Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Site Tools

  • AAAS
  • Subscribe
  • Feedback

Site Search

Search Advanced

Science 1 November 2002:
Vol. 298. no. 5595, p. 945
DOI: 10.1126/science.298.5595.945a
Prev | Table of Contents | Next

News of the Week

EVOLUTIONARY BIOLOGY:
Placentas May Nourish Complexity Studies

Virginia Morell

On page 1018, researchers report that placentas have evolved independently three times in closely related species of guppylike fish in the genus Poeciliopsis. Other species in the genus lack placentas, and some have partial maternal provisioning by means of tissues that might be precursors of placentas. Thus the fish present the full trajectory of steps involved in the evolution of this organ, offering a model system for studying the evolution of complex organs.

Read the Full Text

ADVERTISEMENT
Click Me!

ADVERTISEMENT
Click Me!

To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)