Like the first vertebrates to crawl from the ocean and onto dry land 500 million years ago, Donald Trump emerged from the primordial ooze of reality TV to be elected president of the United States in 2016. And like an invasive species, the star of “The Apprentice” has wreaked havoc on his new ecosystem — declaring war on immigrant communities, doubling down on climate-change denial and weaponizing the federal government against his political enemies.