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Axolotl
The axolotl (; from ) (''Ambystoma mexicanum'') is a neoteny, paedomorphic salamander, one that Sexual maturity, matures without undergoing metamorphosis into the terrestrial adult form; adults remain Aquatic animal, fully aquatic with obvious external gills. This trait is somewhat unusual among amphibians, though this trait is not unique to axolotls, and this is apparent as they may be confused with the Tadpole, larval stage or Ambystoma#Species, other neotenic adult mole salamanders (''Ambystoma spp.''), such as the occasionally paedomorphic tiger salamander (''Ambystoma tigrinum, A. tigrinum'') widespread in North America; or with mudpuppies (''Necturus spp.''), which bear a superficial resemblance but are from a different Family (biology), family of salamanders. Axolotls originally inhabited a system of interconnected wetlands and lakes in the Mexican highlands; they were known to inhabit the smaller lakes of Lake Xochimilco, Xochimilco and Lake Chalco, Chalco, and are al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neoteny
Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the Physiology, physiological, or Somatic (biology), somatic, development of an organism, typically an animal. Neoteny in humans, Neoteny in modern humans is more significant than in other primates. In progenesis or paedogenesis, sexual development is accelerated. Both neoteny and progenesis result in paedomorphism (as having the form typical of children) or paedomorphosis (changing towards forms typical of children), a type of heterochrony. It is the retention in adults of traits previously seen only in the young. Such retention is important in evolutionary biology, domestication, and evolutionary developmental biology. Some authors define paedomorphism as the retention of larval traits, as seen in salamanders.Schell, S. C. ''Handbook of Trematodes of North America North of Mexico'', 1985, pg. 22 History and etymology Julius Kollmann created the term ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Salamander
Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All ten extant salamander families are grouped together under the order Urodela, the sole surviving order from the group Caudata. ''Urodela'' is a scientific Latin term based on the Ancient Greek : ourà dēlē "conspicuous tail". ''Caudata'' is the Latin for "tailed ones", from : "tail". Salamander diversity is highest in eastern North America, especially in the Appalachian Mountains; most species are found in the Holarctic realm, with some species present in the Neotropical realm. Salamanders never have more than four toes on their front legs and five on their rear legs, but some species have fewer digits and others lack hind limbs. Their permeable skin usually makes them reliant on habitats in or near water or other cool, damp places. So ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amphibian
Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excluding the amniotes (tetrapods with an amniotic membrane, such as modern reptiles, birds and mammals). All extant taxon, extant (living) amphibians belong to the monophyletic subclass (biology), subclass Lissamphibia, with three living order (biology), orders: Anura (frogs and toads), Urodela (salamanders), and Gymnophiona (caecilians). Evolved to be mostly semiaquatic, amphibians have adapted to inhabit a wide variety of habitats, with most species living in freshwater ecosystem, freshwater, wetland or terrestrial ecosystems (such as riparian woodland, fossorial and even arboreal habitats). Their biological life cycle, life cycle typically starts out as aquatic animal, aquatic larvae with gills known as tadpoles, but some species have devel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ambystoma Tigrinum
The tiger salamander (''Ambystoma tigrinum'') is a species of mole salamander and one of the largest terrestrial salamanders in North America. Description These salamanders usually grow to a length of with a lifespan of around 12–15 years. They are characterized by having markings varying in color on the back of their head, body, and tail. The coloring of these spots range from brownish yellow to greenish yellow, while the rest of their back is black or dark brown. They are smooth bodied, with costal grooves running down their sides to aid in moisture control. They have short snouts, thick necks, strong legs, and lengthy tails. Tiger salamanders also utilize specialized foot pads for burrowing.Tiger salamanders are a sexually dimorphic species, as the males are larger in body size, as well as have longer and higher tails than females. Some individuals, typically when their aquatic environment is well suited, will retain their larval characteristics and forego metamorphosis. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lake Xochimilco
Lake Xochimilco (; , ) is an ancient endorheic lake, located in the present-day Borough of Xochimilco in southern Mexico City. It is the last remaining habitat of the axolotl. The lake is within the Valley of Mexico hydrological basin, in central Mexico. History Geologic Lake Xochimilco is part of a series of historical lakes, which included: :# Lake Texcoco — ''brackish'' :# Lake Zumpango :# Lake Xaltocan :# Lake Chalco — ''fresh water'' Lake Xochimilco was originally a part of an even larger lake, Lake Texcoco, during the last glacial period. Between 12,000 and 6,000 years ago, the climate in central Mexico warmed and the snowmelt that once fed Lake Texcoco virtually disappeared. This caused the lake to drop hundreds of feet over next several thousand years. By 2,000 years ago Xochimilco became a bay in the southern portion of Texcoco. Then around the 13th or 14th century the Aztecs built large causeways effectively creating a new lake. Mesoamerican These lakes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquatic Animal
An aquatic animal is any animal, whether vertebrate or invertebrate, that lives in a body of water for all or most of its lifetime. Aquatic animals generally conduct gas exchange in water by extracting dissolved oxygen via specialised respiratory system, respiratory organ (biology), organs called gills, cutaneous respiration, through the skin or enteral respiration, across enteral mucosae, although some are evolution, evolved from terrestrial ancestors that re-adaptation, adapted to aquatic environments (e.g. marine reptiles and marine mammals), in which case they actually use lungs to breathing, breathe air and are essentially apnea, holding their breath when living in water. Some species of gastropod mollusc, such as the Elysia chlorotica, eastern emerald sea slug, are even capable of kleptoplastic photosynthesis via endosymbiosis with ingested yellow-green algae. Almost all aquatic animals reproduce in water, either oviparously or viviparously, and many species routinely fish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
External Gills
External gills are the gills of an animal, most typically an amphibian, that are exposed to the environment, rather than set inside the pharynx and covered by gill slits, as they are in most fishes. Instead, the respiratory organs are set on a frill of stalks protruding from the sides of an animal's head. This type of gill is most commonly observed on the aquatic larva of most species of salamanders, lungfish, and bichirs (which have only one large pair), and are retained by neotenic adult salamanders and some species of adult lungfish. They are present on non-transforming salamander species, such as most members of the family Proteidae (the olm and mudpuppies) and the family Sirenidae, which naturally never metamorphose into an air-breathing form. The embryos of frogs A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order Anura (coming from the Ancient Greek , literally 'without tail'). Frog s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spanish Colonization Of The Americas
The Spanish colonization of the Americas began in 1493 on the Caribbean island of Hispaniola (now Haiti and the Dominican Republic) after the initial 1492 voyage of Genoa, Genoese mariner Christopher Columbus under license from Queen Isabella I of Castile. These overseas territories of the Spanish Empire were under the jurisdiction of Crown of Castile until the last territory was lost in Spanish–American War, 1898. Spaniards saw the dense populations of indigenous peoples of the Americas, Indigenous peoples as an important economic resource and the territory claimed as potentially producing great wealth for individual Spaniards and the crown. Religion played an important role in the Spanish conquest and incorporation of indigenous peoples, bringing them into the Catholic Church peacefully or by force. The crown created civil and religious structures to administer the vast territory. Spanish men and women settled in greatest numbers where there were dense indigenous populations ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spanish Conquest Of The Aztec Empire
The Spanish conquest of the Aztec Empire was a pivotal event in the history of the Americas, marked by the collision of the Aztec Triple Alliance and the Spanish Empire. Taking place between 1519 and 1521, this event saw the Spanish conquistador Hernán Cortés, and his small army of European soldiers and numerous indigenous allies, overthrowing one of the most powerful empires in Mesoamerica. Led by the Aztec ruler Moctezuma II, the Aztec Empire had established dominance over central Mexico through military conquest and intricate alliances. Because the Aztec Empire ruled via hegemonic control by maintaining local leadership and relying on the psychological perception of Aztec power — backed by military force — the Aztecs normally kept subordinate rulers compliant. This was an inherently unstable system of governance, as this situation could change with any alteration in the status quo. A combination of factors including superior weaponry, strategic alliances with oppresse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Habitat Destruction
Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease in biodiversity and species numbers. Habitat destruction is in fact the leading cause of biodiversity loss and species extinction worldwide. Humans contribute to habitat destruction through the use of natural resources, agriculture, industrial production and urbanization (urban sprawl). Other activities include mining, logging and trawling. Environmental factors can contribute to habitat destruction more indirectly. Geological processes, climate change, introduction of invasive species, ecosystem nutrient depletion, water and noise pollution are some examples. Loss of habitat can be preceded by an initial habitat fragmentation. Fragmentation and loss of habitat have become one of the most important topics of research in ecology as the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mexico City
Mexico City is the capital city, capital and List of cities in Mexico, largest city of Mexico, as well as the List of North American cities by population, most populous city in North America. It is one of the most important cultural and financial centers in the world, and is classified as an Globalization and World Cities Research Network, Alpha world city according to the Globalization and World Cities Research Network (GaWC) 2024 ranking. Mexico City is located in the Valley of Mexico within the high Mexican central plateau, at an altitude of . The city has 16 Boroughs of Mexico City, boroughs or , which are in turn divided into List of neighborhoods in Mexico City, neighborhoods or . The 2020 population for the city proper was 9,209,944, with a land area of . According to the most recent definition agreed upon by the federal and state governments, the population of Greater Mexico City is 21,804,515, which makes it the list of largest cities#List, sixth-largest metropolitan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wild Type
The wild type (WT) is the phenotype of the typical form of a species as it occurs in nature. Originally, the wild type was conceptualized as a product of the standard "normal" allele at a locus, in contrast to that produced by a non-standard, " mutant" allele. "Mutant" alleles can vary to a great extent, and even become the wild type if a genetic shift occurs within the population. Continued advancements in genetic mapping technologies have created a better understanding of how mutations occur and interact with other genes to alter phenotype. It is now regarded that most or all gene loci exist in a variety of allelic forms, which vary in frequency throughout the geographic range of a species, and that a uniform wild type does not exist. In general, however, the most prevalent allele – i.e., the one with the highest gene frequency – is the one deemed wild type. The concept of wild type is useful in some experimental organisms such as fruit flies ''Drosophila melanogaster'', ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
