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120-401: Amblyrhynchus Brachylophus Cachryx Conolophus Ctenosaura Cyclura Dipsosaurus Iguana Sauromalus The Iguanidae is a family of lizards composed of the iguanas , chuckwallas , and their prehistoric relatives, including the widespread green iguana . Iguanidae is thought to be the sister group to the collared lizards (family Crotaphytidae );

240-441: A lek , but they can occur singly. Medium-sized males roam areas near the territories of large males or walk along beaches looking for females, while small " sneaky " males may enter the territories of large males. To threaten another male, a male will bob his head, walk on stiff legs, raise the spiny crest along the back and open the mouth to reveal the reddish interior. In most cases the suitor will turn away, but if he responds with

360-467: A dispersal. Many kinds of dispersal dormant stages are able to withstand not only desiccation and low and high temperature, but also action of digestive enzymes during their transfer through digestive tracts of birds and other animals, high concentration of salts, and many kinds of toxicants. Such dormant-resistant stages made possible the long-distance dispersal from one water body to another and broad distribution ranges of many freshwater animals. Dispersal

480-588: A female. This rapid mating is necessary because large males will chase them out of their territory as soon as they are discovered. During each breeding season, a male will mate with many females if given the chance, but the female only mates once. Once a female has mated, she rejects other suitors by nodding her head at them. Roughly one month after copulation, the female lays between one and six eggs, typically two or three. The leathery white eggs measure about 9 cm × 4.5 cm (3.5 in × 1.8 in) and weigh 80–120 g (2.8–4.2 oz). This

600-455: A few do succeed in locating spots of bare limestone, where they settle and transform by growth into a polyp . All things being favorable, the single polyp grows into a coral head by budding off new polyps to form a colony. The majority of animals are motile . Motile animals can disperse themselves by their spontaneous and independent locomotive powers. For example, dispersal distances across bird species depend on their flight capabilities. On

720-672: A few million years later at about 35 million years ago, presumably after its dispersal event to the Pacific . All other modern iguana genera formed in the Neogene period. A phylogenetic tree of Iguaninae is shown here: Dipsosaurus Brachylophus Cyclura Ctenosaura Cachryx Amblyrhynchus Conolophus Iguana Sauromalus Iguanas and iguana-type species are diverse in terms of size, appearance, and habitat. They typically flourish in tropical, warm climates, such as regions of South America and islands in

840-511: A few months later. Marine iguanas vary in appearance between the different islands and several subspecies are recognized. Although relatively large numbers remain and it is locally abundant, this protected species is considered threatened , primarily from El Niño cycles, introduced predators and chance events like oil spills . The marine iguana was first described in 1825 as Amblyrhynchus cristatus by Thomas Bell . He recognized several of its distinctive features, but believed that

960-644: A high level of accuracy. By far the largest subpopulation—likely including around 2 ⁄ 5 of all marine iguanas—lives on Fernandina Island, but estimates vary greatly from 15,000 to 120,000 individuals. In contrast, the maximum size of the subpopulations on the islands of San Cristóbal, Darwin and Pinzon is estimated to be 400, 800 and 900, respectively. It is estimated that Marchena Island has 4,000–10,000 marine iguanas, Rabida Island has 1,000–2,000 and Santa Fé Island has 15,000–30,000. Although individuals may on occasion be transferred between islands by ocean currents, marine iguanas are unable to swim between all but

1080-429: A higher survival rate during periods where their normal algal food is reduced. However, the hindgut of marine iguanas is specially adapted to algae feeding, likely restricting the possibility of efficiently switching to other plant types. The algae are digested with the help of endosymbiotic bacteria in their gut. In the first months after hatching, the juveniles mainly feed on feces from larger marine iguanas, gaining

1200-537: A large amount of and diverse set of seeds from urban to rural environments. This could lead to possible sources of invasive species on the urban-rural gradient. Another example of the effects of urbanization could be seen next to rivers. Urbanization has led to the introduction of different invasive species through direct planting or wind dispersal. In turn, rivers next to these invasive plant species have become vital dispersal vectors. Rivers could be seen to connect urban centers to rural and natural environments. Seeds from

1320-422: A large measure of stress, resulting in elevated glucocorticoid levels can cause complications such as reproduction failure. Human activity has been considered a cause of elevated levels of glucocorticoid in species. Results of a study show that marine iguanas in areas central to tourism are not chronically stressed, but do show lower stress response compared to groups undisturbed by tourism. Tourism, thus, does affect

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1440-520: A low mating success rate compared to the large males that maintain a territory. During courtship display, a territorial male nods at the female, may open his mouth, and performs a slow sideways walk towards her. If she accepts, the male will mount her while holding her by the neck. A mating lasts no more than 20 minutes, typically 3 to 4 minutes, but it is comparatively rapid in the small "sneaky" males, which easily are overlooked because their size, general morphology and colours are similar to those of

1560-598: A minute. Most females and smaller males feed on exposed algae in the intertidal zone during low tide, retreating once the water returns and starts washing over them. They often scurry back-and-forth repeatedly, running to a patch of algae to take a few bites and then return fast to higher ground to avoid incoming waves. The separation in feeding behavior is advantageous because the large offshore feeding males experience less competition for food from smaller males and females. A few individuals of intermediate size may use both feeding strategies. In general, each marine iguana has

1680-533: A narrower definition of Iguanidae. Family Iguanidae Family Corytophanidae Family Crotaphytidae Family Hoplocercidae Family Iguanidae Family Opluridae Family Phrynosomatidae Family Polychridae Family Tropiduridae Family Iguanidae Here families and subfamilies are proposed as clade names, but may be recognized under the traditional Linnean nomenclature. Iguanidae Marine iguana 7–11 subspecies; see text The marine iguana ( Amblyrhynchus cristatus ), also known as

1800-520: A negative impact for the surrounding ecosystems. However, human-created habitats such as urban environments have allowed certain migrated species to become urbanophiles or synanthropes . Dispersal has caused changes to many species on a genetic level. A positive correlation has been seen for differentiation and diversification of certain species of spiders in the Canary Islands. These spiders were residing in archipelagos and islands. Dispersion

1920-501: A slightly positive effect to human settlers like honeybees and earthworms . Most animals are capable of locomotion and the basic mechanism of dispersal is movement from one place to another. Locomotion allows the organism to "test" new environments for their suitability, provided they are within the animal's range. Movements are usually guided by inherited behaviors . The formation of barriers to dispersal or gene flow between adjacent areas can isolate populations on either side of

2040-511: A southwestern). However, even the oldest divergence between marine iguana populations is quite recent; no more than 230,000 years and likely less than 50,000 years. On occasion one makes it to another island than its home island, resulting in hybridization between different marine iguana populations. There is one confirmed record of a marine iguana outside the Galápagos Islands; in 2014 an individual appeared on Isla de la Plata near

2160-606: A specific feeding site it returns to day after day. Most feed daily, but large offshore feeding males often only every second or third day. During bad weather with high waves marine iguanas do not feed, sometimes for more than a week. Large males often do not feed for several weeks when maintaining a breeding territory, resulting in them losing up to about one-quarter of their weight. It takes many months for them to return to their original weight. In captivity, individuals have remained strong and active even after fasting for as much as 100 days. Foraging behavior changes in accordance to

2280-409: A study that relied on mtDNA , the marine iguana was estimated to have diverged from land iguanas some 5-15 million years ago, which is older than any of the extant Galápagos islands. It has therefore traditionally been thought that the ancestral species inhabited parts of the volcanic archipelago that are now submerged. However, a more recent study that included both mtDNA and nDNA indicates that

2400-437: A sub-population goes extinct by chance, it is more likely to be recolonized if the dispersal rate is high. Increased connectivity can also decrease the degree of local adaptation. Human interference with the environment has been seen to have an effect on dispersal. Some of these occurrences have been accidents, like in the case of zebra mussels, which are indigenous to Southeast Russia. A ship had accidentally released them into

2520-533: A submissive position and retreats. In general fights between males are harmless and highly ritualized, but on occasion they will bite and injure each other. Males are primarily selected by females on the basis of their body size. Females display a stronger preference for mating with bigger males. It is precisely because of body size that reproductive performance increases and "is mediated by higher survival of larger hatchlings from larger females and increased mating success of larger males." Other factors involved in

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2640-579: Is habitat fragmentation due to human land use. By contrast, natural barriers to dispersal that limit species distribution include mountain ranges and rivers. An example is the separation of the ranges of the two species of chimpanzee by the Congo River . On the other hand, human activities may also expand the dispersal range of a species by providing new dispersal methods (e.g., ballast water from ships ). Many such dispersed species become invasive , like rats or stinkbugs , but some species also have

2760-560: Is a monotypic genus , having only one species, Amblyrhynchus cristatus . Researchers theorize that land iguanas (genus Conolophus ) and marine iguanas evolved from a common ancestor since arriving on the islands from Central or South America, presumably by rafting . The land and marine iguanas of the Galápagos form a clade , the nearest relatives of which are the Ctenosaura iguanas of Mexico and Central America. Based on

2880-605: Is a correlation between longevity and body size, particularly for adult males. Large body size in males is selected sexually, but can be detrimental during El Niño events when resources are scarce. This results in large males suffering higher mortality than females and smaller adult males. The mortality rates of marine iguanas are explained through the size difference between the sexes. Some individuals have been shown to shrink in body size by up to 20% during El Niño events and grow back to their previous size when food became available again. Female marine iguanas reach sexual maturity at

3000-434: Is a critical process for understanding both geographic isolation in evolution through gene flow and the broad patterns of current geographic distributions ( biogeography ). A distinction is often made between natal dispersal where an individual (often a juvenile) moves away from the place it was born, and breeding dispersal where an individual (often an adult) moves away from one breeding location to breed elsewhere. In

3120-501: Is a way to observe the cues of biological dispersal suggesting the reasoning behind the placement. This concept implies that the movement between species also involve information transfer. Methods such as GPS location are used to monitor the social cues and mobility of species regarding habitat selection. GPS radio-collars can be used when collecting data on social animals such a meerkats. Consensus data such as detailed trip records and point of interest (POI) data can be used to predict

3240-494: Is better adapted to its natal environment than the one it ends up in. In social animals (such as many birds and mammals) a dispersing individual must find and join a new group, which can lead to loss of social rank. "Dispersal range" refers to the distance a species can move from an existing population or the parent organism. An ecosystem depends critically on the ability of individuals and populations to disperse from one habitat patch to another. Therefore, biological dispersal

3360-432: Is commonly called the dispersive phase of the life cycle. The strategies of organisms' entire life cycles often are predicated on the nature and circumstances of their dispersive phases. In general, there are two basic types: Due to population density, dispersal may relieve pressure for resources in an ecosystem, and competition for these resources may be a selection factor for dispersal mechanisms. Dispersal of organisms

3480-725: Is completely protected under the laws of Ecuador , and is listed under CITES Appendix II. Almost all its land range is in the Galápagos National Park (only the 3% human-inhabited sections in the archipelago are excluded ) and all its sea range is in the Galápagos Marine Reserve . Certain coastal roads have lower speed limits to reduce the risk posed by cars, especially to the young. There have been attempts of removing introduced predators from some places, but this has not been without problems. Feral dogs mostly feed on large marine iguanas, but also limit

3600-513: Is critical to the stability of ecosystems. Urban areas can be seen to have their own unique effects on the dispersal range and dispersal abilities of different organisms. For plant species, urban environments largely provide novel dispersal vectors. While animals and physical factors (i.e. wind, water, etc) have played a role in dispersal for centuries, motor vehicles have recently been considered as major dispersal vectors. Tunnels that connect rural and urban environments have been shown to expedite

3720-404: Is due to the amount of food available, which depends on sea temperature and algae growth. Marine iguanas are sexually dimorphic with adult males on average being significantly longer and weighing about twice as much as adult females. Additionally, males have broader heads and larger tubercles than females. However, the largest females are only about 20–40% shorter than the largest males. There

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3840-424: Is explained due to their long life spans and slow microevolution. Penguins in the subantarctic have very different foraging behavior from those of subtropical waters; it would be very hard to survive by keeping up with the fast-changing climate because these behaviors took years to shape. A dispersal barrier may result in a dispersal range of a species much smaller than the species distribution. An artificial example

3960-404: Is from 35 to 39 °C (95–102 °F) and the temperature declines throughout a foraging trip to the sea, sometimes by as much as 10 °C (18 °F), the marine iguana has several behavioral adaptations for thermoregulation . At cold temperatures their muscles are less efficient, but their relatively high temperature preference is also related to the optimal temperature for digesting

4080-425: Is large for an iguana , and altogether the eggs may weigh up to one-quarter the weight of the female. The nest sites can be as much as 2 km (1.2 mi) inland, but typically are much closer to the coast. They are occasionally as little as 20 m (66 ft) inland, although they have to be above the high tide water mark. The nest is 30–80 cm (12–31 in) deep and dug in sand or volcanic ash by

4200-418: Is most commonly quantified either in terms of rate or distance. Dispersal rate (also called migration rate in the population genetics literature) or probability describes the probability that any individual leaves an area or, equivalently, the expected proportion of individual to leave an area. The dispersal distance is usually described by a dispersal kernel which gives the probability distribution of

4320-663: Is necessary to accommodate the large salt glands. The head may appear white from encrusted salt. Marine iguanas have mutualistic and commensal relationships with several other animals. Lava lizards may scurry over marine iguanas when hunting flies, and Darwin's finches , mockingbirds and Sally lightfoot crabs sometimes feed on mites and ticks that they pick off their skin. Marine iguanas typically ignore these visits. When underwater, they are often cleaned by fish , like Pacific sergeant majors that pick off moulting skin. Although there are no apparent benefits to either species, marine iguanas commonly live close together with

4440-470: Is possibly related to their need of defending the nest from other females on an island with few suitable sites. Marine iguanas typically range from 12 to 56 cm (4.7–22.0 in) in snout-to- vent length and have a tail length from 17 to 84 cm (6.7–33.1 in). There are major geographical differences, as iguanas from large islands tend to grow relatively large as adults, while those from small islands are smaller in size. In one study,

4560-420: Is speculated that the bones of the iguana actually shorten as shrinkage of connective tissue could only account for a 10% change in length. Marine iguanas have several adaptions that aid their feeding. Their flattened tail is the primary means of propulsion in the water. When on the surface, they may use their legs for maintaining balance. Although their partially webbed feet often are mentioned, this webbing

4680-442: Is suspected that the exact algal diet of each population plays a role in their colour. Females show much less variation between the islands and are typically dark with less contrasting colours than the males. In most places, females do not change colour conspicuously between the breeding and non-breeding season, but at least on Española (subspecies venustissimus ) they do assume relatively bright male-like colours when nesting, which

4800-511: Is very marginal and no greater in extent than in the green iguana , a species that also shares the flattened tail. Marine iguanas have powerful limbs with long, sharp claws for climbing, holding onto rocks and pulling themselves forward when at the sea bottom (adding to the propulsion provided by the tail). They are buoyant and float to the ocean surface if they are not actively swimming or holding on to rocks underwater. However, they have unusually compact ( osteosclerose ) limb bones compared to

4920-569: Is very rare and has only been documented a few times on South Plaza , a tiny island where the usually separated breeding territories and seasons of the two species overlap. The hybrids have intermediate features, stay on land and are infertile . The different marine iguana populations fall into three main clades: western islands, northeastern islands and southeastern islands. These can be further divided, each subclade generally matching marine iguanas from one or two primary island, except on San Cristóbal where there are two subclades (a northeastern and

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5040-533: The Galápagos land iguana ) possibly is a necessity if all the island subspecies are to survive. Biological dispersal Biological dispersal may be contrasted with geodispersal , which is the mixing of previously isolated populations (or whole biotas) following the erosion of geographic barriers to dispersal or gene flow. Dispersal can be distinguished from animal migration (typically round-trip seasonal movement), although within population genetics ,

5160-482: The alarm call of the Galápagos mockingbird , another species that is sometimes preyed upon by the hawk. Marine iguanas can easily be approached by humans as they are very tame and generally make little or no attempt to escape. Individuals that have been caught before are only slightly more wary when again encountering humans. Even when repeatedly caught and deliberately mishandled each time, they do not attempt to bite or lash with their tail in self-defense (although

5280-429: The intertidal zone . They mainly live in colonies on rocky shores where they bask after visiting the relatively cold water or intertidal zone, but can also be seen in marshes, mangrove swamps and beaches. Large males defend territories for a short period, but smaller males have other breeding strategies. After mating, the female digs a nest hole in the soil where she lays her eggs, leaving them to hatch on their own

5400-488: The invasive brown algae Giffordia mitchelliae . When their food algae (red and green algae) disappears during El Niños, the areas may be taken over by this brown algae, causing starvation among the marine iguanas. With global warming , it is expected that El Niño events will be stronger and occur more frequently. Introduced predators, to which they have little or no protection, include animals such as pigs, dogs, cats and rats. Dogs may take adult marine iguanas, while

5520-557: The sea iguana , saltwater iguana , or Galápagos marine iguana , is a species of iguana found only on the Galápagos Islands ( Ecuador ). Unique among modern lizards , it is a marine reptile that has the ability to forage in the sea for algae , which makes up almost all of its diet. Marine iguanas are the only extant lizard that spends time in a marine environment. Large males are able to dive to find this food source, while females and smaller males feed during low tide in

5640-811: The Caribbean and in the Pacific. Iguanas typically possess dorsal spines across their back, a dewlap on the neck, sharp claws, a long whip-like tail, and a stocky, squat build. Most iguanas are arboreal , living in trees, but some species tend to be more terrestrial , which means they prefer the ground. Iguanas are typically herbivores and their diets vary based on what plant life is available within their habitat. Iguanas across many species remain oviparious , and exhibit little to no parental care when their eggs hatch. They do, however, display nest-guarding behavior. Like all extant non-avian reptiles, they are poikilothermic , and also rely on regular periods of basking under

5760-522: The Ecuadorian mainland. Seven or eight subspecies of the marine iguana, listed alphabetically, have traditionally been recognized: In 2017, the first comprehensive taxonomic review of the species in more than 50 years came to another result based on morphological and genetic evidence, including recognizing five new subspecies (three of these are small-island populations that were not previously assigned to any subspecies): Early visitors to

5880-550: The Galápagos Islands considered the marine iguanas ugly and disgusting. In 1798, captain James Colnett of the British Royal Navy wrote: On his visit to the islands in 1835, despite making extensive observations on the creatures, Charles Darwin was revolted by the animals' appearance, writing: Marine iguanas have a thickset body and relatively short, robust limbs. Adults have a row of spines extending from

6000-488: The Madagascar oplurines , as informal groups and not as formal subfamilies. Frost and Etheridge (1989) formally recognized these informal groupings as families . Macey et al. (1997), in their analysis of molecular data for iguanian lizards recovered a monophyletic Iguanidae and formally recognized the eight families proposed by Frost and Etheridge (1989) as subfamilies of Iguanidae. Schulte et al. (2003) reanalyzed

6120-562: The North American Great Lakes and they became a major nuisance in the area, as they began to clog water treatment and power plants. Another case of this was seen in Chinese bighead and silver carp, which were brought in with the purpose of algae control in many catfish ponds across the U.S. Unfortunately, some had managed to escape into the neighboring rivers of Mississippi, Missouri, Illinois, and Ohio, eventually causing

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6240-598: The ability of a species to disperse over a gradually changing environment could enable a population to survive extreme conditions. (i.e. climate change ). As the climate changes , prey and predators have to adapt to survive. This poses a problem for many animals, for example, the Southern Rockhopper Penguins . These penguins are able to live and thrive in a variety of climates due to the penguins' phenotypic plasticity. However, they are predicted to respond by dispersal, not adaptation this time. This

6360-498: The age of 3–5 years, while males reach sexual maturity at the age of 6–8 years. Sexual maturity is marked by the first steep and abrupt decline in bone growth cycle thickness. Marine iguanas can reach an age of up to 60 years, but average is 12 years or less. Reproduction in the marine iguana begins during the last part of the cold and dry season, with breeding from December to March and nesting from January to April. The exact timing varies with location, depending on algal growth and

6480-534: The algal food in their gut. As an ectothermic animal, the marine iguana can spend only a limited time in cold water diving for algae. Afterwards it basks in the sun to warm up. Until it can do so it is unable to move effectively, making it vulnerable to predation. However, this is counteracted by their highly aggressive nature consisting of biting and expansive bluffs when in this disadvantageous state. Their dark shade aids in heat reabsorption. In colder periods with cloudy weather and much wind, juveniles will stay in

6600-605: The almost 1,900 marine iguanas eat about 27–29 tonnes (27–29 long tons; 30–32 short tons) (fresh weight) of algae per year, a rate of consumption that is counterbalanced by the very high growth rate of the algae. They may feed on octopuses , crustaceans , insects (such as grasshoppers and cockroaches ), fish carrion , and sea lion feces and afterbirth on rare occasions. The population on North Seymour Island will supplement their diet with land plants, primarily Batis maritima , or other coastal succulents like Sesuvium portulacastrum . These North Seymour iguanas have

6720-443: The answer lies in the food supply. Plants produce their own food from sunlight and carbon dioxide —both generally more abundant on land than in water. Animals fixed in place must rely on the surrounding medium to bring food at least close enough to grab, and this occurs in the three-dimensional water environment, but with much less abundance in the atmosphere. All of the marine and aquatic invertebrates whose lives are spent fixed to

6840-496: The area they occupy may surpass that of any known reptile. However, their distribution is patchy, and colonies are generally found within 100 m (330 ft) of the ocean, naturally limiting their range. The total population for the entire archipelago is estimated to be 200,000–300,000 individuals, although this number is labelled with considerable uncertainty. Most subpopulations have not been surveyed in detail because their lifestyle and habitat make it difficult to survey with

6960-506: The average snout-to-vent length on Wolf and Darwin Islands (subspecies jeffreysi ) was about 19 cm (7.5 in), and those on Genovesa Island (subspecies nanus ) were only slightly larger. In comparison, Santa Cruz marine iguanas ( hassi ) had an average snout-to-vent length of about 35 cm (14 in), and those of Isabela and Fernandina ( cristatus ) were only slightly smaller. Other subspecies were of intermediate size, in between

7080-879: The bacteria needed for digesting algae. It has been suggested that young iguanas up to about two years old are unable to swim, but studies have shown that even newly hatched marine iguanas are good swimmers; they just strongly try to avoid entering the water. At about 1–2 years old the young may voluntarily swim in shallow water and tide pools, but they do not dive. Marine iguanas can dive as deep as 30 m (98 ft), and can spend up to one hour underwater. When diving to 7 m (23 ft) or deeper, they regularly remain submerged from 15 to more than 30 minutes. Most dives are much shorter in duration and shallower than 5 m (16 ft). Individuals foraging near-shore, often less than 1 m (3.3 ft) deep, typically only spend about 3 minutes underwater. Only 5% of marine iguanas dive for algae offshore and these individuals are

7200-435: The bottom (more or less; anemones are capable of getting up and moving to a new location if conditions warrant) produce dispersal units. These may be specialized "buds", or motile sexual reproduction products, or even a sort of alteration of generations as in certain cnidaria . Corals provide a good example of how sedentary species achieve dispersion. Broadcast spawning corals reproduce by releasing sperm and eggs directly into

7320-512: The breeding season. However, large males defend territories for up to three months during the breeding season, and in this period they sometimes fight other males. A territory can be up to almost 40 m (430 sq ft), but is usually less than half that size, and can be as small as 1 m (11 sq ft). A territory is often delimited by geographic features, like boulders or crevices. The territories tend to occur in clusters with several located adjacent to each other, forming

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7440-522: The broadest sense, dispersal occurs when the fitness benefits of moving outweigh the costs. There are a number of benefits to dispersal such as locating new resources, escaping unfavorable conditions, avoiding competing with siblings , and avoiding breeding with closely related individuals which could lead to inbreeding depression . There are also a number of costs associated with dispersal, which can be thought of in terms of four main currencies: energy, risk, time, and opportunity. Energetic costs include

7560-403: The central tip. It also appears to replace its teeth at a higher rate than other iguanas. As a sea reptile , much salt is ingested. The salt is filtered from their blood and then excreted by specialised cranial exocrine glands at the nostrils, expelled from the body in a process much like sneezing. The marine iguana's cranium has an unusually large nasal cavity compared to other iguanas, which

7680-399: The determination of population and spread of plant species. Many populations have patchy spatial distributions where separate yet interacting sub-populations occupy discrete habitat patches (see metapopulations ). Dispersing individuals move between different sub-populations which increases the overall connectivity of the metapopulation and can lower the risk of stochastic extinction. If

7800-400: The dispersal strategies of both species. This leads to genetic isolation of both populations, resulting in limited gene flow. While the urbanization did have a greater effect on mice dispersal, it also led to a slight increase in inbreeding among bat populations. Few species are ever evenly or randomly distributed within or across landscapes . In general, species significantly vary across

7920-482: The dispersing individual (as mentioned above), it also has consequences at the level of the population and species on both ecological and evolutionary timescales. Organisms can be dispersed through multiple methods. Carrying through animals is especially effective as it allows traveling of far distances. Many plants depend on this to be able to go to new locations, preferably with conditions ideal for precreation and germination. With this, dispersal has major influence in

8040-610: The distance traveled by any individual. A number of different functions are used for dispersal kernels in theoretical models of dispersal including the negative exponential distribution , extended negative exponential distribution, normal distribution , exponential power distribution , inverse power distribution, and the two-sided power distribution. The inverse power distribution and distributions with 'fat tails' representing long-distance dispersal events (called leptokurtic distributions) are thought to best match empirical dispersal data. Dispersal not only has costs and benefits to

8160-613: The effects of dispersal, observers use the methods of landscape genetics .  This allows scientists to observe the difference between population variation, climate and well as the size and shape of the landscape. An example of the use of landscape genetics as a means to study seed dispersal, for example, involves studying the effects of traffic using motorway tunnels between inner cities and suburban area. Genome wide SNP dataset and species distribution modelling are examples of computational methods used to examine different dispersal modes. A genome-wide SNP dataset can be used to determine

8280-465: The emerging divide. The geographic separation and subsequent genetic isolation of portions of an ancestral population can result in allopatric speciation . Seed dispersal is the movement or transport of seeds away from the parent plant. Plants are limited by vegetative reproduction and consequently rely upon a variety of dispersal vectors to transport their propagules, including both abiotic and biotic vectors. Seeds can be dispersed away from

8400-520: The exotic pet trade and illegal introductions into the ecosystems. Other iguanas, like the Galapagos pink iguana ( C. marthae ) are endemic only to specific regions on the Galapagos islands. The Grand Cayman blue iguana, C. lewisi , is endemic only to the Grand Cayman island, limited to a small wildlife reserve. The only non-American iguana species are the members of the genus Brachylophus and

8520-594: The extinct Lapitiguana , which are found on Fiji and formerly Tonga ; their distribution is thought to be the result of the longest overwater dispersal event ever recorded for a vertebrate species, with them rafting over 8000 km across the Pacific from the Americas to the Fiji and Tonga. Several classification schemes have been used to define the structure of this family. The "historical" classification recognized all New World iguanians, plus Brachylophus and

8640-414: The extra energy required to move as well as energetic investment in movement machinery (e.g. wings). Risks include increased injury and mortality during dispersal and the possibility of settling in an unfavorable environment. Time spent dispersing is time that often cannot be spent on other activities such as growth and reproduction. Finally, dispersal can also lead to outbreeding depression if an individual

8760-411: The female's choice of partner are the display frequency by a male (especially head-bobbing) and the quality of a male's territory. Females prefer male territories that include or are near their own resting places, which they choose based on proximity to the sea, access to shade, low midday temperature and the possibility of sunbathing in the afternoon. Males with territories that are near the center of

8880-429: The female. On islands where there are few suitable sites and digging is difficult due to a relatively hard soil and many rocks, the female guards the nest for several days after the eggs have been buried, ensuring that they are not dug up by other nesting females. As in males defending their territory from other males, females defending their nest site from other females begin with a threat display. If this fails to scare

9000-423: The feral cat population. When feral dogs are removed feral cats can thrive and they feed on small marine iguanas. In 2012, the last black rats were eradicated from Pinzón Island. Studies and research have been done on marine iguanas that can help and promote conservation efforts to preserve the endemic species. Monitoring levels of marine algae, both dimensionally and hormonally, is an effective way to predict

9120-491: The first dogs were introduced to the Galápagos Islands more than 100 years ago, but marine iguanas have not developed an anti-predator strategy against them. In general, native predators represent a less serious threat to the marine iguana. Natural land predators include the Galápagos hawk , short-eared owl , lava gull , herons and Galápagos racer snakes that may take small marine iguanas. When swimming, marine iguanas are occasionally attacked and eaten by sharks, although

9240-410: The fitness of the marine iguana species. Exposure to tourism affects marine iguanas, and corticosterone levels can predict their survival during El Niño events. Corticosterone levels in species measure the stress that they face in their populations. Marine iguanas show higher stress-induced corticosterone concentrations during famine (El Niño) than feast conditions ( La Niña ). The levels differ between

9360-586: The food of choice. During neap low tides , however, the usually avoided green algae Ulva lobata is eaten more often since the preferred red algae is not easily available. Brown algae have occasionally also been recorded in their diet, but marine iguanas are unable to easily digest these and will starve if it is the only type present. A 1 kg (2.2 lb) marine iguana typically eats about 8.6 g (0.30 oz) dry weight or 37.4 g (1.32 oz) fresh weight of algae per day. At Punta Espinoza on northeastern Fernandina Island it has been estimated that

9480-567: The genomic and demographic history within the range of collection or observation [Reference needed]. Species distribution models are used when scientists wish to determine which region is best suited for the species under observation [Reference needed]. Methods such as these are used to understand the criteria the environment provides when migration and settlement occurs such as the cases in biological invasion. Human-aided dispersal, an example of an anthropogenic effect , can contribute to biological dispersal ranges and variations. Informed dispersal

9600-470: The higher heart rate of about 100 beats per minute aids in spreading the heat throughout the body. To conserve heat during the night, they often sleep closely together in groups that may number up to 50 individuals, while others sleep alone below plants or in crevices. In general, the time of each foraging trip is directly related to the water temperature; the colder the water the shorter the foraging trip. Additionally, marine iguanas that forage in or near

9720-424: The intertidal zone prefer to do so during low tides, allowing them to remain on land (on rocks exposed by the tide) or return to land faster. Individuals that forage further from the shore by diving are large males, which mainly feed during the hot midday (although it may occur from late morning to early evening), are less affected by the cool water because of their body size and are more efficient swimmers. Under

9840-522: The invasive species were shown to be transported by the rivers to natural areas located downstream, thus building upon the already established dispersal distance of the plant. In contrast, urban environments can also provide limitations for certain dispersal strategies. Human influence through urbanization greatly affects the layout of landscapes, which leads to the limitation of dispersal strategies for many organisms. These changes have largely been exhibited through pollinator-flowering plant relationships. As

9960-553: The islands, and show that survival varies throughout them during an El Niño event. The variable response of corticosterone is one indicator of the general public health of the populations of marine iguanas across the Galápagos Islands, which is a useful factor in the conservation of the species. Another indicator of fitness is the levels of glucocorticoid . Glucocorticoid release is considered beneficial in helping animals survive stressful conditions, while low glucocorticoid levels are an indicator of poor body condition. Species undergoing

10080-460: The land iguana, especially those from the front limbs, providing ballast to help with diving. Other adaptions in marine iguanas are blunt heads (flat noses) and sharp teeth allowing them to graze algae off of rocks more easily. Together with a few Ctenosaurus species, it is the only iguana that never has more than three tips (tricuspid) on each tooth. Uniquely, the side-tips on the marine iguana's teeth are quite large, only somewhat smaller than

10200-409: The landscape in association with environmental features that influence their reproductive success and population persistence. Spatial patterns in environmental features (e.g. resources) permit individuals to escape unfavorable conditions and seek out new locations. This allows the organism to "test" new environments for their suitability, provided they are within animal's geographic range. In addition,

10320-436: The large males. The minimum size of these divers vary with island and subspecies, ranging from 0.6 kg (1.3 lb) on Genovesa Island ( A. c. nanus ) to 3 kg (6.6 lb) on Fernandina Island ( A. c. cristatus ). They are slow swimmers, averaging just 0.45 metres per second (1.5 ft/s). The highest recorded speed is only about twice that figure and this can typically only be sustained in bursts that last less than

10440-400: The lee of rocks, still gaining the heat from the sun. Adults may move inland to low-lying sites with less wind because of bushes and lava ridges but still exposed to direct sun. When in the water and their temperature is falling, their blood circulation is reduced because of a low heart rate of about 30 beats per minute, allowing them to better conserve their warmth. When on land and heating up,

10560-655: The lek tend to have a greater mating success than males with peripheral territories, but the size of a territory does not affect mating success. Large territorial males that frequently display also emit higher levels of certain acidic compounds (including 11-Eicosenoic acid ) from their femoral pores , which may function as pheromones that enhance their chance of attracting females. Females can move freely between different territories, but receive less harassment from opportunistic non-territorial males when inside another male's territory. Medium-sized males attempt to mate by force and small males by stealth and force, but they have

10680-412: The morphological data of Frost and Etheridge in combination with molecular data for all major groups of Iguanidae and recovered a monophyletic Iguanidae, but the subfamilies Polychrotinae and Tropidurinae were not monophyletic. Townsend et al. (2011), Wiens et al. (2012) and Pyron et al. (2013), in the most comprehensive phylogenies published to date, recognized most groups at family level, resulting in

10800-449: The much larger Galápagos sea lions . The two species generally ignore each other and an iguana may even crawl over the body of a sea lion. Marine iguanas are unique as they are marine reptiles that forage on inter- and subtidal algae almost exclusively. They forage in the relatively cold waters around the Galápagos Islands, which typically are between 11 and 23 °C (52–73 °F) at the sea surface. As their preferred body temperature

10920-519: The nape, along the back to the tail. Males have longer spines, and larger bony plates on the top of their head than females. There are some differences in the spines depending on the island and they are most elaborate on Fernandina (subspecies cristatus ). The scales on the top of the head of the marine iguana are quite conical and pointed. Although less extreme, the same can be seen in the Galápagos land iguanas (genus Conolophus ), while these scales at most are slightly domed in other iguanas . Overall

11040-482: The nearest islands in the archipelago because of their slow speed and limited stamina in the relatively cold water. The periodic El Niño events reduce the cold water needed for algae to grow and this can drastically reduce the marine iguana population, on some islands with as much as 90%. Population recoveries after El Niños are fast; even when reduced by 30–50%, the population is generally able to recover within four years. However, recoveries can be partially impeded by

11160-412: The nest they run for cover, and begin their trip to locations that provides optimum conditions for feeding, temperature regulation and shelter. Some hatchlings have been recorded moving as far as 3 km (1.9 mi) in two days. The marine iguana forages almost exclusively on red and green algae in the inter - and subtidal zones . At least 10 genera of algae are regularly consumed, including

11280-634: The nutrient-rich Cromwell Current . It occurs earliest on islands like Fernandina, Isabela, Santa Fé and Genovesa, and latest on islands like Española. An adult marine iguana, whether male or female, will typically breed every other year, but if there is plenty of food a female may breed each year. Marine iguanas live in coastal colonies that typically range from 20 to 500 animals, but sometimes more than 1,000. Their bodies often touch each other, but there are no social interactions like grooming , as commonly seen in social mammals and birds. Females are always highly gregarious and males are gregarious outside

11400-501: The opponent away, the fights between females involve much biting and are less ritualized than the territorial fights between males. Where there are more suitable sites and the soil is loose, females are less likely to fight for a location and do not guard their nest after the eggs have been buried. The eggs hatch after about three to four months. The hatchlings are 9.5–13 cm (3.7–5.1 in) in snout-to-vent length, and weigh 40–70 g (1.4–2.5 oz). As soon as they emerge from

11520-932: The other hand, small animals utilize the existing kinetic energies in the environment, resulting in passive movement. Dispersal by water currents is especially associated with the physically small inhabitants of marine waters known as zooplankton . The term plankton comes from the Greek , πλαγκτον, meaning "wanderer" or "drifter". Many animal species, especially freshwater invertebrates, are able to disperse by wind or by transfer with an aid of larger animals (birds, mammals or fishes) as dormant eggs, dormant embryos or, in some cases, dormant adult stages. Tardigrades , some rotifers and some copepods are able to withstand desiccation as adult dormant stages. Many other taxa ( Cladocera , Bryozoa , Hydra , Copepoda and so on) can disperse as dormant eggs or embryos. Freshwater sponges usually have special dormant propagules called gemmulae for such

11640-433: The others may feed on their young or eggs. This inhibits reproduction and the long-term survival of the species. Introduced predators represent a major problem on the islands of Santa Cruz, Santiago, Isabela, Floreana and San Cristóbal where very few marine iguana hatchlings survive. Marine iguanas are ecologically naïve and have not developed efficient anti-predator strategies against the introduced species. For example,

11760-748: The parent plant individually or collectively, as well as dispersed in both space and time. The patterns of seed dispersal are determined in large part by the specific dispersal mechanism, and this has important implications for the demographic and genetic structure of plant populations, as well as migration patterns and species interactions. There are five main modes of seed dispersal: gravity, wind, ballistic, water, and by animals. There are numerous animal forms that are non-motile, such as sponges , bryozoans , tunicates , sea anemones , corals , and oysters . In common, they are all either marine or aquatic. It may seem curious that plants have been so successful at stationary life on land, while animals have not, but

11880-409: The physiology of marine iguanas. Information of glucocorticoid levels are good monitors in predicting long term consequences of human impact. Although marine iguanas have been kept in captivity, the specialised diet represents a challenge. They have lived for more than a decade in captivity, but have never bred under such conditions. The development of a captive breeding program (as already exists for

12000-492: The pollinator's optimal range of survival is limited, it leads to a limited supply of pollination sites. Subsequently, this leads to less gene flow between distantly separated populations, in turn decreasing the genetic diversity of each of the areas. Likewise, urbanization has been shown to impact the gene flow of distinctly different species (ex. mice and bats) in similar ways. While these two species may have different ecological niches and living strategies, urbanization limits

12120-564: The red algae Centroceras , Gelidium , Grateloupia , Hypnea , Polysiphonia and Pterocladiella . In some populations the green algae Ulva dominates the diet. The algal diet varies depending on algal abundance, individual preferences, foraging behaviour, season and exact island of feeding. Some species with chemical deterrents, such as Bifurcaria , Laurencia and Ochtodes , are actively avoided, but otherwise algal food choice mainly depends on energy content and digestibility. On Santa Cruz Island, 4–5 red algal species are

12240-516: The region also present a threat. For example, the Santa Fé population was reduced by almost 2 ⁄ 3 as a result of the MV Jessica oil spill in 2001, and even low-level oiling may kill marine iguanas. It is suspected that the primary cause of death during these events is starvation due to the loss of their sensitive gut bacteria, which they rely on to digest algae. The marine iguana

12360-413: The same behavior a fight ensues. During fights they typically do not bite each other, instead thrusting their heads together in an attempt to push the other away. The bony plates on the top of their heads are especially suited for interlocking. Fights between males may last for hours, and are often interrupted by periodic breaks. Once a winner has been established through the headbutting, the loser assumes

12480-472: The seasons and foraging efficiency increases with temperature. These environmental changes and the ensuing occasional food unavailability have caused marine iguanas to evolve by acquiring efficient methods of foraging in order to maximize their energy intake and body size. During an El Niño cycle in which food diminished for two years, some were found to decrease their length by as much as 20%. When food supply returned to normal, iguana size followed suit. It

12600-511: The sharp claws can cause painful scratches when the iguana attempts to gain a grip) and only move a few feet once released, allowing themselves to be caught again with ease. Pathogens introduced to the archipelago by humans pose a serious threat to this species. The marine iguana has evolved over time in an isolated environment and lacks immunity to many pathogens. As a result, the iguanas are at higher risk of contracting infections, contributing to their threatened status. Occasional oil spills in

12720-448: The shoes for long periods of time, about 8 hours of walking, but evenly came off. Due to this, the seeds were able to travel far distances and settle into new areas, where they were previously not inhabiting. However, it is also important that the seeds land in places where they are able to stick and grow. Specific shoe size did not seem to have an effect on prevalence. Biological dispersal can be observed using different methods. To study

12840-410: The skeleton of the marine iguana shows many similarities with the chuckwallas (genus Sauromalus ), but this is an example of homoplasy , as the two are not closely related. Marine iguanas are not always black; the young have a lighter coloured dorsal stripe, and some adult specimens are grey. Dark tones allow the lizards to rapidly absorb heat to minimize the period of lethargy after emerging from

12960-759: The small Wolf, Darwin and Genovesa iguanas and the large Santa Cruz, Isabela and Fernandina iguanas. In another study, the largest were from western San Cristóbal Island ( mertensi ), followed by those from Isabela ( cristatus , in part), Floreana ( venustissimus , in part), eastern San Cristóbal ( godzilla ), Fernandina ( cristatus , in part) and Santa Cruz ( hassi ). The smallest by far were from Genovesa ( nanus ), but this study did not include any marine iguanas from Wolf and Darwin Islands. The remaining island populations were of intermediate size. The maximum weight of adult males ranges from 12 kg (26 lb) on southern Isabela to 1 kg (2.2 lb) on Genovesa. This difference in body size of marine iguanas between islands

13080-452: The specimen he had received was from Mexico, a locality now known to be erroneous. Its generic name, Amblyrhynchus , is a combination of two Greek words, Ambly- from Amblus (ἀμβλυ) meaning "blunt" and rhynchus (ρυγχος) meaning "snout". Its specific name is the Latin word cristatus meaning "crested," and refers to the low crest of spines along the animal's back. Amblyrhynchus

13200-619: The subspecies. Males of the relatively small southern islands of Española, Floreana and Santa Fé (subspecies venustissimus and trillmichi ) are the most colourful, with bright pinkish-red and turquoise markings. In comparison, those of the relatively small northern islands of Genovesa, Marchena, Pinta, Wolf and Darwin ( jeffreysi , hayampi , sielmanni and nanus ) are almost all blackish without contrasting markings. Other subspecies tend to resemble duller versions of venustissimus and trillmichi , or are blackish with markings in pale yellowish, ochre , greenish or grey (sooty to near white). It

13320-639: The sun to thermoregulate . All but one of modern iguana genera are native to the Americas, ranging from the deserts of the Southwestern United States through Mexico , Central America , and the Caribbean , to throughout South America down to northernmost Argentina . Some iguanas like I. iguana have spread from their native regions of Central and South America into many Pacific Islands, and even to Fiji, Japan, and Hawai'i, due to

13440-492: The terms 'migration' and 'dispersal' are often used interchangeably. Furthermore, biological dispersal is impacted and limited by different environmental and individual conditions. This leads to a wide range of consequences on the organisms present in the environment and their ability to adapt their dispersal methods to that environment. Some organisms are motile throughout their lives, but others are adapted to move or be moved at precise, limited phases of their life cycles. This

13560-705: The tropical sun, overheating can also be a problem. To avoid this, they pant, and adopt a posture where they face the sun and lift their body up, thereby exposing as little as possible of their body to direct sun and allowing cooling air to pass underneath. The marine iguana has a relatively small range and is currently considered vulnerable by the IUCN . Most subpopulations have the same IUCN rating, but those of San Cristóbal, Santiago and Genovesa Islands are considered endangered . On some shorelines they can be very numerous, with densities as high as 8,000 per kilometer (almost 13,000 per mile), and their biomass compared to

13680-532: The two groups likely diverged during the Late Cretaceous , as that is when Pristiguana and Pariguana , the two earliest fossil genera, are known from. The subfamily Iguaninae , which contains all modern genera, likely originated in the earliest Paleocene , at about 62 million years ago. The most basal extant genus, Dipsosaurus , diverged from the rest of Iguaninae during the late Eocene , about 38 million years ago, with Brachylophus following

13800-443: The two often behave indifferently to each other, even when close together. Of the native predators, the Galápagos hawk is likely the most important, and it may also take weakened adults (not just young), but this hawk is quite rare with a total population numbering only a few hundred individuals. Marine iguanas have anti-predator strategies that reduce the impact of the Galápagos hawk, including an increased vigilance when hearing

13920-406: The two split about 4.5 million years ago, which is near the age of the oldest extant Galápagos islands ( Española and San Cristóbal ). The marine iguana and Galápagos land iguana remain mutually fertile in spite of being separated by millions of years and assigned to distinct genera. They have been known to hybridize where their ranges overlap, resulting in the so-called hybrid iguana . This

14040-416: The water. The marine iguana lacks agility on land but is a graceful swimmer. Its laterally flattened tail provides propulsion and the row of spines along the back provide stability, while its long, sharp claws allow it to hold onto rocks in strong currents. Adult males vary in colour with the season, becoming brighter when breeding. There are also major differences in the colour of the adult males depending on

14160-576: The water. These release events are coordinated by the lunar phase in certain warm months, such that all corals of one or many species on a given reef will be released on the same single or several consecutive nights. The released eggs are fertilized, and the resulting zygote develops quickly into a multicellular planula . This motile stage then attempts to find a suitable substratum for settlement. Most are unsuccessful and die or are fed upon by zooplankton and bottom-dwelling predators such as anemones and other corals. However, untold millions are produced, and

14280-467: Was conducted to test the effects of human-mediated dispersal of seeds over long distances in two species of Brassica in England. The main methods of dispersal compared with movement by wind versus movement by attachment to outerwear. It was concluded that shoes were able to transport seeds to further distances than what would be achievable through wind alone. It was noted that some seeds were able to stay on

14400-413: Was identified as a key factor in the rate of both occurrences. Human impact has had a major influence on the movement of animals through time. An environmental response occurs in due to this, as dispersal patterns are important for species to survive major changes. There are two forms of human-mediated dispersal: Long-distance dispersals are observed when seeds are carried through human vectors. A study

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