Lately in my reading of science news articles, it seems like hybridization in new species as come up several times. I really appreciate the few videos and articles that Rob Carter has put out on the topic of hybridization. Helped me appreciate creation models even more.
But I wanted to share this paper because I thought it was beautiful in its simplicity. As far as I understand it, Jeanson’s model of speciation is created heterozygosity, migration, and isolation, versus a Darwinian model of mutation and natural selection.
With sentences in the paper like this, how can it be argued that created heterozygosity and isolation is not a superior model?
The combination of evidence—visual, bioacoustic, and genetic—confirms that the parents of the described individual were a rose-breasted grosbeak Pheucticus ludovicianus (female parent) and a scarlet tanager Piranga olivacea (male parent). While these two species breed sympatrically across much of eastern North America, they exhibit somewhat different habitat preferences: scarlet tanagers typically prefer unfragmented, mature forest, while rose-breasted grosbeaks often will occupy second growth including forest with a relatively open canopy, although they will utilize adjacent edges or disturbed areas (Mowbray, 2020; Wyatt & Francis, 2020). The two species are phenotypically highly divergent and have likely not shared a common ancestor in >10 million years (Barker et al., 2015).
The genome of the hybrid was exceptionally heterozygous (Figures 3 and 4)—as is expected from an F1 hybrid with highly divergent parents—with a heterozygous base every 100–150 bp. This is also a likely underestimate. First, given that the parental genera were represented by RNA sequence data, the only regions we analyzed in depth here were coding regions, and these regions are constrained by stronger purifying selection than non-coding sequences (Ward & Kellis, 2012). Second, accurately calling heterozygous sites requires high coverage (Song et al., 2016); thus, we presume that many of the sites that differed between the parental genera but where the hybrid had one or the other genotype (i.e., was not heterozygous), might actually be heterozygous in the hybrid, but we lack the coverage depth to decisively call a heterozygous genotype. The fact that the sites where the hybrid had one or the other parental genotype occur in nearly equal frequencies (24 vs. 26 sites of 137) supports this interpretation.
In other news, how is everyone? I’ve been enjoying lots of science lately - had a science experiment birthday party for my oldest, my kids and I have been binging Mark Rober (anyone else a Mark Rober fan?). I’m reading Jennifer Raff’s book as recommended. My family has been enjoying many viruses I assume are recombined mutants to manage to survive covid isolation. Eye infections, ear infections a result. Many symptoms I’d forgotten existed in the world.