Evolution, as a process, favours genes which can endure environmental uncertainty both within an individual’s lifetime and across generations. Therefore, to understand how a lineage survives in an unpredictable environment, multiple, different approaches ought to be considered across various time scales. One such approach maximises individual fitness based on variable short-term rewards gained from ‘risky’ behavioural choices. Alternatively, individuals who avoid risks (bet-hedging) perform reasonably well regardless of circumstances or environment. This approach can be regarded as spreading the risk to reduce the chances of failure. This tactic does not increase the fitness of the individual but rather, the fitness of the lineage in the long term. This model attempts to provide a theoretical framework for the evolution of both risk taking and risk avoidance approaches.
Lineages that avoid risks to gain a consistent payoff will outperform those who take risks to gain potentially more beneficial, but inconsistent payoffs. Two main factors were found to determine whether risk taking, or risk avoidance was most profitable. The first was the frequency of the decision event. If the behaviour was made up of many decision events throughout the individual’s lifetime, such as where to forage, it was more beneficial to take a risk. However, if the decision was a rare event, such as in mating behaviour, it was better to avoid a risk. The second factor was the predictability of environmental conditions. For example, if a generation within a species experienced opposing weather conditions (wet and dry) at the same point in time, taking risks was found to be more profitable. Alternatively, if all individuals within a generation experienced the similar weather conditions but the proceeding generation experienced noticeable different ones, risk avoidance was more beneficial.
This model gives an insight into the evolution of risk avoidance for key lifetime events. This is important when considering the common expression of evolution stating “survival of the fittest”. Here, it is shown that within an unpredictable environment it is not individual fitness that is always most profitable but, maximising long-term fitness of the lineage. Fluctuations in environmental conditions are becoming more unstable. Therefore, understanding potential evolutionary responses to rapid human-induced climate change is of utmost importance. The question posed is whether affected species have the capability to adjust their behaviour to ensure their own survival. Author of entry: Chloe Shergold