Yesterday morning I stumbled across a paper in TREE by Calboli et al. (2011) that calls for scientists to start an amphibian genome project. This got me thinking about amphibians; how fascinating they are, and simultaneously, how much trouble they’re in.
They’re super cool because (as the name implies) they bridge aquatic and terrestrial living (amphi + bio = both + life). Kind of like olympic swimmers… maybe instead of swimming levels like “blue”, “dolphin”, and “shark” they should use “tadpole”, “frog”, and “salamander”! Check out the Japanese Giant Salamander (1.5m), or the Chinese Giant Salamander (1.8m). These fellas are forces to reckon with. Amphibians were also the first vertebrates to drag themselves out of primordial seas to gulp down air 360 million years ago, which means they could tell us a lot about the evolution of life across our little blue planet!
However, if you clicked the Chinese Giant Salamander link, you may have noticed that on the right side Wikipedia lists the conservation status according to IUCN (International Union for Conservation of Nature) which places them as critically endangered (CR). The sad side of the amphibian story is that a lot of them are in trouble: 41% of them are ‘threatened’ or worse. As Calboli et al (2011) points out, that is more than ANY other vertebrate group.
It seems to me that amphibians are especially sensitive to changes in their environments, and since they live in TWO types of environment simultaneously, changes in either habitat can mess with them. Roads and cars will kill them as they move between ponds, acid rain and pesticides will change water chemistry so that they can’t breath properly through their skins, introduced pathogens and fungi kill them in droves all across the world, droughts and climate change dry up their wetlands. Humans intentionally dry up their wetlands too. When I was in elementary school my best friend at the time lived next to a massive swamp in Toronto (Scarborough). When developers wanted to buy the land and turn it into retail space, she and her brother rallied the community and got petitions signed to let the swamp stay. I remember them celebrating – the swamp was saved!! Today there is a Home Depot there. What happened?
When I was a kid we used to tromp about in this swamp wearing big wellington boots (often loosing them to the sticky mud!) and catching tadpoles. Its devastating to me that my friend’s children and their children probably wont have that experience. Even if there are swamps to play in still, pulling out tadpoles to watch how they slowly grow little legs and get bigger and bigger at the front while their tails get smaller and smaller until it’s not a tadpole at all… well, that will be out of the question as they become more threatened. Its devastating because these (sometimes not so little) creatures can tell us so much about why and how life as we know it got to be here. But that window is closing.
I know that there are some captive breeding programs (like at the Toronto Zoo) but there are so many problems with captive breeding in general… For example they often run into inbreeding depression (not enough genetic material to maintain within-species diversity and negative genetic problems begin to surface that eventually decrease survivorship in the captive population). The ultimate goal of captive breeding is supposed to be re-introduction, but that has a whole mess of it’s own problems. If you somehow dodge killing your captive population with diseases or inbreeding, and successfully teach them the skills they need in the wild, then you often need to introduce thousands of individuals a year over multiple years to get them to establish in the slightest. This is all assuming that you can return them to the wild at all; often times there is nowhere to reintroduce them TO because of habitat loss! And then, what’s to stop the same problems that killed them off in the first place from killing them again, making all this work and investment pointless?
Last year I went on a field trip where I heard about captive conservation programs. One thing they told us is that conservation plans are put together to maximize the within-species genetic diversity over a specific time period. To do this, they drag out generation times as long as possible because as soon as an individual mates and has offspring, that offspring represents half of the genetic information that was in the parents (let me know if you want an explanation of why). To keep the greatest amount of genetic diversity for the longest time, they want fewer generations in that period of time. The problem with that is that even though there is more genetic diversity, there are fewer individuals… these species are essentially museum pieces! Sure, they’re alive, but they’re not increasing the population… it feels like a patch, not a fix.
That being said, it’s still these are still the best options available for species that are extinct in the wild. Theoretically there HAVE been a couple of successful reintroductions; Arabian oryx, black footed ferrets, and California condors to name a few. Just because it may not work does not mean we shouldn’t try. Every success is justification for many many more attempts. Besides, captive breeding is supposed to be a last resort, for many amphibian species, the situation is not that desperate yet.
So what can we do? Look for programs like Frog Watch Ontario (sorry, I don’t know what they do in BC yet, I haven’t been here long enough), support conservation programs, fight against wetland destruction, and for goodness sake, don’t pick up frogs. They don’t like that. And it’s not so great for you either.