The evolution of novel, medial fin modifications in surfperches (Embiotocidae)
By: Breana Goldman
Department: Integrative Biology
Faculty Advisor: Dr. Karen Crow
Phenotypic diversity is defined by the evolution of novel traits, and because reproduction is the currency of fitness, reproductive structures and associated secondary sex traits exhibit a high degree of variation. The embiotocids, or surfperches, exhibit novel, sexually dimorphic, medial fin modifications that are likely associated with internal fertilization, but their function is currently unknown. These structures have been loosely characterized, in taxonomic keys and papers that are 100 years old, as bony hooks and serrated plates (Amphisticinae), or enlarged fleshy protuberances (Embiotocinae). We found divergence between subfamilies, species, and sex that have not been previously described. Including a fin ray modification, an ancestral feature present in embiotocines as well as amphisticines, and sexual dimorphism that is not fully penetrant-manifest as diminished character states in females. Six species were evaluated using clear and stain methods. We compared placement and developmental stage of fin ray modifications between species and sexes.