title: Scope for genetic rescue of an endangered subspecies though re-establishing natural gene flow with another subspecies.
abstract: Genetic diversity is positively linked to the viability and evolutionary potential of species but is often compromised in threatened taxa. Genetic rescue by gene flow from a more diverse or differentiated source population of the same species can be an effective strategy for alleviating inbreeding depression and boosting evolutionary potential. The helmeted honeyeater Lichenostomus melanops cassidix is a critically endangered subspecies of the common yellow-tufted honeyeater. Cassidix has declined to a single wild population of ~130 birds, despite being subject to intensive population management over recent decades. We assessed changes in microsatellite diversity in cassidix over the last four decades and used population viability analysis to explore whether genetic rescue through hybridization with the neighbouring Lichenostomus melanops gippslandicus subspecies constitutes a viable conservation strategy. The contemporary cassidix population is characterized by low genetic diversity and effective population size (N(e) < 50), suggesting it is vulnerable to inbreeding depression and will have limited capacity to evolve to changing environments. We find that gene flow from gippslandicus to cassidix has declined substantially relative to pre-1990 levels and argue that natural levels of gene flow between the two subspecies should be restored. Allowing gene flow (~4 migrants per generation) from gippslandicus into cassidix (i.e. genetic rescue), in combination with continued annual release of captive-bred cassidix (i.e. demographic rescue), should lead to positive demographic and genetic outcomes. Although we consider the risk of outbreeding depression to be low, we recommend that genetic rescue be managed within the context of the captive breeding programme, with monitoring of outcomes.
authors.affiliation: School of Biological Sciences, Monash University, Clayton Campus, Clayton, Vic., 3800, Australia.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Harrisson
authors.affiliation: School of Biological Sciences, Monash University, Clayton Campus, Clayton, Vic., 3800, Australia.
authors.forename: Alexandra
authors.identifier: 0000-0001-9455-4124
authors.initials: A
authors.lastname: Pavlova
authors.affiliation: School of Biological Sciences, Monash University, Clayton Campus, Clayton, Vic., 3800, Australia.|Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Vic., 3000, Australia.
authors.forename: Anders
authors.initials: A
authors.lastname: Gonçalves da Silva
authors.affiliation: School of Biological Sciences, Monash University, Clayton Campus, Clayton, Vic., 3800, Australia.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Rose
authors.affiliation: School of Biological Sciences, Monash University, Clayton Campus, Clayton, Vic., 3800, Australia.
authors.forename: James K
authors.initials: JK
authors.lastname: Bull
authors.affiliation: Healesville Sanctuary, Healesville, Vic., 3777, Australia.
authors.forename: Melanie L
authors.initials: ML
authors.lastname: Lancaster
authors.affiliation: Department of Ecology, Environment and Evolution, La Trobe University, Melbourne, Vic., 3086, Australia.
authors.forename: Neil
authors.initials: N
authors.lastname: Murray
authors.affiliation: Department of Environment, Land, Water and Planning, Symes Road, Woori Yallock, Vic., 3139, Australia.
authors.forename: Bruce
authors.initials: B
authors.lastname: Quin
authors.affiliation: Department of Environment, Land, Water and Planning, Arthur Rylah Institute for Environmental Research, Heidelberg, Vic., 3084, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Menkhorst
authors.affiliation: Department of Wildlife Conservation and Science, Zoos Victoria, Parkville, Vic., 3052, Australia.
authors.forename: Michael J L
authors.initials: MJ
authors.lastname: Magrath
authors.affiliation: School of Biological Sciences, Monash University, Clayton Campus, Clayton, Vic., 3800, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Sunnucks
mesh_terms: D000483:Alleles; D000818:Animals; D001947:Breeding; D003247:Conservation of Natural Resources; D056727:Endangered Species; D051456:Gene Flow; D040961:Genetic Drift; D014644:Genetic Variation; D006824:Hybridization, Genetic; D018895:Microsatellite Repeats; D008957:Models, Genetic; D046109:Passeriformes / Q000145:classification / Q000235:genetics*; D011156:Population Density; D017422:Sequence Analysis, DNA
keywords: genetic rescue; genetic restoration; helmeted honeyeater; population viability; vortex; yellow-tufted honeyeater