Given the fact of evolution, one would expect the fossils to document a gradual steady change from ancestral forms to the descendants. But this is not what the paleontologist finds. Instead, he or she finds gaps in just about every phyletic series.
Ernst MayrThe reduced variability of small populations is not always due to accidental gene loss, but sometimes to the fact that the entire population was started by a single pair or by a single fertilized female. These 'founders' of the population carried with them only a very small proportion of the variability of the parent population. This 'founder' principle sometimes explains even the uniformity of rather large populations, particularly if they are well isolated and near the borders of the range of the species.
Ernst MayrThe issue, as correctly emphasized by Carl Sagan, is the probability of the evolution of high intelligence and an electronic civilization on an inhabited world. Once we have life (and almost surely it will be very different from life on Earth), what is the probability of its developing a lineage with high intelligence? On Earth, among millions of lineages of organisms and perhaps 50 billion speciation events, only one led to high intelligence; this makes me believe in its utter improbability.
Ernst MayrA new species develops if a population which has become geographically isolated from its parental species acquires during this period of isolation characters which promote or guarantee reproductive isolation when the external barriers break down.
Ernst MayrI have the honesty to say I'm an Atheist. There is nothing that supports the idea of a personal God.
Ernst MayrA species consists of a group of populations which replace each other geographically or ecologically and of which the neighboring ones integrate or hybridise wherever they are in contact or which are potentially capable of doing so (with one or more of the populations) in those cases where contact is prevented by geographical or ecological barriers.
Ernst Mayr