Reproductive Isolation Quotes

There are no shortcuts in evolution.

We know African and Asian elephants can interbreed, and they're separated by 5 million to 6 million years.

The way to understand how different species evolved is to think about the niches that they fill in an ecosystem - basically, how they make a living.

A creationist can embarrass an evolutionist by asking for a definition of species.

… isolation, by checking immigration and consequently competition, will give time for any new variety to be slowly improved; and this may sometimes be of importance in the production of new species.

The world is well supplied with spiders whose male ancestors died after mating. The world is bereft of spiders whose would-be ancestors never mated in the first place.

That the variability of an organism to a certain extent is a constant and certain condition of life we admit, otherwise there would be no distinguishable individuals of a species.

Exchange of breeding individuals between two populations tends to homogenize their gene pools.

We need to take a leaf out of nature's book. Any species that clones itself will eventually be attacked by a parasite, leading to an inevitable population crash.

I did not claim that speciation occurs only in founder populations.

Each species may have had its origin in a single pair, or individual, where an individual was sufficient, and species may have been created in succession at such times and in such places as to enable them to multiply and endure for an appointed period, and occupy an appointed space on the globe.

In the present epoch of struggle between two worlds the two opposing and antagonistic trends penetrating the foundations of nearly all branches of biology are particularly sharply defined.

I had found again and again that the most aberrant population of a species - often having reached species rank, and occasionally classified even as a separate genus - occurred at a peripheral location, indeed usually at the most isolated peripheral location.

We observe closely related species in sympatry and infer how they evolved from a common ancestor.

Evolution shows that in the long run, if the superior mixes with the inferior, the product is halfway between, and inferior to what you started with in the original superior group - in other words, mongrelized.

It is really laughable to see what different ideas are prominent in various naturalists' minds, when they speak of 'species'; in some, resemblance is everything and descent of little weight-in some, resemblance seems to go for nothing, and Creation the reigning idea-in some, descent is the key,-in some, sterility an unfailing test, with others it is not worth a farthing. It all comes, I believe, from trying to define the undefinable.

The process of speciation is completed with the cessation of genetic exchange.

Formation of a new race takes place when, over several generations, individuals in one group reproduce more frequently among themselves than they do with individuals in other groups.

As a general rule, biology tends to be conservative. It's rare that evolution 'invents' the same process several times.

Ordinary speciation remains fully adequate to explain the causes and phenomenology of punctuation.

The divergence of songs in the new population away from those in the progenitor population would only be prevented if these processes were balanced by repeated immigration and subsequent breeding: song flow.

Splitting and gradual divergence of genera is exemplified very well and in a large variety of organisms.

A race is what zoologists term a variety or subdivision of a species.

Pretty much every plant and animal alive today is the result of eons of natural cross-breeding.

Humans cannot produce viable offspring with our closest animal cousin: the chimpanzee. We cannot impregnate a chimp. So you know what that means? No condoms.