The study’s results call into question current understanding of the development of male and female foetuses of this species, and give scientists a new insight into the importance of sibling sex and what implications this may have for the animals as they mature.
This study shows that when a female is pregnant with mixed-sex twins, the male foetus does not undergo the substantial amount of growth that occurs in a male foetus with a brother, resulting in a sub-optimal birth weight. Saiga males mate with many females and face strong male-male competition during short mating seasons. This means that size matters for males - being smaller than average is one of the major limiting factors for reproductive success.
Aline Kühl from Imperial College London’s Division of Biology, lead author of the paper, explains that although they do not yet understand the precise mechanism behind this suboptimal development in male twins, its existence is clear. “When siblings in a litter vary in sex, maternal investment should be sex-specific, meaning that the male foetus grows bigger than the female. However, it seems there are limitations in the ability of the mother to provision mixed twin litters in the womb,” she said.
The researchers point out that mixed-sex litters have been shown to have an impact on animal health elsewhere in the animal world. In dairy cows for example, it is well known that calves from mixed litters are less fit. Female heifers from mixed litters are generally infertile. But unlike dairy cows, in cases of saiga mixed-sex twins, the male foetus appears to be worse off, not the female.
Aline adds that the effect of size on male saigas later in life cannot be underestimated: “Even a relatively small decrease in birth weight is likely to have an amplified negative effect on male reproductive fitness in species where competition amongst males for mates is very high.”
The saiga antelope provides scientists with an ideal opportunity to investigate the effects of mixed-sex twin litters on size and development, because there are a high proportion of twin births in the population, and because the optimal birth weight for males and females of the species are dramatically different.
The researchers’ study of female saigas and their young also showed that they invest more in their pregnancy than any other hoofed mammal, with some mothers carrying young up to 38% of their own body weight.
The research was carried out on populations of saiga antelopes living on the Eurasian steppe in the autonomous Republic of Kalmykia, Russia. Data from saiga antelope monitoring during Soviet times from the Betpak-dala saiga population in Kazakhstan were also analysed. Both data sets are from different populations of saiga, from both before and after the recent extreme decline in saiga numbers – yet the results of both datasets are qualitatively the same.
The research team, alongside local rangers, weighed and measured saiga calves during the birth season in May over a period of three years. Saiga have a mass calving behaviour, whereby females come together in a densely packed herd to all give birth within a week. This makes it relatively easy to monitor the reproductive state of the population. Such monitoring has become vital since saiga have seen a dramatic decline in numbers of over 95% in recent years, making them one of the most critically endangered species on earth.
Future research will investigate what role sibling sex plays for lifetime reproductive success. The monitoring protocol of saiga antelopes is currently being improved to include non-invasive methods for monitoring to determine fecundity rates (from faeces analysis).
In order to restore saiga antelope populations Imperial’s Dr. E.J. Milner-Gulland, Aline Kühl and long-term colleagues in the saiga’s range states have recently set up the Saiga Conservation Alliance. To find out more visit http://www.iccs.org.uk/SaigaAlliance.htm
Danielle Reeves | alfa
Safeguarding sustainability through forest certification mapping
27.06.2017 | International Institute for Applied Systems Analysis (IIASA)
Dune ecosystem modelling
26.06.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
27.06.2017 | Power and Electrical Engineering
27.06.2017 | Information Technology
27.06.2017 | Physics and Astronomy