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It's The Personality That Counts- Is animal personality related to life-history tradeoffs?

I have a deep personal interest in animal behavior and cognition, so when I came across a research article relating behavioral traits to life-history factors including fecundity and growth, I had to share it. 

Animal personality traits (PTs) vary across individuals, and can be categorized in the same way human behavior is- shyness, boldness, sociability, aggressiveness, activity level, and tendency for exploration. While it is known that individuals vary in their behavior, it's still a bit of a mystery as to why some individuals act consistently different than their local conspecifics. A current hypothesis states that behavioral differences between individuals may be a result of life-history tradeoff differences. 

Given that personality traits (and especially behavior) are somewhat plastic, scientists are also puzzled as to why individual behavior is consistent throughout time. This does not mean that an individual always acts in the same way, but rather that they will always respond similarly to a specific context or stimuli- a response which varies between individuals in the same population. A 2008 study hypothesized that individuals would exhibit similar PTs when their levels of L-H productivity are similar, and when certain PTs are associated with high productivity. For a simple example, if the boldest individuals in a population routinely consume the most food, then individuals with high growth rates should consistently exhibit bold behavior. 

It does make logical sense that differences between individuals' growth and reproduction is likely to be correlated with differences in personality traits- especially those traits related to the acquisition of resources. In class, we have discussed many factors that influence plasticity in growth rates or age at reproduction, but its interesting to approach L-H tradeoffs as both the result and the driver of personality traits in organisms. 

In fishing spiders, house mice, and Atlantic silverside fish, activity level and boldness were correlated with high growth rates and increased fecundity. It makes sense that the two L-H traits are related, since juvenile growth determines adult size, and adult size is positively related with fecundity levels. The fascinating part is the role of behavior in both determining and maintaining these traits. 

Certain individuals have consistently higher growth rates and larger clutch sizes than their counterparts, but how are these traits maintained across time? Obviously there are physiological and genetic factors, but I now believe that there is a complex interaction of the physical and the psychological on organismal productivity. 


Citations

Biro, P. A., & Stamps, J. A. (2008). Are animal personality traits linked to life-history productivity?. Trends in Ecology & Evolution, 23(7), 361-368.

Comments

  1. Kiersten NelsonMarch 15, 2021 at 8:14 AM

    It is really interesting to think about how early life history traits influence personality traits later on in life. Additionally, I wonder how environmental or social conditions during early life development could also play a role in influencing personality traits and what are the underlying mechanisms facilitating these effects? We read a paper for class this week by Bentz et al. 2021 (“Prenatal testosterone triggers long-term behavioral changes in male zebra finches: unravelling the neurogenomic mechanism”) that had me thinking about these sort of questions. I think this is a really interesting field and addressing the underlying mechanisms of these effects is a rather new and exciting component.

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