Question: Why is a relatively high diversity of wildlife species supported in Yosemite?
About the article "Yosemite National Park", section "Habitats".

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With its scrubby sun-baked chaparral, stately groves of pine, fir, and sequoia, and expanses of alpine woodlands and meadows, Yosemite National Park preserves a Sierra Nevada landscape as it prevailed before Euro-American settlement.
In contrast to surrounding lands, which have been significantly altered by logging, the park still contains some of old-growth forest.
Taken together, the park's varied habitats support over 250 species of vertebrates, which include fish, amphibians, reptiles, birds, and mammals.
Along much of Yosemite's western boundary, habitats are dominated by mixed coniferous forests of Ponderosa Pine, Sugar Pine, Incense-cedar, White Fir, Douglas Fir, and a few stands of Giant Sequoia, interspersed by areas of Black Oak and Canyon Live Oak.
A relatively high diversity of wildlife species is supported by these habitats, because of relatively mild, lower-elevation climate and the mixture of habitat types and plant species.
Wildlife species typically found in these habitats include American black bear, Bobcat, Cougar, Gray fox, Mule deer, Mountain kingsnake, Gilbert's skink, White-headed Woodpecker, Brown Creeper, Spotted Owl, and a wide variety of bat species.
In the case of bats, large snags are important as roost sites.
Going higher in elevation, the coniferous forests become purer stands of Red Fir, Western White Pine, Jeffrey Pine, Lodgepole Pine, and the occasional Foxtail pine.
Fewer wildlife species tend to be found in these habitats, because of their higher elevation and lower complexity.
Species likely to be found include Golden-mantled Ground Squirrel, Chickaree, Fisher, Steller's Jay, Hermit Thrush, and Northern Goshawk.
Reptiles are not common, but include Rubber Boa, western fence lizard, and Northern Alligator Lizard.
As the landscape rises, trees become smaller and more sparse, with stands broken by areas of exposed granite.
These include Lodgepole Pine, Whitebark Pine, and Mountain Hemlock that, at highest elevations, give way to vast expanses of granite as treeline is reached.
The climate in these habitats is harsh and the growing season is short, but species such as Pika, Yellow-bellied Marmot, White-tailed Jackrabbit, Clark's Nutcracker, and Black Rosy Finch are adapted to these conditions.
Also, the treeless alpine habitats are the areas favored by Sierra Nevada Bighorn Sheep.
This species, however, is now found in the Yosemite area only around Tioga Pass, where a small, reintroduced population exists.
At a variety of elevations, meadows provide important, productive habitat for wildlife.
Animals come to feed on the green grasses and use the flowing and standing water found in many meadows.
Predators, in turn, are attracted to these areas.
The interface between meadow and forest is also favored by many animal species because of the proximity of open areas for foraging and cover for protection.
Species that are highly dependent upon meadow habitat include Great Grey Owl, Willow Flycatcher, Yosemite Toad, and Mountain Beaver.
The wildlife of São Tomé and Príncipe is composed of its flora and fauna.
São Tomé and Príncipe are oceanic islands which have always been separate from mainland West Africa and so there is a relatively low diversity of species, restricted to those that have managed to cross the sea to the islands.
However the level of endemism is high with many species occurring nowhere else in the world. 
The two islands are oceanic islands which have always been separate from mainland West Africa and so there is a relatively low diversity of species, restricted to those that have managed to cross the sea to the islands.
However the level of endemism is high with many species occurring nowhere else in the world. 
The wildlife of Mauritius is composed of its flora and fauna.
Mauritius is located in the Indian Ocean to the east of Madagascar.
Due to its isolation, it has a relatively low diversity of wildlife; however, a high proportion of these are endemic species occurring nowhere else in the world.
Many of these are now threatened with extinction because of human activities including habitat destruction and the introduction of non-native species.
Some have already become extinct, most famously the dodo which disappeared in the 17th century. 
The Owens River Headwaters are an important point on the migration route of many animals, including mule deer, pine marten and Sierra Nevada bighorn sheep.
Glass Creek Meadow is home to a population of the endangered Yosemite toad and a large diversity of butterflies.
The Owens River is home to several species of trout.