Presentation Title

Sexual Dimorphism of the Dwarf Perch (Micrometrus minimus) Anal Fin

Faculty Mentor

Kristy Forsgren

Start Date

23-11-2019 8:00 AM

End Date

23-11-2019 8:45 AM

Location

61

Session

poster 1

Type of Presentation

Poster

Subject Area

biological_agricultural_sciences

Abstract

Sexual Dimorphism of the Dwarf Perch (Micrometrus minimus) Anal Fin

Panzino, M.E., Bond, E.C., and Forsgren, K.L.

Dwarf perch (Micrometrus minimus) are members of the Embiotocidae family of surfperches. Surfperch reproduce via internal fertilization and females give birth to live young (i.e., viviparity). Males use an intromittent organ to transfer sperm. The flask organs are bulbous pockets with tubular structures present on both sides of the anterior portion on the anal fin and are believed to have a reproductive role during the breeding season. The goal of my project was to determine if male dwarf perch exhibit a modification of the anal fin to support flask organ development. We hypothesized that the anterior region of the anal fin, where flask organ development occurs, is structurally modified. Dwarf perch were captured via a beach seine at Cabrillo Beach, CA. The anal fins were dissected and processed using a clearing and staining technique and photographed. Fin ray morphology was investigated, specifically focusing on fin rays 3-9, the location of flask organ development. Anal fin ray length (dorsal to ventral; mm) was not significantly different (p = 0.4243) between males and females. Anal fin ray width (anterior to posterior; mm) was significantly different (p = 0.0043) between males and females. Overall, it appears that male dwarf perch anal fins are modified to support flask organ development and that females exhibit increased fin ray branching. Our study on dwarf perch anal fin morphology will give us an evolutionary understanding of how anal fin modifications are associated with secondary sex characteristics.

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Nov 23rd, 8:00 AM Nov 23rd, 8:45 AM

Sexual Dimorphism of the Dwarf Perch (Micrometrus minimus) Anal Fin

61

Sexual Dimorphism of the Dwarf Perch (Micrometrus minimus) Anal Fin

Panzino, M.E., Bond, E.C., and Forsgren, K.L.

Dwarf perch (Micrometrus minimus) are members of the Embiotocidae family of surfperches. Surfperch reproduce via internal fertilization and females give birth to live young (i.e., viviparity). Males use an intromittent organ to transfer sperm. The flask organs are bulbous pockets with tubular structures present on both sides of the anterior portion on the anal fin and are believed to have a reproductive role during the breeding season. The goal of my project was to determine if male dwarf perch exhibit a modification of the anal fin to support flask organ development. We hypothesized that the anterior region of the anal fin, where flask organ development occurs, is structurally modified. Dwarf perch were captured via a beach seine at Cabrillo Beach, CA. The anal fins were dissected and processed using a clearing and staining technique and photographed. Fin ray morphology was investigated, specifically focusing on fin rays 3-9, the location of flask organ development. Anal fin ray length (dorsal to ventral; mm) was not significantly different (p = 0.4243) between males and females. Anal fin ray width (anterior to posterior; mm) was significantly different (p = 0.0043) between males and females. Overall, it appears that male dwarf perch anal fins are modified to support flask organ development and that females exhibit increased fin ray branching. Our study on dwarf perch anal fin morphology will give us an evolutionary understanding of how anal fin modifications are associated with secondary sex characteristics.