In genetics , dominance is the phenomenon of one variant ( allele ) of a gene on a chromosome masking or overriding the effect of a different variant of the same gene on the other copy of the chromosome . The first variant is termed dominant and the second is called recessive . This state of having two different variants of the same gene on each chromosome is originally caused by a mutation in one of the genes, either new ( de novo ) or inherited . The terms autosomal dominant or autosomal recessive are used to describe gene variants on non-sex chromosomes ( autosomes ) and their associated traits, while those on sex chromosomes (allosomes) are termed X-linked dominant , X-linked recessive or Y-linked ; these have an inheritance and presentation pattern that depends on the sex of both the parent and the child (see Sex linkage ). Since there is only one copy of the Y chromosome , Y-linked traits cannot be dominant or recessive. Additionally, there are other forms of dominance, such as incomplete dominance , in which a gene variant has a partial effect compared to when it is present on both chromosomes, and co-dominance , in which different variants on each chromosome both show their associated traits.
101-824: The Bengal tiger or Royal Bengal tiger is a population of the Panthera tigris tigris subspecies and the nominate tiger subspecies. It ranks among the biggest wild cats alive today. It is estimated to have been present in the Indian subcontinent since the Late Pleistocene for about 12,000 to 16,500 years. Its historical range covered the Indus River valley until the early 19th century, almost all of India , western Pakistan , southern Nepal , Bangladesh , Bhutan and southwestern China . Today, it inhabits India, Bangladesh, Nepal, Bhutan, and southwestern China. It
202-826: A land bridge . Results of a phylogeographic study using 134 samples from tigers across the global range suggest that the historical northeastern distribution limit of the Bengal tiger is the region in the Chittagong Hills and Brahmaputra River basin, bordering the historical range of the Indochinese tiger . In the Indian subcontinent, Bengal tigers inhabit tropical moist evergreen forests , tropical dry forests , tropical and subtropical moist deciduous forests , mangroves , subtropical and temperate upland forests, and alluvial grasslands. The latter habitat once covered
303-437: A population is often defined as a set of organisms in which any pair of members can breed together. They can thus routinely exchange gametes in order to have usually fertile progeny, and such a breeding group is also known therefore as a gamodeme. This also implies that all members belong to the same species. If the gamodeme is very large (theoretically, approaching infinity), and all gene alleles are uniformly distributed by
404-546: A 1:2:1 genotype ratio with the first two classes showing the (A) phenotype, and the last showing the (a) phenotype, thereby producing the 3:1 phenotype ratio. Mendel did not use the terms gene, allele, phenotype, genotype, homozygote, and heterozygote, all of which were introduced later. He did introduce the notation of capital and lowercase letters for dominant and recessive alleles, respectively, still in use today. In 1928, British population geneticist Ronald Fisher proposed that dominance acted based on natural selection through
505-716: A 20-year-old elephant cow, and another on a 28-year-old sick elephant in Kaziranga National Park ; the latter was eaten by several tigers at once. A king cobra ( Ophiophagus hannah ), an Indian cobra ( Naja naja ), Asian water monitor , rhesus macaque , fish , crabs , and very rarely fishing cats and turtles were found in the stomachs and scat of tigers in the Sundarbans. One in Chitwan National Park has been reported to have hunted three gharials . Results of scat analyses indicate that
606-502: A body length of 371 cm (12 ft 2 in) at death. Two tigers shot in Kumaon District and near Oude at the end of the 19th century allegedly measured more than 370 cm (12 ft). But at the time, sportsmen had not yet adopted a standard system of measurement; some measured 'between the pegs' while others measured 'over the curves'. The greatest length of a tiger skull measured 41.3 cm (16.25 in) "over
707-680: A buffalo calf; it measured 323 cm (127 in) in total length between pegs, and 338 cm (133 in) over curves. Without eating the calf beforehand, it would have likely weighed at least 324.3 kg (715 lb). This specimen is on exhibition in the Mammals Hall of the Smithsonian Institution . In the Central Provinces of India, a male tiger shot weighed 317 kg (699 lb) and measured 3.02 m (9 ft 11 in). The Bengal tiger rivals
808-696: A camera trapping survey was carried out in the Terai Arc Landscape , across an area of 4,841 km (1,869 sq mi) in 14 districts. The country's tiger population was estimated at 163–235 breeding adults comprising 102–152 tigers in the Chitwan-Parsa protected areas, 48–62 in Bardiya- Banke National Parks and 13–21 in Shuklaphanta National Park . Between November 2017 and April 2018,
909-476: A few programs, most notably the Chinese government's one-child per family policy, have resorted to coercive measures. In the 1970s, tension grew between population control advocates and women's health activists who advanced women's reproductive rights as part of a human rights -based approach. Growing opposition to the narrow population control focus led to a significant change in population control policies in
1010-518: A genetic analysis of 32 tiger samples indicate that the Bengal tiger samples grouped into a different clade than the Siberian tiger samples. The Bengal tiger is defined by three distinct mitochondrial nucleotide sites and 12 unique microsatellite alleles. The pattern of genetic variation in the Bengal tiger corresponds to the premise that it arrived in India approximately 12,000 years ago. This
1111-647: A gestation period of 104–106 days, 1–4 cubs are born in a shelter situated in tall grass, thick bush or in caves. Newborn cubs weigh 780 to 1,600 g (1.72 to 3.53 lb) and they have a thick woolly fur that is shed after 3.5–5 months. Their eyes and ears are closed. Their milk teeth start to erupt at about 2–3 weeks after birth, and are slowly replaced by permanent dentition from 8.5 to 9.5 weeks of age onwards. They suckle for 3–6 months, and begin to eat small amounts of solid food at about 2 months of age. At this time, they follow their mother on her hunting expeditions and begin to take part in hunting at 5–6 months of age. At
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#17327982930441212-416: A given gene of any function; one allele can be dominant over a second allele of the same gene, recessive to a third, and co-dominant with a fourth. Additionally, one allele may be dominant for one trait but not others. Dominance differs from epistasis , the phenomenon of an allele of one gene masking the effect of alleles of a different gene. Gregor Johann Mendel , "The Father of Genetics", promulgated
1313-408: A group of human beings with some predefined feature in common, such as location, race , ethnicity , nationality , or religion . In ecology , a population is a group of organisms of the same species which inhabit the same geographical area and are capable of interbreeding . The area of a sexual population is the area where interbreeding is possible between any opposite-sex pair within
1414-626: A huge swath of grassland, riverine and moist semi-deciduous forests along the major river system of the Gangetic and Brahmaputra plains , but has now been largely converted to agricultural land or severely degraded . Today, the best examples of this habitat type are limited to a few blocks at the base of the outer foothills of the Himalayas including the Tiger Conservation Units (TCUs) Rajaji - Corbett , Bardia - Banke , and
1515-453: A membrane-bound H antigen. The I enzyme adds a galactose. The i allele produces no modification. Thus the I and I alleles are each dominant to i ( I I and I i individuals both have type A blood, and I I and I i individuals both have type B blood), but I I individuals have both modifications on their blood cells and thus have type AB blood, so the I and I alleles are said to be co-dominant. Another example occurs at
1616-403: A part of the illegal trade. In Bangladesh, tigers are killed by professional poachers, local hunters, trappers and villagers. Each group of people has different motives for killing tigers, ranging from profit and excitement to safety concerns; and has access to the illegal wildlife trade in body parts. Population Population is the term typically used to refer to the number of people in
1717-406: A pink snapdragon flower. The pink snapdragon is the result of incomplete dominance. A similar type of incomplete dominance is found in the four o'clock plant wherein pink color is produced when true-bred parents of white and red flowers are crossed. In quantitative genetics , where phenotypes are measured and treated numerically, if a heterozygote's phenotype is exactly between (numerically) that of
1818-502: A range of 167–234 kg (368–516 lb); their total length was 282 cm (111 in) with a range of 267–312 cm (105–123 in), and their average shoulder height was 99 cm (39 in); 39 adult female Bengal tigers weighed an average of 132 kg (291 lb) with a maximum of 156 kg (344 lb) and an average total length of 254 cm (100 in) ranging from 239 to 277 cm (94 to 109 in). Several scientists indicated that adult male Bengal tigers in
1919-607: A single area. Governments conduct a census to quantify the size of a resident population within a given jurisdiction. The term is also applied to non-human animals , microorganisms , and plants , and has specific uses within such fields as ecology and genetics . The word population is derived from the Late Latin populatio (a people, a multitude), which itself is derived from the Latin word populus (a people). In sociology and population geography , population refers to
2020-411: A tiger census in 2008, camera trap and sign surveys using GIS were employed to estimate site-specific densities of tiger, co-predators and prey. Based on the result of these surveys, the total tiger population was estimated at 1,411 individuals ranging from 1,165 to 1,657 adult and sub-adult tigers of more than 1.5 years of age. Across India, six landscape complexes were surveyed that host tigers and have
2121-538: A tiger pair at elevations of 3,000 to 4,100 m (9,800 to 13,500 ft). As of 2015, the tiger population in Bhutan was estimated at 89 to 124 individuals in a survey area of 28,225 km (10,898 sq mi). In 2008, a tiger was recorded at an elevation of 4,200 m (13,800 ft) in Jigme Dorji National Park , which is the highest elevation record of a tiger known to date. In 2017,
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#17327982930442222-502: A tiger was recorded for the time in Bumdeling Wildlife Sanctuary . It probably used a wildlife corridor to reach northeastern Bhutan. Bhutan's tiger population was estimated at 90 individuals comprising 60 females and 30 males with a population density estimate of 0.19–0.31 tigers per 100 km (39 sq mi) by March 2015. As of 2022, the population was estimated at 131 individuals. The presence of
2323-400: A transient or sub-adult male at least for a time. A male tiger keeps a large territory in order to include the home ranges of several females within its bounds, so that he may maintain mating rights with them. Spacing among females is less complete. Typically there is partial overlap with neighbouring female residents. They tend to have core areas, which are more exclusive, at least for most of
2424-598: A year and ate a minimum of 5–6.3 kg (11–14 lb) of meat a day. Two males made about 40–50 kills in a year and ate 6.3–7.8 kg (14–17 lb) of meat a day at the least. If injured, old or weak, or when its regular prey species become scarce, Bengal tigers often attack humans and become man-eaters . The tiger in India has no definite mating and birth seasons. Most young are born in December and April. Young have also been found in March, May, October and November. In
2525-990: Is a carnivore and prefers hunting large ungulates such as gaur , sambar , chital , barasingha , water buffalo , nilgai , serow and takin . Medium-sized prey includes wild boar , Indian hog deer , Indian muntjac and northern plains gray langur . Small prey such as porcupine , hare and peafowl form a small part of its diet. Because of the encroachment of humans into tiger habitat, it also preys on domestic livestock. Bengal tigers occasionally hunt and kill predators such as Indian leopard , mugger crocodile , Asian black bear , sloth bear , and dhole . They generally do not attack adult Indian elephant and Indian rhinoceros , but such extraordinarily rare events have been recorded. In Kaziranga National Park , tigers killed 20 rhinoceros in 2007. In 2011 and 2014, two instances of Bengal tigers killing adult elephants were recorded; in Jim Corbett National Park on
2626-401: Is consistent with the lack of tiger fossils from the Indian subcontinent prior to the late Pleistocene, and the absence of tigers from Sri Lanka , which was separated from the subcontinent by rising sea levels in the early Holocene . The Bengal tiger's coat is yellow to light orange, with stripes ranging from dark brown to black; the belly and the interior parts of the limbs are white, and
2727-609: Is not even known to the nearest million, so there is a considerable margin of error in such estimates. Researcher Carl Haub calculated that a total of over 100 billion people have probably been born in the last 2000 years. Population growth increased significantly as the Industrial Revolution gathered pace from 1700 onwards. The last 50 years have seen a yet more rapid increase in the rate of population growth due to medical advances and substantial increases in agricultural productivity, particularly beginning in
2828-611: Is often referred to as the demographic transition . Human population planning is the practice of altering the rate of growth of a human population. Historically, human population control has been implemented with the goal of limiting the rate of population growth. In the period from the 1950s to the 1980s, concerns about global population growth and its effects on poverty, environmental degradation , and political stability led to efforts to reduce population growth rates. While population control can involve measures that improve people's lives by giving them greater control of their reproduction,
2929-880: Is potential tiger habitat. In May 2018, a tiger was recorded in Sahyadri Tiger Reserve for the first time in eight years. In February 2019, a tiger was sighted in Gujarat's Lunavada area in Mahisagar district , and found dead shortly afterwards. Officials assumed that it originated in Ratapani Tiger Reserve and travelled about 300 km (190 mi) over two years. It probably died of starvation. In May 2019, camera traps recorded tigers in Mhadei Wildlife Sanctuary and Bhagwan Mahaveer Sanctuary and Mollem National Park ,
3030-566: Is the traditional type locality of the species and the nominate subspecies Panthera tigris tigris . The validity of several tiger subspecies in continental Asia was questioned in 1999. Morphologically , tigers from different regions vary little, and gene flow between populations in those regions is considered to have been possible during the Pleistocene . Therefore, it was proposed to recognise only two subspecies as valid, namely P. t. tigris in mainland Asia, and P. t. sondaica in
3131-554: Is threatened by poaching , habitat loss and habitat fragmentation . As of 2022, the Bengal tiger population was estimated at 3,167–3,682 individuals in India, 316–355 individuals in Nepal, 131 individuals in Bhutan and around 114 individuals in Bangladesh. Felis tigris was the scientific name used by Carl Linnaeus in 1758 for the tiger. It was subordinated to the genus Panthera by Reginald Innes Pocock in 1929. Bengal
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3232-715: Is very likely that the world's population will stop growing before the end of the 21st century. Further, there is some likelihood that population will actually decline before 2100. Population has already declined in the last decade or two in Eastern Europe, the Baltics and in the former Commonwealth of Independent States. The population pattern of less-developed regions of the world in recent years has been marked by gradually declining birth rates. These followed an earlier sharp reduction in death rates. This transition from high birth and death rates to low birth and death rates
3333-417: The rr (homozygous) individuals have wrinkled peas. In Rr ( heterozygous ) individuals, the R allele masks the presence of the r allele, so these individuals also have round peas. Thus, allele R is dominant over allele r , and allele r is recessive to allele R . Dominance is not inherent to an allele or its traits ( phenotype ). It is a strictly relative effect between two alleles of
3434-553: The Greater Sunda Islands and possibly in Sundaland . The nominate subspecies P. t. tigris constitutes two clades : the northern clade comprises the Siberian and Caspian tiger populations, and the southern clade all remaining continental tiger populations. The extinct and living tiger populations in continental Asia have been subsumed to P. t. tigris since the revision of felid taxonomy in 2017. Results of
3535-673: The Late Pleistocene , for about 12,000 to 16,500 years. In 1982, a sub- fossil right middle phalanx was found in a prehistoric midden near Kuruwita in Sri Lanka , which is dated to about 16,500 years ago and tentatively considered to be of a tiger. Tigers appear to have arrived in Sri Lanka during a pluvial period, during which sea levels were depressed, evidently prior to the last glacial maximum about 20,000 years ago. The tiger probably arrived too late in southern India to colonise Sri Lanka, which earlier had been connected to India by
3636-455: The Siberian tiger in average weight. The Bengal tiger's historical range covered the Indus River valley until the early 19th century, almost all of India , western Pakistan , southern Nepal , Bangladesh , Bhutan , and southwestern China . Today, it inhabits India, Bangladesh, Nepal, Bhutan, and southwestern China. It is estimated to have been present in the Indian subcontinent since
3737-545: The Terai consistently attain more than 227 kg (500 lb) of body weight. Seven adult males captured in Chitwan National Park in the early 1970s had an average weight of 235 kg (518 lb) ranging from 200 to 261 kg (441 to 575 lb), and that of the females was 140 kg (310 lb) ranging from 116 to 164 kg (256 to 362 lb). Two male tigers captured in Chitwan National Park in
3838-569: The 1960s, made by the Green Revolution . In 2017 the United Nations Population Division projected that the world's population would reach about 9.8 billion in 2050 and 11.2 billion in 2100. In the future, the world's population is expected to peak at some point, after which it will decline due to economic reasons, health concerns, land exhaustion and environmental hazards. According to one report, it
3939-403: The 1960s, certain aspects of tiger behaviour at Kanha National Park indicated that the peak of sexual activity was from November to about February, with some mating probably occurring throughout the year. Males reach maturity at 4–5 years of age, and females at 3–4 years. A Bengal comes into estrus (commonly known as "heat") at intervals of about 3–9 weeks, and is receptive for 3–6 days. After
4040-485: The 1980s exceeded weights of 270 kg (600 lb) and are the largest free ranging tigers reported to date. The smallest recorded weights for Bengal tigers are from the Bangladesh Sundarbans, where adult females weigh 75–80 kg (165–176 lb). Three tigresses from the Bangladesh Sundarbans had a mean weight of 76.7 kg (169 lb). The oldest female weighed 75 kg (165 lb) and
4141-684: The Bangladesh Sundarbans to estimate tiger population density. The average of these six sites provided an estimate of 3.7 tigers per 100 km (39 sq mi). Since the Bangladesh Sundarbans is an area of 5,770 km (2,230 sq mi), it was inferred that the total tiger population comprised approximately 200 individuals. Home ranges of adult female tigers were recorded comprising between 12 and 14 km (4.6 and 5.4 sq mi), which would indicate an approximate carrying capacity of 150 adult females. The small home range of adult female tigers and consequent high density of tigers in this habitat type relative to other areas may be related to both
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4242-684: The Bengal tiger in southeastern Tibet Autonomous Region , China was investigated in 1995 when the loss of livestock was high in Mêdog County due to a large predator. Tiger paw prints were found on pastures around several villages. One tiger was shot in 1996, and about 4–5 tigers were reported by officials in the area by 1999. About 8–12 tigers were thought to remain in this area a decade later. A camera trapping and interview survey during 2013–2018 in nine potential sites in Mêdog County revealed that only 1–3 non-resident individuals might be entering
4343-616: The Bengal tigers in Nagarahole National Park preferred prey weighing more than 176 kg (388 lb) and that on average tiger prey weighed 91.5 kg (202 lb). The prey species included chital, sambar, wild pig and gaur. Gaur remains were found in 44.8% of all tiger scat samples, sambar remains in 28.6%, wild pig remains in 14.3% and chital remains in 10.4% of all scat samples. In Bandipur National Park, gaur and sambar together also constituted 73% of tiger diet. In most cases, Bengal tigers approach their victim from
4444-642: The F1 generation are self-pollinated, the phenotypic and genotypic ratio of the F2 generation will be 1:2:1 (Red:Spotted:White). These ratios are the same as those for incomplete dominance. Again, this classical terminology is inappropriate – in reality, such cases should not be said to exhibit dominance at all. Dominance can be influenced by various genetic interactions and it is essential to evaluate them when determining phenotypic outcomes. Multiple alleles , epistasis and pleiotropic genes are some factors that might influence
4545-542: The Indian population was estimated to comprise 3,167–3,682 individuals. In Bangladesh, tigers are now relegated to the forests of the Sundarbans and the Chittagong Hill Tracts . The Chittagong forest is contiguous with tiger habitat in India and Myanmar , but the tiger population is of unknown status. As of 2004, population estimates in Bangladesh ranged from 200 to 419 individuals, most of them in
4646-431: The Sundarbans landscape. By 2009, the tiger population in the Bangladesh Sundarbans was estimated as 100–150 adult females or 335–500 tigers overall. Female home ranges, recorded using Global Positioning System collars, were some of the smallest recorded for tigers, indicating that the Bangladesh Sundarbans could have one of the highest densities and largest populations of tigers anywhere in the world. They are isolated from
4747-429: The Sundarbans. This region is the only mangrove habitat in this bioregion , where tigers survive, swimming between islands in the delta to hunt prey. Bangladesh's Forest Department is raising mangrove plantations supplying forage for spotted deer . Since 2001, afforestation has continued on a small scale in the Sundarbans. From October 2005 to January 2007, the first camera trap survey was conducted across six sites in
4848-496: The United States Census Bureau, the world population hit 6.5 billion on 24 February 2006. The United Nations Population Fund designated 12 October 1999 as the approximate day on which world population reached 6 billion. This was about 12 years after the world population reached 5 billion in 1987, and six years after the world population reached 5.5 billion in 1993. The population of countries such as Nigeria
4949-539: The Western Ghats, where Radhanagari and Sahyadri Tiger Reserves were newly established. The largest population resided in Corbett Tiger Reserve with about 215 tigers. The Central Indian tiger population is fragmented and depends on wildlife corridors that facilitate connectivity between protected areas. By 2018, the population had increased to an estimated 2,603–3,346 individuals. As of 2022,
5050-618: The adjacent Parsa National Park encompassing an area of 2,543 km (982 sq mi) of prime lowland forest. To the west, the Chitwan population is isolated from the one in Bardiya National Park and adjacent unprotected habitat farther west, extending to within 15 km (9.3 mi) of the Shuklaphanta Wildlife Reserve, which harbours the smallest population. From February to June 2013,
5151-654: The age of 19 months. Of the 14 subadults studied, the four females stayed closer to their mother's home range than the 10 males. The latter dispersed between 9.5 and 65.7 km (5.9 and 40.8 mi). None of them crossed open cultivated areas that were more than 10 km (6.2 mi) wide, but moved through prime alluvial and forested habitat. In the Panna Tiger Reserve, an adult radio-collared male tiger moved 1.7 to 10.5 km (1.1 to 6.5 mi) between locations on successive days in winter, and 1 to 13.9 km (0.62 to 8.64 mi) in summer. His home range
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#17327982930445252-566: The age of 2–3 years, they slowly start to separate from the family group and become transient, looking out for an area where they can establish their own home range. Young males move farther away from their native home range than young females. Once the family group has split, the mother comes into heat again. None of the Tiger Conservation Landscapes within the Bengal tiger range is large enough to support an effective population size of 250 individuals. Habitat losses and
5353-482: The area and more probable than cross-breeding with individuals from other areas. In humans , interbreeding is unrestricted by racial differences, as all humans belong to the same species of Homo sapiens. In ecology, the population of a certain species in a certain area can be estimated using the Lincoln index to calculate the total population of an area based on the number of individuals observed. In genetics,
5454-714: The area south of the Yarlung Tsangpo river, but only during the dry season from October to March. In early 2019, a Bengal tiger was photographed twice at an elevation of 2,000 m (6,600 ft) in a broadleaved forest in Yarlung Tsangpo Grand Canyon National Nature Reserve. The basic social unit of the tiger is composed of a female and her offspring. Adult animals congregate only temporarily when special conditions permit, such as plentiful supplies of food. Otherwise, they lead solitary lives, hunting individually for
5555-448: The bone"; this one was shot in the vicinity of Nagina in northern India. In the beginning of the 20th century, a male tiger was shot in central India with a head and body length of 221 cm (87 in) between pegs, a chest girth of 150 cm (59 in), a shoulder height of 109 cm (43 in) and a tail length of 81 cm (32 in), which was perhaps bitten off by a rival male. This specimen could not be weighed, but it
5656-480: The breaking up of a large sexual population (panmictic) into smaller overlapping sexual populations. This failure of panmixia leads to two important changes in overall population structure: (1) the component gamodemes vary (through gamete sampling) in their allele frequencies when compared with each other and with the theoretical panmictic original (this is known as dispersion, and its details can be estimated using expansion of an appropriate binomial equation ); and (2)
5757-509: The collection of the Natural History Museum, London have 21–29 stripes. Another recessive mutant is the golden tiger that has a pale golden fur with red-brown stripes. The mutants are very rare in nature. The greatest skull length of a tiger is 351 mm (13.8 in) in males and 293 mm (11.5 in) in females. It has exceptionally stout teeth. Its canines are 7.5 to 10 cm (3.0 to 3.9 in) long and thus
5858-401: The contribution of modifier genes . In 1929, American geneticist Sewall Wright responded by stating that dominance is simply a physiological consequence of metabolic pathways and the relative necessity of the gene involved. In complete dominance, the effect of one allele in a heterozygous genotype completely masks the effect of the other. The allele that masks are considered dominant to
5959-541: The dominant gene. However, if the F1-generation is further crossed with the F1-generation (heterozygote crossed with heterozygote) the offspring (F2-generation) will present the phenotype associated with the dominant gene ¾ times. Although heterozygote monohybrid crossing can result in two phenotype variants, it can result in three genotype variants - homozygote dominant, heterozygote and homozygote recessive, respectively. In dihybrid inheritance we look at
6060-717: The early 1980s. Recessive Dominance is a key concept in Mendelian inheritance and classical genetics . Letters and Punnett squares are used to demonstrate the principles of dominance in teaching, and the upper-case letters are used to denote dominant alleles and lower-case letters are used for recessive alleles. An often quoted example of dominance is the inheritance of seed shape in peas . Peas may be round, associated with allele R , or wrinkled, associated with allele r . In this case, three combinations of alleles (genotypes) are possible: RR , Rr , and rr . The RR ( homozygous ) individuals have round peas, and
6161-476: The existence of wild tiger populations is the illegal wildlife trade in poached skins and body parts between India, Nepal and China. The governments of these countries have failed to implement adequate enforcement response, and wildlife crime remained a low priority in terms of political commitment and investment for years. There are well-organised gangs of professional poachers, who move from place to place and set up camp in vulnerable areas. Skins are rough-cured in
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#17327982930446262-496: The extremely large-scale incidences of poaching are serious threats to the species' survival. The Forest Rights Act passed by the Indian government in 2006 grants some of India's most impoverished communities the right to own and live in the forests, which likely brings them into conflict with wildlife and under-resourced, under-trained, ill-equipped forest department staff. In the past, evidence showed that humans and tigers cannot co-exist. The most significant immediate threat to
6363-486: The field and handed over to dealers, who send them for further treatment to Indian tanning centres. Buyers choose the skins from dealers or tanneries and smuggle them through a complex interlinking network to markets outside India, mainly in China. Other factors contributing to their loss are urbanisation and revenge killing. Farmers blame tigers for killing cattle and shoot them. Their skins and body parts may however become
6464-575: The first records in Goa since 2013. The tigers in the Sundarbans in India and Bangladesh are the only ones in the world inhabiting mangrove forests. The population in the Indian Sundarbans was estimated as 86–90 individuals in 2018. As of 2014, the Indian tiger population was estimated to range over an area of 89,164 km (34,426 sq mi) and number 2,226 adult and subadult tigers older than one year. About 585 tigers were present in
6565-557: The forest and grassland animals upon which they prey. Resident adults of either sex maintain home ranges, confining their movements to definite habitats within which they satisfy their needs and those of their cubs, which include prey, water and shelter. In this site, they also maintain contact with other tigers, especially those of the opposite sex. Those sharing the same ground are well aware of each other's movements and activities. In Chitwan National Park , radio-collared subadult tigers started dispersing from their natal areas earliest at
6666-691: The gametes within it, the gamodeme is said to be panmictic. Under this state, allele ( gamete ) frequencies can be converted to genotype ( zygote ) frequencies by expanding an appropriate quadratic equation , as shown by Sir Ronald Fisher in his establishment of quantitative genetics. This seldom occurs in nature: localization of gamete exchange – through dispersal limitations, preferential mating, cataclysm, or other cause – may lead to small actual gamodemes which exchange gametes reasonably uniformly within themselves but are virtually separated from their neighboring gamodemes. However, there may be low frequencies of exchange with these neighbors. This may be viewed as
6767-496: The high density of prey and the small size of the Sundarban tigers. Since 2007, tiger monitoring surveys have been carried out every year by WildTeam in the Bangladesh Sundarbans to monitor changes in the Bangladesh tiger population and assess the effectiveness of conservation actions. This survey measures changes in the frequency of tiger track sets along the sides of tidal waterways as an index of relative tiger abundance across
6868-406: The idea of dominance in the 1860s. However, it was not widely known until the early twentieth century. Mendel observed that, for a variety of traits of garden peas having to do with the appearance of seeds, seed pods, and plants, there were two discrete phenotypes, such as round versus wrinkled seeds, yellow versus green seeds, red versus white flowers or tall versus short plants. When bred separately,
6969-610: The individual identification of footprints known as pug marks – a method that has been criticised as deficient and inaccurate. Camera traps are now being used in many sites. Good tiger habitats in subtropical and temperate forests include the Tiger Conservation Units (TCUs) Manas - Namdapha . TCUs in tropical dry forest include Hazaribag Wildlife Sanctuary , Nagarjunsagar-Srisailam Tiger Reserve , Kanha - Indravati corridor, Orissa dry forests , Panna National Park , Melghat Tiger Reserve and Ratapani Tiger Reserve . The TCUs in tropical moist deciduous forest are probably some of
7070-417: The inheritance of two pairs of genes simultaneous. Assuming here that the two pairs of genes are located at non-homologous chromosomes, such that they are not coupled genes (see genetic linkage ) but instead inherited independently. Consider now the cross between parents (P-generation) of genotypes homozygote dominant and recessive, respectively. The offspring (F1-generation) will always heterozygous and present
7171-485: The level of dominance the alleles expresses towards each other. Pleiotropic genes are genes where one single gene affects two or more characters (phenotype). This means that a gene can have a dominant effect on one trait, but a more recessive effect on another trait. Epistasis is interactions between multiple alleles at different loci. Easily said, several genes for one phenotype. The dominance relationship between alleles involved in epistatic interactions can influence
7272-463: The level of homozygosity rises in the entire collection of gamodemes. The overall rise in homozygosity is quantified by the inbreeding coefficient (f or φ). All homozygotes are increased in frequency – both the deleterious and the desirable. The mean phenotype of the gamodemes collection is lower than that of the panmictic original – which is known as inbreeding depression. It is most important to note, however, that some dispersion lines will be superior to
7373-450: The locus for the beta-globin component of hemoglobin , where the three molecular phenotypes of Hb /Hb , Hb /Hb , and Hb /Hb are all distinguishable by protein electrophoresis . (The medical condition produced by the heterozygous genotype is called sickle-cell trait and is a milder condition distinguishable from sickle-cell anemia , thus the alleles show incomplete dominance concerning anemia, see above). For most gene loci at
7474-888: The longest among all cats. The Bengal tiger ranks among the biggest wild cats alive today. Males and female Bengal tigers in Panna Tiger Reserve reach a head-to-body length of 183–211 cm (72–83 in) and 164–193 cm (65–76 in) respectively, including a tail about 85–110 cm (33–43 in) long. Total length ranges from 283 to 311 cm (111 to 122 in) for male tigers and 255–285 cm (100–112 in) for female tigers. They typically range from 90–110 cm (35–43 in) in shoulder height. Subadult males weigh between 130 and 170 kg (290 and 370 lb) and reach 200–260 kg (440–570 lb) when adult; subadult females weigh 80–100 kg (180–220 lb) and reach between 110 and 180 kg (240 and 400 lb) when adult. In central India, 42 adult male Bengal tigers weighed on average 190 kg (420 lb) with
7575-455: The molecular level, both alleles are expressed co-dominantly, because both are transcribed into RNA . Co-dominance, where allelic products co-exist in the phenotype, is different from incomplete dominance, where the quantitative interaction of allele products produces an intermediate phenotype. For example, in co-dominance, a red homozygous flower and a white homozygous flower will produce offspring that have red and white spots. When plants of
7676-513: The most productive habitats for tigers and their prey, and include Kaziranga - Meghalaya , Kanha - Pench , Simlipal and Indravati Tiger Reserves . The TCUs in tropical moist evergreen forests represent the less common tiger habitats, being largely limited to the upland areas and wetter parts of the Western Ghats , and include the tiger reserves of Periyar , Kalakad-Mundathurai , Bandipur and Parambikulam Wildlife Sanctuary . During
7777-423: The next tiger population by a distance of up to 300 km (190 mi). Information is lacking on many aspects of Sundarbans tiger ecology, including relative abundance, population status, spatial dynamics, habitat selection, life history characteristics, taxonomy, genetics, and disease. There is also no monitoring program in place to track changes in the tiger population over time, and therefore no way of measuring
7878-418: The other allele, and the masked allele is considered recessive . When we only look at one trait determined by one pair of genes, we call it monohybrid inheritance . If the crossing is done between parents (P-generation, F0-generation) who are homozygote dominant and homozygote recessive, the offspring (F1-generation) will always have the heterozygote genotype and always present the phenotype associated with
7979-418: The panmictic original, while some will be about the same, and some will be inferior. The probabilities of each can be estimated from those binomial equations. In plant and animal breeding , procedures have been developed which deliberately utilize the effects of dispersion (such as line breeding, pure-line breeding, backcrossing). Dispersion-assisted selection leads to the greatest genetic advance (ΔG=change in
8080-470: The parental hybrid plants. Mendel reasoned that each parent in the first cross was a homozygote for different alleles (one parent AA and the other parent aa), that each contributed one allele to the offspring, with the result that all of these hybrids were heterozygotes (Aa), and that one of the two alleles in the hybrid cross dominated expression of the other: A masked a. The final cross between two heterozygotes (Aa X Aa) would produce AA, Aa, and aa offspring in
8181-499: The phenotype and neither allele masks another. For example, in the ABO blood group system , chemical modifications to a glycoprotein (the H antigen) on the surfaces of blood cells are controlled by three alleles, two of which are co-dominant to each other ( I , I ) and dominant over the recessive i at the ABO locus . The I and I alleles produce different modifications. The enzyme coded for by I adds an N-acetylgalactosamine to
8282-469: The phenotype associated with the dominant allele variant. However, when crossing the F1-generation there are four possible phenotypic possibilities and the phenotypical ratio for the F2-generation will always be 9:3:3:1. Incomplete dominance (also called partial dominance , semi-dominance , intermediate inheritance , or occasionally incorrectly co-dominance in reptile genetics ) occurs when
8383-404: The phenotype of the heterozygous genotype is distinct from and often intermediate to the phenotypes of the homozygous genotypes. The phenotypic result often appears as a blended form of characteristics in the heterozygous state. For example, the snapdragon flower color is homozygous for either red or white. When the red homozygous flower is paired with the white homozygous flower, the result yields
8484-771: The phenotypic mean), and is much more powerful than selection acting without attendant dispersion. This is so for both allogamous (random fertilization) and autogamous (self-fertilization) gamodemes. According to the UN, the world's population surpassed 8 billion on 15 November 2022, an increase of 1 billion since 12 March 2012. According to a separate estimate by the United Nations, Earth's population exceeded seven billion in October 2011. According to UNFPA , growth to such an extent offers unprecedented challenges and opportunities to all of humanity. According to papers published by
8585-535: The phenotypic outcome. Although any individual of a diploid organism has at most two different alleles at a given locus, most genes exist in a large number of allelic versions in the population as a whole. This is called polymorphism , and is caused by mutations. Polymorphism can have an effect on the dominance relationship and phenotype, which is observed in the ABO blood group system . The gene responsible for human blood type have three alleles; A, B, and O, and their interactions result in different blood types based on
8686-427: The plants always produced the same phenotypes, generation after generation. However, when lines with different phenotypes were crossed (interbred), one and only one of the parental phenotypes showed up in the offspring (green, round, red, or tall). However, when these hybrid plants were crossed, the offspring plants showed the two original phenotypes, in a characteristic 3:1 ratio, the more common phenotype being that of
8787-700: The potential to be connected. These landscapes comprise the following: Manas - Namdapha , Orang - Laokhowa and Kaziranga - Meghalaya are Tiger Conservation Units in northeastern India, stretching over at least 14,500 km (5,600 sq mi) across several protected areas . Tigers are also present in Pakke Tiger Reserve . In the Mishmi Hills , tigers were recorded in 2017 up to an elevation of 3,630 m (11,910 ft) in snow. Ranthambore National Park hosts India's westernmost tiger population. The Dangs' Forest in southeastern Gujarat
8888-669: The response of the population to conservation activities or threats. Most studies have focused on the tiger-human conflict in the area, but two studies in the Sundarbans East Wildlife sanctuary documented habitat-use patterns of tigers, and abundances of tiger prey, and another study investigated tiger parasite load. Some major threats to tigers have been identified. The tigers living in the Sundarbans are threatened by habitat destruction , prey depletion, highly aggressive and rampant intraspecific competition , tiger-human conflict, and direct tiger loss. By 2017, this population
8989-430: The side or behind from as close a distance as possible and grasp the prey's throat to kill it. Then they drag the carcass into cover, occasionally over several hundred metres, to consume it. The nature of the tiger's hunting method and prey availability results in a "feast or famine" feeding style: they often consume 18–40 kg (40–88 lb) of meat at one time. In one study, tigresses from Nepal made about 40–50 kills
9090-630: The study area of 100 km (39 sq mi). One of the resident females left her territory to one of her female offspring and took over an adjoining area by displacing another female; and a displaced female managed to re-establish herself in a neighbouring territory made vacant by the death of the resident. Of 11 resident females, 7 were still alive at the end of the study period, two disappeared after losing their territories to rivals, and two died. The initial loss of two resident males and subsequent take over of their home ranges by new males caused social instability for two years. Of four resident males, one
9191-576: The tail is orange with black rings. The white tiger is a recessive mutant , which is reported in the wild from time to time in Assam , Bengal, Bihar and especially in the former State of Rewa . However, it is not an occurrence of albinism . In fact, there is only one fully authenticated case of a true albino tiger, and none of black tigers, with the possible exception of one dead specimen examined in Chittagong in 1846. Fourteen Bengal tiger skins in
9292-626: The temperate forests in the north. Their stronghold appears to be the country's central belt between the Mo River in the west and the Kulong River in the east ranging in elevation from 2,000 to 3,500 m (6,600 to 11,500 ft). By 2015, Bhutan's tiger population was estimated at 103 individuals. Royal Manas and Jigme Singye Wangchuck National Parks form the largest contiguous tiger conservation area in Bhutan representing subtropical to alpine habitat types. In 2010, camera traps recorded
9393-502: The third nationwide survey for tiger and prey was conducted in the Terai Arc Landscape; the country's population was estimated at 220–274 tigers. As of 2022, 316–355 individuals were estimated to live in the country. In Bhutan, tigers have been documented in 17 of 18 districts . They inhabit the subtropical Himalayan foothills at an elevation of 200 m (660 ft) in the south to over 3,000 m (9,800 ft) in
9494-657: The time. Home ranges of both males and females are not stable. The shift or alteration of a home range by one animal is correlated with a shift of another. Shifts from less suitable habitat to better ones are made by animals that are already resident. New animals become residents only as vacancies occur when a former resident moves out or dies. There are more places for resident females than for resident males. During seven years of camera trapping, tracking, and observational data in Chitwan National Park, six to nine breeding tigers, two to sixteen non-breeding tigers, and six to twenty young tigers of less than one year of age were detected in
9595-569: The transboundary TCUs Chitwan - Parsa - Valmiki , Dudhwa - Kailali and Shuklaphanta - Kishanpur . Tiger densities in these TCUs are high, in part because of the extraordinary biomass of ungulate prey. In Pakistan, Khairpur was the last stronghold of the tiger by the late 19th century; the last individuals were shot in 1906 in Bahawalpur in the Indus Riverine jungles. In the 20th century, Indian censuses of wild tigers relied on
9696-420: The two homozygotes, the phenotype is said to exhibit no dominance at all, i.e. dominance exists only when the heterozygote's phenotype measure lies closer to one homozygote than the other. When plants of the F 1 generation are self-pollinated, the phenotypic and genotypic ratio of the F 2 generation will be 1:2:1 (Red:Pink:White). Co-dominance occurs when the contributions of both alleles are visible in
9797-428: Was about 200 km (77 sq mi) in summer and 110 km (42 sq mi) in winter. Included in his home range were the much smaller home ranges of two females, a tigress with cubs and a subadult tigress. They occupied home ranges of 16 to 31 km (6.2 to 12.0 sq mi). The home ranges occupied by adult male residents tend to be mutually exclusive, even though one of these residents may tolerate
9898-554: Was estimated at 84–158 individuals. As of 2018, 114 individuals were estimated to live in the country. A rising sea-level due to climate change is projected to cause a severe loss of suitable habitat for this population in the following decades, around 50% by 2050 and 100% by 2070. The tiger population in the Terai of Nepal is split into three isolated subpopulations that are separated by cultivation and densely settled habitat. The largest population lives in Chitwan National Park and in
9999-474: Was estimated to weigh about 272 kg (600 lb). A male weighing 259 kg (570 lb) was shot in northern India in the 1930s. A male tiger shot in Nepal weighed 320 kg (710 lb) and measured 328 cm (10 ft 9 in) 'over the curves'. The heaviest wild tiger was possibly a huge male killed in 1967 at the foothills of the Himalayas. It weighed 388.7 kg (857 lb) after eating
10100-562: Was in a relatively poor condition at the time of capture. Their skulls and body weights were distinct from those of tigers in other habitats, indicating that they may have adapted to the unique conditions of the mangrove habitat. Their small sizes are probably due to a combination of intense intraspecific competition and small size of prey available to tigers in the Sundarbans, compared to the larger deer and other prey available to tigers in other parts. The very large " Leeds Tiger " on display at Leeds City Museum , shot in 1860 near Mussoorie , had
10201-428: Was still alive and three were displaced by rivals. Five litters of cubs were killed by infanticide, two litters died because they were too young to fend for themselves when their mothers died. One juvenile tiger was presumed dead after being photographed with severe injuries from a deer snare . The remaining young lived long enough to reach dispersal age, two of them becoming residents in the study area. The Bengal tiger
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