If you bite into a chocolate rabbit or egg this weekend, keep in mind that rabbits often eat their own cubs and chickens their own eggs.
In fact, offspring feeding or abandonment has been documented in a variety of mammal and bird species ̵
Now, researchers from the University of Tennessee and the University of Oxford suggest that in some cases, cannibalism and the demise of offspring may even be considered as overweight forms of parental care. Published in Frontiers in Ecology and Evolution shows their mathematical model that overcrowding endangers the survival of children – which can often be a victim, often due to the spread of infection or competition for resources – the most victimized can fall of hard love.
Put all your eggs in a basket
To understand the role of overcrowding or "offspring density" in the survival advantage of filibulary cannibals, researchers focused on species that lay eggs.
"Oviposition of common eggs is common in a number of fish, insects, reptiles and amphibians," says lead author Dr. Ing. Hope Klug, associate professor at the University of Tennessee in Chattanooga. "This makes it easier to protect, cleanse, incubate and feed the eggs – but it can also increase the transmission of disease and the competition for food and oxygen."
Progeny density has been shown to influence egg survival and, in some cases, egg abandonment, in many of these species.
"For example, fathers in the Bollegory Damselfish region tend to eat eggs under low-oxygen conditions," notes Klug. "Such cases have led to the hypothesis that feeding or giving up offspring can be an adaptation to improving the overall survival of offspring by reducing their density."
Model parents eat their offspring
Klug and colleagues created a mathematical model to test this hypothesis.
"The model introduced an imaginary individual with a mutation for childhood cannibalism or the abandonment of offspring to a population of generic egg rodents," explains lead author Dr. Mackenzie Davenport, also from the University of Tennessee.
As in the previous models of the group, the gene for cannibalism spread in the population when it gave parents extra calories.
But for the first time in this model, they found that mortality increases with offspring. Egg laying, both childlike cannibalism and the abandonment of offspring result in increased fitness.
"Under these conditions, the mutants were able to outsmart the generic and replace populations," says Davenport.
This was the case even when cannibal parents were given little or no energy from the extra food – or when it was assumed that abandoned offspring were dying.
"Our findings surprisingly suggest childish cannibalism and abandoning offspring can act as a form of parental care, increasing the survival of all offspring."
Live fast, die young "Be prepared to break off
" also increases with adult mortality rates, especially in the case of child cannibalism, "adds co-author Prof. Michael Bonsall of the University of Oxford.
In other words, if you have fewer reproductive records, you will be "ruthless in protecting your brood, but if the mortality of the children depends on the density, why produce so many eggs at all?"
"Parents can not always predict the environment in which their offspring will land," explains Bonsall. "Factors such as food availability, oxygen availability, the presence of disease and predators can change in an unpredictable way. Similarly, in many fish and other animals, females deposit their eggs in the nests or territories of the males and leave them so that optimal laying densities can not be predicted, given that additional females may later add eggs to the nest. "
" It is up to the empiricists to test these models in different ways, "conclude the authors.
Shall I eat the children? When to nurse, give up or eat your offspring
Limits in Ecology and Evolution DOI: 10.3389 / fevo.2019.00113, https://www.frontiersin.org/articles/10.3389/fevo.2019.00113/full
Sweetheart, I ate the children: The sweet side of childish cannibalism (2019, 16 April)
retrieved on April 16, 2019
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