So long as the starting population of the diverging species is small, there’s really nothing to say one way or another what happens to the bulk of the population or closely related species. At the risk of sounding like I’m making up stories, let’s think about what happens as soon as the transition to a fully aquatic animal happens: all of a sudden they can travel the whole world, but nothing prevents their semi-aquatic brethren from staying put right where they’ve been all along. Or just because a species figures out how to exploit a new ecological niche, and adapts to a different lifestyle in a number of ways, doesn’t mean the old ecological niche that they were well adapted to before isn’t there anymore.
This runs into the old argument, if humans descended from monkeys, why are there still monkeys? The answer is simply that evolution branches like a tree, easily and often.
This might be true to a certain extent, but I don’t think genetically constructed trees assembled by computer programs that map extremely well to morphologically constructed trees are products of bias.
Perhaps I should clarify that I don’t think it’s necessary that all of the proto-whale examples fit into a direct line of descent. However I think the chances that at least a couple of them will prove to have existed as species for a few million years longer than we currently have fossil evidence for are excellent. The “evidence of their existence” you want is all the different whale-related descendants they left.
Related to other comments on this thread, I do think living animals can qualify as transitional species. For example, there are frogs living today and the original amphibians that crawled out of the oceans pretty rapidly became something we would call “frogs,” despite not matching exactly any present-day frog species. Similarly, we would probably look at the original transition to reptilian characteristics and call it a “lizard,” more or less, and the precursor to all of them we would call a “fish.”
If you want to call a chimp an intermediate form between us and baboons, that’s actually fine with me, keeping in mind that chimps do have a few characteristics that our common ancestor didn’t.
The article didn’t at all say you could get practically any result. It was addressing uncertainties much farther back in time than any of the whales or other examples we’re talking about. This is a known issue. We expect DNA trees to start looking fuzzy after enough time elapses that everything is probably mutated, and the solution is to look at things like the genes for mitochondria that can’t change freely while maintaining viable organisms. But this is kingdom/subkingdom levels of uncertainty, not orders like Cetacea. For looking at the recent past, genetic trees are amazingly reliable.
It is a fact that these fossils have a mixture of modern whale features and features from terrestrial mammals. That’s what makes them transitional, and no stories are needed.
That’s not what happens. They use as many genes as possible, and the contradictions are right where we would expect to see them if evolution is true. When you are dealing with deep nodes with little genetic data you would expect contradictory trees for different genes. However, the contradictions are still well within the expected phylogenies. It isn’t as if some mouse genes have them more closely related to squid than to squirrels.
If whales evolved from terrestrial mammals then there should have been species in the past who had a mixture of whale and terrestrial mammal features, correct?
That’s pretty cool! (that bats and dolphins both benefit from what might be some convergent evolution). God’s creation is full of wonderfully complex things! (Wonderful as long as you aren’t a mosquito in some bat’s echolocation cross-hairs, that is!)
If I were going into a florist shop to tell the professional florists that they don’t know anything about flowers, I would first make sure I knew A LOT of A LOT about flowers.
How is it that you believe you can present yourself in the midst of many knowledgeable people, including professional biologists and geneticists, and tell them that they don’t know how to do science?
In just this little section I quote from above, you lay down two charges:
That Evolution does not allow predictions; and
the theory of evolution will predict a continuum over time rather than
vested heirarchies clearly differentiated from each other…
In response to (1), you apparently think you can take any non-predicted part of the discipline of Evolution, and say that if it was real science, these unpredicted things SHOULD have been predicted. This is like Climate Warming Denialists saying climatologist models are useless because they can’t accurately predict average temperatures for the next 12 months. Below is a highly condensed description of a successful prediction of what genetic testing should reveal (in existing whales) regarding those with baleen instead of teeth:
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"Some of the genes known to be used in all mammals for tooth formation were the obvious candidate genes to start with: the products of the ameloblastin, amelogenin, and enamelin genes are all used in the formation of tooth enamel, the hardest structure in the vertebrate skeleton. Researchers went looking for these genes in several Mysticete (i.e. toothless whale) species. The results showed that all the species studied did indeed have these three genes present as pseudogenes (and more specifically, as unitary pseudogenes, a special class of pseudogene we have discussed in detail previously).
Finding these genes as pseudogenes in toothless whales was exactly what evolution predicted, but there was a catch: none of the mutations that removed the functions of these three genes were shared between different species, suggesting that these genes lost their function independently in the species studied. This finding was at odds with data from the fossil record, which suggested that teeth were lost only once, and early in the lineage leading to all modern toothless whales. So, the researchers seemed to have two lines of evidence that at face value contradicted each other. The fossil record suggested that tooth loss occurred once in the common ancestor of all toothless whales, but these three genes seemed to have been inactivated independently, several times over, suggesting that loss of teeth should be happening later in Mysticete evolution, and more than once.
One proposed explanation for the apparent discrepancy (among several put forward) was to predict that a fourth gene required for enamel formation was lost early in Mysticete evolution. The loss of any one gene necessary for forming enamel would be enough to prevent the process altogether. In this case, the loss of this fourth gene would prevent tooth enamel from forming, even though the genetic sequences of the other three enamel genes would still be intact. Once enamel function was lost, random mutations in the remaining enamel genes could then accumulate later in Mysticete evolution after speciation in this group was already underway. To test this hypothesis, the research group went hunting for other enamel genes in toothless whales.
[END OF SECTION]
Is the confirmation of “toothless whale genetics” a rare success? No. What else has evolution successfully predicted? Here is a short list:
1] A biochemical way for information to be passed on from generation to generation that can be subject to mutation
2] Shared transposons between closely related species
3] The synteny between genes on chromosomes
4] Shared pseudogenes with shared means of inactivation
5] Incomplete lineage sorting when we encounter three closely related clades.
6] Mechanisms for new genes to be created
7] Feathered dinosaurs
8] The ability of closely related species to interbreed
9] Countless intermediate forms in the fossil record including this startling find of the Tiktaalik. One group estimated the geologic period and conditions where an intermediate “Fish-to-Tetrapod” should have existed on the Earth. The most accessible place for an intersection of these conditions was on Ellesmere Island, in the
far north of Canada. The team went there… the rest is history.
10] One of the successful predictions easiest to explain was the conclusion that one set of human chromosomes must be a fusion of two chromsomes, “… because we have one fewer pair than other great apes do. Long after that prediction the fusion site was found.”
@Ashwin_s, I’ll tackle your other egregious accusation … [re-stated below]
[ (2) the theory of evolution will predict a continuum over time rather than vested heirarchies clearly differentiated from each other…]
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How do you explain marine reptiles drowning below the KT boundary, while proto whales appear in the middle of the so-called “flood sediments” ? And then when they disappear…suddenly the whales without any feet at all show up … in the so-called “flood sediments”? And then the balleen whales show up above all those other whales… not because they drowned last … but because balleen whales were a later development.
Let’s start with facts both of us should be able to agree about. I will quote some things from the university of Berkeley site from which you seem to have sourced your info from.
The whale “evolutionary tree” does not make any claims about direct decent.
Blockquote
The first thing to notice on this evogram is that hippos are the closest living relatives of whales, but they are not the ancestors of whales. In fact, none of the individual animals on the evogram is the direct ancestor of any other, as far as we know.
Blockquote
Source:The evolution of whales - Understanding Evolution
Asper the above article, Pakicetus was a land based animal that loved 53 million years ago. From the pakicetus we have a line of fossils which are amphibian and said to be more and more aquatic. This is certainly encouraging.
There is a beautiful story of the nostrils shifting from the edge of the nose upwards… let me show the pic…
The only problem is that the fossil of the more aquatic animal with a slightly pushed up nose is only 36 Mya… While the oldest whale fossil is at least 40-46 Mya (more probably 49mya)…
Which means we would have to speculate on/ assume all the “interim species” existed millions of years before their fossils were formed… and actually predated the fully aquatic whale.
That is false. It is OBSERVED that these species have a mixture of terrestrial mammal and cetacean features. This not speculation. This is an observation.
That is also false. Wolves still exist even though wolves evolved into domestic dogs. Modern wolves are sister taxa to domestic dogs. In the same way, these species with a mixture of terrestrial mammal and cetacean features are sister taxa to the direct lineage that led to whales. Those sister taxa still have the transitional features that were found in the direct lineage.
How do you determine how many fossils there should be in our collections? How much of the world do you think we have searched for fossils?
So far as I can tell, the problem with whale evolution that seems to puzzle you is that, per the source you consulted, no fossils-- none whatsoever, zilch, nada–have been found in the period from 47 mya to 36 mya.
Since you mentioned the platypus… Seems like it’s also got bird features…
In addition to the bill… it’s sex chromosome seems to have both mammalian and bird features…
Blockquote
Two centuries after the duck-billed platypus was discovered, monotreme chromosome systems remain deeply puzzling. Karyotypes of males, or of both sexes, were claimed to contain several unpaired chromosomes (including the X chromosome) that form a multi-chromosomal chain at meiosis. Such meiotic chains exist in plants and insects but are rare in vertebrates. How the platypus chromosome system works to determine sex and produce balanced gametes has been controversial for decades. Here we demonstrate that platypus have five male-specific chromosomes (Y chromosomes) and five chromosomes present in one copy in males and two copies in females (X chromosomes). These ten chromosomes form a multivalent chain at male meiosis, adopting an alternating pattern to segregate into XXXXX-bearing and YYYYY-bearing sperm. Which, if any, of these sex chromosomes bears one or more sex-determining genes remains unknown. The largest X chromosome, with homology to the human X chromosome, lies at one end of the chain, and a chromosome with homology to the bird Z chromosome lies near the other end. This suggests an evolutionary link between mammal and bird sex chromosome systems, which were previously thought to have evolved independently
Blockquote
Do we have a winner for the evolution falsifiability test?
It’s got a beak… but it’s not a bird.
It’s skeletons looks like that of a reptile’s … but it’s not a reptile.
It’s reproductive chromosomes are a mix of mammalian and bird types…
I would bet not.
@Chris_Falter : unless we have intermediate fossils that predate whales and show a clear linkage showing plausible route for how whales evolved, we can’t be sure how it happened. Since evolutionary trees are constructed assuming descent, evidence is interpreted in that way. For example, if there is similarity between organisms which are dissimilar in other features, these similarities are called convergent evolution or parallel evolution and considered not related to lineage. This problem is made worse in the genomic/molecular level.
Since the process assumes common descent and all evidence is interpreted in line with that irrespective of whether there is a direct cause effect link/evidence of the same, common descent cannot be falsified by cladistics.
If an anamoly is found, it will be explained away by the plot armour which is the unknown common ancestor. For example, if the duckbill platypus had features similar to birds in their sex chromosomes, it’s assumed that the common ancestor of mammals and the platypus (which is not known and so cannot be put to any kind of test) had these features.
Hence rendering common descent unfalsifiable. Not identifying direct relationships in lineage makes the process unfalsifiable… and very bad science.
Sigh. You have ignored once again how many phylogenies have been created just by molecular evidence alone. AND how they agree with fossil phylogenies that are made separately. And today, scientists use both to get an even better idea as the more data points the better. And again, this was a HUGE opportunity to falsify common descent with genetics… but that is not even close to true.
And you learned that the Berkley site accurately reflects actual scientific papers well. It does a good job of accurately representing peer reviewed publications. But let’s just do a little digging shall we.
Whale Evolution Papers:
From Land to Water: the Origin of Whales, Dolphins, and Porpoises- a summary of what we’ve learned as of 2009, the classic Thewissen paper that you appear to reject for some reason even though you claim to value peer-reviewed papers. They note that before 30 or so years ago, we had NO fossils linking whales to land mammals- and sure enough, they were found!
Eocene Evolution of Whale Hearing- a 2004 paper showing the fossils follow a clear progression from land to sea. Why should this be the case? Why is it that we can actually find any progressions in nature if macroevolution did not occur? Is God just messing with us?
So many chances to falsify common descent, from having no fossils decades ago to genetic analysis demonstrating no common descent… but all of these have failed.
As i have said before, these trees are created by merging evidence from Genetics and morphology of fossils. Let me share excerpts from the 2013 paper shared by you.
Blockquote
A broad-scale reconstruction of the evolutionary remodeling that culminated in extant cetaceans has not yet been based on integration of genomic and paleontological information. Here, we first place Cetacea relative to extant mammalian diversity, and assess the distribution of support among molecular datasets for relationships within Artiodactyla (even-toed ungulates, including Cetacea). We then merge trees derived from three large concatenations of molecular and fossil data to yield a composite hypothesis that encompasses many critical events in the evolutionary history of Cetacea. By combining
diverse evidence, we infer a phylogenetic blueprint that outlines the stepwise evolutionary
development of modern whales
Blockquote
Extensive modifications, including the loss or reduction of many typical mammalian characteristics (Flower, 1883), have rendered modern representatives of Cetacea nearly unrecognizable as mammals (Fig. 2), but molecular data generally position Cetacea deep
within Artiodactyla (even-toed hoofed mammals), closest to Hippopotamidae (Irwin and Arnason, 1994; Gatesy et al., 1996; Gatesy, 1997, 1998; Nikaido et al., 1999; Matthee et al., 2001; Zhouet al., 2011). Hippopotamuses and whales share some aquatic traits (Fig. 1A–C; Gatesy et al., 1996; Gatesy, 1997), but extant cetaceans are still highly derived relative to hippos across nearly all organ systems (Boisserie et al., 2011). Due to extinction, a purely molecular approach is therefore inadequate for deciphering the extended sequence
of change on the lineage that led to extant whales; integration of genomic evidence with the fossil record is required (Gatesy and O’Leary, 2001)
Blockquote
The point being made is that generally, molecular studies are done only for extant organisms. These studies point to the Hippo as the animal with the most genetic similarity to whales. However, there is very little similarity between Hippos and whales with respect to their organ Systems.i.e there should be a huge no: of extinct intermediates in between… and we need the fossils to fill in the blanks.
Point to note here is that, Genetic sequences of the fossils in the evolutionary trees have not been done and it says nothing about the position of extinct fossils in the tree.
To give you an idea what a evolutionary tree derived from genetics looks like, i will paste one below -
Notice that there are no Pakicetids, kutchicetus, Rhodocetus etc… All you have got is several whales/ Dolphins and a Hippo.This is why its ridiculous to claim the genetic evidence supports the fossil inputs into the evolutionary tree. Gene sequencing was not done for these fossils and hence genetics has not yet contributed to where they should be in the evolutionary tree. All molecular genetics says is that the hippo is the closest extant species to the whales.
Just to underscore the point, one more evolutionary tree from a genetic study
So, i hope you wont tell me again that Genomic studies support the evolution story told by berkeley. All genomic studies say is that Whales are genetically more similar to cows/ hippos as compared to say men/insects etc. (Cant be sure about bats though!).Similarity cannot prove common descent unless it is assumed. Even when descent is assumed, there are cases in which similarity is considered to have been arrived at independently/in parallel.
Also, its interesting to note that before, the hippo was found to be the genetically closest animal to the whale… the fossils told a different story which had to be changed to be inline with the genetic studies…So the answer to your question is-
Genetics does not confirm the evolutionary tree proposed by studying fossils. The only point of agreement is an example of Paleontology conforming to genetics.
Edit: In short, genetics falsified the only testable part of the evolutionary tree derived from fossils.
Edit: @Bill_II, @AMWolfe, @gbrooks9, @GJDS, @T_aquaticus, @Mervin_Bitikofer
So i dont have to repeat all this)
No one is saying that similarity by itself is proof or evidence of common descent. What scientists keep saying is that homologous features falling into a nested hierarchy is what evidences common descent. Until you get this basic fact right, the rest of your argument will continue to miss its mark.
“Homologous features”- means features inherited via common descent.
So your claim reads as below-
“Features inherited via common descent falling into a nested hierarchy is what evidences common descent”
This is a tautology. (its like saying the evidence for common decent is… common descent)
Its also isn’t logical. Common descent should create one cluster of similar organisms, not many clusters of organisms such that each cluster is distinct and has a high degree of variation with respect to the other.
Blockquote
A homology is a character shared between species that was also present in their common ancestor.
This can be contrasted with an homoplasy, which is a convergent character shared between species but not present in their common ancestor.
Blockquote Evolution - A-Z - Homologies
I looked up the 49 million year-old whale. It was a jawbone. It had teeth, so it was hardly a modern whale. It appeared to be fully aquatic, which was unexpected, but it suggests that the transition from terrestrial to fully aquatic took only 4 million years in some species instead of 15. That is not a sudden miraculous transition.
Nope. Textbooks and even some biologists get it wrong. Homology is a relation of sameness between two or more characters in two or more organisms. Them being inherited from a common ancestor is the explanation for the homologous characters. Homology is a pre Darwinian concept. A lot people use the definition you used above because everyone (mostly everyone) knows what we are talking about. It’s not necessary to really break down the definition.
