It would make sense for cryonics orgs. to preserve as many endangered species as possible. We should work to rescue other life-forms from oblivion, as well as ourselves. Not only are all life-forms on the planet connected and interdependant (Gaia hypothesis), but we also owe these other points of consciousness and feeling - having brought them to the verge of the void - as well as unborn future generations, who have not yet sprang from non-existence, from our animal loins.
Life-extension must provide for all earthly life, otherwise our struggle for long-life may take us through a century of mass-extinction, only to find ourselves still alive but on a dead rock with only rats, maggots, and domesticated animal for company.
I expect there would be many practical difficulties though. Aside from financial issues (who would pay for it?**), we'd have to aquire the last few individuals of an endangered species (difficult, as they'd be very expensive, very rare, or in someone else's charge) - we'd also have to keep up with the present rate of extinctions and habitat despoilation:
"By conservative reckoning, the planet loses three or four species an hour, eighty or more a day, thirty thousand a year - the highest extinction rate in 65 million years." (Richard Ellis "No Turning Back - the life and death of animal species" 2004 Harper Collins p357)
If cryonicists are ever revived, we might find the spores in our frozen hair, and the undigested meat or plant matter in our stomachs, or even some of the microbes preserved in our bodies, more valuable than our own commonplace lives.
(**Why bother with this? We can just take their DNA and clone them later - indeed, preparation for this project is underway.
http://www.google.ca...red genes&meta=
But I do not think this is enough. It will preserve the biological lineage of present species (those that are rescued anyway), but they would be born without their original habitat, or even given that, they will have no living culture, no older generation from which to learn vital knowledge and copy important behaviours. Many re-introduced species without this guidance quickly become endangered again because they do not know how best to survive. This is why I think it is important to cryopreserve individual animals and not just species DNA.
Imagine what would happen to human babies raised by non-human intelligence too remote to understand - these infants would have no real language and no cultural inheritence. In the wild they would probably die, and all human history would have been wiped out, save for any surviving record.)