3.3. Genetic relationship with baldness
Crown baldness was present in 8/15 King Island scrubtits, including in
both sexes and all three subpopulations, but none of 55 Tasmanian
scrubtits. Logistic regression across all genotyped individuals showed a
weak negative relationship between multi-locus heterozygosity (MLH) and
the probability of crown baldness occurrence (β = -22.152. se = 8.788, z
= -2.52, p = 0.017, Figure 6a). However, this relationship disappeared
when the analysis was restricted to only King Island scrubtits (β =
11.56, se = 21.8, z = 0.53, p = 0.60, Figure 6b), suggesting baldness is
more likely to occur in the King Island scrubtit population than the
Tasmanian scrubtit population, but baldness in King Island scrubtits is
not linked to (relatively) low genome-wide MLH.
After accounting for population structure (k = 3) and adjusting
the p -values, the LFMM identified six loci that were
significantly associated with baldness (Figure S11). Of the six
candidate SNPs, three were genic and three were non-genic (Table S7).
Three SNPs were located on the same assembled contig, including one in
the DOCK11 gene involved in regulation of filopodium assembly.
Filopodia have been implicated in feather follicle formation and feather
branching in chickens (Cheng et al., 2018), suggesting a possible role
of this gene in baldness.