Why are Astyanax mexicanus blind?

What is Astyanax mexicanus?

Astyanax mexicanus, the blind Mexican cave fish. A model for studies in development and morphology. In: Behringer RR, Johnson AD, Krumlauf RE, editors. Emerging model organisms: a laboratory manual, vol. 1.

Is Astyanax aeneus aeneus?

Another cave-adapted population of Astyanax, varying from blind and depigmented to individuals showing intermediate features, is known from the Granadas Cave, part of the Balsas River drainage in Guerrero, southern Mexico, but it is a part of A. aeneus (itself sometimes included in A. mexicanus ).

Why is a mexicanus the preferred vertebrate model for studying evolution and adaptation?

The teleost A. mexicanus is the preferred vertebrate model for studying evolution and adaptation in caves because both the ancestral surface-dwelling form (surface fish) and the derived cave-dwelling forms (cavefish) are available for comparative study within the same species ( Fig. 1 ).

What kind of fish is Astyanax?

Astyanax (fish) Jump to navigation Jump to search. Astyanax is a genus of freshwater fish in the family Characidae of the order Characiformes.

What type of animal is the Astyanax argentatus?

The type species is A. argentatus, now regarded as a form of the Mexican tetra ( A. mexicanus ). The generic name comes from Astyanax, a character in Greek mythology, who was the son of Hector of Troy; in homage to this, several specific epithets also refer to the Iliad.

What kind of tetras live in Texas?

Mexican Tetra The Mexican Tetra originates from the lower Rio Grande and eastern Mexico. It’s also found in the Pecos Rivers in Texas. The fish goes by many trade names. You might see it being referred to as the Blind Cave Tetra. Not all Mexican Tetras are blind.

What is Astyanax fasciatus mexicanus?

Astyanax fasciatus mexicanus has at least 30 different cavefish populations in northern Mexico. Each population has a different degree of eye degeneration ( Jeffery, 2009; Gross, 2012 ). Most populations have nonfunctional, small, degenerated eyes in the head. The rudimental eye is hidden in an orbit that is covered by a flap of skin.

Is Astyanax pirapuan a characid species?

” Astyanax pirapuan: a new characid species from the upper Rio Paraguay system, Mato Grosso, Central Brazil (Characiformes, Characidae)” (PDF). Zootaxa. 2749: 40–46. doi: 10.11646/zootaxa.2749.1.3. hdl: 11449/41580.

Is a mexicanus surface fish a fish?

This A. mexicanus surface fish was collected in a cavein northeastern Mexico andis an immigrant, having left its surface-dwelling group to join the cavefish population, according to the researchers. The freshwater Mexican cavefish is the same species as the surface-dwelling Mexican tetra, although their appearance varies wildly.

Where did the name Astyanax come from?

Astyanax (fish) The type species is A. argentatus, now regarded as a form of the Mexican tetra ( A. mexicanus ). The generic name comes from Astyanax, a character in Greek mythology, who was the son of Hector of Troy; in homage to this, several specific epithets also refer to the Iliad.

Is a mexicanus a good animal for lab experiments?

A. mexicanus can be raised on a simple diet, produces a large number of embryos, and has a relatively short generation time, about 4–6 months, making it a suitable laboratory animal. Surface fish and cavefish embryos are large, clear, and amenable to experimental manipulations, such as tissue ablation and transplantation.

What is adaptation in evolution?

Adaptation is a key evolutionary process in which variation in the fitness of traits and species are adjusted by natural selection to become better suited for survival in specific ecological habitats. The environment acts to promote evolution through changes in development.

What did archaeologists conclude about the evolutionary history of reptiles?

Archeologists comparing the fossil remains of a species of reptile that lived thousands of years ago with the anatomical structure of a modern reptile concluded the species had experienced only minor changes over the entire time period. Which explanation most likely accounts for this lack of significant change?

How did astyanaxcavefish evolve?

Astyanaxcavefish have originated independently several different times from a surface fish ancestor. As expected, the founder cavefish populations have undergone eye and pigmentation regression independently. In addition, it is possible that multiple episodes of regressive evolution occurred after a single colonization event.

How did fish evolve into cave-adapted species?

First, surface fish colonized (or were entrapped in) caves, and their differential survival led to the formation of cave-adapted populations in which regressive evolution could have been initiated.

Is there a model system for the evolution of cave-related phenotypes?

CONCLUSIONS At present, a single model system, the cavefish Astyanax mexicanus, has been developed to study the evolution of cave-related phenotypes. Based on the evidence described above, the following sequence of events may have occured during Astyanaxcavefish evolution.

How have aquatic vertebrates adapted to life in caves?

Some aquatic vertebrates have adapted to life in caves and evolved troglomorphic traits.

Does Astyanax mexicanus (Characidae) exist in Texas?

Notes on the biology and occurrence of Astyanax mexicanus (Characidae, Teleostei) in southeast Texas. Texas Journal of Science 46 (3):293-294.

Is Astyanax mexicanus a freshwater fish?

Consequently, Astyanax mexicanus is a freshwater fish that’s presently present in two varieties: cave and floor fish. Each variety of Mexican cave fish is omnivores and roughly the identical dimension, round three inches lengthy (7.5 centimeters).

Is Astyanax jordani the same as Astyanax mexicanus?

The species is often referred to incorrectly as Astyanax jordani. This congener is a distinct species in its own right and should not be confused with A. mexicanus. The blind form is sometimes referred to as A. fasciatus mexicanus, as? A.? mexicanus is sometimes still considered a subspecies of A.? fasciatus.