The place of origin of the is unknown, but both and , today neatly separated by the Sahara, found their earliest ancestors in the , while a Potamocho… - Colin Groves

There has been a lot of discussion about ‘the species question’ over the past 20–30 years, and several surveys have converged on the essence of what we mean by species: they are evolutionary lineages ... Species thus have a real existence. This settles the ontological status of the species concept, but it does not necessarily solve the question of how to recognise them; the most logical way of defining species operationally is by the so-called Phylogenetic Species Concept: ‘A species is the smallest population or aggregation of populations which has fixed heritable differences from other such populations or aggregations’ ...

The first of the 'complete theories' of evolution developed in modern times was the '' of (1969; translation of work published in 1922). While badly hampered by an ignorance of genetics, slow to reach the Russia of the early twentieth century, Berg's consideration of the Darwinian model led him to the conclusion that it was incompatible, at least as the major mechanism, with what he knew of the pattern of living organisms and their evolution.

This useful book surveys endangered species (and subspecies), stating where each lives and why it is endangered. ...
The non-Australian conservationist will find much of interest here. The devastation wreaked by introduced species has been astounding: so many formerly widespread species have been swept off their entire mainland ranges by competition from the introductions, survivng only if their ranges happened to include offshore islands which were not reached by rabbits, hares, foxes, feral cats, introduced rats and mice, goats, donkeys, horses, camels, buffaloes, sparrows, starlings, blackbirds.