Ch. 10 Signal Evolution

Preadaptations

Signals (and structures needed to send/receive) initially evolve for other purposes

Once preadaptations exist, another party can take advantage of
them...initiating _________

coevolution

Efficacy component

signal must be detected by receiver; Favors conspicuous signals; May be energetically costly, attract eavesdroppers

Strategic component

components designed to maximize fitness by altering receiver behavior; Balance predation risk-to-benefit; Balance cost-to-benefit of honest vs dishonest signaling

Ritualization

turning a cue into a signal

the evolutionary process where functional actions, such as conflict movements or physiological reflexes, transform into stylized, specialized communicative signals

D stands for what in DARR

Development- Signal is elaborated and used intentionally (now associated with communication, not just a cue)

A stands for what in DARR

Amplication - Increase conspicuousness

the first R stands for what in DARR

Repetition - Repeat signal, increase redundancy (temporally, spacially, or modally)

the second R stands for what in DARR

refinement - More stereotyped, precise, efficient

If sender is negatively affected, selective pressures will cause the cue to be ______ from condition

decoupled

Emancipated

Can happen to ritualized signals. Disassociate signal from condition. Sender may then manipulate signal to benefit them at receiver’s expense. Receiver must then develop resistance or improve discrimination

Intention movement

physical cues or preliminary motions that signal an imminent action or behavior serving as communication or preparation that aren’t followed by the original behavior

Ambivalence behaviors

actions stemming from a state of having simultaneous, conflicting feelings or attitudes (positives and negatives) toward a person, object, or decision

Displacement behaviors

normal actions (like grooming, eating, or sniffing) performed out of context, often appearing "pointless" or illogical that may occur when an organism is conflicted between motivations

Redirected behaviors

occur when a highly motivated action (often aggression or frustration) is blocked, causing the animal to direct the behavior toward an alternative, often neutral, target; are appropriate to the context, but directed toward an irrelevant object

Copulating with an inanimate object after rejection or attacking an inanimate object during a conflict are examples of

Redirected behaviors

Autonomic signals

involuntary physiological responses—mediated by the sympathetic and parasympathetic nervous systems—that convey information about an animal's internal state, such as arousal, fear, stress, or excitement

Yawning, sweating, and vasodilation(blushing) can serve as

Autonomic signals

____ system is the basis for evolution of many acoustic signals

Respiratory

Frequency & bandwidth are indicative of ____ state

motivational

A low fundamental Hz and broadband/atonal may indicate

Aggression

A high fundamental Hz and few harmonics/tonal can indicate

Fear

Female reproductive status correlated with upregulation
of certain hormones...which may be expelled with urine. Males who can detect these will have an____ over those
who can’t

advantage

Formicine ants spray formic acid for defense is an example of

Evolution of alarm signals can emerge from anti-predator tactics

deimatic behavior

a sudden, deceptive defensive display used by harmless animals to startle, confuse, or intimidate predators, creating a split-second opportunity to escape

Receiver precursor model

suggests the receiver develops a sensory bias first, and sender evolves communicative traits that exploit that bias

Steps of the Receiver precursor model

1. Adaptive sensory biases may evolve through natural selection

2. Sender must benefit from that sensory bias, and evolve some kind of trait that capitalizes on that bias

3. Receiver may benefit from bias or be
   harmed by bias

Sensory Trap

Sender benefits from receiver’s sensory bias at expense of the receiver

To escape sensory traps receivers

Receivers may become less sensitive to the trait (receiver resistance) and/or increase discrimination between sender’s signal and natural cue

As a predator deterrent, female garter snakes show cloacal gaping upon physical stress. Males can vibrate, push, squeeze, female to stimulate cloacal gaping. This is an example of

Taking advantage of a sensory trap. Males use this sensory bias to get females to open cloaca.

In Receiver Precursor Model the _____ species show receiver bias, but not sender trait

basal (closest to common anncestor)

In Receiver Precursor Model the _____ species show both receiver bias & sender trait

derived (species with evolved trait)

Evolutionarily stable strategies (ESS)

a behavior or phenotype that, if adopted by a population, cannot be invaded by any alternative strategy through natural selection

what are the two forms of Evolutionarily stable strategies (ESS)

Pure ESS and Mixed ESS

Pure Evolutionarily stable strategies

One strategy takes over completely

Mixed Evolutionarily stable strategies (ESS)

Differences in payoffs of strategies can become balanced by differences in frequencies of strategies