The Wonders of Convergence

One of the most captivating things about evolution is its propensity to produce identical twins on opposite sides of the globe. Species that are near inseparable morphologically, ecologically and behaviorally, but which have very different DNA. They don’t have common forebears, at least not recent ones. Instead, having been buffeted by equivalent forces over the millennia, and run a parallel race of natural selection, they’ve reached the same evolutionary sweet spot. They’ve been sculpted by the same chisel and converged.

The wonders of convergence were bought home to me again this week while working on a paper I’ve been meaning to write for some time. It concerns the phenology of mate-calling among frogs from my home town of Melbourne, in southern Australia (‘phenology’ being the timing and determinants of periodic biological events). In my ramblings through the literature, I came across a great paper by Daniel Saenz and colleagues on the phenology of mate-calling in a community of frogs from eastern Texas. Texas, that’s roughly 14,000 km from Melbourne, on the other side of the world’s greatest ocean. And yet, what Saenz et al. had to say about the frogs they studied sounded very familiar. Oddly familiar.

And so, with Google’s help, I set to work looking up these Texan amphibians. Surprise, surprise, they are the same frogs I work on 14,000 km away. Quite unrelated phylogenetically, but counterparts nonetheless. Take a look for yourself. In the following pairs of photos, the Australian species is on the left and its Texan analogue on the right. It’s incredible, isn’t it?

Whistling Tree Frog, Litoria verreauxii

Whistling Tree Frog, Litoria verreauxii

Western Chorus Frog, Pseudacris triseriata

Western Chorus Frog, Pseudacris triseriata

 

 

 

 

 

 

Growling Grass Frog, Litoria raniformis

Growling Grass Frog, Litoria raniformis

Common Bullfrog, Rana catesbeiana

Common Bullfrog, Lithobates catesbeiana

 

 

 

 

 

 

 

Common Froglet, Crinia signifera

Common Froglet, Crinia signifera

Northern Cricket Frog, Acris crepitans

Northern Cricket Frog, Acris crepitans

 

 

 

 

 

 

Peron's Tree Frog, Litoria peronii

Peron’s Tree Frog, Litoria peronii

Gray Tree Frog, Hyla versicolor

Gray Tree Frog, Hyla versicolor

 

 

 

 

 

 

Sudell's Frog, Neobatrachus sudelii

Sudell’s Frog, Neobatrachus sudelii

Eastern Spadefoot Toad, Scaphiopus holbrookii

Eastern Spadefoot Toad, Scaphiopus holbrookii

 

 

 

 

 

 

Spotted Marsh Frog, Limnodynastes tasmaniensis

Spotted Marsh Frog, Limnodynastes tasmaniensis

Southern Leopard Frog, Rana sphenocephala

Southern Leopard Frog, Lithobates sphenocephala

 

 

 

 

 

 

 

Photo sources (those not listed are my own):

Western Chorus Frog –  calphotos.berkeley.edu, photographer Todd Pierson.
Common Bullfrog – http://www.discoverlife.org/, photographer unknown.
Northern Cricket Frog – https://www.flickr.com/photos/52463647@N08/, photographer Melville Osborne.
Gray Tree Frog – http://www.californiaherps.com/noncal/misc/miscfrogs/pages/h.versicolor.html, photographer Gary Nafis.
Sudell’s Frog – www.stewartmacdonald.com.au, photographer Stuart MacDonald.
Eastern Spadefoot Toad – http://www.discoverlife.org/, photographer Todd Pierson
Spotted Marsh Frog – http://bwvp.ecolinc.vic.edu.au/fieldguide/fauna/spotted-marsh-frog, photographer Craig Cleeland
Southern Leopard Frog – http://www.frogforum.net/, photographer John Clare

A Natural High

P1000983Tell me this – have you ever taken drugs? Yes? No? The answer depends on one’s definition, but I’ll bet that many of you will admit to dabbling in some form of stimulant. We are, as a society, obsessed with them. Dark aromatic shots of plant extracts; delicate paper tubes delivering wafts of nicotine; colourful vessels of molten sand filled with fermented fruit juice; little polyethylene baggies carrying a fine dust of crystalline tropane alkaloids. We have employed all our ingenuity in search of a high.

Why? Let me give you my theory. I think our craving for stimulants is an attempt to the replace the pulses of endorphins that once accompanied our daily rambling in the wilds. I can honestly say that nature has given me by far the biggest highs of my life. I’ve stood at the edge of Mt Meg’s spectacular granite bluffs, with blood coursing and nostrils flaring, and believed that I could soar off if only I had the courage to jump. I’ve perched atop dunes of the Big Desert and felt my skin tingle with awe. I’ve stood waist deep in the Merri Creek with a full moon overhead and frogs calling all around, and been so fulfilled that if I’d slipped into the murky depths at that very instant, I would have died happy.

My most recent of these experiences was also the most profound. It was March 2011. La Niña had just prized southern Australia loose from El Niños’ grasp, bringing rain and plenty of it. The Murray-Darling catchment, wilting and gasping after ten years of drought, was reborn. Floods spread across every inch of the basin, coalescing at the junction of the Murray and Darling Rivers in Victoria’s north-west. With haste, my old friend Jeremy Tscharke and I packed the car and headed north to glimpse the spectacle. What we found eclipsed even our wildest dreams. 

Land that two years before was literally dying of thirst was now heaving with life. Supposedly long dead Red Gums re-sprouted in effervescent green. Wetlands that we presumed had seen their last flood years before now brimmed with fish and turtles. Frogs reclaimed the flood plain in such numbers that one had to be careful where they placed their feet. It was stunning, and a truly humbling experience.

The climax was a sunset that Jeremy and I will never forget. We’d headed up a flooded Lindsay River in search of ‘Big Red’ – a Red Gum of gargantuan proportions we’d seen previously on aerial imagery. We found her just as the sun dipped below the western horizon. The sky progressed through golden, to pink and eventually to deep violet. As we marveled at this great tree, we talked about the history it had seen. Big Red would already have been a towering giant when Captain Cook sailed up Australia’s eastern seaboard. She could well have sheltered families of Aboriginal people from inclement weather, and her hollow limbs must have once been home to regionally extinct marsupials. Undoubtedly, she has seen scores of floods of the scale of the 2011 epic. This tree was, quite simply, a living piece of history that we could touch and caress and imbibe. We had found our Totem, and returned to camp with a sense of bliss that no substance could ever hope to replicate.

Dwarfed by Big Red

Dwarfed by Big Red. A little shaky, but steady hands are hard to come by under this beauty. Photo: J. Tscharke

Sunset on the Lindsay River I. Photo: J. Tscharke

Bliss I. Photo: J. Tscharke

Sunset on the Lindsay River II. Photo: J. Tscharke

Bliss II. Photo: J. Tscharke

Sunset on the Lindsay River III. Photo: J. Tscharke

Bliss III. Photo: J. Tscharke

Code and data

Picture3For some time now I’ve been thinking about using this website as a platform for sharing statistical code and data from papers that I’ve published. Well, I’ve finally made a start – take a peak at my imaginatively named new page ‘Code and data’

I’ve got two primary motivations for uploading code and data from my papers. The first is that I’ve benefited on numerous occasions from the generosity of others who have shared their code with me. From supplementary material in published papers to emails with bits of code I’ve requested, I simply could not have completed some of my research without these generous offerings. I hope to return that favour here.

The second reason is that I want the data I’ve collected to be available to others, either for further dedicated analyses or for use in meta-analyses. The further I go through my career the more I realise just how precious data are. The time, effort and money required to gather field data is perhaps evidence enough. Sadly though, recent experience has taught me just how quickly one’s data can become a vital record of what was once was.

So, swing over to ‘Code and data’ and take a look. I’ll update the page as new papers come out, and work on filling in my back catalogue over the next few months.

Just one request – if you use the code or data presented on this website, please cite the relevant paper, or, if there isn’t one to cite, cite this website instead.

Enjoy!

Conservation photos, part II: Big Desert

I’m a big fan of the Big Desert. It’s a subtle place. Like a grassland, you have to get up close and personal with it to discover its treasures. It has no towering trees, no roaring waterfalls, no charismatic megafauna. It is miles and miles of rolling sand dunes and Mallee heath. After a fire, it is white sand and black sticks, little else. And yet the Big Desert is a biodiversity wonderland. Ants, scorpions, centipedes, bees, wasps, butterflies, moths, cicadas. The insects hum day and night. As do the reptiles that chase them, and each other…

Thick-tailed Gecko, Underwoodisaurus milii

Thick-tailed Gecko, Underwoodisaurus milii

 

 

 

 

 

 

 

 

 

Lined Worm Lizard, Aprasia striolata

Lined Worm Lizard, Aprasia striolata

 

 

 

 

 

 

 

 

 

A sample of Mallee heath

A sample of Mallee heath

 

 

 

 

 

 

 

 

 

Mitchell’s Short-tailed Snake, Parasuta nigriceps

Mitchell’s Short-tailed Snake, Parasuta nigriceps

 

 

 

 

 

 

 

 

 

 

Burton's Legless Lizard, Lialis burtonis

Burton’s Legless Lizard, Lialis burtonis

 

 

 

 

 

 

 

 

 

Marbled-faced Delma, Delma australis

Marbled-faced Delma, Delma australis

 

 

 

 

 

 

 

 

 

Wood Gecko, Diplodactylus vittatus

Wood Gecko, Diplodactylus vittatus

 

 

 

 

 

 

 

 

 

Bardick, Echiopsis curta

Bardick, Echiopsis curta

 

 

 

 

 

 

 

 

 

 

Eastern Spiny-tailed Gecko, Strophurus intermedius

Eastern Spiny-tailed Gecko, Strophurus intermedius

 

 

 

 

 

 

 

 

 

And to finish - sunset, Big Desert style.

And to finish – sunset, Big Desert style.