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Rensch's Rule
Rensch's rule is a biological rule on allometrics, concerning the relationship between the extent of sexual size dimorphism and which sex is larger. Across species within a lineage, size dimorphism increases with increasing body size when the male is the larger sex, and decreases with increasing average body size when the female is the larger sex. The rule was proposed by the evolutionary biologist Bernhard Rensch in 1950. After controlling for confounding factors such as evolutionary history, an increase in average body size makes the difference in body size larger if the species has larger males, and smaller if it has larger females. Some studies propose that this is due to sexual bimaturism, which causes male traits to diverge faster and develop for a longer period of time. The correlation between sexual size dimorphism and body size is hypothesized to be a result of an increase in male-male competition in larger species, a result of limited environmental resources, fuelling a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Rules
A biological rule or biological law is a generalized law, principle, or rule of thumb formulated to describe patterns observed in living organisms. Biological rules and laws are often developed as succinct, broadly applicable ways to explain complex phenomena or salient observations about the ecology and biogeographical distributions of plant and animal species around the world, though they have been proposed for or extended to all types of organisms. Many of these regularities of ecology and biogeography are named after the biologists who first described them. From the birth of their science, biologists have sought to explain apparent regularities in observational data. In his biology, Aristotle inferred rules governing differences between live-bearing tetrapods (in modern terms, terrestrial placental mammals). Among his rules were that brood size decreases with adult body mass, while lifespan increases with gestation period and with body mass, and fecundity decreases with life ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primates
Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including humans). Primates arose 85–55 million years ago first from small terrestrial mammals, which adapted to living in the trees of tropical forests: many primate characteristics represent adaptations to life in this challenging environment, including large brains, visual acuity, color vision, a shoulder girdle allowing a large degree of movement in the shoulder joint, and dextrous hands. Primates range in size from Madame Berthe's mouse lemur, which weighs , to the eastern gorilla, weighing over . There are 376–524 species of living primates, depending on which classification is used. New primate species continue to be discovered: over 25 species were described in the 2000s, 36 in the 2010s, and three in the 2020s. Primates have large bra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal Size
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in which their body consists of a hollow sphere of cells, the blastula, during embryonic development. Over 1.5 million living animal species have been described—of which around 1 million are insects—but it has been estimated there are over 7 million animal species in total. Animals range in length from to . They have complex interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as zoology. Most living animal species are in Bilateria, a clade whose members have a bilaterally symmetric body plan. The Bilateria include the protostomes, containing animals such as nematodes, arthropods, flatworms, annelids and molluscs, and the deuterostomes, containing the echinoderms an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ricinidae
The Ricinidae are a family of a larger group Amblycera of the chewing lice. Most commonly they are ectoparasites of birds. The family includes the genus ''Ricinus ''Ricinus communis'', the castor bean or castor oil plant, is a species of perennial flowering plant in the spurge family, Euphorbiaceae. It is the sole species in the monotypic genus, ''Ricinus'', and subtribe, Ricininae. The evolution of cas ...''. Bernard C. Nelson (1972): ''A Revision of the New World Species of ''Ricinus'' (Mallophaga). Occurring on Passeriformes (Aves)'', University of California Publications in Entomology Volume 68, University of California Press, Berkeley & Los Angeles,PDF References Lice Insect families {{louse-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Menoponidae
Menoponidae is a monophyletic family of lice in the superfamily of chewing lice, Amblycera, often referred to as the chicken body louse family. They are ectoparasites of a wide range of birds including chickens, which makes them important to understand for veterinary science and for human health. However, Menoponidae are not exclusive to poultry and are common parasites for migratory birds, with more and more species being discovered every year. Biology Genera and species within the family Menoponidae are identified by their short antennae, concealed in grooves behind the eyes. To the untrained eye, it may appear as though they have no antennae. Most lice also further specialize to specific regions on their hosts such as the fluff at the base of the tail, the head, and the shaft. In fact, if a species that is better suited to tail feathers is presented with the opportunity to infest a different type of feather, they will make an attempt to eat those feathers but will fail to rep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Philopteridae
The Philopteridae are a family of Ischnocera, chewing lice mostly parasitic on birds. The taxonomy and systematics of the group are in need of revision; the Philopteridae are almost certainly paraphyletic. Genera Some notable species are also listed. * '' Acidoproctus'' * '' Acutifrons'' * '' Aegypoecus'' * '' Alcedoecus'' * '' Alcedoffula'' * '' Anaticola'' * '' Anatoecus'' * '' Aquanirmus'' * '' Ardeicola'' * '' Ardeiphagus'' * '' Auricotes'' * '' Austrogoniodes'' * '' Austrophilopterus'' * '' Bedfordiella'' * '' Bizarrifrons'' * '' Bobdalglieshia'' * '' Bothriometopus'' * ''Brueelia'' * '' Bucerocophorus'' * '' Buceroemersonia'' * '' Buceronirmus'' * '' Bucorvellus'' * '' Buerelius'' * ''Campanulotes'' * '' Capraiella'' * '' Caracaricola'' * '' Carduiceps'' * '' Centropodiella'' * '' Chelopistes'' * '' Cirrophthirius'' * '' Colilipeurus'' * '' Colinicola'' * '' Coloceras'' * ''Columbicola'' ** ''Columbicola extinctus ''Columbicola extinctus'', also known as the passenger p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Artiodactyls
The even-toed ungulates (Artiodactyla , ) are ungulates—hoofed animals—which bear weight equally on two (an even number) of their five toes: the third and fourth. The other three toes are either present, absent, vestigial, or pointing posteriorly. By contrast, odd-toed ungulates bear weight on an odd number of the five toes. Another difference between the two is that many other even-toed ungulates (with the exception of Suina) digest plant cellulose in one or more stomach chambers rather than in their intestine as the odd-toed ungulates do. Cetaceans (whales, dolphins, and porpoises) evolved from even-toed ungulates, and are therefore often classified under the same taxonomic branch because a species cannot outgrow its evolutionary ancestry; some modern taxonomists combine the two under the name Cetartiodactyla , while others opt to include cetaceans in the already-existing Artiodactyla. The roughly 270 land-based even-toed ungulate species include pigs, peccaries, hippopota ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pinnipeds
Pinnipeds (pronounced ), commonly known as seals, are a widely range (biology), distributed and diverse clade of carnivorous, fin-footed, semiaquatic, mostly marine mammal, marine mammals. They comprise the extant taxon, extant family (biology), families Odobenidae (whose only living member is the walrus), Otariidae (the eared seals: sea lions and fur seals), and Phocidae (the earless seals, or true seals). There are 34 extant species of pinnipeds, and more than 50 extinct species have been described from fossils. While seals were historically thought to have descended from two ancestral lines, molecular phylogenetics, molecular evidence supports them as a monophyletic lineage (descended from one ancestral line). Pinnipeds belong to the order Carnivora; their closest living relatives are Musteloidea, musteloids (Mustelidae, weasels, Procyonidae, raccoons, skunks, and red pandas), having diverged about 50 million years ago. Seals range in size from the and Baikal sea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylogenetic
In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups of organisms. These relationships are determined by Computational phylogenetics, phylogenetic inference methods that focus on observed heritable traits, such as DNA sequences, protein amino acid sequences, or morphology. The result of such an analysis is a phylogenetic tree—a diagram containing a hypothesis of relationships that reflects the evolutionary history of a group of organisms. The tips of a phylogenetic tree can be living taxa or fossils, and represent the "end" or the present time in an evolutionary lineage. A phylogenetic diagram can be rooted or unrooted. A rooted tree diagram indicates the hypothetical common ancestor of the tree. An unrooted tree diagram (a network) makes no assumption about the ancestral line, and does ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Allometric Law
Allometry is the study of the relationship of body size to shape, anatomy, physiology and finally behaviour, first outlined by Otto Snell in 1892, by D'Arcy Thompson in 1917 in ''On Growth and Form'' and by Julian Huxley in 1932. Overview Allometry is a well-known study, particularly in statistical shape analysis for its theoretical developments, as well as in biology for practical applications to the differential growth rates of the parts of a living organism's body. One application is in the study of various insect species (e.g., Hercules beetles), where a small change in overall body size can lead to an enormous and disproportionate increase in the dimensions of appendages such as legs, antennae, or horns The relationship between the two measured quantities is often expressed as a power law equation (Allometric equation) which expresses a remarkable scale symmetry: : y = kx^a \,\! or in a logarithmic form: : \log y = a \log x + \log k\,\! or similarly \ln y = a \ln x + ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Bimaturism
Sexual bimaturism describes a difference in developmental timing between males and females of the same species. Sexual bimaturism can result in sexual dimorphism, but sexual dimorphism could also develop through differential rates of development. In many insects, the larval period of females is longer than that of males, and as a result of this extended growth period, these female insects are larger than their male conspecifics. Male simian primates are generally larger than females of the same species due in part to extended growth periods. Gorillas demonstrate a particularly high degree of sexual bimaturism. Bimaturism can refer to developmental differences within a sex related to secondary sex characteristics. For example, male orangutans reach sexual maturity around age 15 but undergo an additional period of development later in life before they exhibit cheek flanges. Flanged males are generally preferred by females so that unflanged males need different mating strategies to c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Confounding
In statistics, a confounder (also confounding variable, confounding factor, extraneous determinant or lurking variable) is a variable that influences both the dependent variable and independent variable, causing a spurious association. Confounding is a causal concept, and as such, cannot be described in terms of correlations or associations.Pearl, J., (2009). Simpson's Paradox, Confounding, and Collapsibility In ''Causality: Models, Reasoning and Inference'' (2nd ed.). New York : Cambridge University Press. The existence of confounders is an important quantitative explanation why correlation does not imply causation. Confounds are threats to internal validity. Definition Confounding is defined in terms of the data generating model. Let ''X'' be some independent variable, and ''Y'' some dependent variable. To estimate the effect of ''X'' on ''Y'', the statistician must suppress the effects of extraneous variables that influence both ''X'' and ''Y''. We say that ''X'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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