Population genetics is a moderately technical field (at least at the shallower end of the pool, there are some subfields which veer into applied math), and I am finding it difficult to distill it all down in a very simple fashion to readers who are asking serious questions. To gain a full measure of many of the posts on this website it helps to understand the basics of population genetics. There’s really no short cut, just like you have to do some study if you want to talk about quantum mechanics in any serious fashion. If you are happy reading on a screen, then there are many free resources on the web. I would recommend Graham Coop’s population genetics notes, the classic ones hosted at UConn, and Joe Felsenstein’s Theoretical Evolutionary Genetics, for a start. But if you need a old fashioned book that you can hold in your hands, there are a finite number of choices. To me the closest to a “gold standard” is probably the “Hartl & Clark” text, Principles of Population Genetics. As is the norm among most technical texts it is expensive, though worth it. But notice when you a search that there used copies of the earlier editions which are affordable. The updates in the newest edition due to genomic technologies and such in the are not necessarily worth an extra $80 in my opinion if you just want basic population genetics. If you can understand Principles of Population Genetics, then you can understand population genetics to a level to master all of my posts. And, you know more about the field than the vast majority of professional biologists.
If you want more ecologically relevant illustrations of population genetic questions, you might enjoy Philip Hedrick’s Genetics of Populations. I recall there were some issues relating to spatial and temporal variation in structured populations which this book handled in great depth. But really there’s not that much difference in terms of substance besides that between this and Hartl & Clark from what I can recall. I generally find it a somewhat less elegant work stylistically. On the other hand if human examples are more to your taste, Alan Templeton has a textbook out, Population Genetics and Microevolutionary Theory. Like the Hedrick text it doesn’t pack as dense a punch in my opinion as Hartl & Clark. Also, this is the first edition of the textbook, and I can imagine that will get better in future editions as Templeton gains a better sense of his audience.
The above are comprehensive surveys. Charlesworth & Charlesworth have written a text which is more like an encyclopedia, Elements of Evolutionary Genetics. This is not a compact work at all, and even I find it daunting. Sometimes it feels like this work is basically a “core dump,” but if you want to look up a specific issue in a textbook, then Elements of Evolutionary Genetics will probably cover it. At the other end of the spectrum in terms of comprehensiveness is the classic Gillespie book, Population Genetics: A Concise Guide. This is more an undergraduate level work, and hammers home the most elementary of population genetic principles and fundamentals. It isn’t going to bring you up to speed on how genomics has transformed the whole field over the past 10 years, though if you are new to the discipline then that’s probably not the priority in any case.
In contrast, Rasmus Nielsen and Monty Slatkin’s new textbook, An Introduction to Population Genetics: Theory and Applications, is up-to-date on the latest genomics and computational methods. Because of the authors’ research focus the illustrations also are biased toward humans. This is definitely going to show you how “population genetics is done” in 2014. The focus on site frequency spectrum makes sense only in light of genomic data. A slim text, the main downside is that it’s a first edition, and seems to suffer from light editing. There are many typos and other such errors, which presumably will be cleaned up in future editions (or else there won’t be future editions!).
There are other books out there, such as Andrew Hamilton’s Population Genetics, which I can’t comment on because I don’t own them. Also, Falconer & McKay’s Introduction to Quantitative Genetics is a classic which is complementary to all the works above (it begins with population genetic fundamentals). In no way am I saying you have to buy all these books, or any of these books. The key is that you actually learn a little population genetics, and phylogenetics while you’re at it, if you want to comment intelligently on some of the technical nuances which come up on this blog.