Final answer:
The action that is NOT likely to be a result of a skewed operational sex ratio is a goby fish cannibalizing some of its own eggs (option 4). This behavior is not directly related to competition for mates due to a skewed sex ratio, unlike the other examples which involve sexual competition or selection pressures.
Step-by-step explanation:
Skewed Operational Sex Ratios
An operational sex ratio (OSR) is the ratio of male to female individuals who are available for reproducing at any given time. A skewed OSR can lead to various forms of sexual selection behaviors. When there is a larger number of one sex, especially males, you often see increased competition for mating opportunities, as not every individual will get the chance to reproduce.
Results of a Skewed OSR
Looking at the examples provided:
- Male bighorn sheep butting heads is a classic example of male-male competition which is often seen in species where there is a greater number of males ready to mate compared to females, indicating a skewed OSR.
- The extended head of a stalk-eyed fly is a secondary sexual characteristic that has likely evolved due to sexual selection, which can be a result of a skewed OSR, where males compete for females' attention.
- Female seahorses fighting over egg space in a male's pouch could be a result of a skewed OSR, but in the opposite direction, where there are more females than males, causing females to compete for the limited reproductive resource which is the male's pouch.
- A goby fish cannibalizing some of its own eggs is not typically an outcome of a skewed OSR. Cannibalism of eggs might be a response to environmental conditions or parental investment strategies, but it does not relate directly to competition for mates due to a skewed sex ratio.
Therefore, the action that is not likely to be a result of a skewed operational sex ratio is a goby fish cannibalizing some of its own eggs (option 4).