It is likely the PCC was formerly one metapopulation connected through core and secondary soils (Duncan et al. 2017). When urban growth came to Panama City (incorporated in 1909) the processes of fragmentation and genetic isolation began in the known 13 remaining localized populations.
Genetic analysis of population differentiation and clustering methods to assess population structure suggests that the 13 locations across the PCC’s range are strongly differentiated, with the largest differences occurring between the eastern and western portions of the range (Duncan et al. 2017). The differences between the east and the west likely correspond to patterns of fragmentation from urban development and not necessarily from selective pressures maintaining adaptive differences. Because of the lack of studies using genome wide loci analyses of population structure and genetic diversity, particularly in crayfish, we do not have comparisons for values we would expect to see for estimates of heterozygosity, inbreeding coefficients, and effective population sizes in the PCC (Tables 3.2 and 3.3). However, population genetic measures estimated across the range from 13 primary sampling locations (Figure 3.6) give us insight into current conditions and how strongly these locations will be affected by future environmental change. Generally, genetic variation is low and inbreeding is high across the range, which indicate a high degree of current population isolation. This pattern is generally more pronounced in sampling locations in the west (heavily urbanized areas). Additionally, the St Joe and Star Avenue populations are positioned in the core of the least cost paths corridor identified by the landscape genetic analyses and these core locations could be particularly important for maintaining gene flow and, thus, genetic variation. These two populations also had the highest effective population sizes (Duncan et al. 2017) which indicates some levels of stability compared to the other populations.