Two examples of natural selection

Answer 1

1) A dominant male (alpha-male) takes whatever female he desires, while inferior males in the group can't choose, such is common among apes.

2) Two creatures exist in one environment, but a drought comes. Only the creature that can live through the drought survives.

There are plenty more examples, but this should give you an idea of what natural selection is.

Answer 2

One classic but hypothetical example is Daisyworld. In this hypothetical model, we envision a planet inhabited by a single species of life, a single population of daisies. These come in two variants: black daisies and white. The colour is a trait that is passed on genetically to offspring. In the model, that star at which the planet revolves is variant, increasing or decreasing in intensity, changing the amount of light/heat the planet is exposed to. Black daisies will absorb more sunlight, increasing temperatures at the planet surface, while white daisies reflect more sunlight, cooling the planet. Theoretically, increasing temperatures should make things uncomfortable for the black daisies, who heat up faster because of their colour, relative to the white daisies, so that when solar luminosity increases, white daisies gain a reproductive advantage over the black daisies.

A similar example but from real life is the evolution of the peppered moth during and after the industrial revolution. Initially, lighter moths and darker moths were in equilibrium, but as the industrial revolution caused soot to stain the surfaces on which moths frequently settle, and predators could more easily distinguish the lighter moths against the darkening surfaces, darker moths gained a reproductive advantage, as they more often survived predation.

Two more recent findings are:

Herrel, 2008, Rapid large-scale evolutionary divergence in morphology and performance associated with exploitation of a different dietary resource.

This paper describes how in a few short decades a population of lizards transported to a different environment gained different morphological features by adapting to its new habitat.

Rolshausen, 2009, Contemporary evolution of reproductive isolation and phenotypic divergence in sympatry along a migratory divide.

This paper describes how the interaction between migratory flocks and human settlements is causing a speciation event to occur between flocks that migrate along routes including cities, and those migrating away from cities.