By Kimberley Collins 17/08/2016 1


Dr Helen Taylor is one of thirteen scientists from New Zealand who have entered Thinkable’s 180 seconds of science and is using the opportunity to talk about bird sperm.

The competition, supported by the Royal Society of New Zealand, gives early career researchers a unique opportunity to share their passion for innovative research in a 3 minute video.

Helen’s video investigates what bird sperm and genetic diversity can tell us about the extinction risk of wildlife populations.

What is your video about?

My research explores the link between bottlenecks, inbreeding and reduced reproductive success in birds. We know inbreeding is linked to poor egg hatching success in many bird species, but it’s not known whether this is due to poor male fertility or other issues.  To find out what’s causing the problem, I am measuring bird sperm quality and relating it back to genetic diversity and inbreeding.
One of Helen's study species, the South Island Robin (Photo by Craig McKenzie)
One of Helen’s study species, the South Island Robin (Photo by Craig McKenzie)

Why are so many of our bird populations inbred?

Often, when there’s a drastic reduction in the population size because of predators, habitat loss, or other factors, only a few birds make it through to the other side of this population bottleneck and they can’t carry all the genetic diversity with them.

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An infographic from Helen’s video showing how predators can create a bottleneck in bird populations and reduce genetic diversity.

 

Because we’re also moving birds to predator-free sanctuaries, and can only take a few at a time, there are secondary bottlenecks to consider as well.

What impact does inbreeding have on our native species?

Inbreeding can leads to poor reproductive success and poor survival, which is obviously a problem when you’re trying to breed endangered species. But we can’t fix that problem until we know what causes it.

And what causes poor hatching success?

We’re not sure, but at the moment my research is trying to find out if some male birds are firing blanks or sperm that aren’t able to fertilise eggs as well. We’re taking sperm samples from hihi (stitchbird) and South Island robins.

So how does one collect bird sperm?

A male bird's cloaca will swell with sperm during mating season (Photo by Robyn White)
A male bird’s cloaca will swell with sperm during mating season (Photo by Robyn White)
Helen in the Mobile Laboratory where sperm samples are tested (Photo by Robyn White)
Helen in the Mobile Laboratory where sperm samples are tested (Photo by Robyn White)

Getting sperm samples from birds is tricky. In most bird species, males don’t have a penis – just a hole called the cloaca. During mating season, the male’s cloaca becomes swollen. By gently squeezing it, we can collect a small amount of semen.

We take the sperm sample to a mobile laboratory and put it under a microscope with a video camera that feeds into a laptop. Software on the laptop measures how fast each sperm is swimming and whether it’s going in a straight line or round and round in circles.

Then we take the samples back to the University laboratory and take high-magnification photographs of individual sperm. We measure them and check for abnormalities that might stop them from fertilising an egg. Some might be missing a head, have a broken tail or be shorter than normal.

We also take blood samples to extract DNA and look at the genetic diversity and impact of inbreeding on individual birds and populations.

What does this mean for conserving our native species?

When I am finished, I hope to determine whether inbreeding is causing a problem for male fertility in hihi and South Island robin. If it is, the next step will be to  try and identify the specific parts of the genome being affected so we can manage these and other threatened species more effectively.

You have until 22 August to vote for Helen’s video on bird sperm and conservation.

Check out the full list of entries from New Zealand below:


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