Fernandina Island
Fernandina Island is the third largest, youngest, island of the Galápagos Islands, as well as the furthest west. Like the others, the island was formed by the Galápagos hotspot; the island is an active shield volcano that has most been erupting since April 11, 2009. While anchored in Banks Bay, Captain Benjamin Morrell recorded one of the largest eruptions in Galápagos' history at Fernandina Volcano, his ship escaped to safety and his account of the event was preserved. Fernandina has a height of 1,476 m, with a summit caldera about 6.5 km wide. The caldera underwent a collapse in 1968, when parts of the caldera floor dropped 350 m. A small lake has intermittently occupied the northern caldera floor, most in 1988. Due to its recent volcanic activity, the island does not present much plant life and has a rocky surface. Visitors to Fernandina Island will be taken to see only the outskirts of the crater for safety reasons. Two types of lava flow can be observed, ʻaʻā and pāhoehoe. Punta Espinoza is a narrow stretch of land where hundreds of marine iguanas gather in large groups on black lava rocks.
The famous flightless cormorant inhabits this island as well as penguins and sea lions. The Narborough Island tortoise is a elusive species of Galápagos tortoise restricted to the island, thought extinct when no sighting had been made for 113 years after 1906, one old female being found in 2019. Mangrove forests are found on the island; the southern flank of the volcano La Cumbre had a fissure eruption that generated flows, which subsided within hours. Isla Fernandina supports wildlife, threatened by the April 2009 burst of volcanic activity, according to rangers at Galápagos National Park; as the island has no human residents, no settlements were endangered. Park rangers and a passing tourist boat observed the volcano at 10:00 p.m. local time on April 10, 2009. A sparse human population in the western reaches of the Galápagos Islands means that volcanic activity is not always observed or reported as soon as it starts; the seismic station at Puerto Ayora, on the nearby island of Santa Cruz, recorded no earthquakes associated with this eruption.
Volcanoes of the Galápagos Islands List of volcanoes in Ecuador Special Report: Volcano Erupts on Fernandina Island. Charles Darwin Foundation Fernandina Benjamin Morell and the Galápagos Eruption of 1825 Eruption on Isla Fernandina NASA Earth Observatory
Synapomorphy and apomorphy
In phylogenetics and synapomorphy refer to derived characters of a clade: characters or traits that are derived from ancestral characters over evolutionary history. An apomorphy is a character, different from the form found in an ancestor, i.e. an innovation, that sets the clade apart from other clades. A synapomorphy is a shared apomorphy. In other words, it is an apomorphy shared by members of a monophyletic group, thus assumed to be present in their most recent common ancestor. An apomorphy is a character, different from the form found in an ancestor, i.e. an innovation, that sets the clade apart from other clades. A synapomorphy is a shared apomorphy. In other words, it is an apomorphy shared by members of a monophyletic group, thus assumed to be present in their most recent common ancestor. In most groups of mammals, the vertebral column is conserved, with the same number of vertebrae found in the neck of a giraffe, for example, as in mammals with shorter necks. However, in the Afrotheria clade, which includes elephant shrews, golden moles and elephants, there is an increase in the number of thoracolumbar vertebrae.
This is a synapomorphy of the clade: a shared feature considered to be derived from a common ancestor. The word synapomorphy—coined by German entomologist Willi Hennig—is derived from the Greek words σύν, syn = shared; these phylogenetic terms are used to describe different patterns of ancestral and derived character or trait states as stated in the above diagram in association with synapomorphies. Symplesiomorphy – an ancestral trait shared by two or more taxa. Plesiomorphy – a symplesiomorphy discussed in reference to a more derived state. Pseudoplesiomorphy – is a trait that cannot be identified as neither a plesiomorphy nor an apomorphy, a reversal. Reversal – is a loss of derived trait present in ancestor and the reestablishment of a plesiomorphic trait. Convergence – independent evolution of a similar trait in two or more taxa. Apomorphy – a derived trait. Apomorphy shared by two or more taxa and inherited from a common ancestor is synapomorphy. Apomorphy unique to a given taxon is autapomorphy.
Synapomorphy/Homology – a derived trait, found in some or all terminal groups of a clade, inherited from a common ancestor, for which it was an autapomorphy. Underlying synapomorphy – a synapomorphy, lost again in many members of the clade. If lost in all but one, it can be hard to distinguish from an autapomorphy. Autapomorphy – a distinctive derived trait, unique to a given taxon or group. Homoplasy in biological systematics is when a trait has been gained or lost independently in separate lineages during evolution; this convergent evolution leads to species independently sharing a trait, different from the trait inferred to have been present in their common ancestor. Parallel Homoplasy – derived trait present in two groups or species without a common ancestor due to convergent evolution. Reverse Homoplasy – trait present in an ancestor but not in direct descendants that reappears in descendants. Hemiplasy A new method of measuring phylogenetic characteristics is the use of Relative Apparent Synapomorphy Analysis.
The objective of analysis is to determine if a given characteristic is common between taxa as a result of either shared ancestors or the process of convergence. This method allows for several advantages such as computational efficiency and it administers an unbiased and reliable measure of phylogenetic signal; the concept of synapomorphy is relative to a given clade in the tree of life. What counts as a synapomorphy for one clade may well be a primitive character or plesiomorphy at a less inclusive or nested clade. For example, the presence of mammary glands is a synapomorphy for mammals in relation to tetrapods but is a symplesiomorphy for mammals in relation to one another—rodents and primates, for example. So the concept can be understood as well in terms of "a character newer than" and "a character older than" the apomorphy: mammary glands are evolutionarily newer than vertebral column, so mammary glands are an autapomorphy if vertebral column is an apomorphy, but if mammary glands are the apomorphy being considered vertebral column is a plesiomorphy.
Cladograms are diagrams. These illustrations are accurate predictive device in modern genetics, they are depicted in either tree or ladder form. Synapomorphies create evidence for historical relationships and their associated hierarchical structure. Evolutionarily, a synapomorphy is the marker for the most recent common ancestor of the monophyletic group consisting of a set of taxa in a cladogram. Cladistics, Berkeley
Georg Baur
Georg Baur was a vertebrate paleontologist and Neo-Lamarckian who studied reptiles of the Galapagos Islands the Galápagos tortoises, in the 1890s. He is best known for his subsidence theory of the origin of the Galapagos Islands, where he postulated the islands were the remains of a former landmass, connected to South America via Cocos Island. Baur was born in Weisswasser, Bohemia in 1859, he spent his early years Hohenheim near Stuttgart. As his father was a professor of forestry, Baur planned to study forestry. Where his father was a professor of forestry. However, while at university he became interested in the fields of geology and botany instead. Prior to his work on the Galapagos Islands, Baur was an assistant to Othniel Charles Marsh at Yale University from 1884 until 1890. Baur undertook an expedition to the Galápagos Islands in 1891, leaving New York on May 1, arriving in the Galápagos on June 9, departing the islands on August 26 for Guayaquil and the return to New York. Baur named several subspecies of Galápagos tortoise, including Chelonoidis nigra guentheri, Chelonoidis nigra galapagoensis.
Not all of Baur's tortoise taxa are still considered valid. He studied turtles of the southern United States, naming several species new to science; the following species and subspecies of reptiles were named in his honor by other herpetologists: Kinosternon baurii, Phyllodactylus baurii, Terrapene carolina bauri. He held the position of Docent in osteology and paleontology, Clark University, from 1890 to 1892, after that and chairman of the osteology and vertebrate paleontology department at the University of Chicago until his death in 1898 at age 39.5 years old. Lefalophodon
Chordate
A chordate is an animal constituting the phylum Chordata. During some period of their life cycle, chordates possess a notochord, a dorsal nerve cord, pharyngeal slits, an endostyle, a post-anal tail: these five anatomical features define this phylum. Chordates are bilaterally symmetric; the Chordata and Ambulacraria together form the superphylum Deuterostomia. Chordates are divided into three subphyla: Vertebrata. There are extinct taxa such as the Vetulicolia. Hemichordata has been presented as a fourth chordate subphylum, but now is treated as a separate phylum: hemichordates and Echinodermata form the Ambulacraria, the sister phylum of the Chordates. Of the more than 65,000 living species of chordates, about half are bony fish that are members of the superclass Osteichthyes. Chordate fossils have been found from as early as the Cambrian explosion, 541 million years ago. Cladistically, vertebrates - chordates with the notochord replaced by a vertebral column during development - are considered to be a subgroup of the clade Craniata, which consists of chordates with a skull.
The Craniata and Tunicata compose the clade Olfactores. Chordates form a phylum of animals that are defined by having at some stage in their lives all of the following anatomical features: A notochord, a stiff rod of cartilage that extends along the inside of the body. Among the vertebrate sub-group of chordates the notochord develops into the spine, in wholly aquatic species this helps the animal to swim by flexing its tail. A dorsal neural tube. In fish and other vertebrates, this develops into the spinal cord, the main communications trunk of the nervous system. Pharyngeal slits; the pharynx is the part of the throat behind the mouth. In fish, the slits are modified to form gills, but in some other chordates they are part of a filter-feeding system that extracts particles of food from the water in which the animals live. Post-anal tail. A muscular tail that extends backwards behind the anus. An endostyle; this is a groove in the ventral wall of the pharynx. In filter-feeding species it produces mucus to gather food particles, which helps in transporting food to the esophagus.
It stores iodine, may be a precursor of the vertebrate thyroid gland. There are soft constraints that separate chordates from certain other biological lineages, but are not part of the formal definition: All chordates are deuterostomes; this means. All chordates are based on a bilateral body plan. All chordates are coelomates, have a fluid filled body cavity called a coelom with a complete lining called peritoneum derived from mesoderm; the following schema is from the third edition of Vertebrate Palaeontology. The invertebrate chordate classes are from Fishes of the World. While it is structured so as to reflect evolutionary relationships, it retains the traditional ranks used in Linnaean taxonomy. Phylum Chordata †Vetulicolia? Subphylum Cephalochordata – Class Leptocardii Clade Olfactores Subphylum Tunicata – Class Ascidiacea Class Thaliacea Class Appendicularia Class Sorberacea Subphylum Vertebrata Infraphylum incertae sedis Cyclostomata Superclass'Agnatha' paraphyletic Class Myxini Class Petromyzontida or Hyperoartia Class †Conodonta Class †Myllokunmingiida Class †Pteraspidomorphi Class †Thelodonti Class †Anaspida Class †Cephalaspidomorphi Infraphylum Gnathostomata Class †Placodermi Class Chondrichthyes Class †Acanthodii Superclass Osteichthyes Class Actinopterygii Class Sarcopterygii Superclass Tetrapoda Class Amphibia Class Sauropsida Class Synapsida Craniates, one of the three subdivisions of chordates, all have distinct skulls.
They include the hagfish. Michael J. Benton commented that "craniates are characterized by their heads, just as chordates, or all deuterostomes, are by their tails". Most craniates are vertebrates; these consist of a series of bony or cartilaginous cylindrical vertebrae with neural arches that protect the spinal cord, with projections that link the vertebrae. However hagfish have incomplete braincases and no vertebrae, are therefore not regarded as vertebrates, but as members of the craniates, the group from which vertebrates are thought to have evolved; however the cladistic exclusion of hagfish from the vertebrates is controversial, as they ma
Squamata
Squamata is the largest order of reptiles, comprising lizards and amphisbaenians, which are collectively known as squamates or scaled reptiles. With over 10,000 species, it is the second-largest order of extant vertebrates, after the perciform fish, equal in number to the Saurischia. Members of the order are distinguished by their skins, which bear horny shields, they possess movable quadrate bones, making it possible to move the upper jaw relative to the neurocranium. This is visible in snakes, which are able to open their mouths wide to accommodate comparatively large prey. Squamata is the most variably sized order of reptiles, ranging from the 16 mm dwarf gecko to the 5.21 m green anaconda and the now-extinct mosasaurs, which reached lengths of over 14 m. Among other reptiles, squamates are most related to the tuatara, which superficially resembles lizards. Squamates are a monophyletic sister group to the rhynchocephalians, members of the order Rhynchocephalia; the only surviving member of Rhynchocephalia is the tuatara.
Squamata and Rhynchocephalia form the subclass Lepidosauria, the sister group to Archosauria, the clade that contains crocodiles and birds, their extinct relatives. Fossils of rhynchocephalians first appear in the Early Triassic, meaning that the lineage leading to squamates must have existed at the time. Scientists believe crown group squamates originated in the Early Jurassic based on the fossil record; the first fossils of geckos and snakes appear in the Middle Jurassic. Other groups like iguanians and varanoids appeared in the Cretaceous. Polyglyphanodontians, a distinct clade of lizards, mosasaurs, a group of predatory marine lizards that grew to enormous sizes appeared in the Cretaceous. Squamates suffered a mass extinction at the Cretaceous–Paleogene boundary, which wiped out polyglyphanodontians and many other distinct lineages; the relationships of squamates is debatable. Although many of the groups recognized on the basis of morphology are still accepted, our understanding of their relationships to each other has changed radically as a result of studying their genomes.
Iguanians were long thought to be the earliest crown group squamates based on morphological data, genetic data suggests that geckoes are the earliest crown group squamates. Iguanians are now united with anguimorphs in a clade called Toxicofera. Genetic data suggests that the various limbless groups. A study in 2018 found that Megachirella, an extinct genus of lepidosaur that lived about 240 million years ago during the Middle Triassic, was a stem-squamate, making it the oldest known squamate; the phylogenetic analysis was conducted by performing high-resolution microfocus X-ray computed tomography scans on the fossil specimen of Megachirella to gather detailed data about its anatomy. This data was compared with a phylogenetic dataset combining the morphological and molecular data of 129 extant and extinct reptilian taxa; the comparison revealed. The study found that geckos are the earliest crown group squamates not iguanians; the male members of the group Squamata have hemipenes, which are held inverted within their bodies, are everted for reproduction via erectile tissue like that in the human penis.
Only one is used at a time, some evidence indicates that males alternate use between copulations. The hemipenis has a variety of shapes, depending on the species, it bears spines or hooks, to anchor the male within the female. Some species have forked hemipenes. Due to being everted and inverted, hemipenes do not have a enclosed channel for the conduction of sperm, but rather a seminal groove that seals as the erectile tissue expands; this is the only reptile group in which both viviparous and ovoviviparous species are found, as well as the usual oviparous reptiles. Some species, such as the Komodo dragon, can reproduce asexually through parthenogenesis. There have been studies on how sexual selection manifests itself in lizards. Snakes use a variety of tactics in acquiring mates. Ritual combat between males for the females they want to mate with includes topping, a behavior exhibited by most viperids, in which one male will twist around the vertically elevated fore body of its opponent and forcing it downward.
It is common for neck biting to occur. Parthenogenesis is a natural form of reproduction in which the growth and development of embryos occur without fertilization. Agkistrodon contortrix and Agkistrodon piscivorus can reproduce by facultative parthenogenesis; that is, they are capable of switching from a sexual mode of reproduction to an asexual mode. The type of parthenogenesis that occurs is automixis with terminal fusion, a process in which two terminal products from the same meiosis fuse to form a diploid zygote; this process leads to genome wide homozygosity, expression of deleterious recessive alleles and to developmental abnormalities. Both captive-born and wild-born A. contortrix and A. piscivorus appear to be capable of this form of parthenogenesis. Reproduction in squamate reptiles is ordinarily sexual, with males having a ZZ pair of sex determining chromosomes, females a ZW pair. However, the Colombian Rainbow boa, Epicrates maurus, can reproduce by facultative parthenogenesis resulting in production of WW female pr
Microlophus
Microlophus is a genus of tropidurid lizards native to South America. There are around twenty recognized species and six of these are endemic to the Galápagos Islands where they are popularly known as lava lizards; the remaining, which are called Pacific iguanas, are found in the Andes and along the Pacific coasts of Chile and Ecuador. The distribution of the lava lizards and their variations in shape and behaviour show the phenomenon of adaptive radiation so typical of the inhabitants of this archipelago. One species occurs on all the central and western islands, which were connected during periods of lower sea levels, while one species each occurs on six other more peripheral islands. All have most evolved from a single ancestral species. However, as usual for Tropiduridae they can change their colour individually to some extent, members of the same species occurring in different habitats show colour differences, thus animals living on dark lava are darker than ones which live in lighter, sandy environments.
Listed alphabetically by specific name.. Microlophus albemarlensis – Galápagos lava lizard* Microlophus atacamensis – Atacamen Pacific iguana Microlophus barringtonensis * Microlophus bivittatus – San Cristóbal lava lizard* Microlophus delanonis – Española lava lizard or Hood lava lizard* Microlophus duncanensis – Pinzón lava lizard* Microlophus grayii – Floreana lava lizard* Microlophus habelii – Marchena lava lizard* Microlophus heterolepis Microlophus indefatigabilis – Santa Cruz lava lizard * Microlophus jacobii Santiago lava lizard * Microlophus koepckeorum – Frost's iguana Microlophus occipitalis – knobbed Pacific iguana Microlophus pacificus – common Pacific iguana* Microlophus peruvianus – Peru Pacific iguana Microlophus quadrivittatus – four-banded Pacific iguana Microlophus stolzmanni – Stolzmann's Pacific iguana or Stolzmann's lizard Microlophus tarapacensis – Tarapaca Pacific iguana Microlophus theresiae – Theresia's Pacific iguana Microlophus theresioides – corredor de pica Microlophus thoracicus – Tschudi's Pacific iguana Microlophus tigris – tiger Pacific iguana Microlophus yanezi – Yanez's lava lizardNota bene: A binomial authority in parentheses indicates that the species was described in a genus other than Microlophus.
Duméril AMC, Bibron G. Erpétologie générale ou Histoire naturelle complète des Reptiles. Tome quatrième. Paris: Roret. Ii + 571 pp
Tropiduridae
The Tropiduridae are a family of iguanid lizards. The family is sometimes considered Tropidurinae; the subfamily is native to South America, including the islands of Trinidad and the Galápagos. Known as neotropical ground lizards, most are ground-dwelling animals, the subfamily includes some lizards adapted to cold climates, including those of the Andes mountains and Tierra del Fuego. Several species give birth to live young; the family Tropiduridae contains the following eight genera. Eurolophosaurus Frost, Rodrigues, T. Grant & Titus, 2001 Microlophus A. M. C. Duméril & Bibron, 1837 – lava lizards and Pacific iguanas Plica Gray, 1830 Stenocercus A. M. C. Duméril & Bibron, 1837 – whorltail iguanas Strobilurus Wiegmann, 1834 Tropidurus Wied-Neuwied, 1824 Uracentron Kaup, 1827 – thornytail iguanas Uranoscodon C. Bonaparte, 1832 Data related to Tropiduridae at Wikispecies Bell T; the Zoology of the Voyage of H. M. S. Beagle Under the Command of Captain Fitzroy, R. N. during the years 1832 to 1836. Edited and Superintended by Charles Darwin...
Naturalist to the Expedition. Part V. Reptiles. London: Smith and Company. Vi + 51 pp. + Plates 1-20
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