As I sit here, an ice storm is on the way that will wreck havoc among all of us endotherms that are active at this latitude in January. Our salamander friends, however, are waiting (happily, I hope) below the frost line, looking for signs of spring. Salamanders are ectotherms and have body temperatures (and corresponding metabolic rates) that are primarily influenced by temperatures in the environment. It might seem like an advantage to have high internal body temperatures year round but when the food runs short and the ice storms come, it makes you appreciate that the salamanders have a pretty good system, too.
Earlier this year, my friend Yeong-Choy Kam and I published a paper based on an experiment I conducted in his lab over ten years ago in Taiwan. Time flies! Previously, there had been anecdotal reports of cannibalism in the tadpoles of Polypedates braueri (a large Taiwanese tree frog, see photo below) but no one had tested whether it occurred under controlled conditions. So, we set up a simple experiment where we varied the level of food and the density of tadpoles, expecting that if cannibalism occurs, it should most likely be observed under low food and high density conditions. We did not observe any cannibalism in any of our experimental treatments, suggesting that cannibalism may not actually occur in this species after all (or at least under the conditions we examined).
This was published in the journal Current Herpetology. Glad to have this out, even though it took ten years!
Lehtinen, R.M. and Y.-C. Kam. 2017. No experimental evidence for cannibalism in tadpoles of a rhacophorid treefrog, Polypedates braueri. Current Herpetology 36: 54–57.
Salamander of the Month – the axolotl
The axolotl (Ambystoma mexicanum) commonly referred to as the “Mexican walking fish” is featured as this month’s salamander of the month. This amphibian is interesting due to its ability to regenerate most body parts. The axolotl has the ability to regrow new body parts even including parts of the brain and spinal cord. If an axolotl lost a foot, it has the ability to quickly grow a new limb in under a month! These salamanders are different from most other salamanders because they live their entire lives underwater. Interest in this species is high as they are critically endangered due to expansion of Mexico City, where they are found. If you would like more information on the Axolotl or salamanders in general, follow the link to http://www.livescience.com/52627-salamanders.html
By Brenden Tully, BIOL 311 student
Recently, several colleagues and I published a new taxonomic paper entitled “Cryptic multicolored lizards in the Polychrus marmoratus Group (Squamata: Sauria: Polychrotidae) and the status of Leiolepis auduboni Hallowell) in the journal Amphibian and Reptile Conservation. This paper re-validates an old name for a species of monkey lizards (genus Polychrus) from Venezuela and Trinidad and Tobago. These colorful lizards are found throughout much of South America but the actual diversity within this group has not yet been carefully studied.
Wooster grad Patrick Brennan (‘13) generated the DNA sequences on which a portion of this work in based for his Independent Study thesis. Other unrecognized species likely exist in this group, so our work is not done. Congrats Patrick!
Salamander of the Month – the Olm (Proteus anguinus)
The olm is a cave specialized salamander that lives all of its life in subterranean waters in a few areas of eastern Europe. Most individuals are unpigmented and the eyes are poorly developed, typically being covered by skin. Not surprisingly, they do not use their visual sense much but chemo-reception, mechano-reception and electro-reception are all well developed. The olm also exhibits neoteny, that is, it retains many larval features throughout its life (gills, lateral line neuromasts, etc.) and there is no real metamorphosis (AmphibiaWeb, 2014).
A captive colony of olms in France that has been studied for over 50 years has revealed an extremely long life span. The average adult in this population is approximately 68 years old and the maximum life span has been estimated at over 100 years, making the olm the amphibian with the longest known lifespan. Sexual maturity is not obtained until approximately 15 years (similar to humans) and olms only reproduce once every decade or so thereafter (Voituron et al. 2010).
Given its restricted geographic distribution and specialized habitat, olms can be threatened by water pollution if underground waters become contaminated. Slovenia has honored this special salamander by its placement on one of its coins.
AmphibiaWeb 2014 Proteus anguinus: Olm <http://amphibiaweb.org/species/4229> University of California, Berkeley, CA, USA. Accessed Dec 22, 2016.
Voituron, Y., de Fraipont, M., Issartel, J., Guillaume, O., and Clobert, J. (2010). ”Extreme lifespan of the human fish (Proteus anguinus): a challenge for ageing mechanisms .” Biology Letters, Published online before print July 21, 2010, doi: 10.1098/rsbl.2010.0539.