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Terminal Investment Hypothesis
The terminal investment hypothesis is the idea in life history theory that as an organism's residual reproductive value (or the total reproductive value minus the reproductive value of the current breeding attempt) decreases, its reproductive effort will increase. Thus, as an organism's prospects for survival decreases (through age or an immune challenge, for example), it will invest more in reproduction. This hypothesis is generally supported in animals, although results contrary to it do exist. Definition The terminal investment hypothesis posits that as residual reproductive value (measured as the total reproductive value minus the reproductive value of the current breeding attempt) decreases, reproductive effort increases. This is based on the cost of reproduction hypothesis, which says that an increase in resources dedicated to current reproduction decreases the potential for future reproduction. But, as the residual reproductive value decreases, the importance of this trade- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Life History Theory
Life history theory is an analytical frameworkVitzthum, V. (2008). Evolutionary models of women's reproductive functioning. ''Annual Review of Anthropology'', ''37'', 53-73 designed to study the diversity of life history strategies used by different organisms throughout the world, as well as the causes and results of the variation in their life cycles.Flatt, T., & Heyland, A. (Eds.). (2011). Mechanisms of Life History Evolution : The Genetics and Physiology of Life History Traits and Trade-Offs. Oxford, GB: OUP Oxford. It is a theory of biological evolution that seeks to explain aspects of organisms' anatomy and behavior by reference to the way that their life histories—including their reproductive development and behaviors, post-reproductive behaviors, and lifespan (length of time alive)—have been shaped by natural selection. A life history strategy is the "age- and stage-specific patterns" and timing of events that make up an organism's life, such as birth, weaning, maturation, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northern House Wren
The northern house wren (''Troglodytes aedon'') is a very small passerine in the wren family Troglodytidae. It found in southern Canada, the USA and Mexico. It occurs in most suburban areas in its range. It formerly included many subspecies resident in South America and in the Caribbean that are now considered as separate species. The name ''troglodytes'' means "hole dweller", and is a reference to the bird's tendency to disappear into crevices when hunting insects or to seek shelter. Taxonomy The northern house wren was formally described in 1809 by the French ornithologist Louis Pierre Vieillot under the current binomial name ''Troglodytes aedon''. The specific epithet is from the Ancient Greek ''aēdōn'' meaning "nightingale". The type locality was designated as New York City by Harry Oberholser in 1934. An earlier specific name, ''domestica'' in the combination ''Sylvia domestica'', was introduced in 1808 by the American ornithologist Alexander Wilson. This was rarely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quercus
An oak is a tree or shrub in the genus ''Quercus'' (; Latin "oak tree") of the beech family, Fagaceae. There are approximately 500 extant species of oaks. The common name "oak" also appears in the names of species in related genera, notably '' Lithocarpus'' (stone oaks), as well as in those of unrelated species such as ''Grevillea robusta'' (silky oaks) and the Casuarinaceae (she-oaks). The genus ''Quercus'' is native to the Northern Hemisphere, and includes deciduous and evergreen species extending from cool temperate to tropical latitudes in the Americas, Asia, Europe, and North Africa. North America has the largest number of oak species, with approximately 160 species in Mexico of which 109 are endemic and about 90 in the United States. The second greatest area of oak diversity is China, with approximately 100 species. Description Oaks have spirally arranged leaves, with lobate margins in many species; some have serrated leaves or entire leaves with smooth margins. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spotted Turtle
The spotted turtle (''Clemmys guttata''), the only species of the genus ''Clemmys'', is a small, semi-aquatic turtle that reaches a carapace length of upon adulthood. Their broad, smooth, low dark-colored upper shell, or carapace, ranges in its exact colour from black to a bluish black with a number of tiny yellow round spots. The spotting patterning extends from the head, to the neck and out onto the limbs. Sexually mature males have a concave plastron and a long, thick tail. By contrast, sexually mature females possess a flat plastron and have a tail notable shorter and thinner than mature males. Mature males also have a dark iris and face; females typically have a yellow or orange iris and a similarly coloured face that is distinctly lighter than males. Juveniles appear female-like in this regard and at maturity males begin to develop darker features. Spotted turtles are aquatic omnivores that inhabit a variety of semi-aquatic or in other words, shallow, fresh-water areas su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rùm
Rùm (), a Scottish Gaelic name often anglicised to Rum (), is one of the Small Isles of the Inner Hebrides, in the district of Lochaber, Scotland. For much of the 20th century the name became Rhum, a spelling invented by the former owner, Sir George Bullough, because he did not relish the idea of having the title "Laird of Rum". It is the largest of the Small Isles, and the 15th largest Scottish island, but is inhabited by only about thirty or so people, all of whom live in the hamlet of Kinloch on the east coast. The island has been inhabited since the 8th millennium BC and provides some of the earliest known evidence of human occupation in Scotland. The early Celtic and Norse settlers left only a few written accounts and artefacts. From the 12th to 13th centuries on, the island was held by various clans including the MacLeans of Coll. The population grew to over 400 by the late 18th century but was cleared of its indigenous population between 1826 and 1828. The island the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red Deer
The red deer (''Cervus elaphus'') is one of the largest deer species. A male red deer is called a stag or hart, and a female is called a hind. The red deer inhabits most of Europe, the Caucasus Mountains region, Anatolia, Iran, and parts of western Asia. It also inhabits the Atlas Mountains of Northern Africa; its early ancestors are thought to have crossed over to Morocco, then to Algeria, Libya and Tunisia via the Strait of Gibraltar, becoming the only species of true deer (Cervidae) to inhabit Africa. Red deer have been introduced to other areas, including Australia, New Zealand, the United States, Canada, Peru, Uruguay, Chile and Argentina. In many parts of the world, the meat (venison) from red deer is used as a food source. Red deer are ruminants, characterized by a four-chambered stomach. Genetics, Genetic evidence indicates that the red deer, as traditionally defined, is a species group, rather than a single species, though exactly how many species the group includes rem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhesus Macaque
The rhesus macaque (''Macaca mulatta''), colloquially rhesus monkey, is a species of Old World monkey. There are between six and nine recognised subspecies that are split between two groups, the Chinese-derived and the Indian-derived. Generally brown or grey in colour, it is in length with a tail and weighs . It is native to South, Central, and Southeast Asia and has the widest geographic range of all non-human primates, occupying a great diversity of altitudes and a great variety of habitats, from grasslands to arid and forested areas, but also close to human settlements. Feral colonies are found in the United States, thought to be either released by humans or escapees after hurricanes destroyed zoo and wildlife park facilities. The rhesus macaque is diurnal, arboreal, and terrestrial. It is mostly herbivorous, mainly eating fruit, but will also consume seeds, roots, buds, bark, and cereals. Studies show almost 100 different plant species in its diet. Rhesus macaques are gener ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reindeer
Reindeer (in North American English, known as caribou if wild and ''reindeer'' if domesticated) are deer in the genus ''Rangifer''. For the last few decades, reindeer were assigned to one species, ''Rangifer tarandus'', with about 10 subspecies. A 2022 revision of the genus elevated five of the subspecies to species (see Taxonomy below). They have a circumpolar distribution and are native to the Arctic, sub-Arctic, tundra, boreal forest, and mountainous regions of northern Europe, Siberia, and North America. Reindeer occur in both migratory and sedentary populations, and their herd sizes vary greatly in different regions. The tundra subspecies are adapted for extreme cold, and some are adapted for long-distance migration. Reindeer vary greatly in size and color from the smallest species, the Svalbard reindeer (''R. t. platyrhynchus''), to the largest subspecies, Osborn's caribou (''R. t. osborni''). Although reindeer are quite numerous, some species and subspecies are in d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bet Hedging (biology)
Biological bet hedging occurs when organisms suffer decreased fitness in their typical conditions in exchange for increased fitness in stressful conditions. Biological bet hedging was originally proposed to explain the observation of a Soil seed bank, seed bank, or a reservoir of ungerminated seeds in the soil. For example, an Annual plant, annual plant's Fitness (biology), fitness is maximized for that year if all of its seeds germinate. However, if a drought occurs that kills germinated plants, but not ungerminated seeds, plants with seeds remaining in the seed bank will have a fitness advantage. Therefore, it can be advantageous for plants to "hedge their bets" in case of a drought by producing some seeds that germinate immediately and other seeds that lie dormant. Other examples of biological bet hedging include Polyandry in nature, female multiple mating, foraging behavior in Bumblebee, bumble bees, nutrient storage in rhizobia, and Multidrug tolerance, bacterial persistence in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flatworm
The flatworms, flat worms, Platyhelminthes, or platyhelminths (from the Greek πλατύ, ''platy'', meaning "flat" and ἕλμινς (root: ἑλμινθ-), ''helminth-'', meaning "worm") are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates. Unlike other bilaterians, they are acoelomates (having no body cavity), and have no specialized circulatory and respiratory organ (anatomy), organs, which restricts them to having flattened shapes that allow oxygen and nutrients to pass through their bodies by diffusion. The digestive cavity has only one opening for both ingestion (intake of nutrients) and egestion (removal of undigested wastes); as a result, the food cannot be processed continuously. In traditional medicinal texts, Platyhelminthes are divided into Turbellaria, which are mostly non-parasitic animals such as planarians, and three entirely parasitic groups: Cestoda, Trematoda and Monogenea; however, since the turbellarians have since been prove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mouse
A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus''). Mice are also popular as pets. In some places, certain kinds of field mice are locally common. They are known to invade homes for food and shelter. Mice are typically distinguished from rats by their size. Generally, when a muroid rodent is discovered, its common name includes the term ''mouse'' if it is smaller, or ''rat'' if it is larger. The common terms ''rat'' and ''mouse'' are not taxonomically specific. Typical mice are classified in the genus '' Mus'', but the term ''mouse'' is not confined to members of ''Mus'' and can also apply to species from other genera such as the deer mouse, ''Peromyscus''. Domestic mice sold as pets often differ substantially in size from the common house mouse. This is attributable to breeding a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burying Beetle
Burying beetles or sexton beetles, genus ''Nicrophorus'', are the best-known members of the family Silphidae (carrion beetles). Most of these beetles are black with red markings on the elytra (forewings). Burying beetles are true to their name—they bury the carcasses of small vertebrates such as birds and rodents as a food source for their larvae. They are unusual among insects in that both the male and female parents take care of the brood. They are carnivores. The genus name is sometimes spelled ''Necrophorus'' in older texts: this was an unjustified emendation by Carl Peter Thunberg (1789) of Fabricius's original name, and is not valid under the ICZN. The American burying beetle (''Nicrophorus americanus'') has been on the U.S. endangered species list since 1989. Reproduction Burying beetles have large club-like antennae equipped with chemoreceptors capable of detecting a dead animal from a long distance. After finding a carcass (most usually that of a small bird or a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
