Quotes About Species

El embrión no queda afectado, y sirve como indicio de la pasada condición de las especies. Por eso sucede que las especies existentes, durante los primeros períodos de su desarrollo, se parecen a menudo a formas antiguas y extinguidas

We shall best understand the probable course of natural selection by taking the case of a country undergoing some slight physical change, for instance, of climate. The proportional numbers of its inhabitants will almost immediately undergo a change, and some species will probably become extinct.

I was much struck how entirely vague and arbitrary is the distinction between species and varieties. ... But to discuss whether they are rightly called species or varieties, before any definition of these terms has been generally accepted, is vainly to beat the air.

las variaciones y diferencias individuales favorables, y la destrucción de aquellas que son nocivas, es lo que hemos llamado selección natural o supervivencia de los más aptos.

Until recently the great majority of naturalists believed that species were immutable productions, and had been separately created. This view has been ably maintained by many authors. Some few naturalists, on the other hand have believed that species undergo modification and that the existing forms of life are the the descendants by true generation of pre-existing forms.

But that those belonging to what are called the same genera are lineal descendants of some other and generally extinct species, in the same manner as the acknowledged varieties of any one species are the descendants of that species.

pero la selección natural no puede modificar la estructura de una especie, sin darle ninguna ventaja, para provecho de otra especie;

On peut démontrer ainsi ni la stérilité ni la fécondité ne fournissent aucune distinction certaines entre les espèces et les variétés.

Grâce à cette lutte, les variations, quelque faibles qu'elles soient, et de quelque causes qu'elles proviennent, tendent à préserver les individus d'une espèce et se transmettent ordinairement à leur descendance, pourvu qu'elles soient utiles à ces individus dans leurs rapports infiniment complexes avec les autres êtres organisés et avec la nature extérieure.

Comme il naît beaucoup plus d'individus de chaque espèce qu'il n'en peut survivre; comme, en conséquence, la lutte pour l'existence se renouvelle à chaque instant, il s'ensuit que tout être qui varie quelque peu que ce soit de façon qui lui est profitable a une plus grande chance de survivre; cet être est ainsi l'objet d'une sélection naturelle.

Enfin, tous les naturalistes pourraient citer des cas innombrables d'espèces restant absolument les mêmes, c'est-à-dire qui ne varient en aucune façon, bien qu'elles vivent sous les climats les plus divers. Ces considérations me poussent à attribuer très peu de poids à l'action directe des conditions de vie.

I have called this principle, by which each slight variation, if useful, is preserved, by the term of Natural Selection

When on board H.M.S. 'Beagle,' as naturalist, I was much struck with certain facts in the distribution of the inhabitants of South America

como se producen más individuos que los que pueden sobrevivir, tiene que haber en cada caso una lucha por la existencia, ya de un individuo con otro de su misma especie o con individuos de especies distintas, ya con las condiciones físicas de vida.

FROM THE point of view of modern intellectual life and culture, On the Origin of Species is one of the most important scientific books of all time.

La selección natural obra solamente por medio de la conservación de las variaciones que son en algún concepto ventajosas. Podemos comprender que cualquier forma representada por pocos individuos correrá mucho riesgo de quedar completamente extinguida

species of the same genus would occasionally exhibit reversions to lost ancestral characters.

By a monstrosity I presume is meant some considerable deviation of structure, generally injurious, or not useful to the species.

Great as the differences are between the breeds of pigeons, I am fully convinced that the common opinion of naturalists is correct, namely, that all have descended from the rock-pigeon (Columba livia), including under this term several geographical races or sub-species, which differ from each other in the most trifling respects.

All that at present can be said with certainty, is that, as with the individual, so with the species, the hour of life has run its course, ans is spent.

The number of living creatures of all orders whose existence intimately depends on kelp is wonderful. A great volume might be written describing the inhabitants of one of these beds of seaweed…. I can only compare these great aquatic forests…with terrestrial ones in the intertropical regions. Yet, if in any other country a forest was destroyed, I do not believe so many species of animals would perish as would here, from the destruction of kelp

Whoever is led to believe that species are mutable will do good service by conscientiously expressing his conviction; for only thus can the load of prejudice by which this subject is overwhelmed be removed.

There is continuity between humans and other animals in their emotional lives; there are transitional stages among species, not large gaps; and the differences among many animals are differences in degree rather than in kind

Species that struggle to adapt to survive will become extinct