Biologists give paternity tests to fish (Update)

May 15, 2014
Biologists give paternity tests to fish
Young surfperches from the same brood may have many different fathers. Female surfperch increase their reproductive health by mating with many partners.

(Phys.org) —Paternity tests of surfperch fishes reveal that a single brood may have as many as eight different fathers. And the more mates a female surfperch has, the more offspring she will produce, according to a new report from SF State scientists.

For researchers who study these California coastal fishes, the findings may explain why female surfperch—which are expected to be choosy about their reproductive partners—mate with so many males.

This research also sheds light on a contentious idea in biology, which is based on the supposition that females of a species tend to invest much more time and energy in their offspring compared with males. The theory suggests that males benefit from mating with more females by siring more offspring, but the reverse is not true for females.

Data collected by the SF State scientists, show for the first time in surfperches, that females who mate with increasingly higher numbers of males produce more offspring than females that mate with fewer males.

Unlike most fishes that spawn hundreds to thousands of eggs, surfperches give birth to relatively few live offspring that are born almost fully mature, says Karen Crow, the SF State associate professor of biology who led the new study. But even with the significant investment required to grow and carry a nearly full-grown juvenile before birth, female surfperches improve their reproductive success by mating with multiple males.

When Crow and her colleagues collected pregnant females from two surfperch species, from the shorelines near Pacifica, Calif., they used genetic markers to reveal that each female's brood had multiple fathers. Spotfin surfperch had an average of two to seven fathers per brood, while shiner surfperch had one to eight fathers per brood.

The researchers determined paternity in much the same way that human paternity can be tested, by comparing tiny repeating patterns in DNA called microsatellites. These patterns are molecular markers that are passed on from parents to offspring.

How does multiple mating benefit female surfperches? Crow and her team believe that the unusual reproductive cycle of these fishes allow females to be choosy—just not in the ways that biologists have expected.

Previous research has shown that female surfperch fish can store sperm within the uterus for up to five months. By storing the sperm from multiple males, the females may be able to "choose" when and with which sperm they want to fertilize their eggs. This strategy may set up a kind of competition between sperm from different potential fathers, so that only the best sperm contribute to the next generation. Or it may optimize the genetic diversity within broods, helping the offspring to thrive in varying environmental conditions.

The study "Multiple paternity is a shared reproductive strategy in the live-bearing surfperches (Embiotocidae) that may be associated with female fitness" by SF State undergraduate student John R. LaBrecque; postdoctoral fellow Yvette R. Alva-Campbell; SF State graduate student Sophie Archambeault; and Karen D. Crow was published in the most recent issue of the journal Ecology and Evolution.

Explore further: Sexual conflict affects females more than males, says new research on beetles

More information: LaBrecque, J. R., Alva-Campbell, Y. R., Archambeault, S. and Crow, K. D. (2014), "Multiple paternity is a shared reproductive strategy in the live-bearing surfperches (Embiotocidae) that may be associated with female fitness." Ecology and Evolution. doi: 10.1002/ece3.1071

add to favorites email to friend print save as pdf

Related Stories

Male extinction prevented by promiscuous females

Apr 01, 2014

Female fruit flies with a large number of sexual partners are playing an invaluable role in preventing the extinction of males, research at the University of Liverpool has shown.

Recommended for you

'Tiger heavyweight' Nepal hosts anti-poaching summit

12 hours ago

Nepal's success in turning tiger-fearing villagers into their protectors has seen none of the endangered cats killed for almost three years, offering key lessons for an anti-poaching summit opening in Kathmandu ...

GMO mosquito plan sparks outcry in Florida

Jan 31, 2015

A British company's plan to unleash hordes of genetically modified mosquitoes in Florida to reduce the threat of dengue fever and other diseases has sparked an outcry from fearful residents.

Population genomics unveil seahorse domain

Jan 30, 2015

In a finding vital to effective species management, a team including City College of New York biologists has determined that the lined seahorse (Hippocampus erectus) is more a permanent resident of the we ...

Researchers develop new potato cultivar

Jan 30, 2015

Dakota Ruby is the name of a new potato cultivar developed by the NDSU potato breeding project and released by the North Dakota Agricultural Experiment Station. Dakota Ruby has bright red skin, stores well and is intended ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.