Past energy allocation overwhelms current energy stresses in determining energy allocation trade‐offs

Abstract

Regeneration of lost appendages is a gradual process in many species, spreading energetic costs of regeneration through time. Energy allocated to the regeneration of lost appendages cannot be used for other purposes and, therefore, commonly elicits energetic trade‐offs in biological processes. We used limb loss in the Asian shore crab Hemigrapsus sanguineus to compare the strength of energetic trade‐offs resulting from historic limb losses that have been partially regenerated versus current injuries that have not yet been repaired. Consistent with previous studies, we show that limb loss and regeneration results in trade‐offs that reduce reproduction, energy storage, and growth. As may be expected, we show that trade‐offs in these metrics from historic limb losses far outweigh trade‐offs from current limb losses, and correlate directly with the degree of historic limb loss that has been regenerated. As regenerating limbs get closer to their normal size, these historical injuries get harder to detect, despite the continued allocation of additional resources to limb development. Our results demonstrate the importance of and a method for identifying historic appendage losses and of quantifying the amount of regeneration that has already occurred, as opposed to assessing only current injury, to accurately assess the strength of energetic trade‐offs in animals recovering from nonlethal injury.

Using external morphology as a proxy for stomach size in Hemigrapsus sanguineus

“…These specimens represent the same crabs previously collected and used by Griffen et al. ( 2022 , 2023 ) and Reese et al. ( 2023 ); however, measurements of the carapace progastric region were collected specifically for use in this study.…”

“…Immediately after collection, crabs were placed into individual bags and shipped to Brigham Young University on dry ice, where they were stored at −80°C until dissection. These specimens represent the same crabs previously collected and used by Griffen et al (2022Griffen et al ( , 2023 and Reese et al (2023); however, measurements of the carapace progastric region were collected specifically for use in this study.…”

Factors influencing variation in reproduction in invasive species: a case study of the Asian shore crab Hemigrapsus sanguineus

“…We used H. sanguineus samples that had been collected for previous studies (Griffen et al 2022(Griffen et al , 2023. We collected these samples from five sites spread throughout the range of H. sanguineus (Table 1).…”

“…We then photographed each subsample using a dissecting microscope (Olympus, Model #MVX10) connected to a digital camera (Olympus, Model #DP74) equipped with the cellSens Standard (v. 3.2) imaging program. Following photography, each subsample was recombined with the remaining eggs for that individual crab, rinsed using DI water to avoid salt crystallization, and dried for use in other studies (Griffen et al 2022(Griffen et al , 2023.…”