Micro-evolution and macro-evolution

[PainRack]

Does the term micro-evolution and macro-evolution has any scientific meaning?
And if so, can someone please explain it to little old me?

[Darth Wong]

Does the term micro-evolution and macro-evolution has any scientific meaning?
And if so, can someone please explain it to little old me?

Macro-evolution is generally taken to mean "speciation", but speciation is itself just defined as a sufficiently large amount of deviation. Some say it's all about breeding compatibility, but that doesn't make sense when we have species of plants which reproduce asexually anyway, and hence do not have to be compatible with anything but themselves. Darwin complained about that back in the 19th century: that there is no real hard and fast way to determine the dividing line between variations or species.

[DPDarkPrimus]

talkorigins.org has a FAQ about macroevolution that also discusses microevolutionl

http://talkorigins.org/faqs/macroevolution.html

In evolutionary biology today, macroevolution is used to refer to any evolutionary change at or above the level of species. It means at least the splitting of a species into two (speciation, or cladogenesis, from the Greek meaning "the origin of a branch", see Fig. 1) or the change of a species over time into another (anagenetic speciation, not nowadays generally accepted [note 1]). Any changes that occur at higher levels, such as the evolution of new families, phyla or genera, are also therefore macroevolution, but the term is not restricted to those higher levels. It often also means long-term trends or biases in evolution of higher taxonomic levels.

Microevolution refers to any evolutionary change below the level of species, and refers to changes in the frequency within a population or a species of its alleles (alternative genes) and their effects on the form, or phenotype, of organisms that make up that population or species. It can also apply to changes within species that are not genetic.

I highly suggest reading the whole page over.

[Rye]

It may be context dependent. If you're reading something about fossils, macroevolution may be the total evolution fossil X would've gone through since fossil Y or something, in creationist arguments, it usually refers to speciation and arbitrarily wide amounts of divergence.

[Mayabird]

My (college) biology classes just avoided the terms altogether and just said "evolution". All the micro- and macro- stuff did was give the hecklers/creationists/IDiots/etc. too much fuel, and we might as well use the technical terms and talk about allele frequency and speciation anyway. It's more specific, and big words befuddle stupid people more.

[Alyrium Denryle]

Does the term micro-evolution and macro-evolution has any scientific meaning?
And if so, can someone please explain it to little old me?

It is essentially a meaningless distinction for those that like to split hairs, and typically refers to within species adaptation (microevolution) and species level or higher divergences (macroevolution) though as Mike said, the biological species concept is bad, and is actually in the process of going the way of the Terror Birds. Probably to be replaced by the evolutionary species concept which defines a species as a population on a seperate evolutionary path, even if they have not necessarily diverged genetically.