It'll no doubt come as a surprise to those creationists who believe Earth was created from nothing by magic just about 10,000 years ago to learn that the butterflies and moths have been evolving for 250 million years.
It'll maybe come as a bigger surprise to those creationists who have been fooled into believing that the Theory of Evolution is being discarded by mainstream biologists in favour of their childish fairy tale of magic and supernatural spirits, that yet another group of mainstream biologists regard it as the foundation of modern biology, and are participating in the Darwin Tree of Life Project, which aims to sequence the genome of 70,000 eukaryote species from Britain and Ireland, to learn their evolutionary relationships.
This project also contributes to the much larger, Earth BioGenome Project.
One of the teams taking part in this project, based at the Wellcome Sanger Institute and the University of Edinburgh, Scotland, has just completed the sequencing of 200 high-quality genome of the Lepidoptera order of insects (moths and butterflies) and discovered some interesting facts about the evolution of the order, including that there are some elements in the genomes, which they term 'Merian elements' after the 17th century entomologist Maria Sibylla Merian, which have remained relatively stable over the 250 million years the order has been evolving.
The research is published in the journal Nature Ecology & Evolution and is described in a Welcome Sanger Institute news release:
Comparison of over 200 high-quality butterfly and moth genomes reveals key insights into their biology, evolution and diversification over the last 250 million years, as well as clues for conservation.To understand the following paper, especially how the genomes of the Lepidoptera are organised, it helps to understand the difference between monocentric and holocentric chromosomes:
The most extensive analysis of its kind reveals how butterfly and moth chromosomes have remained largely unchanged since their last common ancestor over 250 million years ago. This stability exists despite the incredible diversity seen today in wing patterns, sizes, and caterpillar forms across over 160,000 species globally.
Researchers from the Wellcome Sanger Institute and their collaborators at the University of Edinburgh analysed and compared over 200 high-quality chromosome-level genomes across butterflies and moths to better understand their evolutionary history.
They further uncovered rare groups of species that broke these genetic norms and underwent genetic rearrangements, including chromosome fusions – where two chromosomes merge – and fissions – where a chromosome splits.
The findings, published today (21 February) in Nature Ecology and Evolution, shed light on the tight constraints governing genome evolution in these ecologically vital insects. They also offer insights into factors that have enabled select species to defy these rules of evolution. These insights that can inform and enhance conservation efforts by guiding targeted strategies, monitoring ecosystem health, adapting to climate change, and incorporating genetic information into broader conservation initiatives.
The work is part of the Darwin Tree of Life Project1, aiming to sequence all 70,000 species in Britain and Ireland, and contributes to the larger Earth BioGenome Project to sequence all 1.6 million named species on Earth2.
The study raises broader questions about how chromosomal changes shape biodiversity over time. The researchers will continue focused efforts to sequence all 11,000 European butterfly and moth species as part of the newly launched Project Psyche3.
Butterflies and moths – collectively called Lepidoptera – represent 10 per cent of all described animal species and are hugely important pollinators and herbivores in many ecosystems.
In this new study, researchers from the Wellcome Sanger Institute and their collaborators set out to understand the processes that drive the evolution of chromosomes of this highly diverse group.
They identified 32 ancestral chromosome building blocks, named “Merian elements” after the pioneering 17th century entomologist Maria Sibylla Merian4, that have stayed intact across most butterfly and moth species since their last common ancestor over 250 million years ago.
With the exception of a single ancient fusion event between two chromosomes that led to the 31 chromosomes seen in most species today5, chromosomes of most current species directly correspond to these ancestral Merian elements. The team found not only were chromosomes incredibly stable, but the order of genes within them was too.
The team found some species with minor changes, mainly involving fusions of small autosomes6 and the sex chromosome. This highlights the role of chromosome length as a driver of evolutionary change.
However, researchers uncovered a rare subset of species such as the blue butterflies – Lysandra – and the group containing cabbage white butterflies – Pieris – that have defied these genome structure constraints. These groups underwent extensive chromosome reshuffling, including breakage of chromosomes, and large scale reshuffling through fission and fusion.
The work increases understanding of factors that lead to genetic diversity within these insects. This can guide efforts to protect and preserve specific species facing unique challenges and environmental changes tied to climate change.
The chromosomes of most butterflies and moths living today can be traced directly back to the 32 ancestral Merian elements that were present 250 million years ago. It is striking that despite species diversifying extensively, their chromosomes have remained remarkably intact. This challenges the idea that stable chromosomes may limit species diversification. Indeed, this feature might be a base for building diversity. We hope to find clues in rare groups that have evaded these rules.
Studies like this, which allow us to delve into these evolutionary processes, are only possible with initiatives like the Darwin Tree of Life project generating high-quality, publicly available genome assemblies. We are amplifying these efforts in Project Psyche, aiming to sequence all 11,000 butterfly and moth species in Europe with collaborators across the continent. As vital pollinators, herbivores, and food sources of various ecosystems, as well as powerful indicators of ecosystem health, a deeper understanding of butterfly and moth biology through Project Psyche will inform future studies on adaptation and speciation for biodiversity conservation.
Professor Mark Blaxter,, senior author Head of the Tree of Life programme
Wellcome Sanger InstituteMore information
- This work is part of the Darwin Tree of Life project aiming to sequence the genomes of 70,000 species of eukaryotic organisms in Britain and Ireland. It is a collaboration between biodiversity, genomics and analysis partners that is transforming the way we do biology, conservation and biotechnology. https://www.darwintreeoflife.org/
- The Earth BioGenome Project is a global network of initiatives and institutes ultimately aiming to sequence all 1.6 million named species on the planet, to drive solutions for preserving biodiversity. https://www.earthbiogenome.org/
- Project Psyche will sequence the genomes of all 11,000 European Lepidopteran species, helping to conserve, protect and drive innovation. https://www.projectpsyche.org/
- For more information on the life of entomologist Maria Sibylla Merian https://www.britishmuseum.org/collection/animals/maria-sibylla-merian-pioneering-artist-flora-and-fauna
- This happened on the evolutionary branch leading to Ditrysia, the most diverse Lepidoptera group, containing over 98 per cent of all described species of butterflies and moths.
- Autosomes are the non-sex chromosomes carrying genetic information that influences traits such as colouration and wing pattern, distinct from those determining the insect’s sex.
What is the difference in terms of function between monocentric and holocentric chromosomes? Monocentric and holocentric chromosomes differ in their structure and function, particularly in how they attach to the spindle apparatus during cell division.In summary, the primary difference between monocentric and holocentric chromosomes lies in their centromere structure and the mechanism by which they segregate during cell division. Monocentric chromosomes have a single centromere, while holocentric chromosomes lack a single centromere and have multiple sites of spindle fiber attachment.
- Monocentric chromosomes:
- Monocentric chromosomes have a single centromere, which is a specialized region where spindle fibers attach during cell division (mitosis and meiosis).
- The centromere plays a crucial role in ensuring that the chromosomes are properly segregated into daughter cells during cell division.
- Examples of organisms with monocentric chromosomes include humans and most other animals.
- Holocentric chromosomes:
- Holocentric chromosomes lack a single defined centromere. Instead, they have multiple sites of attachment for spindle fibers distributed along their length.
- During cell division, the spindle fibers attach to these multiple sites, allowing the chromosome to be pulled apart and segregated into daughter cells.
- Holocentric chromosomes are found in certain organisms such as some species of insects (e.g., certain species of moths and beetles), nematodes, and plants (e.g., some species of flowering plants).
- The absence of a single centromere in holocentric chromosomes offers some advantages, such as potentially greater stability and flexibility during chromosome rearrangements and evolution.
AbstractNot a lot of comfort there for creationists hoping for a crumb of evidence that mainstream research biologists are turning to creationist superstition to explain the real-world facts of biology. Nor is there any comfort for creationists wanting to believe Earth is on about 10,000 years old, with so much of the evolutionary history of the butterflies and moths taking place up to 250 million years before the mythical 'Creation Week'.
Chromosomes are a central unit of genome organization. One-tenth of all described species on Earth are butterflies and moths, the Lepidoptera, which generally possess 31 chromosomes. However, some species display dramatic variation in chromosome number. Here we analyse 210 chromosomally complete lepidopteran genomes and show that the chromosomes of extant lepidopterans are derived from 32 ancestral linkage groups, which we term Merian elements. Merian elements have remained largely intact through 250 million years of evolution and diversification. Against this stable background, eight lineages have undergone extensive reorganization either through numerous fissions or a combination of fusion and fission events. Outside these lineages, fusions are rare and fissions are rarer still. Fusions often involve small, repeat-rich Merian elements and the sex-linked element. Our results reveal the constraints on genome architecture in Lepidoptera and provide a deeper understanding of chromosomal rearrangements in eukaryotic genome evolution.
Main
Chromosomes are the central units of genome architecture in eukaryotic organisms. They determine processes such as recombination and segregation. While chromosomes are generally stable over evolutionary time, large-scale rearrangements, such as fusions and fissions, can occur. Consequently, chromosomes of extant species can be used to infer the linkage groups present in a common ancestor, termed ancestral linkage groups (ALGs). ALGs have been identified in many taxa including Diptera1, flowering plants2, Nematoda3,4, mammals5, vertebrates6 and Metazoa7. Chromosomal rearrangements have important consequences for genome function8, speciation9 and adaptation10. For example, heterozygous chromosomal fusions can interfere with meiosis, resulting in reproductively isolated populations11,12. The evolutionary forces constraining chromosome number and maintaining ALGs remain unclear. Moreover, how and why certain taxa evade such constraints and experience high rates of karyotypic change are not understood.
In monocentric chromosomes, a single region, the centromere, serves as the organizing centre for Mendelian partitioning of homologues during mitosis and meiosis. Discrete centromeres are absent in holocentric chromosomes as centromeric functions are dispersed along the chromosome. Holocentricity has evolved independently several times across the tree of life, including in nematodes, four times in plants and multiple times in arthropods13,14,15,16,17,18. The most speciose of these holocentric groups is Amphiesmenoptera, comprising the insect orders Lepidoptera (moths and butterflies) and Trichoptera (caddisflies), which together account for 15% of all described eukaryotic species19,20. The convergent evolution of holocentricity in many speciose groups indicates that this alternative solution to accurate segregation of chromosomes may be evolutionarily advantageous.
Holocentric chromosomes are suggested to facilitate rapid karyotypic evolution as fragments derived from fission could maintain kinetochore function21,22. Lepidoptera are the most karyotypically diverse group of any non-polyploid eukaryote, with haploid chromosome numbers (hereafter chromosome number, n) ranging from 5 to 223 (refs. 23,24). However, most species have haploid counts of n = 29–31 (refs. 25,26), indicating that further mechanisms must constrain holocentric karyotype evolution. Indeed, chromosome numbers and their gene contents are generally stable over evolutionary time in both holocentric and monocentric taxa27.
Changes in chromosome number alter the recombination rate28,29. In Lepidoptera, where recombination only occurs in males (ZZ), there tends to be one crossover event per chromosome per generation30,31,32. Thus, loci on a fused chromosome formed from two equally sized progenitors will experience a 50% reduction in per base recombination rate relative to the unfused chromosomes. Changes in recombination rate will impact the evolutionary forces that shape genome architecture, altering the effect of selection at linked sites and therefore effective population size. Lower recombination rates also intensify Hill–Robertson interference between tightly linked beneficial loci, hindering adaptive evolution33. However, local adaptation is facilitated by reduced recombination between locally adapted loci in the presence of gene flow34,35.
Here, we infer ALGs for Lepidoptera, which we term Merian elements, from 210 chromosomal genome assemblies using a reference-free, phylogenetically aware approach. We find that Merian elements have remained intact in most species. While infrequent fusions occur, fissions are extremely rare. Constraints on large-scale reorganization have been relaxed in eight lineages, resulting in chromosomes that are the products of either many fissions or numerous fusion and fission events. Across Lepidoptera, we find that fusions are biased towards shorter autosomes and the Z sex chromosome, suggesting that both chromosome length and haploidy in the heterogametic sex play key roles in constraining genome rearrangement.
a, Phylogeny was inferred using the amino acid sequences of 4,947 orthologues that were present and single copy in 90% of all species sampled under the LG substitution model with gamma-distributed rate variation among sites. The tree was rooted using five representative species of the two main suborders from the sister group, Trichoptera (caddisflies). Excluding the ancient fusion between M17 and M20, which is shared by all Ditrysians (purple asterisk), half of the species have retained intact Merian elements since the last common ancestor of Lepidoptera (black lines). Orange branches indicate lineages with at least one fusion or fission event. Orange circles indicate internal nodes where descendants share a fusion event. We inferred no fission events at internal orange nodes. Red branches indicate lineages with extensively reorganized genomes (Lysandra coridon, Lysandra bellargus, Pieris brassicae, Pieris napi, Pieris rapae, Tinea semifulvella, Melinaea menophilus, Melinaea marsaeus, Aporia crataegi, Brenthis ino, Operophtera brumata, Philereme vetulata, Leptidea sinapis and Apeira syringaria). Red nodes indicate internal nodes where extensively reorganized descendants share fusion or fission events. Scale in substitutions per site is shown. b,c, The distribution of haploid chromosome number (n) (b) and genome size (Mb) (c) across 210 lepidopteran species. Alternating shades distinguish different taxonomic families. Source data for this figure can be found in Supplementary Tables 1 and 6 and in the Zenodo repository122.
Wright, C.J., Stevens, L., Mackintosh, A. et al.
Comparative genomics reveals the dynamics of chromosome evolution in Lepidoptera.
Nat Ecol Evol (2024). https://doi.org/10.1038/s41559-024-02329-4
Copyright: © 2024 The authors.
Published by Springer Nature Ltd. Open access.
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
And yet creationism as a cult manages to stagger on by ignoring the real world and pretending its dogmas are based on an alternative reality in which evidence-free superstitions somehow create facts which require no further validation.
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Butterflies, moths, and skippers are generally pleasant examples of Nature, but there are some very unpleasant examples such as venomous stinging caterpillars which inflict an agonizingly painful sting more painful than most snakebites. Some of the caterpillars are also repulsive in appearance such as the Gypsy moth and a few species of moth drink the blood of vertebrates.
ReplyDeleteLepidoptera has some of the most intelligent insects besides bees, wasps, ants, and preying mantis.
Clothes moths are another example of undesirable vermin. They ruin clothing, and they ruin human foods and they ruin pet foods. It's a little annoying to open up a cereal box to find Clothes moths in it. It's disgusting and the food is wasted and has to be thrown in the garbage. Waste of food and waste of money. The creator likes to annoy and torture His creation or is indifferent and blind to the suffering that goes on in the world. It's an ungodly, ungodly being who let's His creation suffer and die.