Unraveling cryptic diversity: Genomic approaches to study the taxonomy and evolution of Woolly-necked storks using museum specimens

The availability of large-scale genomics data for current research in evolutionary biology has enabled a comprehensive examination of the intricate interplay between diverse evolutionary processes associated with speciation. Despite these advancements, the genomic basis of taxonomic classification remains challenging in many species, one such example being the Woolly-necked storks (Ciconia sps.). The Woolly-necked storks are distributed in Asia and Africa with a taxonomic classification (C. episcopus and C. microcelis) that has been a matter of contention and ambiguity. Asian and African Woollynecks were just recently recognized as different species based on their morphological differences, however genetic/genomic studies on Woolly-necked storks are lacking. In this study, we have used [~]70-year-old museum samples to explore the taxonomy and evolution of the Woolly-necked storks. We used a whole-genome sequencing strategy and generated 13.5 million single nucleotide polymorphisms (SNPs) that were polymorphic among populations of Asian and African Woollynecks. Our study has revealed that Asian and African Woollyneck are genetically distinct, consistent with the current taxonomic classification based on morphological features. However, we also found a high genetic divergence between the Asian subspecies C. e. neglecta and C. e. episcopus suggesting this classification harbors cryptic diversity that requires a detailed examination to explore processes of ongoing speciation. Because taxonomic classification directly impacts conservation efforts, and there is evidence of declining populations of Asian Woollynecks in Southeast Asia, our results suggest populations-scale studies are urgent to determine the genetic, ecological, and phylogenetic diversity of these birds. Moreover, our study also provides historical genomic resources to examine genomic signatures of local adaptation associated with the distribution, ecology, and evolution of African and Asian Woollynecks.