"Best" evidence for evolution.

Those groupings are, of course, completely arbitrary. Why 'crows' and not 'birds'? And if we're sticking with crows, does that include ravens? What about jackdaws? Jays?If you mean 'kind', just say 'kind'. It avoids confusion.

Basically all the same: An unbridgeable difference: All the same parts, just slightly rearranged: Completely different parts:

As a reminder, the discussion was about things like a few different species of mice that couldn't interbreed. This is clearly not what is usually meant by macroevolution. Species doesn't have a definition, and it bothers me that people keep pretending it does. Species is a vague and nebulous concept, and while it certainly predates evolution, the definition of a group of organisms capable of interbreeding doesn't - this was only really formally defined in the 20th century. Note that Linneaus included multiple species of human; I don't think he believed them incapable of interbreeding.The Biological Species Concept is inapplicable to broad swathes of biological diversity, and it's rarely actually applied where it is applicable. There are countless examples where different species, different genera and sometimes even different families are not only capable of interbreeding; but engage in it regularly. No one suggests collapsing vast taxonomic groups into single species, because it would make it hard to discuss diversity.So the BSC is an idea that sounds good in principle, but when you test it against the natural world it turns out to be near useless for actual taxanomy. And yet for some reason people keep pretending this outdated idea is the default. It's not.

This makes no sense. If we're just reducing the genetic variation present in an initial parent population, then the alleles each subpopulation possesses were once part of the same population. A genetic mismatch implies something has changed in at least one of the subpopulations; otherwise joining them together would just mean mixing together the original population's alleles. You'd make the original species again.As we can see from real life examples, when you have actual subpopulations with greatly reduced genetic diversity, they are more likely to produce fertile young when mixed together than they are apart. The reason being that you have less individuals homozygous for harmful recessive alleles.

Depends who you ask. To quote one theoretical biologist (Adam Wilkins):

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For most evolutionary biologists, however, microevolution is synonymous with speciation, and the term macroevolution, when it is used at all, denotes those larger evolutionary differences that distinguish higher taxonomic categories, in particular orders, classes and phyla

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My thinking is that it's daft to argue about whether something is macroevolution or not. The more important question is whether that in fact defines a useful concept at all. 'Evolutionary change greater than some arbitrary and undefined quantity' is not a worthwhile concept to define.If creationists want to argue that microevolution is possible but macroevolution isn't; we shouldn't be arguing over the definition of the latter word. It's the responsibility of the creationists to provide a clear definition of what that actually means. There are lots of species that regularly and consistently engage in hybridisation. It's not an occasional and unusual thing, but pervasive, and plays an important part in evolution. I think this fact is underappreciated, which is one of the reasons I keep being crotchety about the subject. Okay, fair enough - I see what you're saying here. But I still think this line of argument leads us on a semantic tangent that puts the emphasis on the wrong place. We go on the endless circle of 'that doesn't count because they're still mice' and 'that's only microevolution' instead of focusing on the core of what's wrong with Faith's arguments.

You think all birds are one species. Your understanding of biological diversity is incoherent.

How?

While of course I have no idea what classification you're referencing, for what little it's worth, Linnaeus didn't use families for animals at all. The concept of Family as a rank between Order and Genus only really became popular later in the 19th centuryThrushes weren't given any special status by Linnaeus. He recognised several species (how many depends on which edition) in the same Genus, Turdus. Turdus, in turn, was placed in the order Passarae of the class Aves.You say that we should class thrushes as birds because they share the characteristics of birds. That is of course true, and both Linnaeus and modern biologists would agree with you there. But thrushes also share specific characteristics with one another that allow us to categorise them as thrushes and, further, share specific characters with most birds that allow us to categorise them as Passeriformes, as distinct from birds like penguins, or flamingos, or ducks, that don't.Birds, in turn, share characteristics with other vertebrates that allow them to be distinguished from invertebrates.None of the above requires arcane knowledge. It was clear to curious naturalists in the early 18th century and the broad outline of relationships described above has mostly held up as accurate right through the development of 21st century molecular biology and the deep statistical analyses of modern computers.Why are the features that unite birds the key ones in Faith-taxonomy, and not those that unite thrushes or vertebrates?Edited by caffeine, : fixed mobile autocorrects

Do you have these wikipedia excerpts stored locally or something? I went to improve the origin of birds one, to discover someone else had already done it long ago.

I was just going to delete this meaningless sentence:

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There could also be a mosaic of interbreeding, much as we see in Homo lineages.

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But it's not in the article. Not sure how long ago it was removed, but definitely before the start of this year.

Apologies then. I would have worded it a bit more delicately if I'd realised they were your words.I the context where you put them, I don't see how they convey any information. We don't have anything like the fine-grained knowledge of early bird evolution that we do of early Homo, on account of the timescales involved. Interbreeding between long-separated populations may well have been involved in the origin of birds. It likely was, since this kind of thing seems ubiquitous. But it's not something special to the origin of birds; nor does any evidence exist to suggest it's particularly relevant in this case compared to, say, the origin of snakes or the origin of iguanas.Placed where it was, it read like a nonsequitur more likely to confuse and distract the reader then to provide them with any useful knowledge.