What are the four types of natural selection? Please give examples.

Natural Selection is gradual 'coming about' of a species in summary. It is the survival of the most well adapted members of said species, which then reproduce and pass their genetic information on, and that entails their characteristics, which helps their offspring to then survive better and reproduce and carry on the pattern.

Separation of a species, or speciation is when a natural event occurs, whether it be tectonic, a flood, a storm, etc, which separates a species and stops contact between members of said species. A short example would be an island, which has a large herd of goats. One fateful day, the island is split in two by a mountain range, the herd of goats is split in two and are separated from each other, in 1000s of years time, the mountain comes down and the two goat herds meet again, they however cannot interbreed as they are too genetically different from one another due to the separation and the long period of time with no contact.
-SPECIATION

Introduction/Removal of a species can 'cause' natural selection, for example. On an island there are 2 birds, one flies and one does not, one day some explorers comes to the island with cats, the flightless one cannot out run or fly away from said cats and explorers and is gradually eaten to extinction. The flying bird lives on, eating fruit and evading explorers and cats, until it one day finds itself having to compete with the explorers for the fruit as the explorers strip the trees bare of their fruit. Gradually, this bird too dies out due to the lack of food. These trees however relied on said bird to reproduce, and die out, leaving the island desolate and extinct of all its indigenous wildlife, bar the now hungry explorers and their hungry cats whom are being eaten by their explorer/owners.
-SPECIES PREDATION/INTRODUCTION/REMOVAL

Change in climate, can lead to natural selection and the emergence of new species, for example. In a low lying area, there is many rats which feed upon the fruit on the top of mangrove trees. One day, the area is flooded, leaving all the mangrove trees sitting in the water. Some of the rats cannot swim or as well as other rats, and so either drown or eventually starve, some rats however are very good at swimming and thrive, they keep breeding with each other until there are only rats which can swim well and eventually are perfected to swimming in the flooded area.
-CHANGE IN CLIMATE

Mutations is what brings about everything in natural selection, if there was not a mutation, said species would go extinct, for example. There are many deer in a field which are predated on by wolves, some deer get away and some are eaten, however, those deer who get away breed, and eventually almost all the deer can escape said wolves, however, the wolves who do get the few deer who can get away from practically all the other wolves keep breeding until they are the only wolves left getting kills and the other wolves are starved. Then said process starts again.

-Hope this helps.

The four categories of natural selection are: 1. Directional selection: this type of selection favors individuals at one extreme of a trait, causing a shift in the average phenotype of the population over time. An example of this is peppered moths during the industrial revolution. 2. Stabilizing selection: this type of selection favors intermediate variants of a trait, reducing the phenotypic variation in a population. An example of this is human birth weight. 3. Disruptive selection: this type of selection favors individuals at both extremes of a trait, resulting in the formation of two distinct phenotypic clusters. 4. Sexual selection: this type of selection favors traits that increase an individual's ability to obtain mates, frequently leading to the development of extravagant trait.