Fast development is often perceived as an advantage, as it enables better harmony with one's environment and readiness to cope with the challenges that it poses. However, research conducted at the University of Haifa, Israel, and University of California, Santa Cruz, and published in the scientific journal PLoS ONE*, found that the acceleration of developmental rate incurs potentially lethal physiological costs for the developing individual. "Our findings are consistent with research findings on other animals and call for further research on rates of development in humans," said Asaf Sadeh who led the study.
This study, part of Sadeh's PhD research, was conducted on the fire salamander (Salamandra infraimmaculata) in conjunction with Prof. Leon Blaustein and Noa Truskanov from the University of Haifa, and with Prof. Marc Mangel from the University of California. The fire salamander in Israel breeds in temporary pools that fill during the winter rains and usually dry up in the spring. The larvae that are born into these pools must complete their development and metamorphose into terrestrial life before their pools dry. Larvae failing in this developmental race are destined to die from desiccation.
In the first part of the study, the scientists examined whether salamander larvae employ some early warning mechanism that alerts them to step up their rates of development to avoid drying. They reared an experimental group of larvae in water, to which they added a minute quantity of powder of ground larvae that had desiccated in natural temporary ponds. The development of these larvae was compared to a control group that was not exposed to the powder. They found that immediately after their birth into the pond, the larvae detected the presence of the dried remains and developed more quickly than the control group. Sadeh and colleagues propose that the chemical composition of the flesh of the dead larvae changes as they toast in the sun, producing a unique "scent of death". These chemicals are released back into the water during the next rains, when the pond fills up again. This apparently provides information to the newborn larvae on the expected water-holding capacity of their pond, and signals them to set a high developmental rate to avoid a similar fate.
While chemicals from previously desiccated larvae can inform as to possible drying of pools in a relatively short time, reducing water levels can serve as a more reliable predictor of imminent pond drying and risk of desiccation. In the second part of the study, the researchers manipulated the water-levels for both groups, to simulate actual drying or non-drying conditions. They found that, after a while, the larvae will adjust their initial rates of development according to the actual water levels of their ponds.
However, they also found that accelerated development carries costs: larvae that developed more quickly suffered greater rates of mortality. Larvae that falsely perceived the pond environment as long-lasting, and thus started life with a slow developmental rate, but then realized their misperception and compensated with significant acceleration, suffered the greatest rates of mortality. The physiological mechanisms underlying these costs are unknown, but are thought to involve both cellular causes such as oxidative damage from increased metabolic rates, and tissue-level causes such as overexploitation of undifferentiated stem cells or disrupted balance between the differentiation and growth of different tissues in the body. These physiological costs may also lead to increased vulnerability to environmental stresses other than drying, such as heat, disease and parasites, and might result in death.
According to Sadeh, these results are consistent with those of recent studies on the costs of acceleration in growth following starvation in various other organisms, including insects, fish, amphibians and mammals. He suggests that this calls for further research on human development, such as motor, immune, sexual and cognitive development. "These new findings are thought-provoking when considered in relation to widespread perceptions of optimal child development. Boosting a certain aspect of a child's development allows the child to cope better with the corresponding aspect of the environment, but may be traded off with some other aspect of development, potentially rendering the child less competent for other environmental challenges," suggested Sadeh, but emphasized that the study of the costs of development rates is in its infancy, and that more work needs to be carried out before any applicable conclusions can be drawn for human development.
* Sadeh A, Truskanov N, Mangel M, Blaustein L (2011) Compensatory Development and Costs of Plasticity: Larval Responses to Desiccated Conspecifics. PLoS ONE 6(1): e15602.
Rachel Feldman | Newswise Science News
The personality factor: How to foster the sharing of research data
06.09.2017 | ZBW – Leibniz-Informationszentrum Wirtschaft
Europe’s Demographic Future. Where the Regions Are Heading after a Decade of Crises
10.08.2017 | Berlin-Institut für Bevölkerung und Entwicklung
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems Holding GmbH about commercial use of a multi-well tissue plate for automated and reliable tissue engineering & drug testing.
MBM ScienceBridge GmbH successfully negotiated a license agreement between University Medical Center Göttingen (UMG) and the biotech company Tissue Systems...
Pathogenic bacteria are becoming resistant to common antibiotics to an ever increasing degree. One of the most difficult germs is Pseudomonas aeruginosa, a...
Scientists from the MPI for Chemical Energy Conversion report in the first issue of the new journal JOULE.
Cell Press has just released the first issue of Joule, a new journal dedicated to sustainable energy research. In this issue James Birrell, Olaf Rüdiger,...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
19.09.2017 | Event News
19.09.2017 | Physics and Astronomy
19.09.2017 | Power and Electrical Engineering