Evolutionary strata on young mating-type chromosomes despite the lack of sexual antagonism.

Add to your list(s) Download to your calendar using vCal

• Professor Tatiana Giraud, Departement Genetique et Ecologie Evolutives, Université Paris-Saclay
• Thursday 07 October 2021, 13:30-14:30
• Zoom meeting.

If you have a question about this talk, please contact Caroline Newnham.

Host: John Welch

Sex chromosomes can display successive steps of recombination suppression known as “evolutionary strata”, which are thought to result from the successive linkage of sexually antagonistic genes to sex-determining genes. However, there is little evidence to support this explanation. We show that evolutionary strata have evolved repeatedly without sexual antagonism in fungi : we found in anther-smut fungi suppressed recombination extending beyond loci determining mating compatibility despite lack of male/female roles associated with their mating types. By comparing full-length chromosome assemblies from anther-smut fungi with or without recombination suppression in their mating-type chromosomes, we inferred the ancestral gene order and derived chromosomal arrangements in this group. This approach shed light on the chromosomal fusion underlying the linkage of mating-type loci in fungi and multiple independent cases of chromosomal rearrangements leading to regions of suppressed recombination linking these mating-type loci in closely related species. Such convergent transitions in genomic architecture of mating-type determination indicate strong selection favoring linkage of mating-type loci into cosegregating supergenes. We also found multiple independent evolutionary strata (stepwise recombination suppression) in several species over a range of ages in mating-type chromosomes. Several evolutionary strata did not include genes involved in mating-type determination. The existence of strata devoid of mating-type genes were found in several other fungi and even around other types of supergenes, despite the lack of sexual antagonism, calls for a unified theory of sex-related chromosome evolution. We therefore developed a theoretical model to test alternative hypotheses and showed that recombination suppression can be selected for sheltering deleterious alleles segregating in genomes near a permanently heterozygous allele.

This talk is part of the Genetics Seminar series.

This talk is included in these lists:

• All Talks (aka the CURE list)
• Bioinformatics and other interests
• Biology
• Centre for Health Leadership and Enterprise
• DevBio
• Genetics Seminar
• Genetics Seminar Series
• Graduate-Seminars
• Life Sciences
• Life Sciences
• ME Seminar
• Neurons, Fake News, DNA and your iPhone: The Mathematics of Information
• PMRFPS's
• Zoom meeting
• ji247's list
• my_list
• ndk22's list
• other talks

Note that ex-directory lists are not shown.