Many create a strawman argument by positing a challenge for a creationist hypothesis or mechanism. Evolution is an attempt to explain the diversity of life based upon purely naturalistic conditions (which could be a false term, since, if a higher power created all things, then nothing is "natural" per se), and creationism is an explanation based upon the actions of an intelligent designer.
To request the processes by which an intelligent designer composed life (DNA for example) is a mocking strawman. It is like asking "How many corners are there on a circle?" or "What does the color blue taste like?" You can ask the question, but by virtue of it's own premise, it is a failed endeavor at discovering any meaningful answers.
I could take a computer program, and then ask you to explain how that computer program came into being without any intelligent agency (evolution) and then tell you that a programmer designed it (creation). To then ask about how the programmer, through the myriad complexities of the programming process, arrived at the decisions in the logic, the order of the code, the purpose of various subroutines, etc. is to go beyond investigation, for that deals with decisions made that are outside of the mere existence of the code.
We can study the results of the creation event, and the implications of various design features AFTERWARDS. It would be like a cosmologist discussing what occurred before planck time, its all very fun and, sometimes even stimulating, but not meaningful. To demand that a creationist propose the methods and strategies of an intelligent designer is a disingenuous request.
As creationists, we would be glad to discuss the cambrian explosion, the bushes of life (not "tree"--a variety of bushes is a much better graphical illustration of the record of life, the "tree" died years ago), the problem of information technology and DNA, common design (not common descent), the impossibility of abiogenesis from a biochemical standpoint (including left-handedness, reducing atmosphere, etc), mathematics, and the well-demonstrated tendency of lab induced "evolution" to achieve stasis within a short generational period.
We could also discuss the built-in error correction in DNA, and the fact that DNA contains not only the encoded language of building life, but that the ability to decode (read) the code must have been present from the beginning (an impossibility "naturally"). You cannot have an "intangible language" that reads the code of the DNA without an intelligent source. Transcription though codons in a 20-amino acid system utilizing 4-bases has been demonstrated to be an ideal, designed process. Werner Gitt (professor of information systems) said: "The coding system used for living beings is optimal from an engineering standpoint. This fact strengthens the argument that it was a case of purposeful design rather than a [lucky] chance".
The only reason that the letters in this sentence are meaningful to you, is because you already possess an understanding of the rules, the grammar, and the vocabulary of the written English language.
Show that previous sentence to a remote tribesman in the Polynesian chain and they will shake their heads, and perhaps shrug their shoulders. The letters (A-G-C-T) in a certain order (AAA+ACT+CAG, etc) define words and phrases (proteins and processes) and some even encode for starts (beginning of a sentence) or the stops (end of sentence or command for protein synthesis).
Point is, the information encoded into DNA is meaningless without a PREVIOUS language to interpret and execute the encoded information. This is an impossible barrier to cross without intelligence, because LANGUAGE is intangible (not natural/physical) and DNA is encoded information (again, not purely natural, due to its specified complexity).
Now, to discuss the various examples of micro-adaptation (which almost always involve the loss of genetic information, not the arrival of optimized, new information) which we have seen in nature, and to then extrapolate in a manner inconsistent with mathematics and known biological boundaries and to postulate that these equivocate into the appearance of new, advanced structures or systems over time, which the fossil record does not support, and then ask those who see irrefutable and demonstrable evidence of intelligent design to discuss the merits of either theory---we will be glad to do. (editors note: that may be the longest run on sentence in this thread---in bio terms, was it merely "junk" DNA???)
Remember: just because you can IMAGINE a process to explain something, does not mean that you have an ACCURATE explanation. Let's say that we find a wooden chair in the middle of desert. Im sure that given enough time, Mr. Naturalist could write up a purely naturalistic explanation for how that thing arrived there (you know, starting from a tree long ago, and through various natural forces eventually ending up in something that looks like a chair) and then, you know, a simple moron walks up and says, "Whoa, dude. Look here on the bottom, there's a sticker and it says 'Made by #4 in China.'" The naturalist scoffs at the simpleton, noting internally that "if this intellectual ant were at my level, he would at once abandon such simple and only-superficially obvious explanations, and would see the infinite merits of my gradual processes!"
The fossil record could best be summarized as: abrupt appearance, stasis, and extinction. Current genetic studies involving multi-generational, induced mutations, again demonstrate limited variation (even marginal) and then stasis. Geologic research reveals a reducing atmosphere during the period mandated for abiogenesis. All major body plans appear in the Cambrian explosion.
"The paleontological data is consistent with the view that all of the currently recognized phyla had evolved by about 525 Ma. Despite half a billion years of evolutionary exploration generated in Cambrian time, no new phylum level designs have appeared since then." ("Developmental Evolution of Metazoan Body Plans: The Fossil Evidence," Valentine, Erwin, and Jablonski, Developmental Biology 173, Article No. 0033, 1996, p. 376.)
"Modern multicellular animals make their first uncontested appearance in the fossil record some 570 million years ago - and with a bang, not a protracted crescendo. This 'Cambrian explosion' marks the advent (at least into direct evidence) of virtually all major groups of modern animals - and all within the minuscule span, geologically speaking, of a few million years." (Gould, Stephen J., Wonderful Life: The Burgess Shale and the Nature of History, 1989, pp. 23-24.)
Dr. Paul Chien (chairman of the biology department at the University of San Francisco) "A simple way of putting it is that currently we have about 38 phyla of different groups of animals, but the total number of phyla discovered during that period of time adds up to over 50 phyla. That means [there are] more phyla in the very, very beginning, where we found the first fossils [of animal life], than exist now."
Stephen J. Gould has referred to this as the reverse cone of diversity. Evolution predicts a single source developing into more phyla over time, and the fossil record shows many phyla originally, and less now (extinction not evolution).
The case for creation hardly ends there, though it is enough evidence. Let's consider DNA. DNA requires both a language and the message to be present simultaneously. This type of system requires intelligence, for it contains specified complexity---something never demonstrated to occur naturally.
I would posit then, that a straight-forward review of the evidence would favor creation.
Now, to discuss the ability of species to adapt based upon environmental factors (which is not evolution, per se) still falls neatly into the creation model. For example, if an architect designed a building for the northeast, he/she would no doubt, design both heating and cooling systems to be present. In certain colder times of the year, the environmental conditions would mandate that the heating system "activate" and in the warmer times, the cooling system would "activate." It is logical that an intelligently designed lifeform would follow similar parameters. The DNA of the creature would contain a range of variation necessary for life in expected climates. Nuff said.
Returning to my opening statement--Be careful of the strawmen you create, they may end up catching on fire and incinerating presuppositions that many hold dear.