chapter  9
Physiology of Social Stress in Fishes
Pages 38

Stress is a much used concept in physiology and medicine, yet, the deŒnition of “stress” as a biological term has along history of inconsistency and controversy. Aconsensus long remained where stress was typically seen as something negative to the organism, threatening homeostasis and survival (e.g., McEwen and Mendelson 1993; Moberg 2000). More recently, stress biology has encompassed the notion that maintaining complete stability is perhaps not the ultimate objective of organisms struggling to survive in a constantly changing world (McEwen and WingŒeld 2003, 2010; Korte et al. 2005). Rather, efŒcient regulation requires anticipating varied challenges and executing physiological responses before the need actually arises. This process is referred to as allostasis or “stability through change” (Sterling and Eyer 1988; McEwen and WingŒeld 2003, 2010). Allostasis thus refers to regulatory mechanisms mediating change through the prediction of an activity required to meet a new demand (Sterling 2012). In this concept, negative effects impairing health, Œtness, and animal welfare emerge only when “allostatic overload” arises from chronic, unpredictable, or uncontrollable conditions which do not merit successful adjustment (McEwen and Stellar 1993; Korte et al. 2007). In their recent review, Koolhaas et al. (2011) suggest that the term “stress” should be restricted to conditions when an environmental demand exceeds the natural regulatory capacity of an organism, and in particular situations that include unpredictability and uncontrollability. Physiologically, such situations would be characterized by either absent or discordantanticipatory responses (unpredictability), or insufŒcient recovery (uncontrollability) of homeostasis.In this chapter, we will see how the unequal access to resources and aggressive interactions

9.1 Stress Biology: An Integrative and Evolutionary View ........................................................ 289 9.2 Social Dominance and Social Stress ....................................................................................290 9.3Physiological Effects of Social Subordination .....................................................................292