Unraveling stress resilience: Insights from adaptations to extreme environments by Astyanax mexicanus cavefish

Abstract

Extreme environmental conditions have profound impacts on shaping the evolutionary trajectory of organisms. Exposure to these conditions elicits stress responses, that can trigger phenotypic changes in novel directions. The Mexican Tetra, Astyanax mexicanus, is an excellent model for understanding evolutionary mechanisms in response to extreme or new environments. This fish species consists of two morphs; the classical surface‐dwelling fish and the blind cave‐dwellers that inhabit dark and biodiversity‐reduced ecosystems. In this review, we explore the specific stressors present in cave environments and examine the diverse adaptive strategies employed by cave populations to not only survive but thrive as successful colonizers. By analyzing the evolutionary responses of A. mexicanus, we gain valuable insights into the genetic, physiological, and behavioral adaptations that enable organisms to flourish under challenging environmental conditions.

Elevated DNA Damage without signs of aging in the short-sleeping Mexican Cavefish

“…For example, in humans, insomnia is associated with many different diseases and increased morbidity, suggesting that sleep is critical for healthy aging [30,31]. Despite the dramatic reduction in sleep, there are no apparently health consequences to cavefish, suggesting an established resilience to sleep loss [32][33][34]. Considering that changes in the levels of DNA breaks are associated with sleep regulation in flies, zebrafish, mice, and humans [10,12,35], it is possible that intrinsic changes in the DNA repair and DDR pathways underlie reduced sleep need in cavefish.…”

Starvation-resistant cavefish reveal conserved mechanisms of starvation-induced hepatic lipotoxicity

“…Across the animal kingdom, numerous species have developed adaptations to cope with starvation, offering potential perspectives into strategies to combat its detrimental effects ( McCue, 2010 ; Olsen et al, 2021 ). To gain mechanistic insights, we used a genetically tractable and naturally occurring model of starvation resistance—the Astyanax mexicanus model system ( Jeffery, 2020 ; Cobham & Rohner, 2024 ). A. mexicanus are teleost freshwater fish found in the Sierra de El Abra region of Mexico.…”

Trawling aquatic life for new models in biomedical research and evolutionary developmental biology

“…As illustrated by this and two other articles, aquatic species often "live on the edge" and thrive in extreme environments, thereby providing insights into resilience mechanisms to environmental stress and the buffering and plasticity of developmental programs. Cobham and Rohner (2024) review how the blind cavefish has adapted to cope with the challenging physiological constraints of living in confined, dark cave environments. Szabó et al (2023) discuss the air-breathing paradise fish as an emerging model for an evolutionarydevelopmental novelty, the respiratory labyrinth organ, which enables them to survive under hypoxic conditions.…”