Dog
The domestic dog exists in a state of profound ecological dependency. Without human support, most breeds would perish within weeks. Those that survive as feral animals do so by scavenging human waste or, in rare cases, reverting to pack hunting behaviours. They have traded ecological independence for guaranteed meals and central heating.
Climate change, food system disruption, or civilizational collapse would render the domestic dog critically vulnerable. The species has bet everything on humanity's continued success, a wager that may prove unwise depending on subsequent centuries.
Kangaroo
The kangaroo has survived 20 million years of planetary upheaval, including ice ages, continental drift, and the arrival of humans bearing spears. Its population currently numbers approximately 50 million individuals, a figure that fluctuates with rainfall but demonstrates robust resilience to environmental variability.
The species requires only grass, water, and space, resources that exist in abundance across the Australian continent. Kangaroos have outlasted the megafauna that once shared their habitat, the indigenous hunting cultures that pursued them, and the pastoral agriculture that displaced their grazing lands. They show every indication of continuing to hop across Australia long after whatever concerns us today have become geological footnotes.