Filial cannibalism

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Filial cannibalism occurs when an adult individual of a species consumes all or part of the young of its own species or immediate offspring. Filial cannibalism occurs in many species ranging from mammals to insects, and is especially prevalent in various types of fish species with males that engage in egg guardianship. [1] The exact evolutionary purpose of the practice in those species is unclear and debated among zoologists, though there is consensus that it may have, or may have had at some point in species' evolutionary history, certain evolutionary and ecological implications.

Contents

Types

Total

Total or whole clutch cannibalism occurs when a parent consumes its entire brood. This usually occurs when a brood is small or of lower quality. The most obvious purpose of total or whole clutch cannibalism is the termination of care for the parents. The main benefit of this action can only be an investment in the future reproduction of potentially larger or healthier broods. [2]

Partial

Partial clutch cannibalism occurs when a parent consumes a part of its offspring. "Parental manipulation of brood size may allow the parent the maximize lifetime reproductive output by adjusting current reproductive costs in favour of future survival and subsequent opportunities for reproduction." [3] Unlike total or whole clutch cannibalism, partial clutch cannibalism invests in both current and future reproduction. [2] Male parents, particularly male fish, may eat some of their offspring to complete their "current parental cycle, and remain in sufficiently good condition to engage in further breeding cycles." [4]

Benefits

The following potential benefits of filial cannibalism have been suggested by zoologists:

Costs

Suggested costs are the loss of immediate fitness [9] and the risk of transmission of diseases and parasites. [3]

Social factors

Competition among a species for resources, mating opportunities, and reproductive dominance are all promoters for filial cannibalism. To compete well in a certain species' social structure, a parent may be compelled to practice filial cannibalism to limit the amount of energy and time they spend raising their young.

Males may compete for mating opportunities by eating the offspring of a female to make that female more sexually receptive or to re-mate. By doing this, a male might be able to prolong its lifetime mating opportunities. [3]

Female fish may compete for mating opportunities with males by raiding the male's nest and eating the eggs inside. Females may also use cannibalism – particularly birds and bees that live in a joint-nesting social structure – as a way to establish reproductive dominance by eating the eggs of a co-breeder. [3]

In some animal cultures, competition may lead to instances of egg thievery, nest takeovers, and cuckoldry. However, the consumption of an animal's brood is often more beneficial than the consumption of unrelated conspecifics, since it takes less energy to eat their own offspring and lessens the chance of getting their own brood raided when getting food while away from their offspring. [10]

Filial cannibalism in fish

Many species of fish with paternal care exhibit total or partial clutch cannibalism. This is likely in order to gain additional energy and nutrients, which might ultimately increase their future reproductive success. [11] Cannibalized offspring can act as a food source for the male fish guarding them. [12]

Often, male fish will consume their entire clutch if it is too small, as the energetic costs of caring for a small clutch may be greater than the reproductive benefits. [11] In other fish, filial cannibalism has been observed to regulate male fish's endocrine systems. For example, in the blenniid fish Rhabdoblennius nitidus, males have an androgen-dependent brood cycle. However, the acquisition of eggs suppresses the secretion of androgen, preventing males from performing courtship displays and obtaining more offspring. As a result, R. nitidus males will cannibalize all their eggs when the clutch size is small, so they can reproduce and care for a larger clutch of eggs (and subsequently have more offspring). [13]

In some cases, the size of the clutch seems to determine whether the male consumes the entire clutch or only part of it. For example, in the fantail darter, males seem to consume a fixed number of eggs regardless of clutch size, which may be in order to cover the energy costs of guarding the eggs. Since the cost of parental care does not increase significantly with a larger clutch size, having small clutch size may not be worth the amount of care that would have to be invested in it. This is further compounded by the fact that in the fantail darter, females prefer males who have already mated and are guarding young eggs, possibly because it would reduce the risk of her eggs being consumed by the male. Specifically, females prefer males with young eggs over old eggs, so caring for smaller broods of older eggs may have little to no net benefit to the male. As a result, smaller clutches may end up being entirely consumed. [11]

Filial cannibalism in insects

Filial cannibalism can act in a way analogous to brood reduction in birds, in order to reduce competition between offspring for resources and maximize the survival of fully developed healthy offspring. For example, the burying beetle Nicrophorus vespilloides exhibits partial filial cannibalism. Burying beetles bury the bodies of small vertebrates as a food source for their offspring; for N. vespilloides, eggs are scattered a few centimeters away from the corpse. Once they hatch, the larvae make their way to the corpse to feed while supervised by their parents.

Clutch sizes can be much larger than the corpse can support, which researchers suggest is due to eggs being laid as insurance for unexpected mortalities, parents being unable to accurately estimate the food capacity of the corpse, or parents being physically constrained to a minimum clutch size (though studies have shown that parents will vary the size of their clutch based on the amount of food available). At higher densities with insufficient food, larvae may not develop completely, resulting in smaller adults that are less likely to find a mate, as well as limiting the maximum clutch size that can be laid. The parents thus kill part of their brood at the earliest stage to maximize the food available for the others. [14]

Filial cannibalism can also serve as a source of energy while simultaneously removing nonviable eggs, such as those that have been parasitized. In the assassin bug Rhinocoris tristis, males are more likely to consume eggs at the periphery of the brood, which are most likely to be parasitized by wasps and are also the easiest for the male to access. Although R. tristis cannot distinguish between parasitized eggs and nonparasitized eggs, their preference for feeding on peripheral eggs may be a general behavior to maximize the chances of feeding on nonviable, parasitized eggs.

In addition, it would reduce the number of peripheral eggs available to parasitic wasps, forcing them into an inner egg where guarding males are more likely to see and fight them off, which could potentially kill the wasp. Furthermore, eggs serve as a source of energy due to the costs of parental care, such as reduced efficiency in feeding and energy used to fend off attackers. R. tristis males also guard adopted broods without a higher rate of cannibalization, suggesting that they cannot discriminate between their own eggs and unrelated ones. [15]

Infanticidal cannibalism among humans

Among humans, cases of newborns or infants being killed because they are "considered unwanted or unfit to live" and then "consumed by the mother, father, both parents or close relatives" are known as infanticidal cannibalism or cannibalistic infanticide. [16] [17] Infanticide followed by cannibalism was practiced in various regions, but is particularly well documented among Aboriginal Australians. [17] [18] [19]

See also

Related Research Articles

<span class="mw-page-title-main">Burying beetle</span> Genus of beetles

Burying beetles or sexton beetles, genus Nicrophorus, are the best-known members of the family Silphidae. Most of these beetles are black with red markings on the elytra (forewings). Burying beetles are true to their name—they bury the carcasses of small vertebrates such as birds and rodents as a food source for their larvae; this makes them carnivorous. They are unusual among insects in that both the male and female parents take care of the brood.

<span class="mw-page-title-main">Behavioral ecology</span> Study of the evolutionary basis for animal behavior due to ecological pressures

Behavioral ecology, also spelled behavioural ecology, is the study of the evolutionary basis for animal behavior due to ecological pressures. Behavioral ecology emerged from ethology after Niko Tinbergen outlined four questions to address when studying animal behaviors: What are the proximate causes, ontogeny, survival value, and phylogeny of a behavior?

<span class="mw-page-title-main">American coot</span> Species of bird

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<span class="mw-page-title-main">Damselfish</span> Group of fishes

Damselfish are those within the subfamilies Abudefdufinae, Chrominae, Lepidozyginae, Pomacentrinae, and Stegastinae within the family Pomacentridae. Most species within this group are relatively small, with the largest species being about 30cm in length. Most damselfish species exist only in marine environments, but a few inhabit brackish or fresh water. These fish are found globally in tropical, subtropical, and temperate waters.

<span class="mw-page-title-main">Blue-footed booby</span> Species of bird

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<span class="mw-page-title-main">Pipefish</span> Subfamily of fishes

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Monogamous pairing in animals refers to the natural history of mating systems in which species pair bond to raise offspring. This is associated, usually implicitly, with sexual monogamy.

<span class="mw-page-title-main">Cannibalism</span> Consuming another individual of the same species as food

Cannibalism is the act of consuming another individual of the same species as food. Cannibalism is a common ecological interaction in the animal kingdom and has been recorded in more than 1,500 species. Human cannibalism is also well documented, both in ancient and in recent times.

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<span class="mw-page-title-main">Infanticide (zoology)</span> Killing of young offspring by an adult animal of the same species

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<span class="mw-page-title-main">Parental care</span> Behavior in animals of taking care of offspring

Parental care is a behavioural and evolutionary strategy adopted by some animals, involving a parental investment being made to the evolutionary fitness of offspring. Patterns of parental care are widespread and highly diverse across the animal kingdom. There is great variation in different animal groups in terms of how parents care for offspring, and the amount of resources invested by parents. For example, there may be considerable variation in the amount of care invested by each sex, where females may invest more in some species, males invest more in others, or investment may be shared equally. Numerous hypotheses have been proposed to describe this variation and patterns in parental care that exist between the sexes, as well as among species.

Mate desertion occurs when one or both parents abandon their current offspring, and thereby reduce or stop providing parental care. Often, by deserting, a parent attempts to increase breeding opportunities by seeking out another mate. This form of mating strategy behavior is exhibited in insects, birds and mammals. Typically, males are more likely to desert, but both males and females have been observed to practice mate desertion.

<i>Microspathodon chrysurus</i> Species of fish

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<span class="mw-page-title-main">Polyandry in animals</span> Class of mating system in non-human species

In behavioral ecology, polyandry is a class of mating system where one female mates with several males in a breeding season. Polyandry is often compared to the polygyny system based on the cost and benefits incurred by members of each sex. Polygyny is where one male mates with several females in a breeding season . A common example of polyandrous mating can be found in the field cricket of the invertebrate order Orthoptera. Polyandrous behavior is also prominent in many other insect species, including the red flour beetle, the adzuki bean weevil, and the species of spider Stegodyphus lineatus. Polyandry also occurs in some primates such as marmosets, mammal groups, the marsupial genus' Antechinus and bandicoots, around 1% of all bird species, such as jacanas and dunnocks, insects such as honeybees, and fish such as pipefish.

<span class="mw-page-title-main">Parental care in birds</span>

Parental care refers to the level of investment provided by the mother and the father to ensure development and survival of their offspring. In most birds, parents invest profoundly in their offspring as a mutual effort, making a majority of them socially monogamous for the duration of the breeding season. This happens regardless of whether there is a paternal uncertainty.

<span class="mw-page-title-main">Matriphagy</span> Consumption of a mother by her offspring

Matriphagy is the consumption of the mother by her offspring. The behavior generally takes place within the first few weeks of life and has been documented in some species of insects, nematode worms, pseudoscorpions, and other arachnids as well as in caecilian amphibians.

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. 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. This encompasses behaviors that aid in the evolutionary success of the offspring and parental investment, which is a measure of expenditure exerted by the parent in an attempt to provide evolutionary benefits to the offspring. Therefore, it is a measure of the benefits versus costs of engaging in the parental behaviors. Behaviors commonly exhibited by the maternal parent include feeding, either by lactating or gathering food, grooming young, and keeping the young warm. Another important aspect of parental care is whether the care is provided to the offspring by each parent in a relatively equal manner, or whether it is provided predominantly or entirely by one parent. There are several species that exhibit biparental care, where behaviors and/or investment in the offspring is divided equally amongst the parents. This parenting strategy is common in birds. However, even in species who exhibit biparental care, the maternal role is essential since the females are responsible for the incubation and/or delivery of the young.

References

  1. ↑ Bose, Aneesh P. H. (October 2022). "Parent–offspring cannibalism throughout the animal kingdom: a review of adaptive hypotheses". Biological Reviews. 97 (5): 1868–1885. doi: 10.1111/brv.12868 . ISSN   1464-7931. PMID   35748275. S2CID   249989939.
  2. 1 2 Hope Klug; Kai Lindström (2008). "Hurry-up and hatch: selective filial cannibalism of slower developing eggs". Biology Letters . 4 (2): 160–162. doi:10.1098/rsbl.2007.0589. PMC   2429927 . PMID   18252661.
  3. 1 2 3 4 5 6 Mark A. Elgar; Bernard J. Crespi (1992). Cannibalism: Ecology and evolution among diverse taxa. New York: Oxford University Press. ISBN   978-0-19-854650-4.
  4. ↑ Adam G. Payne; Carl Smith; Andrew C. Campbell (2002). "Filial cannibalism improves survival and development of beaugregory damselfish embryos". Proceedings of the Royal Society B: Biological Sciences . 269 (1505): 2095–2102. doi:10.1098/rspb.2002.2144. JSTOR   3558871. PMC   1691142 . PMID   12396483.
  5. 1 2 3 4 Andrea Thompson (November 14, 2007). "Why some animals eat their offspring". LiveScience . Retrieved November 28, 2011.
  6. ↑ Matsumoto, Yukio; Tateishi, Tetsunari; Terada, Ryusuke; Soyano, Kiyoshi; Takegaki, Takeshi (September 10, 2018). "Filial Cannibalism by Male Fish as an Infanticide to Restart Courtship by Self-Regulating Androgen Levels". Current Biology. 28 (17): 2831–2836.e3. Bibcode:2018CBio...28E2831M. doi: 10.1016/j.cub.2018.06.056 . ISSN   0960-9822. PMID   30122527. S2CID   52038778.
  7. ↑ Okada, Sumio; Fukuda, Yukihiro; Takahashi, Mizuki K. (January 1, 2015). "Paternal care behaviors of Japanese giant salamander Andrias japonicus in natural populations". Journal of Ethology. 33 (1): 1–7. doi: 10.1007/s10164-014-0413-5 . ISSN   1439-5444. S2CID   254136653.
  8. ↑ Mrowka, Wolfgang (October 1, 1987). "Filial cannibalism and reproductive success in the maternal mouthbrooding cichlid fish Pseudocrenilabrus multicolor". Behavioral Ecology and Sociobiology. 21 (4): 257–265. Bibcode:1987BEcoS..21..257M. doi:10.1007/BF00292507. ISSN   1432-0762. S2CID   35060916.
  9. ↑ M. B. Bonsall; H. Klug (2011). "Effects of among-offspring relatedness on the origins and evolution of parental care and filial cannibalism". Journal of Evolutionary Biology . 24 (6): 1335–1350. doi: 10.1111/j.1420-9101.2011.02269.x . PMID   21507115.
  10. ↑ Andrew J. DeWoody; Dean E. Fletcher; S. David Wilkins; John C. Avise (2001). "Genetic documentation of filial cannibalism in nature" (PDF). Proceedings of the National Academy of Sciences . 98 (9): 5090–5092. Bibcode:2001PNAS...98.5090D. doi: 10.1073/pnas.091102598 . PMC   33168 . PMID   11309508.
  11. 1 2 3 Lindström, Kai; Sargent, R. Craig (1997). "Food Access, Brood Size and Filial Cannibalism in the Fantail Darter, Etheostoma flabellare". Behavioral Ecology and Sociobiology. 40 (2): 107–110. Bibcode:1997BEcoS..40..107L. doi:10.1007/s002650050322. ISSN   0340-5443. JSTOR   4601305. S2CID   18097652.
  12. ↑ DeWoody, J. Andrew; Fletcher, Dean E.; Wilkins, S. David; Avise, John C. (April 24, 2001). "Genetic documentation of filial cannibalism in nature". Proceedings of the National Academy of Sciences. 98 (9): 5090–5092. Bibcode:2001PNAS...98.5090D. doi: 10.1073/pnas.091102598 . ISSN   0027-8424. PMC   33168 . PMID   11309508.
  13. ↑ Matsumoto, Yukio; Tateishi, Tetsunari; Terada, Ryusuke; Soyano, Kiyoshi; Takegaki, Takeshi (September 10, 2018). "Filial Cannibalism by Male Fish as an Infanticide to Restart Courtship by Self-Regulating Androgen Levels". Current Biology. 28 (17): 2831–2836.e3. Bibcode:2018CBio...28E2831M. doi: 10.1016/j.cub.2018.06.056 . ISSN   0960-9822. PMID   30122527. S2CID   52038778.
  14. ↑ Bartlett, J. (September 1, 1987). "Filial cannibalism in burying beetles". Behavioral Ecology and Sociobiology. 21 (3): 179–183. Bibcode:1987BEcoS..21..179B. doi:10.1007/BF00303208. ISSN   1432-0762. S2CID   22981828.
  15. ↑ Thomas, Lisa K; Manica, Andrea (August 1, 2003). "Filial cannibalism in an assassin bug". Animal Behaviour. 66 (2): 205–210. doi:10.1006/anbe.2003.2202. ISSN   0003-3472. S2CID   53185005.
  16. ↑ Siefkes, Christian (2022). Edible People: The Historical Consumption of Slaves and Foreigners and the Cannibalistic Trade in Human Flesh. New York: Berghahn. p. 14. ISBN   978-1-80073-613-9.
  17. 1 2 Travis-Henikoff, Carole A. (2008). Dinner with a Cannibal: The Complete History of Mankind's Oldest Taboo. Santa Monica: Santa Monica Press. p. 196.
  18. ↑ Bates, Daisy (1938). The Passing of the Aborigines. London: John Murray. chs. 10, 17 – via Project Gutenberg Australia.
  19. ↑ Róheim, Géza (1976). Children of the Desert: The Western Tribes of Central Australia. Vol. 1. New York: Harper & Row. pp. 69, 71–72.
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