title: Naturally occurring hybrids of coral reef butterflyfishes have similar fitness compared to parental species.
abstract: Hybridisation can produce evolutionary novelty by increasing fitness and adaptive capacity. Heterosis, or hybrid vigour, has been documented in many plant and animal taxa, and is a notable consequence of hybridisation that has been exploited for decades in agriculture and aquaculture. On the contrary, loss of fitness in naturally occurring hybrid taxa has been observed in many cases. This can have negative consequences for the parental species involved (wasted reproductive effort), and has raised concerns for species conservation. This study evaluates the relative fitness of previously documented butterflyfish hybrids of the genus Chaetodon from the Indo-Pacific suture zone at Christmas Island. Histological examination confirmed the reproductive viability of Chaetodon hybrids. Examination of liver lipid content showed that hybrid body condition was not significantly different from parent species body condition. Lastly, size at age data revealed no difference in growth rates and asymptotic length between hybrids and parent species. Based on the traits measured in this study, naturally occurring hybrids of Chaetodon butterflyfishes have similar fitness to their parental species, and are unlikely to supplant parental species under current environmental conditions at the suture zone. However, given sufficient fitness and ongoing genetic exchange between the respective parental species, hybrids are likely to persist within the suture zone.
authors.affiliation: AIMS@JCU, Australian Institute of Marine Science, College of Science and Engineering, James Cook University of North Queensland, Townsville, QLD, Australia.
authors.forename: Stefano R
authors.identifier: http://orcid.org/0000-0002-4157-4938
authors.initials: SR
authors.lastname: Montanari
authors.affiliation: Department of Environment and Agriculture, Curtin University, Bentley, WA, Australia.
authors.forename: Jean-Paul A
authors.initials: JA
authors.lastname: Hobbs
authors.affiliation: ARC Centre of Excellence for Coral Reef Studies, James Cook University of North Queensland, Townsville, QLD, Australia.
authors.forename: Morgan S
authors.initials: MS
authors.lastname: Pratchett
authors.affiliation: Australian Institute of Marine Science, Townsville, QLD, Australia.
authors.forename: Line K
authors.initials: LK
authors.lastname: Bay
authors.affiliation: College of Science and Engineering, James Cook University of North Queensland, Townsville, QLD, Australia.|Centre for Comparative Genomics, James Cook University of North Queensland, Townsville, QLD, Australia.
authors.forename: Lynne
authors.initials: L
authors.lastname: van Herwerden
mesh_terms: D000818:Animals; D005075:Biological Evolution; D057894:Coral Reefs; D006823:Hybrid Vigor / Q000235:genetics*; D006824:Hybridization, Genetic; D008055:Lipids / Q000302:isolation & purification; D008099:Liver / Q000737:chemistry; D010473:Perciformes / Q000235:genetics* / Q000254:growth & development
chemical_list: D008055:Lipids