Some animals develop adaptations that particularly suit them for survival in their new environment, while others that do not adapt may not be able to survive. In nature, these changes occur very slowly, but humanity has caused many changes to happen at a much faster rate, thereby causing some species to adapt and expand while others to become extinct or greatly diminished. For example, Eastern and Western Screech-owls have a common ancestor, but there populations were gradually separated by geological and climatic changes in North America, leading to the evolution of two new species that were particularly well adapted for their environments. This resulted in the near extinction of some species like Kirtland's Warbler, which could not quickly adapt to this new threat to their breeding success. Let's get back to your question about penguins.
Penguins typically live near and in the very cold oceans of the southern hemisphere.
Their principal food is fish, which are found in abundance in these nutrient rich waters. They are able to nest very close to the water and have no major predators that they need to escape by flying. Since penguins have a sufficient year-round food supply in one location, they do not need to migrate to others areas by flying. Although penguins' ancestors could certainly fly many eons ago, the birds that developed shorter wings with fine dense feathering, and heavy layers of body fat to protect them from the cold, were able to better survive under the conditions they lived in, so they were the ones to pass on their genes and characteristics to future generations. Nearly 4000 Trips Work Outdoors at GORP Jobs Click Here.