Ancient DNA reveals low levels of past genetic diversity in the Andean Condor

Low genetic diversity might be the natural state for this vulture.

Since the first release of Andean Condors (Vultur gryphus) in Colombia in 1989, more than 200 individual birds have be re-introduced in the wild across South America. The goal of these introductions was to reinforce existing populations and re-establish extinct ones. One of the main arguments for such extensive management programs is the augmentation of genetic diversity. However, the relationship between genetic diversity and the risk of species extinction is not always straightforward (see for example this blog post). And in many cases, it is not clear how much genetic variation has been lost over time. So, what about the Andean Condor? A recent study in the journal Ecology and Evolution obtained DNA samples from museum collections to assess the historical levels of genetic diversity in this iconic vulture species.

Haplotypes

Julian Padró and his colleagues sequenced several mitochondrial markers for 42 Andean Condors, covering a time period from 1884 to 2013. The historical and modern samples shared several haplotypes, but one haplotype from 1896 seems to have been lost. This genetic variant belonged to a now extinct population on the Patagonian coast. Demographic analyses indicated that this loss of genetic diversity coincided with the timing of European colonization in South America. Probably, the development of livestock production resulted in conflict between humans and Andean Condors.

In contrast to the southern populations, Andean Condors in the north of their range did lose any haplotypes, despite being driven to near-extinction in recent times. The similar genetic diversity in historical and present times, in combination with the relatively modest loss of one mitochondrial haplotype, suggest that the Andean Condor can cope with low levels genetic diversity. Similar patterns have been reported in other raptor species, such as the Spanish Imperial Eagle (Aquila adalberti) and the Cinereous Vulture (Aegypius monachus).

An overview of the sampling locations for the historical and contemporary samples. The haplotype shows the modest loss of genetic diversity over time. From: Padró et al. (2020) Ecology and Evolution.

Genomics

The researchers concluded that “Low levels of genetic diversity found in the Andean condor represent a natural state of mtDNA, and thus are unlikely to be an immediate threat to long-term viability.” However, mtDNA represents only a tiny fraction of the total genetic diversity in a population. A genomic perspective is needed to assess the impact of population bottlenecks on the genetic make-up of the Andean Condor. These raptors might be able to withstand a decline in mitochondrial diversity, but what if other genomic regions have been eroded?

References

Padró, J., Lambertucci, S. A., Perrig, P. L., & Pauli, J. N. (2020). Andean and California condors possess dissimilar genetic composition but exhibit similar demographic histories. Ecology and Evolution, 10(23), 13011-13021.

Featured image: Andean Condor (Vultur gryphus) © Ltshears | Wikimedia Commons