Submission + - Study Finds Parents Favor Oldest Offspring
Reservoir Hill writes: "Biologists studying a unique species of beetle that raises and cares for its young have found that parents instinctively favor the oldest offspring. "The burying beetle Nicrophorus vespilloides has a similar family structure to that of a human family unit in that there are two parents, a number of offspring and interactions between parents and their young," said Dr Per Smiseth who led the research at the University of Manchester. The young beetles are able to feed themselves but they grow more quickly and become larger when fed by their parents. By generating experimental broods comprising two sets of offspring, one set of older grubs and one younger set, the scientists were able to study their development, first with the parents present and then when left to fend for themselves. Senior offspring (early-hatched) grew faster than juniors (late-hatched) when parents were present and could influence the outcome of sibling competition, whereas seniors and juniors grew at similar rates when parents were removed. One explanation is that parents attach more value to the older offspring as their maturity gives them a better chance of survival than their younger siblings. A second explanation is that the older grubs, being stronger, are able to dominate their younger rivals and, in doing so, better attract the attention of the parents when begging for food. "Even if this second theory is true, the parents are still complicit in the bias towards the older siblings," said Dr Smiseth"
