
Biodegradation of the compounds contained in oil spills can be accomplished by microorganisms. The use of microorganisms to remediate the environment of contaminants (for example, petroleum) is referred to as bioremediation. (Credit: Tasha…
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from article Soil fertility
Close-up view of corn germinating in fertile (nutrient-rich) soil. Proper soil fertility is necessary to support the germination and growth of plants. (Credit: Petro Perutskyi, Shutterstock)
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from article Soil fertility
For the optimal growth of plant tissues, essential nutrients need to be absorbed from the soil. The graph shows plant growth in response to changes in tissue nutrient concentration. (Credit: Based on an original graph by E. Epstein and A. J. Bloom)
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from article Pollination
Photomicrograph of pollen grains. (Credit: Steven P. Lynch)
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from article Pollination
Flowers of Pelargonium suburbanum are probed by the South African meganosed fly (Moegistorhynchus longirostris). Pollinaria (sacs of pollen) from an earlier visit to a nearby orchid dangle from the fly's proboscis. The proboscis length closely…
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from article Pollination
A honeybee (Apis), with pollen attached to its hind leg, pollinating a watermelon flower. (Credit: Stephen Ausmus/U.S. Department of Agriculture)
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from article Social hierarchy
The wolves in a pack will follow social hierarchical structures and ranks. (Credit: Raimund Linke/Radius Images/Getty Images)
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from article Social hierarchy
Displays of social hierarchy often involve aggression and submission. Two elk are exhibiting sparring behaviors to determine dominance. (Credit: Todd Frerichs/U.S. Fish and Wildlife Service)
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from article Fossil humans
Skeletal remains of Homo naledi (an offshoot of the hominin family) from a South African cave. The partial skeleton in the center consists of bones from several individuals. (Copyright © Lee Berger)
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from article Fossil humans
Human phylogeny over the last 35 million years, showing the skulls of the major known fossil relatives and possible ancestors of modern humans. (Copyright © McGraw-Hill Education)
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from article Fossil humans
Face (cast) of Ouranopithecus macedoniensis from Xirochori, Greece, about 9.7 million years old. (Credit: L. Meeker; copyright © E. Delson)
