Why are tetrapods with ZZ/ZW sex-determination systems more male-skewed than XY/XX?. Phylogenetic analyses of a large dataset of wild #tetrapod species reveal that #SexDetermination systems influence adult #SexRatio via sex-biased adult mortality @PLOSBiology https://plos.io/43qTysJ
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Let me tell you 'bout the birds and the bees and the octopuses:
3-Feb-2025
#Octopuses have some of the oldest known #sexChromosomes
New research at the UO shows they’ve been using one that’s been around for 480 million years
https://www.eurekalert.org/news-releases/1072206 #science #evolution #chromosomes #genome #sexDetermination #cephalopods
EurekAlert!Octopuses have some of the oldest known sex chromosomesUniversity of Oregon researchers have identified a sex chromosome in the California two-spot octopus. This chromosome has likely been around for 480 million years, since before octopuses split apart from the nautilus on the evolutionary tree. That makes it one of the oldest known animal sex chromosomes. The finding also is evidence that octopuses and other cephalopods, a class of sea animals that includes squid and nautiluses, do use chromosomes to determine their sex, answering a longstanding mystery among biologists.
Call of the Mole Vole https://synapsida.blogspot.com/2025/02/call-of-mole-vole.html
"There are over 170 recognised species of vole... And then, there are the #MoleVoles... most (but not all) mole vole species lack a Y chromosome. In these species, the males have exactly the same XX karyotype that females do... As of 2025, we have no clue as to how #SexDetermination works in these species."
Genetic mechanism of alternating sexes in #walnut #trees has some parallels to #SexDetermination in humans https://phys.org/news/2025-01-genetic-mechanism-alternating-sexes-walnut.html
Ancient structural variants control sex-specific #flowering time morphs in #walnuts and #hickories https://www.science.org/doi/10.1126/science.ado5578
"A walnut #tree produces #flowers of one sex, then the other in the same season, but trees differ in which one comes first. Individual trees are consistently male-first or female-first in flowering."
8-Jan-2025
A nearly gapless #genome sequence of the #echidna, an egg-laying mammal with multiple #sexChromosomes, helps researchers to track genomic reorganization events that gave rise to a highly unusual #sexDetermination system.
related to the system of the #platypus which was the cover story in my book "Der Kuss des Schnabeltiers" / "The birds, the bees, and the platypuses." 15 years later I can't remember how that worked but I loved the story.
EurekAlert!Unraveling the events leading to multiple sex chromosomes using an echidna genome sequenceThe short-beaked echidna (Tachyglossus aculeatus) is one of Australia’s most iconic animals. Belonging to a unique group of mammals called “monotremes” (with the platypus as the other prominent member), echidnas may at first glance be mistaken for a weird-looking hedgehog, but they are in fact egg-laying mammals. An international team of authors, led by Guojie Zhang and Qi Zhou at Centre for Evolutionary & Organismal Biology at Zhejiang University, Yang Zhou from BGI-research and Frank Grutzner from Adelaide University now present an almost gapless genome sequence of the short-beaked echidna. This work is part of the international Vertebrate Genome Project, and hosted in the VGP Genome Ark Database. The authors used the new data to better understand the evolutionary origin of the highly complex configuration of multiple sex chromosomes which is characteristic for monotremes. The work is published in the open science journal GigaScience.
2-Jan-2025
Genetics of alternating sexes in #walnuts
https://www.eurekalert.org/news-releases/1069346 #science #plants #SexDetermination
EurekAlert!Genetics of alternating sexes in walnutsThe genetics behind the alternating sexes of walnut trees has been revealed by biologists at UCDavis. The research reveals a mechanism that has been stable in walnuts and their ancestors going back 40 million years — and which has some parallels to sex determination in humans and other animals.
30-JUL-2024
#Platypus and chicken reveal how chromosomes balance between the sexes
EurekAlert!Platypus and chicken reveal how chromosomes balance between the sexesGeneticists uncover new insights into how sex chromosome systems work in the platypus and the chicken—which will lead to better understandings of our own sex chromosome evolution and gene regulation.
First raiding Mastodon here, with our brand-new perspective on @GenomeBiolEvol about the growing importance of #bivalves in #sexDetermination studies especially in the light of comparative #genomics 
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Sex #chromosomes, environmental sex determination, #mitochondria inheritance and sex-related #genes are some of the topics bivalves may help to study.
A huge thanks to my co-authors!!
Beyond X and Y: #Fish have different methods of sex determination https://oceanbites.org/beyond-x-and-y-fish-have-different-methods-of-sex-determination/
Rapid turnover and #evolution of sex-determining regions in Sebastes #rockfishes https://onlinelibrary.wiley.com/doi/10.1111/mec.17090
"Some fish even change sex partway through their adult life, based on size or age! Closely related species of fish often have different #SexChromosomes or lack clear sex #chromosomes altogether, indicating that #SexDetermination evolves quickly and is highly variable."
Cryptic #sexChromosome was found after removing a master sex-determining #chromosome. This result suggests that #polygenic #sexDetermination system may be more prevalent than previously thought.
Open access article by Kitano et al. now available ahead of print!
How and why temperatures determine the sex of turtles? https://phys.org/news/2023-06-temperatures-sex-turtles.html
Higher temperatures directly increase germ cell number, promoting feminization of #RedEaredSlider turtles https://www.cell.com/current-biology/fulltext/S0960-9822(23)00758-3
"Warmer temperatures make more #turtle eggs become female hatchlings... those females also have a higher capacity for egg production, even before their sex is set. This may explain why many #animals besides #turtles have temperature-dependent #SexDetermination"
Smaga, C. R., S. L. Bock, J. M. Johnson and B. B. Parrott (2022). "Sex Determination and Ovarian Development in Reptiles and Amphibians: From Genetic Pathways to Environmental Influences." Sexual Development. https://www.karger.com/DOI/10.1159/000526009
#ovarydevelopment
#sexdetermination
#reptiles #amphibians #environmentalsexdetermination
www.karger.comSex Determination and Ovarian Development in Reptiles and Amphibians: From Genetic Pathways to Environmental InfluencesBackground: Reptiles and amphibians provide untapped potential for discovering how a diversity of genetic pathways and environmental conditions are incorporated into developmental processes that can lead to similar functional outcomes. These groups display a multitude of reproductive strategies, and whereas many attributes are conserved within grou
Published Science. Bacteria that kill males
Study identifies genomic region related to #SexDetermination of macroalga #Undaria pinnatifida https://phys.org/news/2022-12-genomic-region-sex-macroalga-undaria.html Paper: https://onlinelibrary.wiley.com/doi/10.1111/jpy.13295 #algae #genomics
Undaria pinnatifida is an economically important brown macroalga. There are 3 sexual phenotypes: female, male, and monoicous. However, the sex-determining mechanisms was unknown.
Novel #SexDetermination mechanism revealed in mammals
https://phys.org/news/2022-11-sex-determination-mechanism-revealed-mammals.html
The #AmamiSpinyRat is an endangered rodent found only on #Amami Oshima, #Japan. It is one of just 4 mammals known to lack a Y chromosome. In the Amami spiny rat, the the Sry gene is completely absent; thus, the animal has evolved a novel sex-determining mechanism independent of Sry.