Fight, or flight? ... or die.

As a predator approaches, prey make escape decisions based on trade-offs between fitness consequences of fleeing and not fleeing (Cooper & Wilson, 2007). Sometimes, escaping is a high cost when there is an opportunity to stay and increasing their fitness instead. This is especially evident in some males, which are less wary of approaching predators when fleeing means that they are abandoning courtship or mate guarding (Cooper & Wilson, 2007).

For example, male striped plateau lizards (Sceloporus virgatus) permit closer approach before fleeing when given the opportunity to court or perform aggressive behaviour, whereas females flee much sooner as they cannot justify taking the risk of staying (Cooper & Wilson, 2007). 

Female Sceloporus virgatus

Author unknown 

The primary measure of weariness is the flight initiation distance (FID - the distance between predator and prey when escape begins) and the escape theory predicts that FID increases with degree of predation risk of a predator and decreases with cost of escaping (Cooper & Wilson, 2007). This demonstrates a clear trade-off between staying to increase fitness/exposing itself to more danger and fleeing to survive/decreasing the opportunity to increase its fitness.

Another option, which is rather strange… is to essentially commit suicide.

This is an act of altruism which is commonly found in eusocial groups of insect species, especially ants, and it obvisouly decreases the actor’s fitness whilst benefiting the rest of the colony (Shorter & Rueppell, 2012). Whilst other insects display defences such as coloration, toxins, stinging, biting, spraying venom, wing shimmering, and structure building, the  Carpenter Ant (Camponotus saundersi) displays an instantaneous defence known as autothysis, which is basically self-explosion which results in the release of a caustic secretion; killing the attacker (Shorter & Rueppell, 2012).  The ant has an enlarged mandibular gland which contains poisonous chemicals and a glue-like substance, and when threatened they contract their abdominal muscles which such strength that these glands explode and the ant dies. 

Camponotus saundersi committing suicide for the good of the colony

Author: Mark Moffett 

Workers use this type of event either in one-on-one confrontations of territorial defence far away from the nest (Shorter & Rueppell, 2012). In turn, the rest of the colony is protected and reproduce, creating more generations of Kamikaze Ants!

That’s a pretty extreme cost, in my opinion…

References:

• Cooper Jr, W.E. & Wilson, D.S. 2007, "Sex and social costs of escaping in the striped plateau lizard Sceloporus virgatus",Behavioral Ecology, vol. 18, no. 4, pp. 764-768.
• Shorter, J.R. & Rueppell, O. 2012, "A review on self-destructive defense behaviors in social insects", Insectes Sociaux, vol. 59, no. 1, pp. 1-10.
• Viewed 1^st June 2014 <http://news.discovery.com/animals/photo-shows-suicide-bomber-ant-selfdetonating.htm>
• Viewed 1^st June 2014 <http://blog.nus.edu.sg/lsm1303student2013/2013/04/11/suicide-bomber-ant/
• Viewed 1^st June 2014 <http://www.journalofanimalecology.org/view/0/newshighlights.html>