An experimental evaluation with Drosophila melanogaster of a novel dynamic system for the management of subdivided populations in conservation programs

Abstract

A dynamic method (DM) recently proposed for the management of captive subdivided populations was evaluated using the pilot species Drosophila melanogaster. By accounting for the particular genetic population structure, the DM determines the optimal mating pairs, their contributions to progeny and the migration pattern that minimize the overall co-ancestry in the population with a control of inbreeding levels. After a pre-management period such that one of the four subpopulations had higher inbreeding and differentiation than the others, three management methods were compared for 10 generations over three replicates: (1) isolated subpopulations (IS), (2) one-migrant-per-generation rule (OMPG), (3) DM aimed to produce the same or lower inbreeding coefficient than OMPG. The DM produced the lowest co-ancestry and equal or lower inbreeding than the OMPG method throughout the experiment. The initially lower fitness and lower variation for nine microsatellite loci of the highly inbred subpopulation were restored more quickly with the DM than with the OMPG method. We provide, therefore, an empirical illustration of the usefulness of the DM as a conservation protocol for captive subdivided populations when pedigree information is available (or can be deduced) and manipulation of breeding pairs is possible.

Figure 1

Experimental design during the pre-management and management periods. This full scheme was replicated three times (corresponding to the three experimental replicates). IS, isolated subpopulations; OMPG, one-migrant-per-generation method; DM1, dynamic method 1; DM2, dynamic method 2 (see text). N indicates the subpopulation size. A subpopulation was intended to be more inbred and differentiated from the others, and this corresponds to the shaded square.

Figure 2

(a) Observed population inbreeding coefficient and (b) global coancestry for the three experimental replicates for each management strategy. IS, isolated subpopulations; OMPG, one-migrant-per-generation method; DM1, dynamic method 1; DM2, dynamic method 2 (see text).

Figure 3

(a) Simulated population inbreeding coefficient and (b) global coancestry averaged over three simulation replicates for each management strategy. Black lines: IS, isolated subpopulations; OMPG, one-migrant-per-generation method; DM1, dynamic method 1; DM2, dynamic method 2. Grey lines: IS-R, isolated subpopulations without management; OMPG-R, subpopulations without management with one-migrant-per-generation migration.

Figure 4

Subpopulation parameters averaged over replicates for each management strategy (thick line for the highly inbred subpopulation and thin lines for the other subpopulations). (a) Subpopulation inbreeding coefficient, (b) number of alleles, (c) expected heterozygosity, (d) couple success rate (cs) and (e) competitive fitness (cw). Bars indicate one s.e.