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| Blind but ferocious: The Iberian mole (Talpa occidentalis) that is common in Spain and Portugal has a peculiar property – the females develop strong muscles and testicular tissues due to increased levels of male sex hormones © David Carmona, Departamento de Genética, Universidad de Granada, Granada, Spain. |
Only yesterday, for example, I wrote about two recent pieces of research that, looked at objectively, should tell any Creationist with a modicum of intellectual honesty and personal integrity that there is something wrong with their dogmas. And here, today, are two more papers that utterly refute Creationist claims quite incidentally and with no intention of doing so on the part of the authors.
Science reveals the truth. It's not complicated; if the truth is at variance with your beliefs than your beliefs are wrong and need to be revised. If you subscribe to a 'faith' that prevents you changing your mind when the evidence demands it, then you don't have free will and are a slave to someone else's dogmas.
The first paper shows how a mutation can be beneficial and illustrates how new genetic information can arise. Both these are in direct contradiciton with the claims of Creationist dogmas which aregue that all mutations are deleterious and that it is imposible for new genetic information to arise because that somehow contradicts the Second Law of Thermodynamics.
Moles: Intersexual and genetically doped | MDC Berlin
In this paper, international researchers led by Professor Stefan Mundlos of the Max Planck Institute for Molecular Genetics, Berlin, Germany, showed that the phenomenon of female intersexuality seen in some species of moles is caused by gene duplication and inversion. The joint press release from the Max Planck Institute for Molecular Genetics, Charité – Universitätsmedizin Berlin and the Max Delbrück Center for Molecular Medicine, explains:
Moles are special creatures that roam in an extreme habitat. As mammals that burrow deep into the earth, they have forepaws with an extra finger and exceptionally strong muscles. What’s more, female moles are intersexual while retaining their fertility. Typical for mammals, they are equipped with two X chromosomes, but they simultaneously develop functional ovarian and testicular tissues. In female moles, both tissue types are united in one organ, the ovotestis – something that is unique among mammals.
A lot of testosterone in the female mole’s blood
The testicular tissue of the female mole does not produce sperm, but large amounts of the sex hormone testosterone, meaning the females have similarly high levels as the males. Presumably this natural “doping” makes the female moles aggressive and muscular, an advantage for life underground, where they have to dig burrows and fight for resources.
In a study in the journal Science, Berlin scientists are now reporting on the genetic peculiarities that lead to this characteristic sexual development in moles. According to the study, it is primarily changes in the structure of the genome that lead to altered control of genetic activity. In addition to the genetic program for testicular development, this also stimulates enzymes for male hormone production in the females. The study was conducted by an international team co-led by Professor Stefan Mundlos, Research Group leader at the Max Planck Institute for Molecular Genetics (MPIMG) and Director at the Institute for Medical Genetics and Human Genetics at Charité – Universitätsmedizin Berlin and by Dr. Darío Lupiáñez, Research Group Leader at the Berlin Institute for Medical Systems Biology (BIMSB), which is part of the Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC).
Genomic mechanisms of evolution
“Since Darwin, it has been generally accepted that the different appearances of living organisms are the result of gradual changes in genetic makeup that have been passed onto subsequent generations,” says Mundlos. “But how are DNA changes and their manifestations in the appearance of an organism related in concrete terms, and how can we uncover such changes?”
To pursue this question, the researchers have completely sequenced the genome of the Iberian mole (Talpa occidentalis) for the first time. Moreover, they examined the three-dimensional structure of the genome within the cell. In the nucleus, genes and their associated control sequences form regulatory domains – relatively isolated “neighborhoods” consisting of large regions where DNA sections interact frequently with each other.
“We hypothesized that in moles, there are not only changes in the genes themselves, but particularly in the regulatory regions belonging to these genes,” says Mundlos. In the course of the moles’ evolution, then not only would individual letters of the DNA have changed, also larger pieces of the genome would have shifted, says the researcher. If segments of DNA move from one location to another, completely new or reorganized regulatory domains can emerge and thus activate new genes and enhance or attenuate their expression.
Within topologically associating domains (TADs), genes and their regulators interact with each other (represented by triangular shapes). Regulators like enhancers often act tissue-specific and activate their corresponding genes accordingly. A genomic inversion can alter this organization and shift the boundaries between domains. Certain regulatory elements might become associated with another gene and hence activate it in other tissues.
© Thomas Splettstoesser,
MPI f. mol. Genet.Program for testicular development
“The sexual development of mammals is complex, although we have a reasonably good idea on how this process takes place,” says Darío Lupiáñez. “At a certain point, sexual development usually progresses in one direction or another, male or female. We wanted to know how evolution modulates this sequence of developmental events, enabling the intersexual features that we see in moles.” In fact, when comparing the genome to that of other animals and humans, the team discovered an inversion – i.e., an inverted genomic segment – in a region known to be involved in testicular development. The inversion causes additional DNA segments to get included in the regulatory domain of the gene FGF9, which reorganizes the control and regulation of the gene. “This change is associated with the development of testicular tissue in addition to ovarian tissue in female moles,” explains Dr. Francisca Martinez Real, lead author of the study and scientist at the MPIMG as well as the Institute for Medical Genetics and Human Genetics at Charité. The team also discovered a triplication of a genomic region responsible for the production of male sex hormones (androgens), more specifically the androgen production gene CYP17A1. “The triplication appends additional regulatory sequences to the gene – which ultimately leads to an increased production of male sex hormones in the ovotestes of female moles, especially more testosterone,” says Real.
Wild moles and transgenic mice
The highly territorial moles cannot be kept in the laboratory, which particularly challenged the work of the researchers. “We had to do all our research on wild moles,” says Lupiáñez. He and Real spent months in southern Spain collecting samples for their experiments. “However, this drawback also became a strength in our study. Our results are not limited to laboratory animals, but extend our knowledge to wild animals.”
In mice, the activation of the CYP17A1 gene by a regulator leads to the production of testosterone. Moles have multiples of the DNA sequences that activate the gene, leading to a higher testosterone level in the blood of the animals.
© Francisca M. Real, Darío Lupiáñez,
MPI f. Mol. Genet.
The research group proved that the two genome mutations actually contribute to the special sexuality of female moles by creating a mouse model in which they mimic the genomic changes observed in moles. Of the altered animals, the female mice had androgen levels that were as high as in normal male mice. They were also significantly stronger than their unaltered conspecifics.
Evolution makes use of the genetic toolbox
With moles, the sexes are not that clearly delimited from one another; instead, females move on a spectrum between typically female and typically male phenotypes, i.e., they are intersexual.
In other words, because of genetic mutations involving duplication and triplication, then changes in the duplicated DNA, female moles act like females doped with performance-enhancing testosterone, and so are able to cope with the challenging environment and highly territorial behaviour. As mentioned in the press release, the results are published in science today:
Abstract
Linking genomic variation to phenotypical traits remains a major challenge in evolutionary genetics. In this study, we use phylogenomic strategies to investigate a distinctive trait among mammals: the development of masculinizing ovotestes in female moles. By combining a chromosome-scale genome assembly of the Iberian mole, Talpa occidentalis, with transcriptomic, epigenetic, and chromatin interaction datasets, we identify rearrangements altering the regulatory landscape of genes with distinct gonadal expression patterns. These include a tandem triplication involving CYP17A1, a gene controlling androgen synthesis, and an intrachromosomal inversion involving the pro-testicular growth factor gene FGF9, which is heterochronically expressed in mole ovotestes. Transgenic mice with a knock-in mole CYP17A1 enhancer or overexpressing FGF9 showed phenotypes recapitulating mole sexual features. Our results highlight how integrative genomic approaches can reveal the phenotypic impact of noncoding sequence changes.
M. Real, Francisca;Haas, Stefan A.;Franchini, Paolo;Xiong, Peiwen;Simakov, Oleg;Kuhl, Heiner;Schöpflin, Robert;Heller, David;Moeinzadeh, M-Hossein;Heinrich, Verena;Krannich, Thomas;Bressin, Annkatrin;Hartmann, Michaela F.;Wudy, Stefan A.;Dechmann, Dina K. N.;Hurtado, Alicia;Barrionuevo, Francisco J.;Schindler, Magdalena;Harabula, Izabela;Osterwalder, Marco;Hiller, Michael;Wittler, Lars;Visel, Axel;Timmermann, Bernd;Meyer, Axel;Vingron, Martin;Jiménez, Rafael;Mundlos, Stefan;Lupiáñez, Darío G.
The mole genome reveals regulatory rearrangements associated with adaptive intersexuality
Science 9 Oct 2020; 379(6513); pp 208-214; DOI: 10.1126/science.aaz2582
Copyright © 2020 The Authors. Published by the American Association for the Advancement of Science.
Reprinted by kind permission under license #4924711428334
The second paper which incidentally refutes another sacred Creationist dogma concerns an example of very rapid evolution -in this case, of sexual dimorphism in a bird from Sulawesi in Southeast Asia - the Sulawesi Babbler (Pellorneum celebense). Creationists hate these because they are often readily observable and documented examples of something of which they declare there to be no observed and recorded examples. These evolutionary changes occurred over a known period of 30,000 years since the small, offshore islands of Kabaena, Muna and Buton became detached from the main island of Sulawesi.
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| Sulawesi babbler, Pellorneum celebense |
Researchers from Trinity College, Dublin, Ireland, led by PhD candidate, Fionn Ó Marcaigh, showed that, while there was little sexual dimorphism on the main island, the populations on the off-shore islands showed a mixture of larger and smaller birds which, when genetically analysed were shown to be sexually dimorphic, with males being the larger.
Sex is determined in birds with two sex chromosomes Z and W, with males being homozygous (zz) and females being heterozygous (ZW). The team analysed the blood of captive birds after measuring their beaks, wings and skull using electrophoresis which shows two bands for females (one each for w and z) and a single dark band for males (2 Zs). The results showed a very strong division between males and females with the males measurably larger than females, unlike their mainland counterparts (assumed to be the parent population).
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| There were two groups in the babbler population, with birds from one being considerably larger than the other. DNA confirmed that the larger birds were the males and the smaller ones were female. |
Here then are two more examples of where Creationist dogma and false claims are refuted by science, quite incidentally and without any intent by the scientists, simply by revealing facts which flatly contradict the claims Creationist frauds mislead their credulous dupes with.
It really is time that Creationists began to realise that, when they tell us their faith disagrees with science, they are telling us their faith is wrong. They alone don't seem to have realised that yet, while most of us realised it a long time ago when we used science to find it out.
My sixth grade teacher explained anti-intellectualism to me. She told me that the reason my classmates did not like me was because they couldn't understand me. This made them mad. Not that they wanted to understand me, however, but that they simply wanted to prove me wrong and didn't know how to do that. Ultimately I changed schools when we move to another town and I had to learn to tone it down a little. But I think most of us understand where anti-intellectualism comes from. It's comes from the same phrase my first husband used to use: you think you're so damn smart.
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