Helping a dominant female cichlid take care of her young may give subordinate females the chance to reproduce successfully, according to a study published in a recent issue of the journal PLoS ONE.
Dik Heg and coauthors studied the cooperatively breeding cichlid Neolamprologus pulcher, in which subordinate females assist an unrelated dominant breeding pair in raising their young (alloparental care).
Previously, it was thought that the subordinate females practiced alloparental care in return for the right to stay with the group and increase their likelihood of surviving long enough to obtain a breeding position in the future (~pay-to-stay hypothesis).
However, Heg and coauthors tested the hypothesis that the subordinate female cichlids were helping in return for a more immediate direct reproductive benefit.
The authors conducted a series of experiments in which they measured maternal and alloparental brood care and reproductive success (total number of eggs produced) of dominant and subordinate females in four different experiments, summing the data per female over 30 days.
The authors found that subordinate females that performed more alloparental care were more likely to produce eggs themselves. They speculated that the most likely mechanism is that assisting a dominant pair in raising their young ensures that a subordinate has access to the breeding substrate, which she needs to lay eggs.
For more information, see the paper: Heg, D, E Jutzeler, JS Mitchell and IM Hamilton (2009) Helpful female subordinate cichlids are more likely to reproduce. PLoS ONE 4, e5458. doi:10.1371/journal.pone.0005458