Recent changes in genetic diversity, structure, and gene flow in a passerine experiencing a rapid population decline, the Dupont's lark (Chersophilus duponti)

Monitoring temporal dynamics in genetic diversity is of great importance for conservation, especially for threatened species that are suffering a rapid population decline and increased fragmentation. Here, we investigate temporal variation in genetic diversity, structure, and gene flow in the Dupont’s lark (Chersophilus duponti) across most of its range. This species shows increasing levels of population fragmentation, substantial population declines, and severe range contraction, so temporal losses of genetic diversity, increasing differentiation, and decreasing gene flow are expected when comparing present day data with previous situations. To address this, we resampled sites (nine regions in two countries) after 12–15 years (five-to-seven generations) and assessed changes in genetic parameters using 11 microsatellite markers. We found no substantial loss in genetic diversity over time at the species level, but we detected considerable variation among regions in the amount of allelic diversity and heterozygosity lost over time. Temporal variation in allele frequencies (common, rare, and private alleles), and changes in genetic differentiation and gene flow over time suggest a major role of connectivity for the stability of the overall metapopulation. Our results agree with the hypothesis that connectivity rescues genetic diversity via immigration and gene flow. However, evidence of recent genetic bottleneck and the substantial changes detected in some regions are clear signs of genetic erosion and may be signalling a rapid decline of the populations. Urgent actions must be carried out to stop and reverse human impacts on this threatened lark and its habitat.

This study was partially funded by the Spanish Agency for International Cooperation (AECI; C/3868/05), and the LIFE Ricoti (LIFE15-NAT-ES-000802) and LIFE Connect Ricoti (LIFE20-NAT-ES-000133) projects, supported by the European Commission. D.B.R. was supported by the FPI-UAM fellowship from the Universidad Autónoma de Madrid (UAM). The Instituto de Investigación en Recursos Cinegéticos, IREC (CSIC-UCLM-JCCM), provided vehicles for the Moroccan expeditions and the laboratory for DNA analysis. This is a contribution to the REMEDINAL-TE Network (ES2018-EMT-4338).

This study was partially supported by the European Commission (Life Ricotí project LIFE15-NAT-ES-000802 and Life Connect Ricotí project LIFE20-NAT-ES-000133) and the BBVA Foundation (BBVA-Dron Ricotí project). This paper contributes to project REMEDINAL TE-CM (P2018/EMT4338).

Peer reviewed