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Philopatry- (Philo-"liking", Greek-"fatherland") - the tendency for an animal or a certain species to remain or return to a particular area of its birth for many different reasons. Some of the known reasons for organisms to be philopatric would be for mating (reproduction), survival, migration, parental care, resources, etc.. In most species of animals, individuals will benefit from living in groups, because depending on the species, individuals are more vulnerable to predation and more likely to have difficulty finding resources and food. Therefore, living in groups increases a species chances of survival, which correlates to finding resources and reproducing. Again, depending on the species, returning to their birthplace where that particular species occupies that territory is the more favorable option. The birthplaces for these animals serve as a territory for them to return for feeding and refuge, like fish from a coral reef. In an animal behavior study conducted by Paul Greenwood, overall female mammals are more likely to be philopatric, while male mammals are more likely to disperse. Male Birds are more likely to philopatric, while females are more likely to disperse. Philopatry will favor the evolution of cooperative traits because the direction of sex has consequences from the particular mating system.

Natal Philopatry- the tendency for animals return to their birthplace to breed. Natal philopatry is the most common form of philopatry in females because it decreases competition for mating and increases the rate of reproduction and a higher survival rate for offspring. Natal philopatry also leads to a kin-structured population, which is when the population is more genetically related than less related between individuals in a species. This can also lead to inbreeding and a higher rate of natural and sexual selection within a population.

Research Examples:

In a research study conducted by Andrew Spinks in 2000, Spinks states examples of philopatry in common mole-rats due to the climate of the habitat they live in. Either arid or mesic habitat. Mole-rats are more likely to return to mesic habitats and disperse from the arid habitats due to the function of the group size and wherever the majority of the population migrates too. Mole-rats have a higher chance of survival in a mesic habitat due to the supply well-balanced moisture rather than the arid habitat. Due to the nature of "following" the group, mole-rats want to stay together which they do in the mesic habitat more so than the arid habitat which is more individual survival and lifestyle. So philopatry in the example is that mole-rats return to their mesic habitat because of their social, community lifestyle rather than an individual, survival lifestyle.

In another research study conducted by James Sedgwick in 2004. Sedgwick had three sites where he studied the philopatry of willow flycatcher birds in southeast Oregon over a 10-year period. He found that natal philopatry was low in willow flycatcher birds at 7.8% for both males and females and seemed to be due to site quality. The birds seemed to disperse from one site and return to the other two sites. This was due to the quality of the habitats and was the main influence for philopatry; the birds wanting to return to a habitat with good quality to breed and care for their offspring. His results somewhat supported his hypothesis that previously successful females that switched territories underperformed the females that did not switch and previously unsuccessful females that switched territories outperformed the females that did not switch.

A research study conducted by Charlotte Hemelrijk in 1998 studied the behavioral movement of primates. Hemelrijk determined that the main source of variation between primates was because of the competition for food and a safe location to live, mate and raise offspring. This study was to determine if females would remain philopatric or disperse to a larger group of males because of the number of males living together. Usually, the "better" condition would be to live with a group of multiple males because that would mean more mating opportunities and would increase survival and food sources. Hemelrijk hypothesized that philopatric female primates would suffer from the competition for males because females are usually restrained to their native groups instead of dispersing to "better" conditions, where more males would be located. Hemelrijk's second hypothesis stated that males that remain in large groups are better able to defend territories that have large food sources, which helps females search for food and lowers competition within females. To complete this study, Hemelrijk followed 10 philopatric female primates and four female primates that dispersed to other groups. Hemelrijk found that the sex ratio was higher in populations where the degree of grooming reciprocation was high. The degree of grooming reciprocation was positively correlated to a relationship with a single mate rather than with multiple mates. This was also positively correlated with staying within the same group. When female primates were philopatric it lowered the competition between males for females which increases reproduction, grooming reciprocation and survival. Males that stay in large groups increase the number of food sources and resources due to large numbers working together, but the competition for females would be higher due to the low availability of females in large groups of males.

Costs and Benefits from Philopatry:

Philopatry in social groups can have many advantages; larger population results in more protection and means of survival and a higher intake of resources like food, mates, and the quality of the habitat being occupied by a specific species. Individuals remain philopatric because individuals gain direct or indirect fitness benefits. The reasons for philopatry and dispersal can all be correlated between one and another, meaning all things will lead from one thing to another for the overall quality of a species. Reasons are the rate of development because a species needs to develop their habitat to be able to support individuals living in it. Developing a habitat needs to be done in a timely manner due to the rate of reproduction and care that will be taking place. Survival and food resources are also reasons for philopatry and dispersal because organisms will move to the habitat that gives their species the best chance of living for a long time with the resources available to do so. Nesting is an extremely important reason for philopatry and dispersal because when individuals care for their offspring, the quality of their nest or home will determine the number of offspring that will survive and if that available territory is an ideal territory that species will stay for future generations. The risk of leaving or returning to an organism's place of birth can be rewarding but can also be devastating to an organism if conditions are not what is expected. Mate limitation is one of the main reasons females and males will be philopatric or disperse because without the ability to mate and reproduce species will become extinct. So always having the right conditions to reproduce is important for the survival of a species. Fitness and sociality can be correlated when it comes to philopatry because when individuals live in groups their fitness will increase because of a "teamwork" system for gaining more resources and having more mates which will lead to all the other factors listed. All of these factors are why individuals are philopatric and why individuals disperse and are extremely important in selection and the overall development and evolution of species.

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