The Bearded Vulture (Gypaetus barbatus) is a threatened species. Many conservation programs aim to increase population size by improving survival and reproduction; however, density dependence may...

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A female rotifer (Brachionus calyciflorus) with two eggs. The eggs are the result of parthenogenesis, or asexual reproduction by the female, which occurs in rotifers when growing conditions are...

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A female silver studded blue butterfly (Plebejus argus) on a shrub in the Donana National Park of southern Spain. P. argus has a mutualistic association with ants of the genus Lasius and uses the...

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In mammals, lactation has important effects on maternal and offspring fitness. Pinnipeds (fin-footed mammals) are a good mammalian group for research studies that focus on lactation because in...

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This article provides formulas to understand the bioeconomics of world fishery harvesting.

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A group of bluehead wrasse (Thalassoma bifasciatum) shoal (group together) above a reef at St. Croix, U.S. Virgin Islands. Shoaling is a common anti-predator behavior for reef fishes such as the...

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A herd of alpine ibex (Capra ibex) struggles through deep snow. A recent study examined 45 years of census data for a population of alpine ibex in Gran Paradiso National Park in northwestern Italy....

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A juvenile Marbled Murrelet (Brachyramphus marmoratus) sits on its nest platform high in an old-growth Douglas fir. The Marbled Murrelet is an endangered seabird. A recent study used age-ratio...

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A periodical cicada (left) has mostly freed itself from its old exoskeleton (right). The cicada's new exoskeleton is light in color and has not yet hardened. Every 13 or 17 years, periodical cicadas...

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This article provides a reproductive value equation, along with a hypothetical life table, for teachers of introductory biology and ecology classes

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