Fertilisation Success in Acanthaster cf. solaris and Acanthaster brevispinus and Reciprocal Hybrid Crosses Across a Range of Sperm Concentrations and Development to the Hybrid Juvenile
- 1University of Sydney Camperdown New South Wales Australia
Abstract
Novel species interactions between resident and range shifting species in response to warming are posing challenges for conservation and management. This is especially the case when major predatory species are involved, as seen in the appearance of a mixed species outbreak of coral‐eating crown‐of‐thorns sea stars Acanthaster cf. solaris (As) and the lesser‐known Acanthaster brevispinus (Ab) in the tropical to subtropical transition zone in eastern Australia. The outbreak consisted of reproductively mature animals, and we investigated the potential for cross‐species hybridisation in fertilisation experiments across a range of sperm concentrations to sperm limitation conditions (10 ⁶ –10 ² sperm mL ⁻¹ ). Fertilisation was successful in all combinations of parents (As ♂ × As ♀, Ab ♂ × Ab ♀, Ab ♀ × As ♂, As ♀ × Ab ♂) with successful hybrid crosses in sperm dilutions as low as 10 ² sperm ml ⁻¹ . Development in conspecific and heterospecific crosses was similar through the bipinnaria and brachiolaria larval stages to the juvenile. Juvenile hybrids had typical juvenile Acanthaster spp. development with a stellate five‐armed profile post metamorphosis, gaining arms after ~78 days. At no stage did the juvenile hybrids develop the distinctive pink colour trait that is characteristic of Acanthaster cf. solaris juveniles. Our results indicate that hybridisation is not restricted by sperm limitation conditions, with subsequent development of hybrids to the advanced juvenile stage. Our results highlight the potential for hybridisation and species introgression when range shifting species overlap with sister taxa. This may facilitate further range expansion or development of resilient hybrid progeny as a risk to vulnerable high latitude coral communities.
Related
- Renewed research interest in crown-of-thorns starfish (Acanthaster spp.) reflecting the increasing imperative to manage ongoing coral reef degradation
- Contrasting defensive strategies underlie differential susceptibility of corals to crown-of-thorns sea star (CoTS; Acanthaster cf. solaris ) predation
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BibTeX
@article{hill2026fertilisation,
title = {{Fertilisation Success in Acanthaster cf. solaris and Acanthaster brevispinus and Reciprocal Hybrid Crosses Across a Range of Sperm Concentrations and Development to the Hybrid Juvenile}},
author = {Ronan T. Hill and Matthew Clements and Monique Webb and Brigitte Sommer and Maria Byrne},
journal = {Ecology and Evolution},
year = {2026},
month = nov,
doi = {10.1002/ece3.74560},
url = {https://onlinelibrary.wiley.com/doi/10.1002/ece3.74560},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Fertilisation Success in Acanthaster cf. solaris and Acanthaster brevispinus and Reciprocal Hybrid Crosses Across a Range of Sperm Concentrations and Development to the Hybrid Juvenile
AU - Ronan T. Hill
AU - Matthew Clements
AU - Monique Webb
AU - Brigitte Sommer
AU - Maria Byrne
PY - 2026
DA - 2026/11/06
JO - Ecology and Evolution
DO - 10.1002/ece3.74560
UR - https://onlinelibrary.wiley.com/doi/10.1002/ece3.74560
AB - Novel species interactions between resident and range shifting species in response to warming are posing challenges for conservation and management. This is especially the case when major predatory species are involved, as seen in the appearance of a mixed species outbreak of coral‐eating crown‐of‐thorns sea stars Acanthaster cf. solaris (As) and the lesser‐known Acanthaster brevispinus (Ab) in the tropical to subtropical transition zone in eastern Australia. The outbreak consisted of reproductively mature animals, and we investigated the potential for cross‐species hybridisation in fertilisation experiments across a range of sperm concentrations to sperm limitation conditions (10 ⁶ –10 ² sperm mL ⁻¹ ). Fertilisation was successful in all combinations of parents (As ♂ × As ♀, Ab ♂ × Ab ♀, Ab ♀ × As ♂, As ♀ × Ab ♂) with successful hybrid crosses in sperm dilutions as low as 10 ² sperm ml ⁻¹ . Development in conspecific and heterospecific crosses was similar through the bipinnaria and brachiolaria larval stages to the juvenile. Juvenile hybrids had typical juvenile Acanthaster spp. development with a stellate five‐armed profile post metamorphosis, gaining arms after ~78 days. At no stage did the juvenile hybrids develop the distinctive pink colour trait that is characteristic of Acanthaster cf. solaris juveniles. Our results indicate that hybridisation is not restricted by sperm limitation conditions, with subsequent development of hybrids to the advanced juvenile stage. Our results highlight the potential for hybridisation and species introgression when range shifting species overlap with sister taxa. This may facilitate further range expansion or development of resilient hybrid progeny as a risk to vulnerable high latitude coral communities.
SN - 2045-7758
SN - 2045-7758
ER -