Observation of the Dolgan hunter-gatherers of northern Russia suggested that, while reciprocal food-sharing occurs between both kin and non-kin, there are larger and more frequent asymmetrical transfers of food to kin. Kin are also more likely to be welcomed to non-reciprocal meals, while non-kin are discouraged from attending. Finally, even when reciprocal food-sharing occurs between families, these families are often very closely related, and the primary beneficiaries are the offspring. Other research indicates that violence in families is more likely to occur when step-parents are present and that "genetic relationship is associated with a softening of conflict, and people's evident valuations of themselves and of others are systematically related to the parties' reproductive values". Numerous other studies suggest how inclusive fitness may work amongst different peoples, such as the Ye’kwana of southern Venezuela, the Gypsies of Hungary, and the doomed Donner Party of the United States. Vervet monkeys display kin selection between siblings, mothers and offspring, and grandparent-grandchild. These monkeys utilise allomothering, where the allomother is typically an older female sibling or a grandmother. Other studies have shown that individuals will act aggressively toward other individuals that were aggressive toward their relatives. "Synalpheus regalis" is a eusocial shrimp that protects juveniles in the colony. By defending the young, the large defender shrimp can increase its inclusive fitness. Allozyme data revealed that relatedness within colonies is high, averaging 0.50, indicating that colonies in this species represent close kin groups. Though originally thought unique to the animal kingdom, evidence of kin selection has been identified in the plant kingdom. Competition for resources between developing zygotes in plant ovaries increases when seeds are sired by different fathers. How developing zygotes differentiate between full siblings and half-siblings in the ovary is undetermined, but genetic interactions are thought to play a role. Nonetheless, competition between zygotes in the ovary is detrimental to the reproductive success of the mother plant, as fewer zygotes mature into seeds, and is also thought to harm the mother plant itself. As such, the reproductive traits and behaviors of plants suggests the evolution of behaviors and characteristics that increase the genetic relatedness of fertilized eggs in the plant ovary, thereby fostering kin selection and cooperation among the seeds as they develop. These traits differ among plant species. Some species have evolved to have fewer ovules per ovary, commonly one ovule per ovary, thereby decreasing the chance of developing multiple, differently fathered seeds within the same ovary.