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A Tricky Trait: Applying the Fruits of the “ Function Debate ” in the Philosophy of Biology to the “ Venom Debate ” in the Science of Toxinology

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ABSTRACT

The “function debate” in the philosophy of biology and the “venom debate” in the science of toxinology are conceptually related. Venom systems are complex multifunctional traits that have evolved independently numerous times throughout the animal kingdom. No single concept of function, amongst those popularly defended, appears adequate to describe these systems in all their evolutionary contexts and extant variations. As such, a pluralistic view of function, previously defended by some philosophers of biology, is most appropriate. Venom systems, like many other functional traits, exist in nature as points on a continuum and the boundaries between “venomous” and “non-venomous” species may not always be clearly defined. This paper includes a brief overview of the concept of function, followed by in-depth discussion of its application to venom systems. A sound understanding of function may aid in moving the venom debate forward. Similarly, consideration of a complex functional trait such as venom may be of interest to philosophers of biology.

No MeSH data available.


Flow chart illustrating basic application of evolutionary theories of function to properties of traits.
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toxins-08-00263-f001: Flow chart illustrating basic application of evolutionary theories of function to properties of traits.

Mentions: Evolutionary theories of function (Figure 1) are concerned with the question of how traits arise and are maintained. Two main categories of evolutionary theories of function are etiological and propensity theories. Etiological theories define the function of a trait according to the past effects of the trait that led to its current presence, i.e., what effect of this trait was selected for over the course of its evolutionary history? Etiological theories seem to do more of the work required by evolutionary biologists than causal role theories, since they attempt to explain the presence of a trait. On the other hand, they are unable to account for the de novo appearance of functions. Essentially, if a trait acquires an additional effect, even if it makes an immediate contribution to the fitness of the organism, an etiological theory would not consider this a “true” function. Although this would be a brief setback, presumably disappearing as soon as the trait was maintained (by selection) into the next generation [11], it represents a weakness of straightforward etiological theories. This weakness is often highlighted by critics that draw attention to the concept of exaptation [7]—a trait may be selected for a particular function that inadvertently increases its likelihood of acquiring an additional function [12]. These additional functions are not accounted for by etiological theories until/unless they are directly selected for.


A Tricky Trait: Applying the Fruits of the “ Function Debate ” in the Philosophy of Biology to the “ Venom Debate ” in the Science of Toxinology
Flow chart illustrating basic application of evolutionary theories of function to properties of traits.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037489&req=5

toxins-08-00263-f001: Flow chart illustrating basic application of evolutionary theories of function to properties of traits.
Mentions: Evolutionary theories of function (Figure 1) are concerned with the question of how traits arise and are maintained. Two main categories of evolutionary theories of function are etiological and propensity theories. Etiological theories define the function of a trait according to the past effects of the trait that led to its current presence, i.e., what effect of this trait was selected for over the course of its evolutionary history? Etiological theories seem to do more of the work required by evolutionary biologists than causal role theories, since they attempt to explain the presence of a trait. On the other hand, they are unable to account for the de novo appearance of functions. Essentially, if a trait acquires an additional effect, even if it makes an immediate contribution to the fitness of the organism, an etiological theory would not consider this a “true” function. Although this would be a brief setback, presumably disappearing as soon as the trait was maintained (by selection) into the next generation [11], it represents a weakness of straightforward etiological theories. This weakness is often highlighted by critics that draw attention to the concept of exaptation [7]—a trait may be selected for a particular function that inadvertently increases its likelihood of acquiring an additional function [12]. These additional functions are not accounted for by etiological theories until/unless they are directly selected for.

View Article: PubMed Central - PubMed

ABSTRACT

The “function debate” in the philosophy of biology and the “venom debate” in the science of toxinology are conceptually related. Venom systems are complex multifunctional traits that have evolved independently numerous times throughout the animal kingdom. No single concept of function, amongst those popularly defended, appears adequate to describe these systems in all their evolutionary contexts and extant variations. As such, a pluralistic view of function, previously defended by some philosophers of biology, is most appropriate. Venom systems, like many other functional traits, exist in nature as points on a continuum and the boundaries between “venomous” and “non-venomous” species may not always be clearly defined. This paper includes a brief overview of the concept of function, followed by in-depth discussion of its application to venom systems. A sound understanding of function may aid in moving the venom debate forward. Similarly, consideration of a complex functional trait such as venom may be of interest to philosophers of biology.

No MeSH data available.