Chapter 36.6, Problem 1MC

Summary Introduction

To determine:

Why the evolution selects for males that mimic females, even though the chances of success is relatively low.

Concept introduction:

Australian giant cuttlefish (Sepia apama) show sexual dimorphism. The males and females of the species greatly differ from each other in appearance. Females have shorter arms and dark patches on a white background. On the other hand, the males have longer arms and are whiter.

The species has a sex ration of four males to one female, leading to fierce competition among males for fathering the offspring. The largest males mate with the females and guard them after insemination. The males fight with other males that try to inseminate the females. This behavior accounts for larger male’s reproductive success.

The smaller males use another behavioral strategy called deception. They disguise themselves as a female by hiding the arms and changing skin color. This behavior allows the smaller males to increase their chances of reproductive success.