Cichlid speciation and predictable Intelligent Design dismissal

Jewel cichlid

Jewel cichlid

I have split this post into two parts: the actual science and intelligent design response.  Skip down below if you are familiar with the recent Cichlid research.

The Research

African cichlids are a favorite among fish collectors due to the wide variation of species. These species are naturally found in the many isolated lakes in Africa. It is easy to understand how the species that are found in different lakes have evolved differently over time, but cichlid speciation in the same lake is harder to understand. In a recent article in Nature, Ole Seehausen and colleagues seem to have discovered a probable mechanism for this speciation.

They believe that they are observing what is called sensory-driven speciation. The idea here is that slightly different environments lead to slightly different optimal communication systems (visual, olfactory, etc.). These changes lead to reproductive isolation (one definition of species) due to easy to detect characteristics being favored in each environment. The interesting thing is that this can occur within one population with slightly different environment as is seen with the cichlids in the research article.

Lake Victoria is a lake in Africa that has many different species of Cichlids. It is also a lake that has diverse environments that could allow for the creation of many species of cichlids. One example of different environments is depth and turbidity of the water. In some areas the water is relatively clear, but as you get deeper and deeper the water gets more cloudy. This results in two distinct environments: Close to the surface is clear where blue light is more prevalent and close to the bottom where there is mostly red light.

How does this lead to speciation? Seehausen and colleagues caught closely related species of Cichlids at various depths of water. When they looked at the color sensing chemicals in the fish’s eyes, they found that the fish at the surface were more sensitive to blue and the fish at the bottom were more sensitive to red. Since sexual preference in cichlids is believed to be based on how conspicuous the male fish is, blue fish at the surface and red fish at the bottom will be more successful at mating. Interestingly, when the researchers looked around areas where it got cloudy rapidly, they did not see this distinction in red vs blue fish distribution with depth. Furthermore, they did not see any female mating preference based on color at these sites.

Intelligent Design Response

Jonathon Wells posted at the Evolution News and Views blog that this work is “One long Bluff.”

But the researchers did not observe the origin of a new species. They did what biologists have been doing for a long time: They analyzed differences in existing species to find evidence to support a particular hypothesis of speciation.

Since when is finding evidence to support a hypothesis a bad thing?  I guess it is bad if you are stooped in pseudoscience.  What the researches did do is give support to a type of speciation that had only been hypothesized previously.  Wells continues:

Although “genetic mutations helped some fish adapt” might sound as though the researchers induced mutations that helped some fish adapt to new conditions, all they really did was compare existing species and find a correlation between differences in their DNA and differences in their vision.

The authors actually went out in the field and looked to find evidence that supported their hypothesis.  If this had all been done in the lab, Wells would then have complained about how these mutation could never have arisen in the wild.  Either way, the goal posts would have been moved.

British physicist David Tyler had slightly more reasonable assessment of the research, but still had some objections to the findings:

There is no new genetic information – just fine-tuning of existing genetic systems. There is no evidence that these new species lack the potential to interbreed. Indeed, the differences are so slight that hybridisation to produce fertile offspring can be predicted with some confidence.

There is new genetic “information”. The cichlids examined have different chemical sensors in their eyes than other cichlids. One is optimized to see in red and one is optimized to see in blue. The authors noted that the mutation that shifted the red chemical led to an increase in sensitivity by 10%. Surely this is also an example of a gain-of-function change, of which we are led by intelligent design proponents to believe don’t exist .

As to Tyler’s objection that the species can still interbreed, the point of the article is that they are recently or in the process of diverging into new species. If the cichlids were completely unable to breed, then the findings would not be considered as early in a speciation event.

He goes on to say:

These variations allow organisms to diversify and prosper in new ecological niches as they become accessible. However, these variations have nothing to do with the origin of cichlids, eyes or complex specified information.

There were never any claims that this research showed anything involved the “origin of cichlids.” The research here simply showed an example of how a small change in environments could lead to speciation. This diversification is completely in line with evolutionary theory. Small changes over short time periods add up to large changes over long periods.

Self described “journalist and grandmother ” Denyse O’ Leary doesn’t add much to what Tyler said, but did say:

The problem isn’t with the researchers, who sound suitably cautious. It’s the pop science media that jump on something like this and make far more of it than the current state of knowledge would justify.

So journalists are trying to oversell a story. That is their job.  They do it in every story because it is the nature of their business. That doesn’t mean that there isn’t anything important to learn from the research.

I find it interesting how none of the responses that I could find deny the research or even try to spin it into evidence for intelligent design. I guess this new evidence is not a big deal to them since it is just another rock on top of a mountain of evidence.

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Speciation: more evidence ignored by intelligent design

Darwin's finches: historical example of speciation

In promoting his book, The Politically Incorrect Guide to Darwinism and Intelligent Design, Jonathan Wells makes this statement:

the most fundamental problem of evolution, the origin of species, remains unsolved. Despite centuries of artificial breeding and decades of laboratory experiments, no one has ever observed speciation through variation and selection.

I believe the act of catching speciation in the act is nearly impossible, but to say that no one has ever observed speciation is just being willfully ignorant. I say that it is nearly impossible because of the timescales that are evolutionarily relevant. Remember that our lives, and scientific thought for that matter, is only a blink of an eye in evolutionary time. Therefore, one would not expect to be able to see speciation except in the most rare occurrence.

Another problem with the idea of speciation is that the term and idea of species is somewhat nebulous. A common definition of species is a population of organisms that can interbreed resulting in offspring that are also able to interbreed. This definition has a couple problems. What if only 1% of one population can interbreed with another population? Are those distinct species? What if two populations never mate in the wild due to completely different mating practices, but do mate when pressured to by isolation (e.g. in a lab).  Are they different species?

These problems defining species and the extremely long time for speciation events to usually occur allow ID/creation proponents, like Jonathon Wells, to say it has never been observed.  They are looking for an example where a population of creatures produces a completely new creature over a short period.  This strawman argument will convince the uninformed, but should not deter reasonable individuals.

Here I am going to list a few examples of speciation that we would expect from our understanding of evolution.  I want to limit this discussion to historically observed speciation events, the type that Wells believes do not exist. The list of known speciation events is enormous and can’t be easily covered in such a short space (see African ciclids, Darwin’s finches, cave salamanders, etc.).

  1. Apple maggot fruit fly, R. pomonella. The ancestor of this species of fly mates near hawthorn trees and lays its eggs inside the fruit. However, with the introduction of domestic apples to North America, these flies began using apples instead of the thorn apples. Now, there are two distinct populations of flies. These populations have distinct genetic differences and have varying times until maturity.
  2. Madeira island house mice. 500 years ago, house mice were introduced to the small island of Madeira off the coast of Africa. Six populations of mice were found containing chromosomal abnormalities that precludes their interbreeding.
  3. Radish and a cabbage hybrid. Russian biologist Georgii Karpechenko bred a radish and a cabbage to produce fertile offspring that had a completely new morphology. Unfortunately this new form was the leaves of the radish and the roots of the cabbage.

These three examples already disprove Wells’ contention.  However, these examples are just the beginning of observed instances of speciation.  For further reading, please see here and here.

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