Benefits to Females
Image 7: Aquarius paludum (Adapted from Slot, N, 2003: http://www.biopix-foto.de/aquarius-paludum_photo-83807.aspx)
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In some water strider species, such as Aquarius paludum (where post-copulatory guarding is much more extended than other species), males guard females by staying on their backs after mating; and while these males extend the period they remain being carried by females and increasing costs associated with this. Costs such as decreased mobility and increased predation risks that come with carrying a male (Fairbain, 1993; Amano and Hayashi, 1998) , this may also bring some benefits to females.
As pre-mating struggles by females to dislodge males (Arnqvist, 1997) cause females to expend much more energy (Watson et al., 1998), carrying a male on her back decreases the harassment by other males and hence reduces risks such as injury, predation and a waste of energy. These same females that carry males for longer periods also foraged much more effectively than single females that were not able to avoid harassment (Wilcox, 1984). |