title: Cryptic inbreeding depression in a growing population of a long-lived species.
abstract: Genetic effects are often overlooked in endangered species monitoring, and populations showing positive growth are often assumed to be secure. However, the continued reproductive success of a few individuals may mask issues such as inbreeding depression, especially in long-lived species. Here, we test for inbreeding depression in little spotted kiwi (Apteryx owenii) by comparing a population founded with two birds to one founded with 40 birds, both from the same source population and both showing positive population growth. We used a combination of microsatellite genotypes, nest observations and modelling to examine the consequences of assessing population viability exclusively via population growth. We demonstrate (i) significantly lower hatching success despite significantly higher reproductive effort in the population with two founders; (ii) positive growth in the population with two founders is mainly driven by ongoing chick production of the founding pair; and (iii) a substantial genetic load in the population founded with two birds (10-15 diploid lethal equivalents). Our results illustrate that substantial, cryptic inbreeding depression may still be present when a population is growing, especially in long-lived species with overlapping generations.
authors.affiliation: School of Biological Sciences, Victoria University of Wellington, Kelburn Parade, Wellington, New Zealand.
authors.forename: Helen R
authors.identifier: http://orcid.org/0000-0001-7951-0772
authors.initials: HR
authors.lastname: Taylor
authors.affiliation: Department of Conservation, Manners Street, Wellington, New Zealand.
authors.forename: Rogan M
authors.initials: RM
authors.lastname: Colbourne
authors.affiliation: Department of Conservation, Manners Street, Wellington, New Zealand.
authors.forename: Hugh A
authors.initials: HA
authors.lastname: Robertson
authors.affiliation: School of Biological Sciences, Victoria University of Wellington, Kelburn Parade, Wellington, New Zealand.
authors.forename: Nicola J
authors.initials: NJ
authors.lastname: Nelson
authors.affiliation: Montana Conservation Genetics Lab, University of Montana, Missoula, MT, USA.
authors.forename: Fred W
authors.initials: FW
authors.lastname: Allendorf
authors.affiliation: Department of Biology & Geology, University of South Carolina Aiken, 471 University Parkway, Aiken, SC, USA.
authors.forename: Kristina M
authors.initials: KM
authors.lastname: Ramstad
mesh_terms: D000818:Animals; D056727:Endangered Species; D040741:Genetic Load; D005828:Genetics, Population; D005838:Genotype; D000071422:Inbreeding Depression; D018895:Microsatellite Repeats; D046108:Palaeognathae / Q000235:genetics*; D011156:Population Density
keywords: conservation; inbreeding depression; kiwi; population growth; reproductive success