Genetic study of red deer populations in Lower Saxony

Project description

Particularly in our highly fragmented cultural landscape, genetic exchange between the remaining, spatially separated wildlife populations is essential to maintain healthy populations, to ensure the long-term adaptive capacity of species and to halt ongoing extinction processes (Frankham 2008, 2022; Hoban et al. 2020, 2021, 2023).

In Germany, the genetic diversity of red deer has declined significantly over the past 150 years (Hoffmann et al. 2016; Willems et al. 2016; Reiner and Willems 2019). As a result of historical and current management practices, the populations are restricted to only a few per cent of the country's land area (Kinser et al. 2010), and by international comparison, German red deer populations already show below-average genetic diversity (Zachos and Hartl 2011). Studies in Schleswig-Holstein, Hesse and North Rhine-Westphalia have demonstrated strong isolation of populations (Laumeier 2024; Edelhoff et al. 2020; Reiner et al. 2021), and some areas already show serious signs of inbreeding depression, for example in the form of shortened lower jaws (Zachos et al. 2007; Reiner and Willems 2021). A Germany-wide study (Westekemper 2022) showed that only 2 of the 34 areas examined reach an effective population size of at least 500 to 1,000, which would be required to prevent further loss of genetic diversity (Frankham et al. 2014). The same study also showed that inbred individuals are very common in some areas and that insufficient gene flow between red deer areas is mainly impeded by human infrastructure such as roads and settlements.

However, the study by Westekemper (2022) included only 69 samples from Lower Saxony, all originating from the Lüneburg Heath and the western Harz. Both consist of large populations whose genetic diversity is still relatively high compared with other German populations. Smaller areas such as the Deister, Osterwald, Ith, Solling or the population near the Dutch border (Grafschaft Bentheim) were not sampled. Yet it is precisely such small areas that serve as important stepping stones for the large-scale connectivity of populations (Weiss and Kimura 1965; Cox and Durrett 2002). At the same time, these small and isolated populations are particularly threatened by genetic drift (Willi et al. 2006; Frankham et al. 2019). This is also reflected in recent detailed analyses from the neighbouring federal states of Hesse (Reiner and Willems 2021; Reiner et al. 2021) and North Rhine-Westphalia (Laumeier 2024). There is therefore a particular need and urgency to investigate and quantify the current situation in Lower Saxony in detail. The expected results will provide the basis for future red deer management, as they allow mere assumptions to be replaced by facts in an unbiased manner.

Identifying genetic bottlenecks in the exchange between populations and removing them is the most efficient way to increase or maintain the genetic diversity of populations (Urbina et al. 2023; Penjor et al. 2024).

Project objectives

The project aims to answer the following questions:

• How high is the genetic diversity of red deer populations in Lower Saxony?
• What are the effective population sizes of red deer populations in Lower Saxony?
• To what extent does gene flow occur between the different red deer populations in Lower Saxony?
• How pronounced is inbreeding in the different red deer populations in Lower Saxony?
• What is the association between microsatellite and SNP markers?