Adaptability of Bony Armor Elements of the Threespine Stickleback Gasterosteus aculeatus (Teleostei: Gasterosteidae): Ecological and Evolutionary Insights from Symmetry Analyses
More On Article
- HEAS Member Gerhard Weber interviewed for Spektrum on Homo Naledi Cave
- Impact of prolonged heating on the color and crystallinity of bone.
- Impact of a recent wildfire on tortoises at Cape Point, South Africa, and implications for the interpretation of heated bones in the archaeological record
- HEAS Member Philipp Mitteroecker is the 2023 recipient of the Rohlf Medal for Excellence in Morphometric Methods and Applications
- Predictive use of modern reference osteological collections for disentangling the shape of Eurasian equid cheek teeth and metapodials in archaeological material
Schröder, M., Windhager, S., Schaefer, K., Ahnelt, H., 2023. Adaptability of Bony Armor Elements of the Threespine Stickleback Gasterosteus aculeatus (Teleostei: Gasterosteidae): Ecological and Evolutionary Insights from Symmetry Analyses. Symmetry 15, 811.
Abstract:
Differentiation in the defensive armor of the threespine stickleback, Gasterosteus aculeatus, is caused by predator-driven divergent selection. Most studies considered armor traits related to swimming behavior, hence combining pre- and post-capture responses to gape-limited predators. Here, we focus exclusively on the defensive complex (DC), the post-capture predator defense. This complex consists of a series of bony elements surrounding the anterior part of the abdomen. Relaxation from predation pressure not only drives reduction of bony elements but is also expected to increase asymmetry in the DC. To test this hypothesis, we used four Austrian freshwater populations that differed distinctly in the formation of the DC. We found significant left–right asymmetries in the DC in the population with a distinctly reduced DC and, surprisingly, also in the population with a significantly enhanced DC. These populations occur in vastly different habitats (stream and lake) characterized by distinct regimes of gape-limited predators (none vs. many). Apparently, both a shift to very low and very high pressure by gape-limited predators can boost asymmetry. We conclude that greater asymmetries in the two populations at the opposite ends of the predatory gradient result from an ongoing process of adaptation to decreased or increased environmental stress.
Keywords: asymmetry; defensive complex; left–right differences; post-capture defense; predation pressure