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This is a concise description of some sexually cannibalistic species, but provides sufficient background to understand the conditions for sexual cannibalism’s adaptive value.

A parental investment hypothesis for sexual cannibalism

In order to produce viable offspring, females must first obtain and process huge amounts of nutrients ( [link] ). Females have evolved a variety of adaptations for efficient food acquisition, including increased consumption rate, selective consumption of certain food types, and dietary mixing (Wilder and Rypstra 2008a). Some researchers argue that, from a female perspective, sexual cannibalism is simply one in a litany of strategies for gaining more food. This foraging strategy hypothesis states that sexual cannibalism has adaptive value for both sexes, since the male soma provides a female with nutrients that increase her fecundity ( [link] ; Barry et al. 2008). Though the male loses lifetime survivorship, he gains overall fitness from passing on genes to more vigorous offspring. Male self-sacrifice is therefore considered a beneficial form of paternal investment .

chart showing impact of sexual canaibalism on ootheca mass in Mantids
Mass of first ootheca from females who cannibalized and did not cannibalize their mates. Cannibals had more massive ootheca (p=.017) than non-cannibals (Barry et al. 2008).

The impact of diet on fecundity in mantises and spiders

Research on praying mantis species shows that females’ diet impacts two distinct phases of their development. Firstly, the diet of juveniles determines how long their body becomes as they mature. Length is a limiting factor for weight, so the adult’s initial body condition restricts its potential for weight gain throughout its life, which in turn impacts fecundity (Eisenberg et al. 1981). Mantises’ food intake is positively related to the female's maximum attained mass, the mass of her first and second ootheca, the rate of ootheca production, and the number of total young produced (Birkhead et al. 1988).

Similar studies in orb-weaving and wolf spiders indicate that spider females achieve a higher body mass when fed with a high-quality diet (Hebets et al. 2007). Well-fed wolf spiders also mature at a faster rate, which is important for fecundity since females must produce ootheca within a seasonal time frame (they can produce more offspring if they reach the adult stage earlier). Thus, food acquisition is fundamentally linked to fecundity of mantises and spiders, supporting the hypotheses that it is adaptive to engage in sexual cannibalism, especially when the male can provide a nutritive meal.

In order to test this hypothesis, researchers regulated the diets of three groups of Pseudomantis albofimbriata (mantis) females, feeding them with crickets on low to high frequency schedules to produce low to high body conditions (Barry et al. 2008). The foraging hypothesis predicted that sexual cannibalism would be motivated by the female’s drive to acquire food (and, on the ultimate level, increase her fecundity), so hungrier, needier individuals were expected to cannibalize more mates. Indeed, females of poor initial body condition, who were starved for nutrients, cannibalized their mates more often than robust females. Additionally, results showed that cannibalistic females most significantly improved their body condition and produced heavier ootheca than non-cannibalistic subjects, due to food gained from the mate’s biomass ( [link] ; Barry et al. 2008). Similar evidence exists in tests involving wolf spiders (Wilder and Rypstra 2008a; Hebets et al. 2008; Hurd et al. 1994). Overall, the incidence of sexual cannibalism appears to be positively related to reproductive output, so the behavior can increase the fitness of both sexes.

chart showing effect of sexual canaibalism on female body condition
Female body condition before and after a trial in which females either cannibalized or did not cannibalize mates. Cannibalistic females were in poorer condition initially, but their body condition improved more than that of non-cannibals throughout the test ( p 0.001 ) (Barry et al. 2008).

Questions & Answers

what is the stm
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Damian
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Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
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what king of growth are you checking .?
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What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
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Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
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biomolecules are e building blocks of every organics and inorganic materials.
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research.net
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Introduction about quantum dots in nanotechnology
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nano basically means 10^(-9). nanometer is a unit to measure length.
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s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
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Damian
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Tarell
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Source:  OpenStax, Mockingbird tales: readings in animal behavior. OpenStax CNX. Jan 12, 2011 Download for free at http://cnx.org/content/col11211/1.5
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