2.6 Isolation by distance and isolation by phenotype
We investigated whether the genetic structure of A. buergerianavar. buergeriana reflects geographic distance or trait
differences. In general, populations separated by greater distances are
more genetically differentiated than populations close together (Wright,
1943). On the other hand, if populations with similar traits are also
genetically similar, then we can expect to find a correlation between
differences in traits between populations and the degree of genetic
differentiation. We used GenoDive software version 3.0 (Meirmans, 2020)
to calculate the genetic isolation (F ST) between
populations. The geographic distance between populations was calculated
from the latitude and longitude of the populations, and the difference
in the average spur length of each population was used as the trait
difference. We calculated the relationship between pairwiseF ST orF ST/(1
β F ST) and geographic distance between
populations, as well as the relationship between pairwiseF ST or F ST/(1 βF ST) and trait difference between populations,
following methods in Rousset (1997) and Noutsos et al. (2014). The
relationship between genetic isolation and geographic or trait distance
was tested by Mantel tests using the R package βade4β with 10,000
Monte-Carlo permutations.