Sunday, 5 February 2012

Ston(e)y Creek frogs revisited


[Update: You can see Litoria jungguy males and females at Wild Wings & Swampy Things.]
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‘Went out spotlighting in the garden last night. Saw some Litoria jungguy.’

‘How do you know?’

‘?’
‘They’re impossible to tell apart from wilcoxii. ‘

‘This map here shows only L. jungguy in this area.’

‘But how do you know that you’ve got jungguy?’

‘I don’t care.’

‘And you call yourself a taxonomist...’


What was known as Lesueur’s frog (Litoria lesueuri Dumeril and Bibron, 1841) was long suspected to have actually been a group of species. No one was sure exactly how many species made up this anuran Legion, because they were impossible to tell apart just on appearance alone. In 2004, Steve Donnellan and Michael Mahony took a closer look at the frogs. Using allozyme electrophoresis and karyotype analysis, they cracked this conundrum.

Lesueur’s frog as-was had a wide distribution along the east coast from Far North Queensland to eastern Victoria and occurred in a range of habitats from sea level to mountain top (where mountains are less than 1200 m). Donnellan and Mahony identified three distinct species — yer genuine Litoria lesueuri from Victoria and southern NSW, Litoria wilcoxii Gunther, 1864, from southern NSW to Far North Queensland, and an undescribed Far North + mid-east Queensland species that they named Litoria jungguy. To confuse things more, both L. wilcoxii and L. jungguy are known as the Stoney Creek frog.

The ranges of the two Stoney Creek frogs overlap, but populations appear to be separated by habitat. Litoria junguuy seems to prefer rainforest, whereas L. wilcoxii lives in sclerophyll (eucalypt) forest. But the two species are also known to hybridise, which would suggest that they are not completely isolated by their specific habitat requirements. We all know what frogs are like*.

I plotted the distributions using data from NQ and FNQ in Donnellan and Mahony (2004). (Their map is difficult to read on screen.) According to their records, the two species have reasonably discrete core ranges. Hybridisation in this area only occurs along the western edge of the Atherton Tablelands, where rainforest gives way to wet sclerophyll forest. Interestingly, it does not appear to be an inevitable consequence of populations meeting, because no hybrids were found at Granite Creek (white spot). This might reflect the actual situation or be a function of sample size. Needs moar material.

L. wilcoxii = yellow
L. jungguy = blue
hybrids = green
co-occurence = white

So, on the basis of this, I am not at all confident that the Stoney Creek frogs at my place are Litoria jungguy Donnellan and Mahony, 2004, karyoptype analysis or not. I'm hoping that someone will revisit these species with a DNA lab and a few more specimens. I'll lay a very small amount of money on the mid east Queensland population being a different species altogether.

(If this work has already been done and I've overlooked it, let me know. It won't be the first time.)

Reference
Donnellan, S. C. and Mahony, M.J. (2004). Allozyme, chromosomal and morphological variability in the Litoria lesueuri species group (Anura: Hylidae), including a description of a new species. Australian Journal of Zoology 52: 1 - 28.

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* Rabbits.

4 comments:

Denis Wilson said...

I has hoping for a few sticky frog photos.
But you are going for DNA analysis.
Best of luck getting species IDs.
Cheers
Denis

Snail said...

I had some photos but I accidentally deleted them! Mind you, they were all of the local species, so probably wouldn't have helped me much.

laurak@forestwalkart said...

hmmmmm...so you accidentally deleted the frog photos, you say.

are you sure they just didn't happen to be photos that were taken while the frogs were acting like rabbits...and...uh...maybe you thought they would be a little risque?

good luck with your DNA stuff...i hope you get it figured out...and you're prob right!

Snail said...

You've worked it out!

Sadly, no, they were pics that I uploaded to the old version of blogger but didn't use. And then I somehow lost them while writing the post. Aaaargh!