Coevolution not healthy for the female sea monkey

Jun 20, 2011 by Deborah Braconnier report
Artemia urmiana
Artemia urmiana

(PhysOrg.com) -- In a new study titled Male-Female Coevolution in the Wild: Evidence from a Time Series in Artemia Franciscana and published in Evolution, evolutionary ecologist Nicolas Rode from the Centre for Functional and Evolutionary Ecology looked at the sexual behavior of the sea monkey and what happened when females were bred with past and future generations.

Sea monkeys, or brine shrimp, lay eggs that are tough in nature and are able to survive for long periods of time. They can lay dormant for years, as in the case of a drought, and then once the water returns are then able to hatch.

Looking at the Great Salt Lake in Utah, researchers collected eggs from layers that had formed in 1985, 1996 and 2007. They took these eggs back to the lab and allowed them to hatch. Keeping each generation separate, the researchers then bred the females with eggs from their generation and previous and past generations.

What they discovered was that the longer the time difference between the male and female partner, the sooner the female sea monkey died. When a female from 1985 was bred with a male from 2007, her was cut short by as much as 12 percent.

The research seems to match the idea of and that female shrimp are best suited to breed with their own generation. It appears males and females adapt new mating strategies through different generations and this proves deadly for the female sea monkey.
The change in from a different generation did not however seem to have an effect on the female’s reproductive success. Even though they were dying faster, they were also producing eggs at a faster rate.

The one mystery still puzzling the researchers is just how the males are harming the females and shortening their lifespan.

Explore further: Rock-paper-scissors model helps researchers demonstrate benefits of high mutation rates

More information: MALE-FEMALE COEVOLUTION IN THE WILD: EVIDENCE FROM A TIME SERIES IN ARTEMIA FRANCISCANA, Evolution, DOI: 10.1111/j.1558-5646.2011.01384.x

ABSTRACT
Sexual conflicts are ubiquitous in nature and are expected to lead to an antagonistic coevolution between the sexes. This coevolutionary process is driven by selection on sexually antagonistic traits that can either be directional or fluctuating. In this study, we used dormant cysts of Artemia franciscana, collected in the same population in three different years over a 23-year period (corresponding to ∼160 generations in this system), to investigate male-female coevolution in natural conditions over time. We performed a cross experiment study where reproduction of females mated to males from the past, present or future was monitored until death. In agreement with a model of ‘fluctuating selection’, we found that females survived better and had longer interbrood intervals when mated with their contemporary males compared to when mated with males from the future or the past. However, female weekly and lifetime reproductive successes displayed no differences between contemporary and non-contemporary matings. Finally, the coevolutionary patterns (‘arms race dynamics’ or ‘fluctuating selection dynamics’) possibly acting on female relative fitness could not be discriminated. This study is the first direct demonstration that the process of male – female coevolution, previously revealed by experimental evolution in laboratory artificial conditions, can occur in nature on a short evolutionary time scale.

Related Stories

Female guppies risk death to avoid sexual harassment

Aug 06, 2008

Sexual harassment from male guppies is so bad that long-suffering females will risk their lives to escape it, according to new research from Dr Safi Darden and Dr Darren Croft from Bangor University. Their work, which was ...

The cost of keeping eggs fresh for mother cockroaches

Feb 26, 2007

One of the defining differences between the sexes is in the size of their gametes. Males make many tiny sperm while females make only a few large eggs. This suggests that sperm are cheap while eggs are expensive. ...

'Stick men' may be rendered obsolete in insect world

Mar 24, 2010

(PhysOrg.com) -- Male stick insects are becoming increasingly redundant, with new research showing some New Zealand female stick insects can reproduce as efficiently on their own as with a male mate.

Sex is thirst-quenching for female beetles

Aug 28, 2007

Female beetles mate to quench their thirst according to new research by a University of Exeter biologist. The males of some insect species, including certain types of beetles, moths and crickets, produce unusually large ejaculates, ...

Recommended for you

Plants with dormant seeds give rise to more species

Apr 18, 2014

Seeds that sprout as soon as they're planted may be good news for a garden. But wild plants need to be more careful. In the wild, a plant whose seeds sprouted at the first warm spell or rainy day would risk disaster. More ...

Researchers successfully clone adult human stem cells

Apr 18, 2014

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

gwargh
not rated yet Jun 20, 2011
Why in the world would you have that title, physorg?

It's not coevolution that's unhealthy, it's precisely the lack of it that caused the decreased lifespans of the females. They are unable to adapt to the sexual characters of future males as well (toxins to destroy other males' sperm, sexual organ changes, etc.)

More news stories

Researchers successfully clone adult human stem cells

(Phys.org) —An international team of researchers, led by Robert Lanza, of Advanced Cell Technology, has announced that they have performed the first successful cloning of adult human skin cells into stem ...

Airbnb rental site raises $450 mn

Online lodging listings website Airbnb inked a $450 million funding deal with investors led by TPG, a source close to the matter said Friday.

Health care site flagged in Heartbleed review

People with accounts on the enrollment website for President Barack Obama's signature health care law are being told to change their passwords following an administration-wide review of the government's vulnerability to the ...