Lizard gender bends at altitude: Study

Tasmanian lizard has different ways of determining sex of its offspring, depending on the altitude.

Melbourne: Scientists claimed to have discovered that a small Tasmanian lizard has different ways of determining the sex of its offspring, depending on the altitude.

At low altitudes, the lizard`s gender is determined by temperature, while at high altitudes where the climate is more extreme, it`s all down to their genes, ABC reported qouting a
study in "Nature".

Researchers from Australia, the United Kingdom and the Netherlands studied what happened when the snow skink, Niveoscincus ocellatus, which lives at a range of different altitudes in Tasmania, got pregnant or gave birth under different temperature conditions.

One of the authors, Erik Wapstra from Tasmania University said the first reptile, and only the second animal species, ever shown to have two types of sex determination in
different populations.

The snow skink is a small six centimetre long lizard which lives in coastal and sub-alpine areas beneath rock slabs, eating insects and wild berries.

It gives birth to live young rather than laying eggs, producing between one and six babies.\

Previous research showed that the sex of baby skinks is determined during the first half of the pregnancy, depending on how long the mother remains in warm sunshine.

Warm temperatures generally produce females, while cooler temperatures produce males.
The researchers took heavily pregnant females from both the lowland and highland populations and put them in cages in the lab until they gave birth.

The sex ratios of the offspring were recorded. They also collected females who had just become pregnant - before the sex of the offspring had been locked in - from both populations.

Each group was split in two, with one subgroup exposed to 10 hours of sunshine per day, and the other group to only four hours of sunshine per day.

The researchers found that lowland mothers had very different ratios of boys to girls, depending on how much sunshine they had.

By contrast, the highland mothers showed no difference in sex ratio of offspring, regardless of how long they spent in the Sun Based on data collected in the field, the
researchers developed a model to predict how these lizards would evolve over thousands of years.

The model showed that the divergence of sex determination mechanisms was caused by temperature differences, Wapstra said.


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