Across Asia and beyond: The evolutionary story of the Common Pheasant

Genetic study reconstructs the Asian diversification of the Common Pheasant.

When I visit my family in Belgium, we often go for walks with our dog Mira (a Hungarian vizsla). While strolling through the local nature reserves, we sometimes disturb a Common Pheasant (Phasianus colchicus) hiding in the tall grass. Females mostly fly off with a loud alarm call, whereas males tend to run away in a seemingly random direction. These colorful birds – the males anyway – are not native to this part of Europe, but were introduced for hunting purposes. Common Pheasants originated in Asia where they display an amazing diversity of male plumage, resulting in a proliferation of more than 30 subspecies.

A recent study in the Journal of Biogeography focused on the native range of the Common Pheasant and reconstructed its evolutionary history based on a handful of genetic markers. The researchers found that this species diversified into eight distinct lineages during the Late Pleistocene. Let’s explore the Asian expansion of the Common Pheasant.

Spreading across Asia

Simin Liu and colleages sampled more than 200 individuals across the range of the Common Pheasant, which extends from the Black Sea to Korea. Analyses of seven nuclear and two mitochondrial genes revealed that the diversification within this species started at the end of the Pleistocene, between 700,000 and 200,000 years ago. Our evolutionary story starts at the eastern edge of the Qinghai-Tibetan Plateau from where several lineages spread in different directions.

One population expanded to the Chinese mountain ranges in the south-east, giving rise to the elegans-lineage. Because the climate remained relatively stable in this region, this lineage shows a stable population size of time and did not diversify into more sub-lineages. A second expansion to the east brought pheasants into a more unstable area where periods of drought promoted diversification into multiple lineages. Here, we currently find the torquatus and strauchi–vlangallii lineages that were occasionally connected by gene flow. One population traveled further east and became isolated on the island of Taiwan (the formosanus-lineage). Finally, a third movement to the west resulted in the evolution of several Central Asian lineages: tarimensis,, mongolicus, principalis–chrysomelas and colchicus. The exact evolutionary relationships between these lineages remain to be disentangled.

The genetic analyses pointed to eight distinct lineages (see phylogeny on top) that spread across Asia from the Qinghai-Tibetan Plateau (map below). From: Liu et al. (2020) Journal of Biogeography.

Taxonomic Decisions

This study nicely shows how different environmental conditions affect the evolutionary trajectory of a population. The relatively stable climate of the Chinese mountains resulted in a stable population of Common Pheasants, making further diversification of this lineage (elegans) unlikely. Other populations ended up in regions with more pronounced climatic cycles that led to diversification into several separate lineages. Ultimately, the researchers could discriminate between eight distinct lineages.

Taxonomic-minded readers might be wondering if all these lineages should be elevated to species rank. At the moment, the researchers argue that the diversity within the Common Pheasant can be captured in three species: the Yunnan Pheasant (P. elegans), the Chinese Pheasant (P. vlangallii which includes the torquatus, strauchi–vlangallii and formosanus lineages) and the Turkestan Pheasant (P. colchicus which includes the tarimensis, principalis–chrysomelas, mongolicus and colchicus lineages). However, more research is needed to justify this classification.

References

Liu et al. (2020) Regional drivers of diversification in the late Quaternary in a widely distributed generalist species, the common pheasant Phasianus colchicus. Journal of Biogeography47(12), 2714-2727.

Featured image: Common Pheasant (Phasianus colchicus) © David Croad | Wikimedia Commons

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