Cave Biodiversity and Ecology of the Sierra de El Abra Region

Elliott, William R.

doi:10.1016/b978-0-12-802148-4.00003-7

Cited by 21 publications

(22 citation statements)

References 8 publications

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“…Importantly, caves are characterized by a number of selective forces, including low food resources and the absence of light (Elliott, 2015; Jeffery, 2015). Despite this absence of light, prior transcriptomic studies were carried out on cavefish reared under a 12:12 LD schedule.…”

Section: Introductionmentioning

confidence: 99%

Dark‐rearing uncovers novel gene expression patterns in an obligate cave‐dwelling fish

2020

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Extreme environments often result in the evolution of dramatic adaptive features. The Mexican tetra, Astyanax mexicanus, includes 30 different populations of cavedwelling forms that live in perpetual darkness. As a consequence, many populations have evolved eye loss, reduced pigmentation, and amplification of nonvisual sensory systems. Closely-related surface-dwelling morphs demonstrate typical vision, pigmentation, and sensation. Transcriptomic assessments in this system have revealed important developmental changes associated with the cave morph, however, they have not accounted for photic rearing conditions. Prior studies reared individuals under a 12:12 hr light/dark (LD) cycle. Here, we reared cavefish under constant darkness (DD) for 5+ years. From these experimental individuals, we performed mRNA sequencing and compared gene expression of surface fish reared under LD conditions to cavefish reared under DD conditions to identify photic-dependent gene expression differences. Gene Ontology enrichment analyses revealed a number of previously underappreciated cave-associated changes impacting blood physiology and olfaction. We further evaluated the position of differentially expressed genes relative to QTL positions from prior studies and found several candidate genes associated with these ecologically relevant lighting conditions. In sum, this work highlights photic conditions as a key environmental factor impacting gene expression patterns in blind cave-dwelling fish.

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Section: Introductionmentioning

confidence: 99%

Dark‐rearing uncovers novel gene expression patterns in an obligate cave‐dwelling fish

2020

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“…To investigate the role of catecholamines in the regulation of foraging behaviors and responses to potential predatory cues, we examined the brains of the teleost fish Astyanax mexicanus, a species that is experiencing allopatric speciation in recently invaded cave habitats (Fumey et al, 2018). Surface and cave Astyanax have significantly different behaviors related to the abundance of resources and predators (Duboué et al, 2011;Elliott, 2015;Hinaux et al, 2015;Keene et al, 2015;Protas et al, 2008;Rétaux et al, 2015;Salin et al, 2010;Schemmel, 1967;1974;1980;Yoshizawa et al, 2010;. For example, blind cave Astyanax continuously search for food whereas surface Astyanax both exhibit diurnal changes in foraging activity and use a sit-and-wait strategy in which movement is dramatically increased in the presence of food cues (Jaggard et al, 2017;Romero et al, 2003;Salin et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Differences in behavior between surface and cave Astyanax mexicanus may be mediated by changes in catecholamine signaling

Gallman

Fortune

Rivera

et al. 2020

J of Comparative Neurology

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Astyanax mexicanus is a teleost fish that is in the process of allopatric speciation. Ancestral Astyanax are found in surface rivers and derived blind forms are found in cave systems. Adaptation to life in nutrient poor caves without predation includes the evolution of enhanced food seeking behaviors and loss of defensive responses. These behavioral adaptations may be mediated by changes in catecholaminergic control systems in the brain. We examined the distribution of tyrosine hydroxylase, a conserved precursor for the synthesis of the catecholamines dopamine and noradrenaline, in the brains of surface and cave Astyanax using immunohistochemistry. We found differences in tyrosine hydroxylase staining in regions that are associated with nonvisual sensory perception, motor control, endocrine release, and attention. These differences included significant increases in the diameters of tyrosine hydroxylase immunoreactive soma in cave Astyanax in the olfactory bulb, basal telencephalon, preoptic nuclei, ventral thalamus, posterior tuberculum, and locus coeruleus. These increases in modulation by dopamine and noradrenaline likely indicate changes in behavioral control that underlie adaptations to the cave environment.

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“…The Mexican tetra, Astyanax mexicanus is a powerful model to study the genetic basis of evolution. It is a single species of fish that exists as a river-adapted form (surface fish) found in rivers from Central Mexico to Southern Texas, and a cave-adapted form (cavefish) found in perpetually dark limestone caves of the Sierra del Abra region in Northeastern Mexico (Elliott, 2015). Surface fish and cavefish have adapted to dramatically different diets; river fish consume plants and insects throughout the year, while most cavefish populations are dependent on external sources of food brought in by seasonal flooding or bat droppings (Turner, 2017).…”

Section: Introductionmentioning

confidence: 99%

Genetic architecture underlying changes in carotenoid accumulation during the evolution of the Blind Mexican cavefish,Astyanax mexicanus

Riddle

Aspiras

Damen

et al. 2019

Preprint

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Research Highlights• Cavefish accumulate carotenoids in the visceral adipose tissue (VAT)• Genetic mapping reveals candidate genes associated with yellow VAT • Carotenoid accumulation is linked with decreased expression of carotenoidprocessing genes AbstractCarotenoids are yellow to orange pigments produced by plants, bacteria, and fungi. They are consumed by animals and metabolized to produce molecules essential for gene regulation, vision, and pigmentation. Cave animals represent an interesting opportunity to understand how carotenoid utilization evolves. Caves are devoid of light, eliminating primary production of energy through photosynthesis and therefore limiting carotenoid availability. Moreover, the selective pressures that favor carotenoid-based traits, like pigmentation and vision, are relaxed. Astyanax mexicanus is a species of fish with riveradapted (surface) and multiple cave-adapted populations (i.e. Tinaja, Pachón, Molino).Cavefish exhibit regressive features such as loss of eyes and melanin pigment, and constructive traits, like increased sensory neuromasts and starvation resistance. Here we show that unlike surface fish, Tinaja and Pachón cavefish accumulate carotenoids in the visceral adipose tissue (VAT). Carotenoid accumulation is not observed in Molino cavefish indicating that it is not an obligatory consequence of eye loss. We used quantitative trait loci mapping and RNA sequencing to investigate genetic changes associated with this trait.Our findings suggest that multiple stages of carotenoid processing may be altered in cavefish, including absorption and transport of lipids, cleavage of carotenoids into unpigmented molecules, and differential development of intestinal cell types involved in carotenoid assimilation. Our study establishes A. mexicanus as a model to study the genetic basis of natural variation in carotenoid accumulation and how it impacts physiology.

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Cave Biodiversity and Ecology of the Sierra de El Abra Region

Cited by 21 publications

References 8 publications

Dark‐rearing uncovers novel gene expression patterns in an obligate cave‐dwelling fish

Dark‐rearing uncovers novel gene expression patterns in an obligate cave‐dwelling fish

Differences in behavior between surface and cave Astyanax mexicanus may be mediated by changes in catecholamine signaling

Genetic architecture underlying changes in carotenoid accumulation during the evolution of the Blind Mexican cavefish,Astyanax mexicanus

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