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The young are typically raised in a nest; the parents catch food and regurgitate it for the young. Some birds such as pigeons create a " crop milk " which they similarly regurgitate. [ 55 ] David Lack developed a hypothesis that clutch size has evolved in response to the costs of parental care known as Lack's principle .
The provision of care, by either males or females, is presumed to increase growth rates, quality, and/or survival of young, and hence ultimately increase the inclusive fitness of parents. [ 2 ] [ 3 ] [ 4 ] In a variety of vertebrate species (e.g., about 80% of birds [ 5 ] and about 6% of mammals), [ 6 ] both males and females invest heavily in ...
Kavanau (1987) was the first to find that unique bi-parental care seen in modern birds probably evolved from extinct birds. They developed the ability to provide protection, escorting, nurturing and egg guarding abilities for their young. Evolution of homeothermy and flight most likely occurred in bi-parental birds with precocial chicks.
Vertebrate maternal behavior is a form of parental care that is specifically given to young animals by their mother in order to ensure the survival of the young. [1] Parental care is a form of altruism, which means that the behaviors involved often require a sacrifice that could put their own survival at risk. [1]
Some animals starve to death shortly after birthing their young while others are eaten by their own young -- but these mothers make the ultimate sacrifice. Click through for 10 animal mothers that ...
Sexual selection is an evolutionary concept that has been used to explain why, in some species, male and female individuals behave differently in selecting mates. In 1930, Ronald Fisher wrote The Genetical Theory of Natural Selection, [3] in which he introduced the modern concept of parental investment, introduced the sexy son hypothesis, and introduced Fisher's principle.
The publication also found that, while living with family rent-free may seem like a great way to save up, for various economic and emotional reasons it may work against young people in the long run.
There is little advantage in adaptations that permit successful competition with other organisms, because the environment is likely to change again. Among the traits that are thought to characterize r-selection are high fecundity, small body size, early maturity onset, short generation time, and the ability to disperse offspring widely.