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Philopatry is the “tendency of an organism to stay in, or return to, its home area”. The causes of philopatry are numerous, but natal philopatry, where animals return to their birthplace to breed, is probably the most common form. The term "philopatry" derives from the Greek 'home-loving', although in recent years the term has been applied to more than just the animal's birthplace. Recent usage refers to animals returning to the same area to breed despite not being born there, and migratory species that demonstrate site fidelity: reusing stopovers, staging points, and wintering grounds. ==Breeding-site philopatry== One type of philopatry is breeding philopatry, or breeding-site fidelity, and involves an individual, pair, or colony returning to the same location to breed, year after year. Among animals that are largely sedentary, breeding-site philopatry is common. It is advantageous to reuse a breeding site, as there may be territorial competition outside of the individual’s home range, and since the area evidently meets the requirements of breeding. Such advantages are compounded among species that invest heavily in the construction of a nest or associated courtship area. For example, the megapodes (large, ground-dwelling birds such as the Australian malleefowl, ''Leipoa ocellata'') construct a large mound of vegetation and soil or sand to lay their eggs in. Megapodes often reuse the same mound for many years, only abandoning it when it is damaged beyond repair, or due to disturbance. Nest fidelity is highly beneficial as reproducing is time and energy consuming (malleefowl will tend a mound for five to six months per year). Breeding fidelity is also well documented among species that migrate or disperse after reaching maturity. Birds, in particular, that disperse as fledglings will take advantage of exceptional navigational skills to return to a previous site. Philopatric individuals exhibit learning behaviour, and do not return to a location in following years if a breeding attempt is unsuccessful. The evolutionary benefits of such learning are evident: individuals that risk searching for a better site will not have lower fitness than those that persist with a poor site. Philopatry is not homogenous within a species, with individuals far more likely to exhibit philopatry if the breeding habitat is isolated. Similarly, non-migratory populations are more likely to be philopatric that those that migrate. In species that exhibit lifelong monogamous pair bonds, even outside of the breeding season, there is no bias in the sex that is philopatric. However, among polygynous species that disperse (including those that find only a single mate per breeding season), there is a much higher rate of breeding-site philopatry in males than females among birds, and the opposite bias among mammals. Many possible explanations for this sex bias have been posited, with the earliest accepted hypothesis attributing the bias to intrasexual competition, and territory choice.〔 The most widely accepted hypothesis is that proposed by Greenwood (1980).〔 Among birds, males invest highly in protecting resources – a territory – against other males. Over consecutive seasons, a male that returns to the same territory has higher fitness than one that is not philopatric.〔 Females are free to disperse, and assess males. Conversely, in mammals, the predominant mating system is one of matrilineal social organisation. Males generally invest little in the raising of offspring, and compete with each other for mates rather than resources. Thus dispersing can result in reproductive enhancement, as greater access to females is available. On the other hand, the cost of dispersal to females is high, and thus they are philopatric. This hypothesis also applies to natal philopatry, but is primarily concerned with breeding-site fidelity. A more recent hypothesis builds on Greenwood’s findings, suggesting that parental influence may play a large role. Because birds lay eggs, adult females are at risk of being cuckolded by their daughters, and thus would drive them out. On the other hand, young male mammals pose a threat to their dominant father, and so are driven to disperse while young. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Philopatry」の詳細全文を読む スポンサード リンク
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