Most animals, like humans, have separate sexes. We are born, live out our lives and reproduce as one sex or the other, but some animals live as one sex in part of their lifetime and then switch to the other sex, a phenomenon called sequential hermaphroditism. Yale scientists believe the bigger puzzle is why the phenomenon is so rare, since their analysis shows the biological “costs” of changing sexes rarely outweigh the advantages.
This process is even evolutionarily favored, they say, so its rarity cannot be explained by an analysis of the biological costs vs benefits.
Sequential hermaphroditism naturally occurs in various organisms from plants to fishes. Following four decades of research that established why sex change is advantageous, the question remained why it is rare among animals. In this study, Yale graduate student Erem Kazancioglu and his advisor Suzanne Alonzo, assistant professor of ecology and evolutionary biology, demonstrate that sex change is surprisingly robust against costs.
While the adaptive advantage of sex change is well understood, it is not clear why relatively few animals change sex. According to Alonzo, “An intuitive, yet rarely studied, explanation is that the considerable time or energy it takes to change sex make hermaphroditism unfeasible for most animals.”
To test whether the biological costs of changing sex affect sex change actually occurs, the researchers built theoretical models of the hermaphrodite and separate-sex life histories. In their “game” models, sex change “players” vary the age of their sex change, while the separate-sex strategy responds by altering the number of male and female offspring it produces.
“We were surprised to see that a hermaphrodite could spend 30 percent of its lifetime in the process of change sex, and still persist in a population,” said Kazancioglu. “This suggests that only huge costs can disfavor sex change.”
So, why is sex change so rare? And, why does one species of fish reproduce strictly as separate sexes, while another very closely related species flexibly changes sex? A comparative study of hermaphroditic and separate-sex mating systems, which the authors are currently performing, may provide a clue, according to Kazancioglu, “Reproductive behaviors such as parental care seem to disfavor sex change in some species. We are investigating whether general patterns like these may explain the rarity of hermaphroditism.”
Yale University and the National Science Foundation funded the research.
Citation: The American Naturalist (March 2008)
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- More Electricity In Developing Nations Had Little Impact On Climate Change
- Amenhotep III: Ancient Egyptian Mummies Didn't Have Spinal Arthritis
- Ebola Transmission Via Public Transport
- From Mindless Physics To Physics Of Mind
- #GAMERGATE Style Harassment Does Not Happen in the Male Dominated Sciences
- 24 hours with Windows 10 on a Surface Pro 3
- The Resource Curse: Science Cities Suffer
- "Robert H. Olley, Let's have a big party, maybe Thomas Dunkan's relatives being declared Ebola free..."
- "Nice bit of news for us all:Ebola crisis: Nigeria set to be declared free of virusRead about the..."
- "But it never stands still, how is that boring. To stagnate within a belief like religion that does..."
- "I was hard wired as in raised JW. We switched at the death of 2 of my sisters, when flowers were..."
- "“All I've ever done is defend a fellow scientist who wrote a book and was harassed for it, which..."
- Natural Resources Defense Council sues EPA to block rollout of Dow Enlist Duo GMO system
- Enviros file suit to block new Dow AgroSciences GMO herbicide and seeds
- Couples can protect children from devastating mutations with new IVF methods
- Food 2.0: Will farmers be able to meet the ecological challenges ahead?
- General Mills’ Cascadian Farm launches ‘bee-friendly’ campaign, GMO critics unimpressed
- Can genes pass from genetically modified food into our blood, posing dangers?
- Heart rate may predict survival and brain function in comatose cardiac arrest survivors
- Study shows medication is frequently, unintentionally given incorrectly to young children
- Mummy remains refute antiquity of ankylosing spondylitis
- Scientists say national Alzheimer's plan milestones must be strengthened to meet goal by 2025
- Head injury causes the immune system to attack the brain