Sex and age-biased nematode prevalence in reptiles

Aug 04, 2014
Sex and age-biased nematode prevalence in reptiles

Rising testosterone levels in male slow worms at breeding season may make them more susceptible to infections, say NERC-funded scientists.

The study, published in Molecular Ecology, looked into whether nematodes – parasites like roundworms - affect more male or more female slow worms.

They found that more male slow worms contracted the parasite overall, and that this was even higher during the – the first example of testosterone suppressing a slow worm's immune system.

'Slow worms are a common reptile in the UK, but there's not many studies so we don't know much about them,' says Dr David Brown of Cardiff University, lead researcher on the study.

The team had been looking into the slow worms' diet using molecular tools to analyse the animals faeces for DNA to determine which species they'd been eating. During this study they noticed that there were also lots of in the faeces.

'If you're not a taxonomist it's really difficult to identify parasitic species as many of them look very similar so we wanted to prove we could develop a tool to make screening or monitoring parasitism in species easier,' Brown says.

'I collected the faecal samples for the diet study by pulsating the animal until it defecated in my hand. Using DNA analysis to investigate diet is quite a cheap, simple, non-invasive process so I wondered if I could use it to look at parasitism as well,' he says.
Testosterone is known to act as an immunosuppressant, so the team were expecting to find that the males were more susceptible to the parasite. But they were surprised to find that the samples collected in April had more parasites than those collected later in the year.

'The samples collected later on had more equal numbers of between the males and females,' explains Brown. 'April is their breeding season so the theory is that during breeding season the slow worms have more testosterone, which can surpress their immune system and make the animal more susceptible.'

While nematodes are known to be a parasite the researchers aren't sure what damage they cause to the worms during breeding season.

'The larger, older slow are less likely to have the parasite. This is either because they've built up immunity or because the parasite is killing them and removing them from the population so we're not finding them. If the latter is the case then it suggests longer term detriment, but this study can't confirm that,' says Brown.

The team are now hoping to study a different species of nematode that also affects the slow worm to better understand the relationship between the two types of parasite and find out if contracting one makes the animal more likely to contract the other.

Explore further: 'Killer sperm' prevents mating between worm species

More information: Brown, D. S. and Symondson, W. O. C. (2014), "Sex and age-biased nematode prevalence in reptiles." Molecular Ecology, 23: 3890-3899. DOI: 10.1111/mec.12688

Related Stories

Dracunculus insignis infection found in cats

Feb 20, 2014

When Cornell veterinarians found half-foot-long worms living in their feline patients, they had discovered something new: The worms, Dracunculus insignis, had never before been seen in cats.

'Killer sperm' prevents mating between worm species

Jul 29, 2014

The classic definition of a biological species is the ability to breed within its group, and the inability to breed outside it. For instance, breeding a horse and a donkey may result in a live mule offspring, ...

Parasitic worm genome uncovers potential drug targets

Aug 28, 2013

Researchers have identified five enzymes that are essential to the survival of a parasitic worm that infects livestock worldwide and is a great threat to global food security. Two of these proteins are already ...

Exploring a parasitic tunnel boring machine

Jun 15, 2014

Researchers have deduced essential biological and genetic information from the genome sequence of the whipworm, an intestinal parasitic worm that infects hundreds of millions of people in developing countries.

Recommended for you

The math of shark skin

5 hours ago

"Sharks are almost perfectly evolved animals. We can learn a lot from studying them," says Emory mathematician Alessandro Veneziani.

Seafaring spiders depend on their 'sails' and 'anchors'

10 hours ago

Spiders travel across water like ships, using their legs as sails and their silk as an anchor, according to research published in the open access journal BMC Evolutionary Biology. The study helps explain how sp ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.