'Sexual conflict' is a form of
evolutionary conflict where
males and
females do not share interests over
reproduction.
This can be in two forms:
1)
interlocus sexual conflict, where male alleles have conflicting interests with females. This can be in the form of conflict over
parental care, where males are more prone to abandon offspring. Another form is sexual harassment, where males harm females to gain access to
matings, such as when toxins are released in sperm by male ''
Drosophila melanogaster''.
2)
intralocus sexual conflict, where the same set of alleles in males and females have different optima. i.e. they are expressed differently in the sexes. A classic example is the human
hip, where females need larger hips for childbirth.
Some regard sexual conflict as a subset of
sexual selection, while others suggest it is a separate
evolutionary phenomena.
Sexual conflict may lead to 'sexually antagonistic co-evolution', in which one sex (usually males) evolves a "manipulative" trait which is countered by a "resistance" trait in the other sex.
Manifestations
Infanticide
Infanticide is a behavior that occurs in many species where an adult kills younger individuals, including eggs. Sexual conflict is one of the most common causes, although other cases are seen, such as male
bass eating their own juvenile descendants.
[M. A. Elgar and Bernard J. Crespi (eds.). 1992. ''Cannibalism: Ecology and Evolution of Cannibalism among Diverse Taxa'' Oxford University Press, New York. (361pp) ISBN 0198546505] It is usually the males who perpetrate such behavior, though it is not unknown for females to behave in the same way.
Vertebrates have received the most research, with cases such as
hanuman langurs,
lions,
house sparrows and
mice being studied. This behavior also occurs in the
invertebrates, however. One such case is the spider ''
Stegodyphus lineatus'', where males invade female nests and toss out their egg sacs.
[Schneider, J. M. & Y. Lubin (1996) Infanticidal male eresid spiders. ''Nature''. '381':655-656.] Females only have one clutch in their lifetime, and experience reduced reproductive success if they lose them. This results in vicious battles in which injuries and even death are not uncommon. ''
Jacana jacana'', a tropical
wading bird, offers one example of infanticide by the female sex.
[1] Females guard a territory while males care for their young. As males are a limiting resource, females will commonly displace or kill their young. Males then mate with them and care for the young of the female which destroyed their previous offspring.
This behavior is costly to both sides, and counter-adaptations have evolved in the victim sex ranging from cooperative defense of their young to loss minimization strategies such as aborting existing offspring upon the arrival of a new male (the
Bruce effect).
See also
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Extra-pair copulation
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Genomic imprinting
★
Intragenomic conflict
★
Parent-offspring conflict
★
Sexual cannibalism
Notes
1. Emlen, S. T., N. J. Demong, and D. J. Emlen (1989) Experimental induction of infanticide in female wattled jacanas. ''Auk''. '106':1-7.
References
★ Arnqvist, G. & Rowe, L. (2005) ''Sexual conflict''. Princeton University Press, Princeton ISBN 0691122172
★
Thierry Lodé, (2006) ''La guerre des sexes chez les animaux''. (The war of the sexes in animal kingdom) Odile Jacob Eds, Paris
External links
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Intralocus Sexual Conflict Diminishes the Benefits of Sexual Selection