Investigating the first stages of coevolution between the Pacific koel and its newest host,the red wattlebird [article]

Virginia Abernathy, University, The Australian National, University, The Australian National
2017
Avian obligate brood parasites lay their eggs in the nests of other bird species and never provide their own parental care. This behaviour is a model example of coevolution and while multiple studies and reviews have discussed the different types of adaptations and counter-adaptations hosts and brood parasites evolve, there have only been a handful of empirical studies focused on how quickly coevolution can occur in a host-brood parasite system. Additionally, little is known about the early
more » ... es of brood parasite and host coevolutionary interactions. Understanding the rates of coevolution between brood parasites and their hosts is an important step in uncovering aspects about the process of speciation, determining which traits represent true genetic change and can aid in conservation decisions of endangered potential hosts, especially as brood parasites expand their breeding ranges with environmental changes. I investigated these issues by capitalising on the recent exploitation of the Red Wattlebird (Anthochaera carunculata) by the brood-parasitic Pacific Koel (Eudynamys orientalis). I conducted a literature review on factors that influence the rate of coevolution between avian obligate brood parasites and their hosts and performed observational and experimental studies at two sites where wattlebirds have experienced different durations of parasitism: Sydney (parasitism for 38-86 years) and Canberra (parasitism for 8-33 years). I determined that host switching can pose challenges for both the host and brood parasite, as parasitised wattlebird nests fledged significantly fewer young than unparasitised wattlebird nests, but fledged similar numbers of wattlebird and koel young. The koel's later breeding season relative to the wattlebird's and the koel's poor timing of egg laying may have contributed to the low success of koel eggs. Mobbing experiments demonstrated that naïve hosts can learn to recognise a brood parasite within 33 years or less, but the speed at which this defence spreads throughout the population [...]
doi:10.25911/5d723fc691f28 fatcat:mnhfrno3zjcp3npjf7f46hjhb4