How Do Energetic Costs of Signaling Mediate Growth and Energy Allocation in Nestling Birds?. Eli Awad, Ian Santino, Elise Lauterbur. Evolutionary Signaling Theory.
Eli Awad, Ian Santino, Elise Lauterbur
What if a nestling begged for food, even when it was full? Energy Allocation in Nestling Birds?
What if a nestling begged constantly?
Why don’t we see this happening in nature?
It would get fed even if it didn’t need it.
It would get fed constantly.
Glad you asked…Lies and the Lying Liars That Tell Them
According to the “basics” of signaling theory…
Short Term Energy Allocation in Nestling Birds?
Baby gets fed more than it “needs”, which is a good thing from its little point of view
Parents expend more energy to feed the baby and increase their risk of death from exhaustion and predation. Also may increase baby’s exposure to parasites
Parents may attenuate to the over-expressed signal.
Parents that can detect deceit, and only feed their babies what they “need” will survive longer and have more offspring, spreading their “mind reading” genes through the population.Consequences of Deceit
Cost: Energy Allocation in Nestling Birds?
Direct: Overworked parents are less efficient providers, increased feeding trips also mean increased risk of exposure to parasites.
Indirect: A nestling faces a trade-off between increasing its own fitness at the expense of the fitness of its parents and siblings. In the long term, the indirect fitness costs may outweigh the immediate energetic benefits.
In other words: The information in the begging signal corresponds to the actual condition of the nestling.
We expect any signaling system to contain at least a kernel of reliability. Otherwise, what possible evolutionary significance could it have?Signals must have some cost that renders the signaling system reliable
So we asked: If a signal is costly, then how can we model the effects of the costs on a nestling’s growth and size at fledging (read: fitness)?
What about a Lotka-Volterra Hybrid with a twist?
No Feed ME!
A function of Latent Energy x Nestling size
Determines fraction of total energy put towards signaling
Determines Signal Threshold: function of Nestling Size / Latent Energy
Single Nestling Energy Allocation in Nestling Birds?
Over-representing need harms the nestling in the long run, but under- representing need can be beneficial.
Pair of Nestlings Energy Allocation in Nestling Birds?
* Died at 2322 time units
** Died at 2292, due to parent mortality
Pair of Nestlings, Nestling 1 Deceit Set at 0.3, Nestling 2 is “Honest”
Max. size: 23 g
Baby number 1 “tries to save energy”
by signaling less, but all the “extra”
food is given to his “honest” brother
Max. size: 32 g
Baby 1 is “honest” and baby 2 is just a Energy Allocation in Nestling Birds?little dishonest (deceit set at 1.1)…
Max. size: 23 g
At this slight level of deceit, it
actually does benefit the liar to lie
Max. size: 25 g
The End! Energy Allocation in Nestling Birds?