Ambystoma
Spring 2024; BIOL 2022 Laramie County Community College April 18th, 2024
Taxonomy
Von, Tschudi Johann Jakob. Classification Der Batrachier, MIT Berucks. Der Fossilen Thiere Dieser Abtheilung Der Reptilien, 1838. 1-100.
Phylum: Chordata
The phylum chordata is triploblastic, meaning there are three living cell layers. They are also deuterostomes meaning the anus forms first from the gastrula. They also have a postanal tail that can be present in the adult stages but also may be lost before the adult stages.
Class: Amphibia
Ambystoma have a mucous layer on skin that is slimy. They are also ectothermic, this meaning they rely on their environment to regulate their temperatures. Ambystoma have a complete digestive tract. For respiration they use gills or lungs that can be turned off and cutaneous respiration can be used instead.
Order: Urodela
The order Urodela or in some cases called Caudata falls under the phylum chordata and the class amphibia as Urodela means tailed amphibians.
Family: Ambystomatidae
The family Ambystomatidae falls under the order Urodela, Ambystomatidea simply means mole salamander. All species within this family posses tails and have small eyes that are typically found on the top of the head.
Phylogeny
Williams, Joshua S. et al. “Species tree reconstruction of a poorly resolved clade of salamanders (Ambystomatidae) using multiple nuclear loci.” Molecular phylogenetics and evolution 68 3 (2013): 671-82 .
The phylogeny of Ambystoma is interesting in the fact that it describes winter, aquatic breeding species as an ancestor of this group. Though these are winter breeding species, it is now learned that the early breeding in the fall months has evolved differently between the species that lay their eggs in the water vs. the species that lay their eggs on land. In testing the phylogenies, professionals started by clustering all specimens into four group. Clade A was formed by all the unisexuals, no matter the body types. Sister group, Clade B, contained A. barbouri. These specimens were specifically from southern Ohio and just west of the Kentucky rivers in central Kentucky. Clade C also contained the same species, but from north or east of the Kentucky river and north of the Ohio river, as well has western Kentucky. Clade C corresponded to the "northern clade" which was previously identified by Niedzwiecki. Clade D contained the same species, but from Tennessee, and A. texanum, which was also from Tennessee. This monophyly is unique in the sense that it does not fully correspond with clade A and clade B.
Geologic History
Most geologic history of Ambystoma have been reported in the early Cenozoic deposits, most common in Quaternary fossil deposits. Most fossils are found across North America, identified as isolated vertebrae. Unfortunately, there is limited information in identifying fossilized vertebrae below the genus level. This setback can bring uncertainty in the fossils identified. Patterns found in fossils have helped to characterized intraspecific and intercolumnar variation that have shown implications in fossil identification. However, the fossils did show that the evolution of ambystoma have varied considerably. The fossils in Tiger Salamander found have shown the evolution in skull size in this species. This has helped to indicate the fact that Ambystoma are sensitive to environmental changes, which is a factor in evolution. Though there is not many findings on the geological history of ambystoma, the information that has been found has helped scientists to draw conclusions on deciding factors in evolution.
Bruzgul, Judsen & Long, Webb & Hadly, Elizabeth. (2005). Temporal response of the tiger salamander (Ambystoma tigrinum) to 3,000 years of climatic variation. BMC ecology. 5. 7. 10.1186/1472-6785-5-7.
Conservation Issues
Ambystoma mexicanum, the Axolotl is classified as critically endangered as of October 23, 2019. The estimated population decline is more than 80% over the past three generations, which puts them in this category as critically endangered. This species has originally populated wetlands and lakes in the Mexican Central Valley. This species does not populate this area anymore, but it does populate three parts of Southern Mexico City. The abundance of this species is inferred to be 467 km 2 . This number is still actively decreasing.
Sweet-Metazoa. “Ambystoma Mexicanum.” Tumblr, 20 Jan. 2016, sweet-metazoa.tumblr.com/post/137666064272/ambystoma-mexicanum.
What Causes This Status?
The decrease in this species is due to multiple reasons. There has been a recent increase in population to owning this species, which is a large factor to why this species is rapidly declining - due to trapping and captivating. Urbanization and population increase can also lead to habitat loss and pollution, which harms these fragile organisms.
What Can We Do To Take Action?
To actively help this species, we can take the steps to help conserve these animals. The first step in taking action is properly educating yourself and other around you about this species and how fragile they are. Taking action in water and land protection can also help the Axolotl to keep their habitat and decrease pollution. Taking these steps can help slow the rapid decline in this species and work towards repairing the conservation status.
Interesting Aspects of Biology
Metamorphosis in Salamanders is argued upon as a pro or a con. However, there are many more cons to metamorphosis than pros. Many of the cons pose threats to the survival of salamanders. The first con is their locomotion, as when they get older they become slower as the structure of their legs change. This was tested by something called burst speed, meaning a sudden increase in speed for a short period of time. They determined that their burst speed after metamorphosis was lower than before metamorphosis causing them to move slower and affecting multiple other aspects of their lives. These aspects being the way salamanders feed, the types of prey they can go after, and their potential predators.
This can be interesting as one process changes almost everything about the way the salamander survives, eats, and moves. The process of metamorphosis is interesting as well because of the internal changes that occur.
Metamorphosis is not something that is unique to the salamander, other phylums go through this process as well, including mollusks and other amphibians. Even jellyfish go through this process as well. The animals that go through the most similar metamorphosis process would be other amphibians, such as frogs.
Geographic Distribution
The mole salamander is mainly located in North America with some of a few species in European countries. Many species show are heavily concentrated in Mexico and the Eastern portion of the United States. They are located near aquatic or environments with more moisture.
Ambystoma
Citations
Anne Marie Helmenstine, Ph.D. “Axolotl? We’ve Got a Lot of Answers.” ThoughtCo, ThoughtCo, 2 Apr. 2019, www.thoughtco.com/axolotl-ambystoma-mexicanum-4162033.
BABU, SANDRA. TAXONOMIC IDENTIFICATION OF CLASS: AMPHIBIA AND FEW MINOR-PHYLA. Diss. St Teresa's College (Autonomous), Ernakulam, 2023.
Baitchman, Eric J., and Timothy A. Herman. "Caudata (Urodela): tailed amphibians." Flowers zoo and wild animal medicine 8 (2014): 13-20.
Bi, K., Bogart, J.P. Time and time again: unisexual salamanders (genus Ambystoma) are the oldest unisexual vertebrates. BMC Evol Biol 10, 238 (2010). https://doi.org/10.1186/1471-2148-10-238
Bruzgul, Judsen & Long, Webb & Hadly, Elizabeth. (2005). Temporal response of the tiger salamander (Ambystoma tigrinum) to 3,000 years of climatic variation. BMC ecology. 5. 7. 10.1186/1472-6785-5-7.
Hale, Rebecca E., et al. "Does breeding ecology alter selection on developmental and life history traits? A case study in two Ambystomatid salamanders." Evolutionary Ecology, vol. 30, no. 3, June 2016, pp. 503+. Gale Academic OneFile, link.gale.com/apps/doc/A714113648/AONE?u=wylrc_laramiecc&sid=summon&xid=917b1ed0. Accessed 17 Apr. 2024.
IUCN SSC Amphibian Specialist Group (IUCN SSC). “The IUCN Red List of Threatened Species.” IUCN Red List of Threatened Species, 23 Oct. 2019, www.iucnredlist.org/species/1095/53947343.
Ivanović, Ana, and Jan W. Arntzen. "Evolution of skull shape in the family Salamandridae (Amphibia: Caudata)." Journal of Anatomy 232.3 (2018): 359-370.
Shaffer, H. Bradley, et al. “The Consequences of Metamorphosis on Salamander (Ambystoma) Locomotor Performance.” Physiological Zoology, vol. 64, no. 1, 1991, pp. 212–31. JSTOR, http://www.jstor.org/stable/30158520 . Accessed 21 Mar. 2024.