Inheritance & Variation of Traits, Inheritance 4: Asexual/Sexual (MS), Inheritance 4: Population Genetics (HS), Life Science, Natural Selection & Evolution, NSE 1: Evolution Evidence (HS), NSE 4: Adaption (HS), NSE 4: Fitness (MS), NSE 5: Natural Selection (MS)

Rotifers Eating Foreign DNA

Evidence Supporting the Uptake and Genomic Incorporation of Environmental DNA in the “Ancient Asexual” Bdelloid Rotifer Philodina roseola

SUMMARY: This study looked at whether bdelloid rotifers were better at taking in DNA compared to Monogononta rotifers. Bdelloids are a class of rotifers that only reproduce asexually. There has never been a male observed, no meiosis, and evidence shows that they create genetic diversity using horizontal gene transfer. This is interesting for scientists because strictly asexual reproduction is usually an evolutionary dead end. The researchers also looked at whether or not bdelloid rotifers were better at intaking DNA when desiccated (dried out) or hydrated. Bdelloids turned out to take in more DNA than Monogononta rotifers, preferred DNA from species that they were more closely related to, and were better at taking in DNA while hydrated compared to desiccated. Foreign DNA was labeled with a radioactive tag. To look at how “fit” the rotifers were, researchers counted the number of eggs they produced.

LESSON COMMENTS: This article can be used to talk about evolution, DNA tagging, DNA repair, and meiosis, binary fission, horizontal gene transfer, asexual and sexual reproduction. One can also talk about the importance of biodiversity and other ways in which organisms can increase biodiversity.

For younger students, pond water microscopy labs can be conducted and students can learn to identify the different classes of rotifers and their roles in pond ecosystems. This can then be used as a model for larger ecosystems.

Bininda-Emonds, O. R., Hinz, C., & Ahlrichs, W. H. (2016). Evidence Supporting the Uptake and Genomic Incorporation of Environmental DNA in the “Ancient Asexual” Bdelloid Rotifer Philodina roseola. Life (Basel, Switzerland), 6(3), 38.