DETERMINING THE EFFECTS OF PATERNITY ON LOCOMOTIVE PERFORMANCE AND MORPHOLOGICAL VARIATION IN LOGGERHEAD HATCHLINGS

Reptiles, including marine and terrestrial turtles, often exhibit multiple paternity in their clutch of eggs. Thus, more than one male contributes genetically to a single clutch. In sea turtles, multiple paternity may enhance female and hatchling fitness by increasing genetic diversity within nests. If paternal contributions improve offspring quality, females may benefit by mating with multiple males to boost the chances of increased hatchling survival. While 31–70% of loggerhead (Caretta caretta) nests in Florida show evidence of multiple paternity, no studies have examined this phenomenon in the large breeding aggregations along Florida’s Gulf Coast. This study focused on the loggerhead rookery in Sarasota County, the largest nesting site in the Gulf, to determine the frequency of multiple paternity and assess whether it influenced hatchling locomotive performance or morphology. Hatchlings (N = 259) from 14 clutches were genotyped using eight microsatellite loci, and paternity was assigned using Geneious and COLONY software with manual marking of peaks. Locomotive performance was assessed via determination of crawling distance and righting response, along with measurement of morphological traits, including body depth, head width, straight carapace length and width, body mass, and scute pattern. Composite scores were calculated to quantify overall locomotive efficiency by combining crawling and righting metrics. Multiple paternity was detected in 50% of nests, with 30 individual fathers identified. We found significant differences in composite scores (p = 0.003) and distance traveled (p = 0.049) between hatchlings from single versus multiple paternity nests, with hatchlings from multiple paternity nests outperforming those from single paternity nests. Hatchlings from multiple paternity nests were also 0.64 mm thicker in body depth (p = 0.00002) but 0.46 mm narrower in straight carapace width (p = 0.0001). Within-nest comparisons revealed significant differences in righting response scores among fathers in Nest 4 (p = 0.0404) and in straight carapace width in Nest 7 (p = 0.044). 11 These results demonstrate that multiple paternity can influence hatchling performance and morphology, providing valuable insight into reproductive strategies and their conservation implications for threatened sea turtle populations.