T.G. Forrest Behavior: Spring 2006 Page 1

BEHAVIORAL UNITS IN CRICKET COURTSHIP One of the key concepts Konrad Lorenz and Nikko Tinbergen introduced that changed the way that ethologists study animal behavior that was concept of Fixed Action Patterns (FAP). A FAP is a discrete behavioral unit that is stereotyped (shows little variation among individuals), is innate (unlearned), and is performed in an all-or-none fashion once the animal receives a certain trigger called the Sign Stimulus. Lorenz and Tinbergen envisioned the animal’s nervous system as a filter that ‘ignores’ most environmental stimuli. However, when a sign stimulus is received it triggers an Innate Releasing Mechanism (IRM) within the nervous system that generates the motor output to produce the FAP. These innate behavior patterns are extremely important for animals in situations where learning can be costly, e.g. anti-predator behavior. An ethogram is a description or catalogue of all the behavior patterns (innate and learned) exhibited by members of a particular species. The purpose of an ethogram is to define the behavior patterns so that qualitative and quantitative analysis of the patterns can be made. In a real ethogram, sequences of behavior patterns are measured and 'flow charts' of these sequences developed. Thus, the information provides data about the likelihood of one behavior following another (how dependent they are). These dependencies may change and could be used to measure the affects of changing environment, such as the social organization of a group, on probabilities in the behavioral sequences. Figure 1 shows a portion of the ethogram of the field cricket, Gryllus bimaculatus, during courtship (Adamo & Hoy 1994). Figure 1. Ethogram for the mating behavior of G. bimaculatus. Note that courtship singing does not occur before antennal contact. Male behavior patterns are shown in roman text, females are shown in italics. Only significant transitions are shown. Ant. Contact: Antennal Contact. Other behavior patterns are listed in Table I. PURPOSE: The purpose of this laboratory is to give you experience in making DETAILED behavioral observations and providing operational descriptions of behavioral units.

PAUSE

WITHDRAW (either sex) Move

(female)

Move (male)

Ant Contact (female)

Ant Contact (male)

Courtship singing

Ant Contact (female)

Ant Contact(male)

female follows Mounts

male pushes back

Withdraw (female)

Pause (female)

Male steps forward

Turns

Behavior: Spring 2006 Behavioral Units Page 2

For many species, behavioral outputs come in discrete, repeatable units known as Fixed Action Patterns or FAPs. House crickets exhibit a number of these patterns given in Table I. Over the next week you will watch the behavior of a pair of house crickets (Acheta domesticus). Your task is to provide a DETAILED DESCRIPTION of any two of the behavior patterns that you think fit the name given by Adamo and Hoy (1994). Table I. Behavioral units during courtship in Gryllus bimaculatus (Adamo & Hoy 1994).

Both Sexes Male Female Antennal contact Aggressive song Mount Antennal fencing Calling song Bite Courtship song Follows Pushes back Grooming Turns Kick Moves Palp Pause Rock body Withdraw

Written Assignment (Due 27 Jan 2006) (1) You must describe two behavioral units from the list above. Hand in a short 4 to 6-sentence,

typed description of the movements etc occurring during the behavior. Be sure to use the appropriate terms for the insect’s body parts in your description (see diagram below). Be quantitative, telling how fast, how many, or at what rate the behavior occurs. Your description should allow someone else observing the crickets to know when the behavior is occurring.

References Cited Adamo, S.A. and R.R. Hoy. 1994. Mating behavior of the field cricket Gryllus bimaculatus and its dependence on social and environmental cues. Animal Behaviour 47: 857-868.

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