Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Male seahorses are nature's Mr. Mom

05.05.2008
Male seahorses are nature’s real-life Mr. Moms – they take fathering to a whole new level: Pregnancy.

Although it is common for male fish to play the dominant parenting role, male pregnancy is a complex process unique to the fish family Syngnathidae, which includes pipefish, seahorses and sea dragons. Texas A&M University evolutionary biology researcher Adam Jones and colleagues in his lab are studying the effects of male pregnancy on sex roles and sexual selection of mates and are trying to understand how the novel body structures necessary for male pregnancy evolved. By doing this, the researchers hope to gain a better understanding of the evolutionary mechanisms responsible for changes in the structure of organisms over time.

“We are using seahorses and their relatives to address one of the most exciting areas of research in modern evolutionary biology: the origin of complex traits,” Jones said. “The brood pouch on male seahorses and pipefish where females deposit eggs during mating is a novel trait that has had a huge impact on the biology of the species because the ability for males to become pregnant has completely changed the mating dynamics.”

When seahorses mate, the female inserts her ovipositor into the male’s brood pouch (an external structure that grows on the body of the male) and deposits her unfertilized eggs into the pouch. The male then releases sperm into the pouch to fertilize the eggs. “It wouldn’t be that interesting if the brood pouch were just a flap of skin where the females put regular fish eggs and they developed in the bag instead of on the sea floor,” Jones said. “But the male pregnancy in some species of seahorses and pipefish is physiologically much more complex than that.”

... more about:
»Evolutionary »Jones »Sex »Trait »brood »deposit »mate »mating »pipefish »pouch »pregnancy »species »steps

After the female deposits her unfertilized eggs into the male, the outer shell of the eggs breaks down, and tissue from the male grows up around the eggs in the pouch. After fertilizing the eggs, the male closely controls the prenatal environment of the embryos in his pouch. The male keeps blood flowing around the embryos, controls the salt concentrations in the pouch, and provides oxygen and nutrition to the developing offspring through a placenta-like structure until he gives birth.

Male pregnancy has interesting implications for sex roles in mating, Jones explained, because in most species, males compete for access to females, so you usually see the evolution of secondary sex traits in males (for example, a peacock’s tail or antlers in deer). But in some species of pipefish, the sex roles are reversed because males become pregnant and there is limited brood pouch space. So females compete for access to available males, and thus secondary sex traits (such as brightly colored ornamentation) evolve in female pipefish instead of males.

“From a research standpoint, it’s interesting because there aren’t very many species in which there is a sex role reversal,” Jones said. “It provides a unique opportunity to study sexual selection in this reversed context.”

To study the mating behavior of seahorses and pipefish, Jones’ lab uses molecular markers for forensic maternity analysis to figure out the mother of a male’s offspring. The lab found that gulf pipefish mate according to the “classic polyandry” system, where each male receives eggs from a single female per pregnancy, but females can mate with multiple males. Because attractive females can mate multiple times, this system results in very strong competition in sexual selection, and female gulf pipefish have evolved strong secondary sexual traits, Jones said.

Seahorses, however, are monogamous within a breeding season, and each seahorse only mates with one other seahorse. In this system, if there are equal sex ratios, there is not as much competition among females because there are enough mates for everyone, Jones explained. So seahorses have not evolved the strong secondary sexual traits that pipefish have.

Male pregnancy also results in a reversal in sex-related behaviors, Jones said. “Females exhibit a competitive behavior that’s normally a male-type attribute, and males end up being choosy, which is normally a more female-type attribute,” he said. His lab studies the evolutionary steps leading to that reversal in behavior and the role that hormones play in the change.

Jones’ lab also studies how the brood pouch first evolved in seahorses and pipefish. “A big question in evolutionary biology is how a novel structure gets all of the necessary genes and parts to function,” Jones said. “So we are trying to understand how the brood pouch and the genes required for male pregnancy arose over evolutionary time.”

One of the interesting things about the brood pouch is that it appears to have evolved independently multiple times. There are two major lineages of seahorses and pipefish – trunk-brooding and tail-brooding – and the brood pouch structure independently evolved in each of these groups, Jones said.

Another area Jones’ lab is researching is the evolutionary steps that led to the unique overall shape of seahorses. “How do you go from just being a regular-old looking fish to being something really unusual like a seahorse?” Jones said. “There are a lot of evolutionary steps involved in that.”

Jones explained that the first step in the evolutionary process was the elongation of the fish’s body, which the lab is currently studying. The next step was the addition of other unique structural features that seahorses possess, such as the bending of the fish into its unique shape. The head of a seahorse is unusual because unlike most fish, a seahorse’s head is at a 90-degree angle to its body, Jones explained. Seahorses also have a prehensile tail, meaning that, unlike most fish, they can use their tail to grasp onto things.

“These are all interesting changes, and we’re interested in studying how these novel traits arose and the evolutionary steps that led to them,” Jones said. “Ultimately, we hope to gain deeper insights into some of the evolutionary mechanisms responsible for the incredible changes in the structure of organisms that have occurred during the history of life on Earth.”

Keith Randall | EurekAlert!
Further information:
http://www.tamu.edu

Further reports about: Evolutionary Jones Sex Trait brood deposit mate mating pipefish pouch pregnancy species steps

More articles from Life Sciences:

nachricht Catalysts for climate protection
19.08.2019 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

nachricht From the tiny testes of flies, new insight into how genes arise
19.08.2019 | Rockefeller University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A miniature stretchable pump for the next generation of soft robots

Soft robots have a distinct advantage over their rigid forebears: they can adapt to complex environments, handle fragile objects and interact safely with humans. Made from silicone, rubber or other stretchable polymers, they are ideal for use in rehabilitation exoskeletons and robotic clothing. Soft bio-inspired robots could one day be deployed to explore remote or dangerous environments.

Most soft robots are actuated by rigid, noisy pumps that push fluids into the machines' moving parts. Because they are connected to these bulky pumps by tubes,...

Im Focus: Vehicle Emissions: New sensor technology to improve air quality in cities

Researchers at TU Graz are working together with European partners on new possibilities of measuring vehicle emissions.

Today, air pollution is one of the biggest challenges facing European cities. As part of the Horizon 2020 research project CARES (City Air Remote Emission...

Im Focus: Self healing robots that "feel pain"

Over the next three years, researchers from the Vrije Universiteit Brussel, University of Cambridge, École Supérieure de Physique et de Chimie Industrielles de la ville de Paris (ESPCI-Paris) and Empa will be working together with the Dutch Polymer manufacturer SupraPolix on the next generation of robots: (soft) robots that ‘feel pain’ and heal themselves. The partners can count on 3 million Euro in support from the European Commission.

Soon robots will not only be found in factories and laboratories, but will be assisting us in our immediate environment. They will help us in the household, to...

Im Focus: Scientists create the world's thinnest gold

Scientists at the University of Leeds have created a new form of gold which is just two atoms thick - the thinnest unsupported gold ever created.

The researchers measured the thickness of the gold to be 0.47 nanometres - that is one million times thinner than a human finger nail. The material is regarded...

Im Focus: Study on attosecond timescale casts new light on electron dynamics in transition metals

An international team of scientists involving the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) in Hamburg has unraveled the light-induced electron-localization dynamics in transition metals at the attosecond timescale. The team investigated for the first time the many-body electron dynamics in transition metals before thermalization sets in. Their work has now appeared in Nature Physics.

The researchers from ETH Zurich (Switzerland), the MPSD (Germany), the Center for Computational Sciences of University of Tsukuba (Japan) and the Center for...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

The power of thought – the key to success: CYBATHLON BCI Series 2019

16.08.2019 | Event News

4th Hybrid Materials and Structures 2020 28 - 29 April 2020, Karlsruhe, Germany

14.08.2019 | Event News

What will the digital city of the future look like? City Science Summit on 1st and 2nd October 2019 in Hamburg

12.08.2019 | Event News

 
Latest News

Stanford builds a heat shield just 10 atoms thick to protect electronic devices

19.08.2019 | Information Technology

Researchers demonstrate three-dimensional quantum hall effect for the first time

19.08.2019 | Physics and Astronomy

Catalysts for climate protection

19.08.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>