Strong isolation by distance argues for separate population management of endangered blue duck (Hymenolaimus malacorhynchos)

Genetic analysis of red deer (Cervus elaphus) administrative management units in a human-dominated landscape

Red deer (Cervus elaphus) throughout central Europe are influenced by different anthropogenic activities including habitat fragmentation, selective hunting and translocations. This has substantial impacts on genetic diversity and the long-term conservation of local populations of this species. Here we use genetic samples from 480 red deer individuals to assess genetic diversity and differentiation of the 12 administrative management units located in Schleswig Holstein, the northernmost federal state in Germany. We applied multiple analytical approaches and show that the history of local populations (i.e., translocations, culling of individuals outside of designated red deer zones, anthropogenic infrastructures) potentially has led to low levels of genetic diversity. Mean expected heterozygosity was below 0.6 and we observed on average 4.2 alleles across 12 microsatellite loci. Effective population sizes below the recommended level of 50 were estimated for multiple local populations. Our estimates of genetic structure and gene flow show that red deer in northern Germany are best described as a complex network of asymmetrically connected subpopulations, with high genetic exchange among some local populations and reduced connectivity of others. Genetic diversity was also correlated with population densities of neighboring management units. Based on these findings, we suggest that connectivity among existing management units should be considered in the practical management of the species, which means that some administrative management units should be managed together, while the effective isolation of other units needs to be mitigated.

Old divergence and restricted gene flow between torrent duck (Merganetta armata) subspecies in the Central and Southern Andes

AIM

To investigate the structure and rate of gene flow among populations of habitat-specialized species to understand the ecological and evolutionary processes underpinning their population dynamics and historical demography, including speciation and extinction.

LOCATION

Peruvian and Argentine Andes.

TAXON

Two subspecies of torrent duck (Merganetta armata).

METHODS

We sampled 156 individuals in Peru (M. a. leucogenis; Chillón River, n = 57 and Pachachaca River, n = 49) and Argentina (M. a. armata; Arroyo Grande River, n = 33 and Malargüe River, n = 17), and sequenced the mitochondrial DNA (mtDNA) control region to conduct coarse and fine-scale demographic analyses of population structure. Additionally, to test for differences between subspecies, and across genetic markers with distinct inheritance patterns, a subset of individuals (Peru, n = 10 and Argentina, n = 9) was subjected to partial genome resequencing, obtaining 4,027 autosomal and 189 Z-linked double-digest restriction-associated DNA sequences.

RESULTS

Haplotype and nucleotide diversities were higher in Peru than Argentina across all markers. Peruvian and Argentine subspecies showed concordant species-level differences (ΦST mtDNA = 0.82; ΦST autosomal = 0.30; ΦST Z chromosome = 0.45), including no shared mtDNA haplotypes. Demographic parameters estimated for mtDNA using IM and IMa2 analyses, and for autosomal markers using ∂a∂i (isolation-with-migration model), supported an old divergence (mtDNA = 600,000 years before present (ybp), 95% HPD range = 1.2 Mya to 200,000 ybp; and autosomal ∂a∂i = 782,490 ybp), between the two subspecies, characteristic of deeply diverged lineages. The populations were well-differentiated in Argentina but moderately differentiated in Peru, with low unidirectional gene flow in each country.

MAIN CONCLUSIONS

We suggest that the South American Arid Diagonal was preexisting and remains a current phylogeographic barrier between the ranges of the two torrent duck subspecies, and the adult territoriality and breeding site fidelity to the rivers define their population structure.