Multispecies hybridization in birds

Abstract

Hybridization is not always limited to two species; often multiple species are interbreeding. In birds, there are numerous examples of species that hybridize with multiple other species. The advent of genomic data provides the opportunity to investigate the ecological and evolutionary consequences of multispecies hybridization. The interactions between several hybridizing species can be depicted as a network in which the interacting species are connected by edges. Such hybrid networks can be used to identify 'hub-species' that interbreed with multiple other species. Avian examples of such 'hub-species' are Common Pheasant (Phasianus colchicus), Mallard (Anas platyrhynchos) and European Herring Gull (Larus argentatus). These networks might lead to the formulation of hypotheses, such as which connections are most likely conducive to interspecific gene flow (i.e. introgression). Hybridization does not necessarily result in introgression. Numerous statistical tests are available to infer interspecific gene flow from genetic data and the majority of these tests can be applied in a multispecies setting. Specifically, model-based approaches and phylogenetic networks are promising in the detection and characterization of multispecies introgression. It remains to be determined how common multispecies introgression in birds is and how often this process fuels adaptive changes. Moreover, the impact of multispecies hybridization on the build-up of reproductive isolation and the architecture of genomic landscapes remains elusive. For example, introgression between certain species might contribute to increased divergence and reproductive isolation between those species and other related species. In the end, a multispecies perspective on hybridization in combination with network approaches will lead to important insights into the history of life on this planet.

Genomic evidence for a hybrid origin of the yeast opportunistic pathogen Candida albicans

“…Many hybrids have been described in animals and plants. Examples go from butterflies to birds, nematodes, or even sunflowers [9][10][11][12]. In fungi, advances in nextgeneration sequencing have recently allowed the identification of many hybrid lineages as well [13,14], of which some have importance for biotechnology and food or beverage industries [15][16][17].…”

Genomic nucleotide-based distance analysis for delimiting old world monkey derived herpes simplex virus species

“…There are multiple challenges in defining species, for example recently, even in defined species, fertile hybrids among plants, birds, fish, and even mammals are not uncommon [76][77][78][79], suggesting reproductive barriers may not always separate species. This may call into question as to what constitutes a species.…”

Genomic Nucleotide-Based Distance Analysis for Delimiting Old World Monkey Derived Herpes Simplex Virus Species.

“…The genetic distance cutoff method provides a quantitative threshold to determine species status and could be another tool for establishing species status among viral cryptic species complexes. Challenges and Issues There are multiple challenges in defining species, for example recently, even in defined species, fertile hybrids among plants, birds, fish, and even mammals are not uncommon [78][79][80][81], suggesting reproductive barriers may not always separate species. This may call into question as to what constitutes a species.…”