Re: Questions for Richard Dawkins
"[...] Darwinism is so weak in crucial areas - such as gradualism, species and the supremacy of natural selection as the sole explanation of evolution."
To the best of my knowledge, not a single evolutionary biologist today believes that natural selection is the sole force acting to shape the long-term patterns and trends of evolution. No one denies the significant roles played by exaptation, evolutionary constraints, pure luck, and genetic drift in the life history of any organism, species, or what-have-you. However, not a single force other than natural selection (whether it acts on genetic or epigenetic phenomena within a population) has ever been proposed (and sustained the test of evidence and time) which could serve to explain adaptive complexity on a smaller scale, that is to say on the level of variations within a single generation. Without selection, evolution could not proceed towards adaptedness. The fact that the way in which any given lineage will acheive an evolutionary equilibrium of adaptedness is largely dependent on stochastic factors is wholly irrelevant to the fact that the only driving force towards that equilibrium is selection.
With regards to criticisms levelled against the concept of species, it is evident to anyone who accepts evolution as a fact that this concept must inevitably be somewhat blurred, since all extant and fossil forms were at some point in the past related, and capable of interbreeding in a continuous chain leading down to the common ancestor. However, the reliance on the concept of species is almost entirely absent from neo-Darwinist views such as that held by Dawkins. Rather, this emphasis is found mainly in Gould's punctuated equilibrium, which credits "species-level selection" with a major role in the patterns of macro-evolution. Robert Caroll's Patterns and Processes of Vertebrate Evolution is a text which covers most issues pertaining to macro-evolutionary trends in significant detail, with ample arguments from the fossil record and extant species.
As to your last point, that of gradualism, there are two ways of interpreting it (as Dawkins and Dennett have repeatedly pointed out.) One is gradualism as it is opposed to saltationism. In this form, every evolutionary biologist today is a gradualist. All of them. This is because saltationism (through macromutation) is a completely untenable theory of evolution, which cannot account for adaptive complexity. The second form of gradualism can be called "constant speedism", the term coined by Dawkins in The Blind Watchmaker, and states that evolution proceeds at a constant slow and steady rate. In this form, there are no gradualists. None. Not even Darwin. Take my second to favourite passage from The Origin of Species as proof to this effect:
"[...]the period during which each species underwent modification, though long as measured by years, was probably short in comparison with that during which it remained without undergoing any change."
So I hope I've managed to resume 20 years of debate on the topic into three neat little responses to three common accusations, ones which I would have hoped would no longer arise so often after the publication of at least four books and a number of papers carefully refuting them (The Blind Watchmaker, Darwin's dangerous idea, Natural language and natural selection, and The extended phenotype, to name just those that come to mind.)
It would be a lot easier if people actually read the works they critiqued, but I certainly realize it's impossible to read everything, and that sometimes you just have to take someone else's word for it. This only becomes a problem when that someone else misrepresents their opponents ideas, as Gould and others have so often done in dealing with the modern Darwinian synthesis.