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Phyletic Dwarfism
Phyletic dwarfism is the decrease in average size of animals of a species. There are a few circumstances that often lead to species doing this. Lack of predators of smaller creatures can allow smaller members of a species to survive. The lack of resources to sustain a large population of larger animals can pick off the largest specimens. Available resources being more beneficial for smaller creatures can also do so. These circumstances are common on islands, making insular dwarfism the most common form of phyletic dwarfism. Examples of this are the Channel Island fox, extinct dwarf elephant Dwarf elephants are prehistoric members of the order Proboscidea which, through the process of allopatric speciation on islands, evolved much smaller body sizes (around ) in comparison with their immediate ancestors. Dwarf elephants are an example ...s of Crete, and '' Brookesia micra'', a minuscule chameleon from Madagascar. An noninsular example is the evolution of dwarfed marmosets and ta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Predation
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the host) and parasitoidism (which always does, eventually). It is distinct from scavenging on dead prey, though many predators also scavenge; it overlaps with herbivory, as seed predators and destructive frugivores are predators. Predators may actively search for or pursue prey or wait for it, often concealed. When prey is detected, the predator assesses whether to attack it. This may involve ambush or pursuit predation, sometimes after stalking the prey. If the attack is successful, the predator kills the prey, removes any inedible parts like the shell or spines, and eats it. Predators are adapted and often highly specialized for hunting, with acute senses such as vision, hearing, or smell. Many predatory animals, both vertebrate an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Insular Dwarfism
Insular dwarfism, a form of phyletic dwarfism, is the process and condition of large animals evolving or having a reduced body size when their population's range is limited to a small environment, primarily islands. This natural process is distinct from the intentional creation of dwarf breeds, called dwarfing. This process has occurred many times throughout evolutionary history, with examples including dinosaurs, like ''Europasaurus'' and '' Magyarosaurus dacus'', and modern animals such as elephants and their relatives. This process, and other " island genetics" artifacts, can occur not only on islands, but also in other situations where an ecosystem is isolated from external resources and breeding. This can include caves, desert oases, isolated valleys and isolated mountains (" sky islands"). Insular dwarfism is one aspect of the more general "island effect" or "Foster's rule", which posits that when mainland animals colonize islands, small species tend to evolve larger bod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Island Fox
The island fox (''Urocyon littoralis'') is a small fox that is endemic to six of the eight Channel Islands of California. There are six subspecies, each unique to the island it lives on, reflecting its evolutionary history. They are generally docile, show little fear of humans, and are easily tamed. Island foxes played an important role in the spiritual lives of native Channel Islanders. They have been likely semi-domesticated as pets, used as pelts, or for other functions, like pest control. Taxonomy and evolution The island fox shares the genus ''Urocyon'' with the mainland gray fox (''U. cinereoargenteus''), the species from which it is descended. Its small size is a result of insular dwarfism, a form of allopatric speciation. Because the island fox is geographically isolated, it has not acquired immunity to parasites and diseases brought in from the mainland and is especially vulnerable to those that the domestic dog may carry. In addition, predation by the golden eagle (' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dwarf Elephant
Dwarf elephants are prehistoric members of the order Proboscidea which, through the process of allopatric speciation on islands, evolved much smaller body sizes (around ) in comparison with their immediate ancestors. Dwarf elephants are an example of insular dwarfism, the phenomenon whereby large terrestrial vertebrates (usually mammals) that colonize islands evolve dwarf forms, a phenomenon attributed to adaptation to resource-poor environments and selection for early maturation and reproduction. Some modern populations of Asian elephants have also undergone size reduction on islands to a lesser degree, resulting in populations of pygmy elephants. Fossil remains of dwarf elephants have been found on the Mediterranean islands of Cyprus, Malta (at Għar Dalam), Crete (in Chania at Vamos, Stylos and in a now-underwater cave on the coast), Sicily, Sardinia, the Cyclades Islands and the Dodecanese Islands. Other islands where dwarf ''Stegodon'' have been found are Sulawesi, Flores, T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brookesia Micra
''Brookesia micra'', also known as the Nosy Hara leaf chameleon is a species of chameleons from the islet of Nosy Hara in Antsiranana, Madagascar. At the time of its discovery, it was the smallest known chameleon and among the smallest reptiles, until the 2021 discovery of the even smaller '' B. nana''. Adult ''B. micra'' can grow up to in length. Taxonomy ''Brookesia micra'' was discovered and named by a team of researchers led by Frank Glaw of the Bavarian State Collection of Zoology. Glaw and his colleagues have been conducting expeditions into the Malagasy forests for eight years. Members of the species had previously been labelled as ''Brookesia'' sp. "Nosy Hara" in 2007 by Glaw and Vences. Etymology The specific epithet of ''B. micra'' is a derivation of the Latin form of the Greek word "μικρός" (''mikros''), which means either "tiny" or "small" and refers to the small body size. Description The males of ''Brookesia micra'' reach a maximum snout-vent length of , ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Callitrichidae
The Callitrichidae (also called Arctopitheci or Hapalidae) are a family of New World monkeys, including marmosets, tamarins, and lion tamarins. At times, this group of animals has been regarded as a subfamily, called the Callitrichinae, of the family Cebidae. This taxon was traditionally thought to be a primitive lineage, from which all the larger-bodied platyrrhines evolved. However, some works argue that callitrichids are actually a dwarfed lineage.Naish, DarrenMarmosets and tamarins: dwarfed monkeys of the South American tropics Scientific American November 27, 2012 Ancestral stem-callitrichids likely were "normal-sized" ceboids that were dwarfed through evolutionary time. This may exemplify a rare example of insular dwarfing in a mainland context, with the "islands" being formed by biogeographic barriers during arid climatic periods when forest distribution became patchy, and/or by the extensive river networks in the Amazon Basin. All callitrichids are arboreal. They a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolution Of Animals
The history of life on Earth traces the processes by which living and fossil organisms evolved, from the earliest emergence of life to present day. Earth formed about 4.5 billion years ago (abbreviated as ''Ga'', for ''gigaannum'') and evidence suggests that life emerged prior to 3.7 Ga. Although there is some evidence of life as early as 4.1 to 4.28 Ga, it remains controversial due to the possible non-biological formation of the purported fossils. The similarities among all known present-day species indicate that they have diverged through the process of evolution from a common ancestor. Only a very small percentage of species have been identified: one estimate claims that Earth may have 1 trillion species. * However, only 1.75–1.8 million have been named "A version of this article appears in print on Nov. 9, 2014, Section SR, Page 6 of the New York edition with the headline: Prehistory's Brilliant Future." and 1.8 million documented in a central database. These currently ... [...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] |
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