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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 elephants of Crete, and '' Brookesia micra'', a minuscule chameleon from Madagascar. An noninsular example is the evolution of dwarfed marmosets and tamarins among New World monkeys. Phyletic dwarfism may have also helped give rise to birds from their much larger dinosaur ancestors. References Evolution of animals Animal size Dwarfism {{zoology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Predation
Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation (which usually do not kill the Host (biology), host) and parasitoidism (which always does, eventually). It is distinct from Scavenger, scavenging on dead prey, though many predators also scavenge; it overlaps with Herbivore, herbivory, as Seed predation, seed predators and destructive frugivores are predators. Predation behavior varies significantly depending on the organism. Many predators, especially carnivores, have evolved distinct hunting strategy, hunting strategies. Pursuit predation involves the active search for and pursuit of prey, whilst ambush predation, ambush predators instead wait for prey to present an opportunity for capture, and often use stealth or aggressive mimicry. Other predators are opportunism, opportunistic or om ... [...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 various species of Dwarf elephant, dwarf elephants that evolved during the Pleistocene epoch, as well as more ancient examples, such as the dinosaurs ''Europasaurus'' and ''Magyarosaurus''. 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 Foster's rule, "island effect" or "Foster's rule", which posits that w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Island Fox
The island fox (''Urocyon littoralis'') is a small fox species that is endemic to six of the eight Channel Islands of California. Evolved from their mainland gray fox (''U. cinereoargenteus'') recent and larger ancestor, they diversified into six distinct subspecies, each confined to a single island and exhibiting insular dwarfism. Island fox 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. Genetic and archaeological evidence suggests that the foxes arrived on the islands over 7,000 years ago, likely assisted by early human populations. Taxonomy and evolution Genetic and archaeological evidence indicates that the species descends from a population of the mainland gray fox that arrived on the islands around 7,300 years ago, possibly due to having been intr ... [...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 shoulder height) 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 lack of predation and competition. Fossil remains of dwarf elephants have been found on the Mediterranean islands of Cyprus, Malta, Crete, Sicily, Sardinia, the Cyclades Islands and the Dodecanese Islands, which are mostly members of the genus ''Palaeoloxodon'', descending from the large tall straight-tusked elephant (''Palaeoloxodon antiquus'') of mainland Europe'','' though two species represent dwarf mammoths. Dwarf species of elephants and '' Stegodon'' have been found on the islands of Indonesia and the Philippi ... [...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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolution Of Animals
The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the 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. The similarities among all known present-day species indicate that they have diverged through the process of evolution from a common ancestor. The earliest clear evidence of life comes from biogenic carbon signatures and stromatolite fossils discovered in 3.7 billion-year-old metasedimentary rocks from western Greenland. In 2015, possible "remains of biotic life" were found in 4.1 billion-year-old rocks in Western Australia. There is further evidence of possibly the oldest forms of life in the form of fossilized microorganisms in hydrothermal vent precipitates from the Nuvvuagittuq Belt, that may have lived as early as 4.28 billion years ago, not long after the oceans formed 4.4 bi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal Size
Animals are multicellular, eukaryotic organisms in the Biology, biological Kingdom (biology), kingdom Animalia (). With few exceptions, animals heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, have myocytes and are motility, able to move, can reproduce sexually, and grow from a hollow sphere of Cell (biology), cells, the blastula, during embryonic development. Animals form a clade, meaning that they arose from a single common ancestor. Over 1.5 million extant taxon, living animal species have been species description, described, of which around 1.05 million are insects, over 85,000 are molluscs, and around 65,000 are vertebrates. It has been estimated there are as many as 7.77 million animal species on Earth. Animal body lengths range from to . They have complex ecologies and biological interaction, interactions with each other and their environments, forming intricate food webs. The scientific study of animals is known as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
