In Zebra Finches, as in most other bird species, both parents contribute to offspring rearing. The social partner of a female, however, is not always the biological father of the young. If the opportunity arises, females will choose to pair with partners other than their primary mate – with the interesting result that the offspring of different fathers have different qualities. And, as evolutionary ecologists from the University of Zurich and biologists from Macquarie University in Sydney have discovered, offspring sired by an extra-pair partner develop larger color ornaments and are more attractive to females than their social half-brothers.
A Zebra Finch male displaying his color ornaments.
Extra-pair males are not more attractive
Up to now, the quality differences between social and extra-pair offspring have generally been assumed to reflect the genetic superiority of the extra-pair male. Indeed, females are believed to engage in extra-pair copulation with genetically superior males to obtain better genes for their offspring. Now, Barbara Tschirren, professor for evolutionary ecology at the University of Zurich, and her team have challenged the idea of the exceptional male. In a study published in «Proceedings of the Royal Society» the researchers demonstrate that – despite the observed quality differences – the fathers of attractive sons are neither better looking nor genetically superior.
The first eggs receive preferential treatment
According to the study, attractive sons are not the result of exceptional genes; rather, their enhanced ornamentation is due to the mother’s investment in the eggs. Tschirren was able to demonstrate that maternal resource investment decreases steadily over the course of the laying sequence of a Zebra Finch, with eggs laid early in a clutch being larger and containing more nutrients and hormones. Favoring early eggs and the first hatchlings is a worthwhile investment for the mother as these offspring have a demonstrably higher chance of survival. «It appears that there is strong competition among males to fertilize these valuable eggs early in a female’s laying sequence», explains lead author Barbara Tschirren. «They try to exploit the female’s egg investment bias to ensure a head start for their own offspring.» She hypothesizes that sperm competition might decide the battle, with males with faster sperm being able to fertilize the most valuable eggs.Literature:
Nathalie Huber | idw
22.02.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau
Separate brain systems cooperate during learning, study finds
22.02.2018 | Brown University
Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...
For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.
In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...
Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale
Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...
For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.
But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...
Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.
The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...
15.02.2018 | Event News
13.02.2018 | Event News
12.02.2018 | Event News
22.02.2018 | Life Sciences
22.02.2018 | Physics and Astronomy
22.02.2018 | Earth Sciences