Ibiza wall lizard
Ibiza wall lizard
In an entirely unsurprising finding, a group of researchers led by Professor Tobias Uller of Lund University, Sweden, believe they have explained the present range and diversity of wall lizards in the Mediterranean region as the result of major environmental changes caused by changes in the climate and sea-level about 6 million years ago.
This should come as no surprise to anyone familiar with the way a changing environment is the main driver of evolution and diversification.
This is also an example of how the TOE is supported by different strands of science, since it predicts that periods of significant evolution will be accompanied by periods of significant environmental change.
According to the Lund University news item:
Wall lizards date back around 20 million years. However, species formation seems to have picked up speed shortly after the Messinian Salinity Crisis 6 million years ago. During this period the Mediterranean almost dried out, only to rapidly fill up with water again as the Strait of Gibraltar opened.
Left panel shows representative male phenotypes of six Podarcis species: P. siculus (top left), P. filfolensis (top right), P. erhardii (middle left), P. tauricus (middle right), P. waglerianus (bottom left) and P. muralis (bottom right). Some Podarcis species are extraordinarily variable, as illustrated by the right panel that shows representative male phenotypes of six distinct populations of Podarcis pityusensis, a species endemic to Ibiza, Formentera and adjacent islets.
Photo credits: Birgit and Peter Oefinger (https://www.eurolizards.com/) for all six species on the left panel, and for P. pityusensis Day’s Edge Productions (top left, middle right, bottom left) and Mike Zawadzki (top right, middle left and bottom right).
Photo credits: Birgit and Peter Oefinger (https://www.eurolizards.com/) for all six species on the left panel, and for P. pityusensis Day’s Edge Productions (top left, middle right, bottom left) and Mike Zawadzki (top right, middle left and bottom right).
Our results show that the dramatic changes at the time probably contributed to the emergence of new species. They also shed light on why biodiversity looks the way it does today.
We believe that hybridization has fuelled evolution, promoting biodiversity and extraordinary adaptability among certain species.
By comparing the DNA from 26 species and 8 subspecies the team found evidence of occasional hybridization as isolated populations met again and shared DNA. These hybridizations gave rise to new species with new DNA combinations. One example is the diverse population of wall lizards on the island of Ibiza in the Balearics, which shows a wide range of colour forms.
We believe that hybridization has fuelled evolution, promoting biodiversity and extraordinary adaptability among certain species.
”Professor Tobias Uller, Lead author
Professor of evolutionary ecology
Lund University, Sweden
Professor of evolutionary ecology
Lund University, Sweden
Again, according to the same Lund University news item:
Half of their genes come from wall lizards that today live on the Iberian Peninsula, and the other half from those found in the Balkans and among the Greek islands. The species in Ibiza thus originated as a hybrid, which provided evolution with great opportunities to combine old genes in new ways. According to the researchers, this probably explains why species like the Ibiza wall lizard are so strikingly variable in colouration: despite close relationships and geographic proximity, they are a single colour on one island, but a variety of colours on the next, for example.
Click image to enlarge
Phylogeny of Podarcis wall lizards.
a The time-calibrated ML phylogenetic tree of the 34 major lineages of wall lizards based on whole-genome sequences (outgroup not shown). All nodes were 100% supported with 1000 bootstrap replicates, but not across all local trees (grey-scale of nodes signifies proportion of local trees derived from 200 kb windows in support of a given node). The lower panel shows the geological time scale of the evolutionary history of Podarcis and the estimated diversification rate. The thick red line indicates the Messinian Salinity Crisis (~6.0–5.3 MYA). The coloured rectangles on the tips of the tree denote geographically coherent groups of wall lizards.
b A summary of the similarities, given as normalized Robinson–Foulds distances, between all phylogenies reported in this study
Abbreviations: Cala. Calabrian, Gel. Gelasian, Mid. Middle, Piac. Piacenzian.
a The time-calibrated ML phylogenetic tree of the 34 major lineages of wall lizards based on whole-genome sequences (outgroup not shown). All nodes were 100% supported with 1000 bootstrap replicates, but not across all local trees (grey-scale of nodes signifies proportion of local trees derived from 200 kb windows in support of a given node). The lower panel shows the geological time scale of the evolutionary history of Podarcis and the estimated diversification rate. The thick red line indicates the Messinian Salinity Crisis (~6.0–5.3 MYA). The coloured rectangles on the tips of the tree denote geographically coherent groups of wall lizards.
b A summary of the similarities, given as normalized Robinson–Foulds distances, between all phylogenies reported in this study
Abbreviations: Cala. Calabrian, Gel. Gelasian, Mid. Middle, Piac. Piacenzian.
Click image to enlarge
Extensive genetic exchange among major wall lizard lineages.
a A phylogram indicating the phylogenetic relationship among the six major groups of wall lizards and a map showing their geographic distributions. Note that the tree includes the splits within the Western Islands group and the Sicilian-Maltese group that are relevant for the origin of the mosaic genomes of island species. Red arrows indicate the introgression events.
b The qpGraph of the major clades of wall lizards. The solid line represents the ‘tree-like’ evolution, whereas the dashed lines with arrows represent the parental ancestry of reticulations. The numbers next to dashed lines indicate the percentage of alleles derived from a given introgressive hybridization.
a A phylogram indicating the phylogenetic relationship among the six major groups of wall lizards and a map showing their geographic distributions. Note that the tree includes the splits within the Western Islands group and the Sicilian-Maltese group that are relevant for the origin of the mosaic genomes of island species. Red arrows indicate the introgression events.
b The qpGraph of the major clades of wall lizards. The solid line represents the ‘tree-like’ evolution, whereas the dashed lines with arrows represent the parental ancestry of reticulations. The numbers next to dashed lines indicate the percentage of alleles derived from a given introgressive hybridization.
Click image to enlarge
Reticulate evolution of wall lizards in the Sicilian-Maltese group.
a Proposed scenarios for the evolutionary history of wall lizards in Sicily and its surrounding area based on phyloNet networks: M1—consensus tree with no introgression; M2—an ancient introgression from the MRCA of Balkan and the two island groups into the P. siculus clade; M3—introgressions from P. muralis and P. siculus clades into the MRCA of the Sicilian subclade (P. raffonei and P. waglerianus); M4—all three reticulations combined.
b The minimal errors for the four scenarios fitted by linear algebra and numerical optimization.
c The observed D-statistic values for the species in the testing topologies. The dots represent the D-statistic scores, and the error bars represent their standard deviations. d Proportion of tree topologies supporting alternative relationships among P. muralis, P. siculus and the Sicilian subclade.
e Distribution of tree topologies across the genome. Each colour concords with the topology in panel d.
f 50 Kb window-based Dxy and fd statistics between P. muralis and the Sicilian subclade across Chromosome 15. The area shaded in grey marks a genomic block (36.3–39.5 Mb) of introgressed ancestry with low Dxy and high fd values containing 39 coding genes.
g The genome-wide distribution of Dxy values between P. muralis and the Sicilian subclade based on 50 Kb window. The black line indicates the Dxy for the genomic block highlighted in panel f.
a Proposed scenarios for the evolutionary history of wall lizards in Sicily and its surrounding area based on phyloNet networks: M1—consensus tree with no introgression; M2—an ancient introgression from the MRCA of Balkan and the two island groups into the P. siculus clade; M3—introgressions from P. muralis and P. siculus clades into the MRCA of the Sicilian subclade (P. raffonei and P. waglerianus); M4—all three reticulations combined.
b The minimal errors for the four scenarios fitted by linear algebra and numerical optimization.
c The observed D-statistic values for the species in the testing topologies. The dots represent the D-statistic scores, and the error bars represent their standard deviations. d Proportion of tree topologies supporting alternative relationships among P. muralis, P. siculus and the Sicilian subclade.
e Distribution of tree topologies across the genome. Each colour concords with the topology in panel d.
f 50 Kb window-based Dxy and fd statistics between P. muralis and the Sicilian subclade across Chromosome 15. The area shaded in grey marks a genomic block (36.3–39.5 Mb) of introgressed ancestry with low Dxy and high fd values containing 39 coding genes.
g The genome-wide distribution of Dxy values between P. muralis and the Sicilian subclade based on 50 Kb window. The black line indicates the Dxy for the genomic block highlighted in panel f.
Abstract
The Mediterranean basin is a hotspot of biodiversity, fuelled by climatic oscillation and geological change over the past 20 million years. Wall lizards of the genus Podarcis are among the most abundant, diverse, and conspicuous Mediterranean fauna. Here, we unravel the remarkably entangled evolutionary history of wall lizards by sequencing genomes of 34 major lineages covering 26 species. We demonstrate an early (>11 MYA) separation into two clades centred on the Iberian and Balkan Peninsulas, and two clades of Mediterranean island endemics. Diversification within these clades was pronounced between 6.5–4.0 MYA, a period spanning the Messinian Salinity Crisis, during which the Mediterranean Sea nearly dried up before rapidly refilling. However, genetic exchange between lineages has been a pervasive feature throughout the entire history of wall lizards. This has resulted in a highly reticulated pattern of evolution across the group, characterised by mosaic genomes with major contributions from two or more parental taxa. These hybrid lineages gave rise to several of the extant species that are endemic to Mediterranean islands. The mosaic genomes of island endemics may have promoted their extraordinary adaptability and striking diversity in body size, shape and colouration, which have puzzled biologists for centuries.
Yang, Weizhao; Feiner, Nathalie; Pinho, Catarina; While, Geoffrey M.; Kaliontzopoulou, Antigoni; Harris, D. James; Salvi, Daniele; Uller, Tobias
Extensive introgression and mosaic genomes of Mediterranean endemic lizards
Nature Communication 12, 2762 (2021). https://doi.org/10.1038/s41467-021-22949-9
Copyright: © 2021 The authors. Published by Springer Nature Ltd.,
Open access
Reprinted under a Creative Commons Attribution 4.0 International License (CC BY 4.0)
When a population becomes isolated on, for example, an island, there may be little reason for it to diverge into two or more daughter species and, more importantly, little evolutionary pressure to evolve reproductive isolation with barriers to hybridization. Then when populations can come into contact with parent or sibling populations, they may still have the ability to interbreed. The period of filling, then drying up before filling again created just these conditions and allowed a period when previously isolated populations could hybridize to create the present mosaic pattern of genomes across the region and a wide range of diversity in body size and colouration.
This illustrates the key role the environment plays in the evolutionary process, giving direction and emergent order from the chaos of random mutations on which the environment acts.
Creationists might like to ponder on the role of the Theory of Evolution in the interpretation of the results of this analysis of lizard genomes across several species and subspecies. Without it, none of the data would make any sense, but with it, the reason for the close correlation between changes in thr genomes at particular periods in history and changes in the geological and climatological record make perfect sense. It is infact predicted by the TOE.
It also confirms again how the TOE is supported by several different strands of science, in this case as diverse as genomics and geology.
For some reason, papers such as this seem to go completely unnoticed by Creationist frauds such as Ken Ham, Kent Hovind and Ray Comfort who continue to feed their dupes the lie that the TOE is a theory in crisis. Creationism, of course could never be described as a theory in crisis, because it doesn't qualify as a theory. It's simply a guess with no supporting evidence from the infancy of our species, that has long passed its sell-by date and should be consigned to the dustbin of history, along with phlogiston, miasmas, geocentrism and magic.
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