More often. please correct me if I am wrong
The animals that cannot adapt to their changing enviroment will not be able to survive and reproduce.
Answer: The size.
Explanation: On the one hand the Emperor Penguin is bigger reaching up to 48 Inches (120cm) of height and 100 Lb in weight, on the other hand the Galápagos Penguin is much smaller. For example a large adult usually goes up to 21 Inches (53cm) and 5 Lb of weight.
This is directly related to the temperature of the environment in which each one develops, because a body exchanges heat in two dimensions through the surface. So, it's easier for a big creature to maintain core temperature stable.
This is really important in environments like the Arctic where temperature goes below zero and the opposite happen in the Equator where there is a tropical weather all the time.
Reproductive isolation. Species refer to the group of organisms which share common morphological features and can interbreed and produce a viable offspring. Thus, the organisms of one species are reproductively isolated from the organisms of other species
