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David Brown


Two main implications can be deduced from Antipredator defense as a limited resource performed by Dr. Cocroft. The implications can be drawn from the results and discussion sections of the report written by Dr. Crocroft.

The first implication comes from the result showing that maternal care of U. crassicornis is not equally distributed among the nymphs. This begs the question: How is maternal care distributed then if it is not equal The conclusion that maternal care is distributed unequally among the nymphs implies that there is competition among the offspring for defense against predators from the mother. Although the study showed that sibling rivalry for maternal protection is not found in nymph signaling for maternal care, it is possible that the nymphs attempt to position themselves close to the mother. Nymphs were not as likely to be removed by a wasp if they were located on the proximal portion of the branch, which is where the mother resided when not protecting her offspring from a predator. These results imply that nymphs would compete for this position since it allows for a higher survival rate.

The second implication is that nymphs would also compete for location on the branch independent of the mother's location. Nymphs located on the edges of the aggregation were 23 time more likely to be removed by a predator than offspring located in the center of the aggregation. This is known as the edge effect. This result implies that nymphs will compete for central locations on the branch. Interference competition (i.e., shoving) was not observed although exploitation competition is possible. If certain nymphs occupy and remain in a central position on the branch, other nymphs are forced to the edges.

It should also be noted that two implications cannot be deduced from the experiment, as it shows these implications to be untrue. Nymphs signaled in unison for maternal care, with no nymph signaling louder or longer than any other nymph, although this type of competition for maternal care would seem possible. Signaling of the nymphs for maternal care was cooperative and the mother did not respond to any nymph or nymphs unequally. The mother distributed her protection equally throughout the entire aggregation along the length of the branch.

Main Points:

Location in relation to the mother is possibly competitive
Location independent of the mother is possibly competitive, but only exploitation competition
Signaling is not competitive for maternal care, it is cooperative and the mother distributes protection along the aggregation equally.

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