Lizard sex linked to climate

Oct 28, 2010
A snow skink (Niveoscincus ocellatus), whose sex is linked to climate

(PhysOrg.com) -- A Tasmanian lizard has evolved to give birth to more male or more female offspring depending on climatic conditions, Oxford University scientists have discovered.

The snow skink (Niveoscincus ocellatus) is a small lizard that lives in both the warm lowlands and cooler highlands of . New research shows that while at high altitudes skinks give birth to an equal ratio of sons and daughters, at lower altitudes the produce mainly sons when it is cool and cloudy and favour daughters when it is sunny and warm.

A report of the research is published in this week’s Nature.

‘What we have found is that this single species of lizard has evolved two different ways of determining the sex of its , one based on genetics, the other controlled by temperature,’ said Dr Tobias Uller of Oxford University’s Department of Zoology, an author of the report. ‘Our results help to explain how can interact with the fundamental biology of animals, and how in animal populations this can cause a rapid shift between different mechanisms for determining sex.’

In the cooler climate of high altitudes, around 1000m, there is little evolutionary advantage in skinks favouring one sex over another as the cold conditions mean that all offspring develop slowly and neither sex can get a ‘head start’ – so skinks produce an equal ratio of sons and daughters.

At warmer lower altitudes close to sea level, however, choosing to produce daughters early in the season in warmer years means female offspring get a ‘head start’ and are able to grow larger and mature earlier than any late-born rivals (large body size is less important for male skinks).

‘Snow skinks give birth to live young but our research shows that they have evolved a way of changing the sex of their offspring to match climate conditions in a similar way to their egg-laying cousins,’ said Dr Uller. ‘Our results suggest that temperature-dependent sex determination can evolve in cold-blooded animals whenever there is an advantage in offspring of a particular sex being born or hatched earlier. As climate often influences whether such advantages exist, climatic variation seems to be an important factor in causing evolutionary shifts in sex determination.’

Explore further: Pollen on birds shows feeding grounds

Related Stories

Boy or girl? In lizards, egg size matters

Jun 04, 2009

Whether baby lizards will turn out to be male or female is a more complicated question than scientists would have ever guessed, according to a new report published online on June 4th in Current Biology. The study shows that f ...

Diet prior to pregnancy determines sheep's gender

Jun 09, 2008

Maternal diet influences the chances of having male or female offspring. Research published today in BioMed Central's open access journal Reproductive Biology and Endocrinology has demonstrated that ewes fed a diet enrich ...

Small But Mighty Female Lizards Control Genetic Destiny

Apr 05, 2010

(PhysOrg.com) -- "Be faithful in small things because it is in them that your strength lies." Mother Teresa's words echo throughout the world. They ring particularly true in the biological kingdom among brown ...

Researcher finds Laysan albatross employs 'dual mommies'

May 28, 2008

What's a girl to do if there's a shortage of males and she needs help raising a family? The Laysan albatross employs a strategy called reciprocity, where unrelated females pair together and take turns raising offspring.

Recommended for you

Calcium and reproduction go together

Aug 22, 2014

Everyone's heard of the birds and the bees. But that old expression leaves out the flowers that are being fertilized. The fertilization process for flowering plants is particularly complex and requires extensive communication ...

User comments : 0