Saturday, April 21, 2012
Living Easy: Podarcis lilfordi and Daphne rodriguezii
The lizard, Podarcis lilfordi, is found on the Balearic Islands off the coast of Spain . However, unlike other lizards, this species shares a mutualistic relationship with the shrub Daphne rodriquezii . D. rodriquezii is characterized from its beautiful white flowers and it also contains many fruits that the lizards like to consume . The lizards consume and disperse the seeds of the plant by eating the fruits that grow from the shrubs .
P. lilfordi is a medium sized lizard that grows to a maximum of 80mm. Its body mass can be anywhere between 4.2 to 9.5 grams. The females reproduce cyclically, producing 2-4 eggs per clutch. They can lay multiple clutches in one season . However, as new predators and lizards show up to the islands and compete for resources, the population of P. lilfordi has slowly started to decline . The shrub, D. rodriguezii, starts to grow during the early spring season. They contain very small, white flowers. The sepals and petals unite, forming a tube called the hypanthium that usually has purple dyes and is 7 to 11 mm in length. During the summer, the shrubs mature and produce red-orange, fleshy globose fruits. The shrubs rarely grows above 50 centimeters in height .
Description of the Relationship:
P. lilfordi are very productive seed-dispersers for the shrubs. It is a mutualistic relationship, in which the lizards use the shrubs not only as a food source, but also as a second home . The lizard eats the fruits that D. rodriguezii produces, and it also uses the shrub as a home, keeping it out of sight from other predators and the hot sun . In return, the shrub gets the benefit of having the lizards disperse their seeds for them. They are then better able to spread their offspring to other areas .
However, P. lilfordi also has other priorities and responsibilities on the ecosystem found on the Balearic Islands. It is also a pollinator of the aroid Dracunculus muscivorus, and a seed disperser for Withania frutescens and Phillyrea media .
Cost Benefit Analysis:
As mentioned before, the mutualistic association between P. lilfordi and D. rodriguezii is very straightforward. D. rodriguezii serves as both a food source and a shelter for P. lilfordi, and in return P. lilfordi disperses the seeds of the shrub through fecal defecation. Without D. rodriguezii being present in nature, P. lilfordi would still be able to survive and reproduce in nature. However, it would have a better chance to pass its progeny if D. rodriguezii was present, as it would have an extra food source and shelter . D. rodriguezii, however, would have a much harder time reproducing in nature as their seeds would not get dispersed if P. lilfordi was not present in the environment.
Posted by Charles Zhu at 8:57 PM