Loïs Rancilhac
@loisrancilhac.bsky.social
Evolutionary biologist: speciation, adaptation, genomics, phylogeography of birds and lizards. Keen naturalist (birder, herper, entomologist, botanist and more), climber, cyclist, hiker.
Currently in Madrid, formerly France, Germany, Sweden & Cyprus.
Currently in Madrid, formerly France, Germany, Sweden & Cyprus.
I think that acknowledging the subjective nature of species delimitation and that in many cases different taxonomic decisions are reasonable would also help moving away from endless “species concept” debates (12/)
May 26, 2025 at 4:10 PM
I think that acknowledging the subjective nature of species delimitation and that in many cases different taxonomic decisions are reasonable would also help moving away from endless “species concept” debates (12/)
I think this points to a need for the fields of taxonomy and speciation to work more integratively towards understanding species diversification. Taxonomic classification can then be seen as a bi-product of a better understanding of speciation rather than an end in itself (11/)
May 26, 2025 at 4:09 PM
I think this points to a need for the fields of taxonomy and speciation to work more integratively towards understanding species diversification. Taxonomic classification can then be seen as a bi-product of a better understanding of speciation rather than an end in itself (11/)
(To be clear, I’m not arguing against integrative taxonomy as a general approach. I think it works in many cases, but remains flawed if the link between the characteristics studied and speciation is not understood (10/))
May 26, 2025 at 4:09 PM
(To be clear, I’m not arguing against integrative taxonomy as a general approach. I think it works in many cases, but remains flawed if the link between the characteristics studied and speciation is not understood (10/))
Bearing that in mind, studying the biological causes of phenotypic/genetic variation should be much more informative about species limits than just quantifying differences in many characteristics (9/)
May 26, 2025 at 4:08 PM
Bearing that in mind, studying the biological causes of phenotypic/genetic variation should be much more informative about species limits than just quantifying differences in many characteristics (9/)
This gives the perception that populations with more differences should be at a later stage of the speciation continuum and thus more likely to be considered taxonomic species. But there are many examples in nature contradicting this linear perception (8/)
May 26, 2025 at 4:08 PM
This gives the perception that populations with more differences should be at a later stage of the speciation continuum and thus more likely to be considered taxonomic species. But there are many examples in nature contradicting this linear perception (8/)
I think this traces back to the “universal species concept” which conveys a view of speciation where differences corresponding to specific concepts are accumulated linearly as lineages become species. (7/)
May 26, 2025 at 4:07 PM
I think this traces back to the “universal species concept” which conveys a view of speciation where differences corresponding to specific concepts are accumulated linearly as lineages become species. (7/)
The blog post suggests that integrative taxonomy should be applied in such a case. I disagree. Different lines of evidence should be considered for species delimitation only if they can inform about the process of speciation versus alternative processes (6/)
May 26, 2025 at 4:07 PM
The blog post suggests that integrative taxonomy should be applied in such a case. I disagree. Different lines of evidence should be considered for species delimitation only if they can inform about the process of speciation versus alternative processes (6/)
There is no indication that redpolls are at an intermediate stage in a continuum between one and multiple species. Rather, phenotypic variation is maintained by selection in the face of homogeneizing gene flow, apparently without participating in reproductive isolation (5/)
May 26, 2025 at 4:07 PM
There is no indication that redpolls are at an intermediate stage in a continuum between one and multiple species. Rather, phenotypic variation is maintained by selection in the face of homogeneizing gene flow, apparently without participating in reproductive isolation (5/)
The redpolls cited in the blog post are a good example here because the latest evidence suggests that the phenotypic variation that originally led to several species being described is due to local adaptation along a latitudinal gradient. (4/)
May 26, 2025 at 4:07 PM
The redpolls cited in the blog post are a good example here because the latest evidence suggests that the phenotypic variation that originally led to several species being described is due to local adaptation along a latitudinal gradient. (4/)
This emphasis on the “gray area” as an intermediate state in the speciation process is rather flawed because there are many biological processes that generate phenotypic and genetic divergence (discrete or continuous) without being necessarily related to speciation (3/)
May 26, 2025 at 4:06 PM
This emphasis on the “gray area” as an intermediate state in the speciation process is rather flawed because there are many biological processes that generate phenotypic and genetic divergence (discrete or continuous) without being necessarily related to speciation (3/)
The “universal species concept” kind of acknowledges that with its “gray area” of speciation, but this gives a deterministic view of speciation where satisfying a single species concept is already evidence enough that two species exist (2/)
May 26, 2025 at 4:06 PM
The “universal species concept” kind of acknowledges that with its “gray area” of speciation, but this gives a deterministic view of speciation where satisfying a single species concept is already evidence enough that two species exist (2/)
It seems the link to the paper in the first post does not work, so here it is again: academic.oup.com/sysbio/advan...
Introgression across narrow contact zones shapes the genomic landscape of phylogenetic variation in an African bird clade
Abstract. Genomic analyses of hybrid zones provide excellent opportunities to investigate the consequences of introgression in nature. In combination with
academic.oup.com
May 14, 2025 at 4:14 PM
It seems the link to the paper in the first post does not work, so here it is again: academic.oup.com/sysbio/advan...
This is part of broader work on speciation and color evolution in tinkerbirds led by @akirschel.bsky.social. Thanks a lot to him and to all co-authors, as well as reviewers and editors at Syst Biol. (10/10)
May 14, 2025 at 3:15 PM
This is part of broader work on speciation and color evolution in tinkerbirds led by @akirschel.bsky.social. Thanks a lot to him and to all co-authors, as well as reviewers and editors at Syst Biol. (10/10)
Another cool result is that the gene CYP2J19, coding for red v. yellow forecrown, supports the species tree, while surrounding regions support an 'introgressed' topology. It also shows a deeper divergence between Red-fronted taxa, further supporting a single ancient origin the red coloration. (9/10)
May 14, 2025 at 3:13 PM
Another cool result is that the gene CYP2J19, coding for red v. yellow forecrown, supports the species tree, while surrounding regions support an 'introgressed' topology. It also shows a deeper divergence between Red-fronted taxa, further supporting a single ancient origin the red coloration. (9/10)
We studied RADseq markers across two hybrid zones and found that, although geographic clines tended to be narrow, markers in regions supporting putative 'introgressed' topologies followed wider clines. This supports that contemporary gene flow indeed contributes to gene-tree heterogeneity. (8/10)
May 14, 2025 at 3:12 PM
We studied RADseq markers across two hybrid zones and found that, although geographic clines tended to be narrow, markers in regions supporting putative 'introgressed' topologies followed wider clines. This supports that contemporary gene flow indeed contributes to gene-tree heterogeneity. (8/10)
The question we asked is whether gene-tree heterogenity is driven by ongoing introgression through hybrid zones, or is a legacy of past gene flow when reproductive isolation may have been weaker. (7/10)
May 14, 2025 at 3:12 PM
The question we asked is whether gene-tree heterogenity is driven by ongoing introgression through hybrid zones, or is a legacy of past gene flow when reproductive isolation may have been weaker. (7/10)
When inferring a phylogeny using only regions of the genome with very low recombination rate (and low introgression rate), we recovered another topology where Red-fronted tinkerbirds are monophyletic. We believe this best represents the species tree of this group. (6/10)
May 14, 2025 at 3:11 PM
When inferring a phylogeny using only regions of the genome with very low recombination rate (and low introgression rate), we recovered another topology where Red-fronted tinkerbirds are monophyletic. We believe this best represents the species tree of this group. (6/10)
We found that this topology was over-represented in regions of the genome with a high recombination rate, which also show increased introgression rate. It is then likely that this topology reflects introgression. (5/10)
May 14, 2025 at 3:09 PM
We found that this topology was over-represented in regions of the genome with a high recombination rate, which also show increased introgression rate. It is then likely that this topology reflects introgression. (5/10)
However, we also found substantial variation in phylogenetic signal across the genome. The aforementionned topology, although being the most common, is only supported by ~15% of the genome. (4/10)
May 14, 2025 at 3:08 PM
However, we also found substantial variation in phylogenetic signal across the genome. The aforementionned topology, although being the most common, is only supported by ~15% of the genome. (4/10)
When building a phylogeny using whole-genome data, we recovered a fully-supported topology where Red- and Yellow-fronted lineages are not reciprocally monophyletic. (3/10)
May 14, 2025 at 3:07 PM
When building a phylogeny using whole-genome data, we recovered a fully-supported topology where Red- and Yellow-fronted lineages are not reciprocally monophyletic. (3/10)
We studied Red- and Yellow-fronted Tinkerbirds, which form several hybrid zones across Africa. (2/10)
May 14, 2025 at 3:07 PM
We studied Red- and Yellow-fronted Tinkerbirds, which form several hybrid zones across Africa. (2/10)