Mating behavior and the effects of turbidity on preferences for size in the fountain darter, Etheostoma fonticola
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Rising turbidity levels from anthropogenic stressors impact visual communication systems in aquatic communities and may affect the behavior of individual animals, including altering foraging and anti-predator behavior as well as mating preferences. The fountain darter, Etheostoma fonticola, is federally endangered making it an especially important species for examining the effects of turbidity on social behavior. Etheostoma fonticola is endemic to only two clear, spring-fed rivers in central Texas that are currently facing a number of anthropogenic threats that may potentially influence turbidity levels. We tested male and female association preferences and the effects of low (~40NTU) turbidity on association preferences in E. fonticola. We found that association preferences for larger size were not present in adult male or female E. fonticola. However, low levels of turbidity did significantly decrease female strength of preference for larger males. Similarly, male and female E. fonticola spent less time associating with individuals of the opposite sex when their vision was reduced by simulated low levels of turbidity than when vision was not reduced. These results suggest that rising levels of turbidity may have significant consequences on the mating behavior of the federally endangered E. fonticola. While association preferences are frequently used as a proxy for mate choice in fishes, excluding potentially important influences of intrasexual selection may provide misleading results when examining mating preferences. We examined whether female E. fonticola prefer to mate with larger males. We also examined whether larger and smaller male E. fonticola exhibit differences in agonistic behaviors and consequently, mating success. We found that larger males exhibited higher rates of aggressive behaviors and smaller males in turn exhibited more defensive behaviors. However, differences between larger and smaller males in male-male interactions were not correlated with differences in spawning success. These results suggest that male size influences dominance relationships in E. fonticola but not mating success.