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
Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel
Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)
Magnetic resonance imaging, or MRI, is a widely used medical tool for taking pictures of the insides of our body. One way to make MRI scans easier to read is...
At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.
Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
26.04.2018 | Medical Engineering
26.04.2018 | Power and Electrical Engineering
26.04.2018 | Information Technology