Eric Ward from the Northwest Fisheries Science Center, Seattle, USA, coordinated a team of researchers who studied killer whales inhabiting the inland and nearshore waters of Washington state (USA) and British Columbia (Canada).
They used a 30-year dataset collected by the Center for Whale Research and Canada’s Department of Fisheries and Oceans. He said, “During annual photographic surveys, nearly every individual in the population has been recorded. Each animal has unique pigmentation, scars, and fin shapes, allowing us to track the survival and reproductive performance of each female over time”.
The authors aimed to investigate what benefits killer whales derive from the menopause. One theory, termed the “attentive mother hypothesis”, is that giving birth to calves and then losing the ability to reproduce helps the mother to focus on bringing up her offspring, without wasting time and energy on further pregnancies.
The authors’ results support this theory to an extent in that during a calf’s first year of life, having a mother who was nearing menopause increased chances of survival. According to Ward, “We found that the oldest mothers may also be the best mothers. Older females may be more successful in raising young because of maternal experience, or they may allocate more effort to their offspring relative to younger females”.
Killer whales are extremely long lived, with one female believed to be more than 90 years old. Males rarely live past 50, but female life expectancy is considerably longer. Females can produce their first calf as early as age 10, and continue to produce offspring until their early 40s.
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21.06.2019 | Friedrich-Schiller-Universität Jena
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19.06.2019 | Julius-Maximilians-Universität Würzburg
From June 25th to 27th 2019, the Fraunhofer Institute for Digital Media Technology IDMT in Ilmenau (Germany) will be presenting a new solution for acoustic quality inspection allowing contact-free, non-destructive testing of manufactured parts and components. The method which has reached Technology Readiness Level 6 already, is currently being successfully tested in practical use together with a number of industrial partners.
Reducing machine downtime, manufacturing defects, and excessive scrap
The quality of additively manufactured components depends not only on the manufacturing process, but also on the inline process control. The process control ensures a reliable coating process because it detects deviations from the target geometry immediately. At LASER World of PHOTONICS 2019, the Fraunhofer Institute for Laser Technology ILT will be demonstrating how well bi-directional sensor technology can already be used for Laser Material Deposition (LMD) in combination with commercial optics at booth A2.431.
Fraunhofer ILT has been developing optical sensor technology specifically for production measurement technology for around 10 years. In particular, its »bd-1«...
The well-known representation of chemical elements is just one example of how objects can be arranged and classified
The periodic table of elements that most chemistry books depict is only one special case. This tabular overview of the chemical elements, which goes back to...
Light can be used not only to measure materials’ properties, but also to change them. Especially interesting are those cases in which the function of a material can be modified, such as its ability to conduct electricity or to store information in its magnetic state. A team led by Andrea Cavalleri from the Max Planck Institute for the Structure and Dynamics of Matter in Hamburg used terahertz frequency light pulses to transform a non-ferroelectric material into a ferroelectric one.
Ferroelectricity is a state in which the constituent lattice “looks” in one specific direction, forming a macroscopic electrical polarisation. The ability to...
Researchers at TU Graz calculate the most accurate gravity field determination of the Earth using 1.16 billion satellite measurements. This yields valuable knowledge for climate research.
The Earth’s gravity fluctuates from place to place. Geodesists use this phenomenon to observe geodynamic and climatological processes. Using...
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