Phylogeny

What is Phylogeny?

Phylogeny is the study of the evolutionary development of a species, or its phenotypic traits such as an organ or a behavior. To locate what caused Hematophagy to develop in Trichomycteridae, the family of catfish which populate South and Central America, it is therefore useful to look at the Clade. In the family Trichomycteridae there are 8 subfamilies, the Tridentinae, Vandellinae, Stegophilinae, Trichomycterinae, Sarcoglanidinae, Glanapteryginae, Copionodontinae, and the Trichogeninae. The Scleronema and Ituglanis are a monophyletic group that are not classified in any of the subfamilies.

 

Figure 2. The arrow locates where the Trichomycteridae group begins, while the label “H” signifies the two species which are formally known to the public as the “Candiru” or “Carnero” fish. This image was provided by Adraiens, in affiliation with Universiteit Gent, and based upon the Marcus de Pinna study.

Further, both the Stegophilinae and Vandellinae rely entirely upon Hematophagy for food, while the Tridentinae also can consume fish scales, and other debris making the Tridentinae only partially parasitic.

Figure 3. While this graph shows a genetic difference for the hematophagic Vandellinae in respect to any of its cousin Trichomycteridae subfamilies, more investigation needs to be done in regards to whether these genes contribute to the hematophagic behavior.

Unfortunately, due to the dynamic nature of the Trichomycteridae family, over sixteen hundred species formed in a short time frame across a huge area so as to make tracing the evolutionary development difficult. However, what can be said about the hitch-hiking behavior is that while it is closely tied with parasitic behavior of hematophagy, the two behaviors did not develop simultaneously.

Several members of the Vandellinae genus Paracanthopoma parva have been found hitch-hiking on the giant jau catfish. However, the uniqueness of their behavior is due to the length of their snout and teeth, which enabled them to bore into the host's skin. While some of the species of Tridentinae subfamily are capable to hitch-hike for short distances in the host fish's gills, what makes the Vandellinae's behavior unique is the location of the attachment, usually caudal and pectoral fins.