Meeting Abstract
P1.34 Friday, Jan. 4 Island Dwarfism Affects Female Fecundity in Fowler’s Toad: Quantity Versus Quality? DOWNS, L.K.*; BARRILE, G.M.; BOWER, C.D.; HRANITZ, J.M.; KLINGER, J.M.; MOORE, J.T.; Bloomsburg University, Bloomsburg lkd30583@huskies.bloomu.edu
Previous research comparing island and mainland populations of Anaxyrus (formerly Bufo) fowleri documented high population densities and island dwarfism in the population on Assateague Island, Virginia. The small insular body size compared to mainland size does not appear to be caused by a simple factor, such as low genetic diversity. Instead, age structure, competition, and harsh conditions on the island remain hypothetical causes that need to be integrated with organismal life history responses. One of the life history responses analyzed in this study is reproductive output, as corresponding intraspecific variation may be related to insular body size differences. In 2011, we conducted a pilot study of female fecundity in the population of A. Fowleri on Assateague Island compared to those on the adjacent mainland by measuring clutch size (number of eggs) and egg diameter. We found that island and mainland populations differed, with the mainland females depositing larger clutches. We hypothesized this was due to their larger SVL. We found no difference in egg diameter. In 2012, we increased our sample size, collecting from the same locations as the previous year and adding an additional mainland site. Our results indicated that, although there was still a significant difference between island and mainland populations, there were also annual differences in clutch sizes of eggs collected at the same mainland site from 2011 to 2012. There was no significant difference in egg diameter in 2012. These findings may result from annual climate variation and resource variability. If so, such variation may affect their activity levels thereby limiting storage reserves for egg production. These results also indicate that dwarfism affects reproductive output through clutch size but not egg size, highlighting a quantity not quality based trade off.
