Channel Islands (California)
The Channel Islands form an eight-island archipelago along the Santa Barbara Channel in the Pacific Ocean off the coast of southern California. Five of the islands are part of Channel Islands National Park, the waters surrounding these islands make up Channel Islands National Marine Sanctuary; the islands were first colonized by the Chumash and Tongva Native Americans 13,000 years ago, who were displaced by Spaniards who used the islands for fishing and agriculture. The U. S. military uses the islands as training grounds, weapons test sites, as a strategic defensive location. The Channel Islands and the surrounding waters house a diverse ecosystem with many endemic species and subspecies; the islands harbor 150 unique species of plant that are found only on the Islands and nowhere else in the world. The eight islands are split among the jurisdictions of three separate California counties: Santa Barbara County, Ventura County, Los Angeles County; the islands are divided into two groups. The four northern Islands used to be a single landmass known as Santa Rosae.
The archipelago extends for 160 miles between San Miguel Island in the north and San Clemente Island in the south. Together, the islands' land area totals about 346 square miles. Five of the islands were made into the Channel Islands National Park in 1980; the Channel Islands National Marine Sanctuary encompasses the waters six nautical miles off these islands. Santa Catalina Island is the only one of the eight islands with a significant permanent civilian settlement—the resort city of Avalon and the unincorporated town of Two Harbors. University of Southern California houses its USC Wrigley Institute for Environmental Studies marine lab in Two Harbors. Natural seepage of oil occurs at several places in the Santa Barbara Channel. Tar balls or pieces of tar in small numbers are found on the beaches. Native Americans used occurring tar, for a variety of purposes which include roofing, waterproofing and some ceremonial purposes; the Channel Islands at low elevations are frost-free and constitute one of the few such areas in the 48 contiguous US states.
It snows only on higher mountain peaks. Separated from the California mainland throughout recent geological history, the Channel Islands provide the earliest evidence for human seafaring in the Americas, it is the site of the discovery of the earliest paleontological evidence of humans in North America. The northern Channel Islands are now known to have been settled by maritime Paleo-Indian peoples at least 13,000 years ago. Archaeological sites on the island provide a unique and invaluable record of human interaction with Channel Island marine and terrestrial ecosystems from the late Pleistocene to historic times; the Anacapa Island Archeological District is a 700-acre historic district, listed on the National Register of Historic Places in 1979. The northern islands were occupied by the island Chumash, while the southern islands were occupied by the Tongva. Author Scott O'Dell wrote about the indigenous peoples living on the island in his novel Island of the Blue Dolphins. Aleut hunters visited the islands to hunt otters in the early 1800s.
The Aleuts purportedly clashed with the native Chumash. Aleut interactions with the natives were detailed in O'Dell's book; the Chumash and Tongva were removed from the islands in the early 19th century and taken to Spanish missions and pueblos on the adjacent mainland. For a century, the Channel Islands were used for ranching and fishing activities, which had significant impacts on island ecosystems, including the local extinction of sea otters, bald eagles, other species. Several of the islands were used by whalers in the 1930s to hunt for sperm whales. With most of the Channel Islands now managed by federal agencies or conservation groups, the restoration of the island ecosystems has made significant progress. An example of conservation progress has been the bald eagle, threatened due to DDT contamination, but whose populations are now recovering. With the help of scientists from the USC Wrigley Institute for Environmental Studies, the Catalina Island Fox has recovered from a low of 100 individual foxes to over 1,500 foxes in 2018.
In 1972, in "a bit of political theater”, twenty-six Brown Berets sailed to Catalina Island on tourist boats, set up a small encampment near the town of Avalon, put up a Mexican flag and claimed the island on behalf of all Chicanos, citing the Treaty of Guadalupe Hidalgo. Twenty-four days sheriff's deputies took everyone back to the mainland. Channel Islands National Park's mainland visitor center received 342,000 visitors in 2014; the islands attract around 70,000 tourists a year, most during the summer. Visitors can travel to the islands via public airplane transportation. Camping grounds are available on Anacapa, Santa Rosa, Santa Cruz, San Miguel, Santa Barbara Islands in the Channel Islands National Park. Attractions include whale watching, snorkeling and camping; the United States Navy controls San Nicolas Island and San Clemente Island, has installations elsewhere in the chain. During World War II all of southern California’s Channel Islands were put under military control, including the civilian-populated Santa Catalina where tourism was halted and established residents needed permits to travel to and from the mainland.
San Miguel Island was used as a bombing range and Santa Barbara Island as an early warning outpost under the presumed threat of a
Sceloporus occidentalis bocourtii
Sceloporus occidentalis bocourtii known as the Coast Range fence lizard, is a subspecies of Sceloporus occidentalis, the Western fence lizard. This taxon, S. o. bocourtii, is found in the state of California, from Sonoma County south to Santa Barbara County. The subspecies S. o. bocourtii is in the family Phrynosomatidae, North American spiny lizards. The subspecific name, bocourtii, is in honor of French herpetologist Marie Firmin Bocourt. Great Basin fence lizard Island fence lizard Northwestern fence lizard Sierra fence lizard Hogan, C. Michael. "Western fence lizard". Globaltwitcher, ed. Nicklas Stromberg. ITIS report: Sceloporus occidentalis bocourtii. Bell, Edwin L.. "A Preliminary Report on the Subspecies of the Western Fence Lizard, Sceloporus occidentalis, its Relationships to the Eastern Fence Lizard, Sceloporus undulatus ". Herpetologica 10: 31-36.. Boulenger GA. Catalogue of the Lizards in the British Museum. Second Edition. Volume II. Iguanidæ... London: Trustees of the British Museum.. Xiii + 497 pp. + Plates I-XXIV..
Smith, Hobart M.. Reptiles of North America: A Guide to Field Identification. New York: Golden Press. 240 pp. ISBN 0-307-13666-3, paperback.
Sceloporus occidentalis occidentalis
Sceloporus occidentalis occidentalis is a subspecies of the western fence lizard. The common name for this taxon is the northwestern fence lizard; this lizard occurs in the state of Washington in the United States. Media related to Sceloporus occidentalis occidentalis at Wikimedia Commons Coast Range fence lizard Island fence lizard ITIS report: Sceloporus occidentalis occidentalis C. Michael Hogan "Western fence lizard", Globaltwitcher, ed. Nicklas Stromberg
Iguania is an infraorder of squamate reptiles that includes iguanas, chameleons and New World lizards like anoles and phrynosomatids. Using morphological features as a guide to evolutionary relationships, the Iguania are believed to form the sister group to the remainder of the Squamata. However, molecular information has placed Iguania well within the Squamata as sister taxa to the Anguimorpha and related to snakes. Iguanians are arboreal and have primitive fleshy, non-prehensile tongues, although the tongue is modified in chameleons; the group has a fossil record. The Iguania include these extant families: Clade Acrodonta Family Agamidae – agamid lizards, Old World arboreal lizards Family Chamaeleonidae – chameleons Clade Pleurodonta – American arboreal lizards, iguanas Family Leiocephalidae Genus Leiocephalus: curly-tailed lizards Family Corytophanidae – helmet lizards Family Crotaphytidae – collared lizards, leopard lizards Family Hoplocercidae – dwarf and spinytail iguanas Family Iguanidae – marine, Galapagos land, rock, desert and chuckwalla iguanas Family Tropiduridae – tropidurine lizards subclade of Tropiduridae Tropidurini – neotropical ground lizards Family Dactyloidae – anoles Family Polychrotidae subclade of Polychrotidae Polychrus Family Phrynosomatidae – North American spiny lizards Family Liolaemidae – South American swifts Family Opluridae – Malagasy iguanas Family Leiosauridae – leiosaurs subclade of Leiosaurini Leiosaurae subclade of Leiosaurini Anisolepae Below is a cladogram from the phylogenetic analysis of Daza et al. showing the interrelationships of extinct and living iguanians
Molecular phylogenetics is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominately in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to determine the processes by which diversity among species has been achieved; the result of a molecular phylogenetic analysis is expressed in a phylogenetic tree. Molecular phylogenetics is one aspect of molecular systematics, a broader term that includes the use of molecular data in taxonomy and biogeography. Molecular phylogenetics and molecular evolution correlate. Molecular evolution is the process of selective changes at a molecular level throughout various branches in the tree of life. Molecular phylogenetics makes inferences of the evolutionary relationships that arise due to molecular evolution and results in the construction of a phylogenetic tree; the figure displayed on the right depicts the phylogenetic tree of life as one of the first detailed trees, according to information known in the 1870s by Haeckel.
The theoretical frameworks for molecular systematics were laid in the 1960s in the works of Emile Zuckerkandl, Emanuel Margoliash, Linus Pauling, Walter M. Fitch. Applications of molecular systematics were pioneered by Charles G. Sibley, Herbert C. Dessauer, Morris Goodman, followed by Allan C. Wilson, Robert K. Selander, John C. Avise. Work with protein electrophoresis began around 1956. Although the results were not quantitative and did not improve on morphological classification, they provided tantalizing hints that long-held notions of the classifications of birds, for example, needed substantial revision. In the period of 1974–1986, DNA-DNA hybridization was the dominant technique used to measure genetic difference. Early attempts at molecular systematics were termed as chemotaxonomy and made use of proteins, enzymes and other molecules that were separated and characterized using techniques such as chromatography; these have been replaced in recent times by DNA sequencing, which produces the exact sequences of nucleotides or bases in either DNA or RNA segments extracted using different techniques.
In general, these are considered superior for evolutionary studies, since the actions of evolution are reflected in the genetic sequences. At present, it is still a expensive process to sequence the entire DNA of an organism. However, it is quite feasible to determine the sequence of a defined area of a particular chromosome. Typical molecular systematic analyses require the sequencing of around 1000 base pairs. At any location within such a sequence, the bases found in a given position may vary between organisms; the particular sequence found in a given organism is referred to as its haplotype. In principle, since there are four base types, with 1000 base pairs, we could have 41000 distinct haplotypes. However, for organisms within a particular species or in a group of related species, it has been found empirically that only a minority of sites show any variation at all, most of the variations that are found are correlated, so that the number of distinct haplotypes that are found is small. In a molecular systematic analysis, the haplotypes are determined for a defined area of genetic material.
Haplotypes of individuals of related, yet different, taxa are determined. Haplotypes from a smaller number of individuals from a different taxon are determined: these are referred to as an outgroup; the base sequences for the haplotypes are compared. In the simplest case, the difference between two haplotypes is assessed by counting the number of locations where they have different bases: this is referred to as the number of substitutions; the difference between organisms is re-expressed as a percentage divergence, by dividing the number of substitutions by the number of base pairs analysed: the hope is that this measure will be independent of the location and length of the section of DNA, sequenced. An older and superseded approach was to determine the divergences between the genotypes of individuals by DNA-DNA hybridization; the advantage claimed for using hybridization rather than gene sequencing was that it was based on the entire genotype, rather than on particular sections of DNA. Modern sequence comparison techniques overcome this objection by the use of multiple sequences.
Once the divergences between all pairs of samples have been determined, the resulting triangular matrix of differences is submitted to some form of statistical cluster analysis, the resulting dendrogram is examined in order to see whether the samples cluster in the way that would be expected from current ideas about the taxonomy of the group. Any group of haplotypes that are all more similar to one another than any of them is to any other haplotype may be said to constitute a clade, which may be visually represented as the figure displayed on the right demonstrates. Statistical techniques such as bootstrapping and jackknifing help in providing reliability estimates for the positions of haplotypes within the evolutionary trees; every living organism contains deoxyribonucleic acid, ribonucleic acid, proteins. In general related organisms have a high degree of similarity in the molecular structure of these substances, while the molecules of organisms distantly related s
Lizards are a widespread group of squamate reptiles, with over 6,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic as it excludes Amphisbaenia. Lizards range in size from chameleons and geckos a few centimeters long to the 3 meter long Komodo dragon. Most lizards are quadrupedal. Others are legless, have long snake-like bodies; some such as the forest-dwelling Draco lizards are able to glide. They are territorial, the males fighting off other males and signalling with brightly colours, to attract mates and to intimidate rivals. Lizards are carnivorous being sit-and-wait predators. Lizards make use of a variety of antipredator adaptations, including venom, reflex bleeding, the ability to sacrifice and regrow their tails; the adult length of species within the suborder ranges from a few centimeters for chameleons such as Brookesia micra and geckos such as Sphaerodactylus ariasae to nearly 3 m in the case of the largest living varanid lizard, the Komodo dragon.
Most lizards are small animals. Lizards have four legs and external ears, though some are legless, while snakes lack these characteristics. Lizards and snakes share a movable quadrate bone, distinguishing them from the rhynchocephalians, which have more rigid diapsid skulls; some lizards such as chameleons have prehensile tails. As in other reptiles, the skin of lizards is covered in overlapping scales made of keratin; this reduces water loss through evaporation. This adaptation enables lizards to thrive in some of the driest deserts on earth; the skin is tough and leathery, is shed as the animal grows. Unlike snakes which shed the skin in a single piece, lizards slough their skin in several pieces; the scales may be modified into spines for display or protection, some species have bone osteoderms underneath the scales. The dentitions of lizards reflect their wide range of diets, including carnivorous, omnivorous, herbivorous and molluscivorous. Species have uniform teeth suited to their diet, but several species have variable teeth, such as cutting teeth in the front of the jaws and crushing teeth in the rear.
Most species are pleurodont, though chameleons are acrodont. The tongue can be extended outside the mouth, is long. In the beaded lizards and monitor lizards, the tongue is forked and used or to sense the environment, continually flicking out to sample the environment, back to transfer molecules to the vomeronasal organ responsible for chemosensation, analogous to but different from smell or taste. In geckos, the tongue is used to lick the eyes clean: they have no eyelids. Chameleons have long sticky tongues which can be extended to catch their insect prey. Three lineages, the geckos and chameleons, have modified the scales under their toes to form adhesive pads prominent in the first two groups; the pads are composed of millions of tiny setae which fit to the substrate to adhere using van der Waals forces. In addition, the toes of chameleons are divided into two opposed groups on each foot, enabling them to perch on branches as birds do. Aside from legless lizards, most lizards are quadrupedal and move using gaits with alternating movement of the right and left limbs with substantial body bending.
This body bending prevents significant respiration during movement, limiting their endurance, in a mechanism called Carrier's constraint. Several species can run bipedally, a few can prop themselves up on their hindlimbs and tail while stationary. Several small species such as those in the genus Draco can glide: some can attain a distance of 60 metres, losing 10 metres in height; some species, like chameleons, adhere to vertical surfaces including glass and ceilings. Some species, like the common basilisk, can run across water. Lizards make use of their senses of sight, touch and hearing like other vertebrates; the balance of these varies with the habitat of different species. Monitor lizards have acute vision and olfactory senses; some lizards make unusual use of their sense organs: chameleons can steer their eyes in different directions, sometimes providing non-overlapping fields of view, such as forwards and backwards at once. Lizards lack external ears, having instead a circular opening in which the tympanic membrane can be seen.
Many species rely on hearing for early warning of predators, flee at the slightest sound. As in snakes and many mammals, all lizards have a specialised olfactory system, the vomeronasal organ, used to detect pheromones. Monitor lizards transfer scent from the tip of their tongue to the organ; some lizards iguanas, have retained a photosensory organ on the top of their heads called the parietal eye, a basal feature present in the tuatara. This "eye" has only a rudimentary retina and lens and cannot form images, but is sensitive to changes in light and dark and can detect movemen