From a Darren E. Irwin article:
Ernst Mayr called ring species “the perfect demonstration of speciation” because they show a range of intermediate forms between two species. They allow us to use variation in space to infer how changes occurred over time. This approach is especially powerful when we can reconstruct the biogeographical history of a ring species, as has been done in two cases.
Speciation being geographic and/or sexual isolation between two directly related phyla, essentially the same
phyla, but acquiring variations. The variations produce the 'ring', and at a point where sexual isolation occurs, or the ability to breed only hybrids, then speciation has occurred.
Due to times required, it is difficult to observe these occurrences, although with various insects (drosophila et al), it has been observed due to the short gestation times. Here's an example I came across of arthropod experiments along those lines:http://biology.mcgill.ca/faculty/loreau/pdfs/fournierloreauecography.pdf
With ground-beetles, examples are given of variations, things like 'habit preferences' such as eating habits [phytophagus, v. carnivorous, or plant eating v. eating each other], and population location preferences. Noted was that the adding of hedges within their populations produced group separations due to habitat preferences.http://www.actionbioscience.org/evolution/irwin.html
Another example is beak sizes with Darwin's finches and various fish populations, such as the Ensatina Salamanders, which over time, differed in color and size, and ceased interbreeding. But was it totally genetic, or just preferential? One of the frustrations in defining species, whether fish or beetles, is determining when-in-fact speciation has actually occurred.
Speciation occurs [Ernst Mayr's definition of species], but is difficult to determine. Alleged speciations have occurred, but have returned to a single cohabital species over time. And
, there are alleged to be 250 to 350 thousand beetle species worldwide. But guess what? They're all nearly identical in bodily components, varying only in color, proportions, and some metabolic features. Yeah, they're still
So the question I raise is this:
Can speciation alone (microevolution) result in novel phylogenetic change (macroevolution)?
Or as Student of Allah stated:
"macro" is like a sum of the "micro"s.
I say yes in select cases where ecological effects may in fact work harmoniously with favorable (and fortuitous) morphological changes which luckily occurred as needed in a changing environment, and were selected upon. These abilities, inherent within phyla, enhance survival and minimize extinctions. But I view this very adaptive ability itself as a 'designed-in' function.
But there have been instances of what I term as 'radical speciation', where the complexity of requisite alterations needed far exceeded the ability to progress via random mutations. Not only would the series of changes need occur with no 'look-ahead' abilitiy to forsee a future requirement, but the extended
series of changes (the intermediates) would
• have no immediate selective advantage,
• generally be deleterious to extant function(s),
• and fail due to needed co-dependencies not yet in place.
To summarize: Adaptive mutations occur, that I feel [predict] are the result of 'designed'in' variances, available within the genome by design
, to aid in survival. Theses in no way are the means to 'radical speciation' alterations like bird flight, whale evolution including echolocation, and giraffe necks to name only three.
Evolution occurs naturally, but guided alterations [genetic engineering] have occurred along the way.