Buxton, J.T., Robert, K.A., Marshall, A.T., Dutka, T.L. & Gibb, H.

A cross-species test of the function of cuticular traits in ants (Hymenoptera: Formicidae)

The trait-based approach to ecology promises greater generality in our understanding of how species assemblages are structured. The value of this approach depends on linking traits with ecological functions, but no studies have tested the proposed functional values of many commonly used and easily measured traits. We used a cross-species comparison to investigate the function of the cuticular traits “pilosity” and “sculpturing” in ants. These traits have been linked to a range of environmental variables through a correlative approach, but the mechanisms underlying these associations are poorly understood. Here, we tested the association among these traits and with a suite of physiological traits (heat tolerance, desiccation tolerance, hydrophobicity and protection from physical forces). Further, we tested whether physiological traits differed between species that were active at day or night or ants from semi-arid and mesic environments. Many cuticlerelated traits were inter-correlated and not independent of other morphological traits, suggesting that it is appropriate to consider ant responses as an “ecological strategy”. Although within-assemblage variation was high, night-active and mesic ants had lower heat tolerance than day-active and semi-arid ants, reflecting similar differences in environmental exposure. Pilosity was associated with both heat and desiccation tolerance. Sculpturing was strongly linked to cuticle thickness and hardness and desiccation tolerance. However, it was negatively associated with heat tolerance, possibly because many highly sculptured ants were nocturnal in this study. This work provides strong support for the continued use of easily measured cuticle traits. However, empirical investigations of trait function across a broader range of ecosystems are critical to ensure that the ecological importance of trait-environment relationships and their inter-relatedness as components of an “ecological strategy” are better understood.

Open access, licensed under CC BY 4.0. © 2021 The Author(s).

Buxton, J.T., Robert, K.A., Marshall, A.T., Dutka, T.L. & Gibb, H.

A cross-species test of the function of cuticular traits in ants (Hymenoptera: Formicidae)

The trait-based approach to ecology promises greater generality in our understanding of how species assemblages are structured. The value of this approach depends on linking traits with ecological functions, but no studies have tested the proposed functional values of many commonly used and easily measured traits. We used a cross-species comparison to investigate the function of the cuticular traits “pilosity” and “sculpturing” in ants. These traits have been linked to a range of environmental variables through a correlative approach, but the mechanisms underlying these associations are poorly understood. Here, we tested the association among these traits and with a suite of physiological traits (heat tolerance, desiccation tolerance, hydrophobicity and protection from physical forces). Further, we tested whether physiological traits differed between species that were active at day or night or ants from semi-arid and mesic environments. Many cuticlerelated traits were inter-correlated and not independent of other morphological traits, suggesting that it is appropriate to consider ant responses as an “ecological strategy”. Although within-assemblage variation was high, night-active and mesic ants had lower heat tolerance than day-active and semi-arid ants, reflecting similar differences in environmental exposure. Pilosity was associated with both heat and desiccation tolerance. Sculpturing was strongly linked to cuticle thickness and hardness and desiccation tolerance. However, it was negatively associated with heat tolerance, possibly because many highly sculptured ants were nocturnal in this study. This work provides strong support for the continued use of easily measured cuticle traits. However, empirical investigations of trait function across a broader range of ecosystems are critical to ensure that the ecological importance of trait-environment relationships and their inter-relatedness as components of an “ecological strategy” are better understood.

Open access, licensed under CC BY 4.0. © 2021 The Author(s).