Abstract The relationship between Yucca moths from Tegeticula, Parategeticula and Prodoxous with the Yucca plant (Agavaceae) has been observed over centuries. The strength of their interaction has created contradictory theories. Whether the relationship is obligate or falcultative is one of the ideas providing differing views. The effects of external influences have also been studied by many. In this review I have compared and contrasted the results found by five different groups of scientists in relation to the yucca-yucca moth symbiosis. I conclude that there are different views as to the strength of the relationship and that there are some holes in the …show more content…
She tested if the survivorship of T.cassandra is controlled by the extrinsic factors dehydration and predation. She did this in a few stages, first testing larval survivorship by comparing the number of scars present, indicating eggs under the surface of the flower, to the number of mature larvae. She then conducted a flower microclimate experiment in which mesh bags were placed over individual plants to determine if abiotic (non-living) factors were important in relation to the survival of genomes. Measurements were taken on the changes in microclimate, in relation to temperature and relative humidity. The impact of larval feeding was recorded; measured by number of larvae per fruit and the number of seeds consumed by each larva. It was noted that the presence or absence of predators doesn't seem to have any affect on the plant survivorship, but increase in vapor pressure results in a greater survivorship. She therefore came to the conclusion that the stability of mutualisms can in fact be affected by some extrinsic factors. This proves that just because the yucca-yucca moth relationship exists doesn't mean that their interaction guarantees their survival. In some cases their existence is also hindered by their relationship if it is obligate. She suggests future long-term research into a wider variety of extrinsic sources and larger geographic areas, in order to fully understand the evolution of the symbiosis. The article is well presented and provides a decent amount of information to its readers. It is relatively easy to follow, but there are quite a few equations that are hard to