Alena Arnold, AJ Lashway, Alyssa Baxter, Katherine Walter, Makenna Juergens, and Alax Crawford

“Comparing recently mated and stored sperm derived broods in the sailfin molly Poecilia latipinna

About Sailfin Mollies:

The sailfin molly, Poecilia latipinna, is a species of fish related to guppies. Sailfin mollies are found in shallow waters from estuaries to ditches along the coast of northeastern Mexico and the southern United States. These fish have a unique reproductive system, both giving birth to live babies in broods and having the capacity to store male sperm for future reproduction. We investigated how the use of sperm storage affected the size and growth rates of fry, as well as the success of broods overall.


Sailfin mollies’ use of stored sperm may be beneficial in cases such as a previous mating with a preferred male or lack of access to a mate during a reproductive cycle. However, as sperm viability decreases over time, females may adjust maternal investment (how much energy the mother invests in each brood) relative to offspring size or resources. We used the sailfin molly to better understand whether females vary in their investment within a reproductive cycle, depending on whether their brood was produced with fresh or stored sperm.




We compared females that had access to a mate during their reproductive receptive period to females that relied exclusively on stored sperm to produce a brood. We kept each female isolated; half were provided with a male so that they could at least have the option to mate.  Half were kept alone, so to produce a brood they would have to rely on stored sperm. We then measured the length of the babies, recorded how many babies each female had per brood, and noted how often females failed to produce broods.

To the right is a photograph of a single brood one week after they were born.

Sperm storage might require females to allocate more resources to the offspring.

We found that females that relied on stored sperm had fewer offspring compared to females who were given the opportunity to remate and were more likely to fail to produce a brood. Offspring size and growth rate, however, did not differ between treatments.

This suggests that females did not or could not compensate for smaller broods by having larger offspring or by allocating resources that might increase offspring growth rates. These results show that, while females can rely on stored sperm, they may be unable to adjust their own maternal investment to broods produced from sperm that has been stored for a long time.

Our Findings

Our team presented our research at the Indiana University Animal Behavior Conference. We are also writing a paper to publish our findings!

Link to our ABC Video Presentation

Contact Info


Slocum Hall
65 S. Sandusky St.
Delaware, OH 43015
P 740-368-3880

David Markwardt, Associate Dean of the OWU Connection