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First evidence of bitterling larvae's minute tubercles as an adaptation to prevent premature ejection by host mussels
  • Hyeong Kim
Hyeong Kim
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1. Bitterlings are small freshwater fish that use long ovipositors to place eggs in host mussels and have morphological adaptations to increase larval survival. The most well-known adaptations are the minute tubercles on the skin surface of larvae, which are developed in early-stage larvae with weak swimming ability and disappear in free-swimming larvae before they leave the host mussel. 2. In the present study, a comprehensive analysis of the developmental stages of Rhodeus pseudosericeus larvae, their morphological and physiological characteristics, their migration inside mussels, and the development of minute tubercle are presented as direct evidence of the morphological function of the minute tubercles. These tubercles began to develop 1 day after hatching (formation stage), grew for 2–5 days (growth stage), reached the peak height after 6–7 days (peak stage), abruptly reduced in height after 8–10 days (abrupt reduction stage), and went through a final gradual reduction (reduction stage) until completely disappearing 27 days after hatching (disappearance stage). 3. The larvae remained in the mussels’ interlamellar space of the gill demibranchs until 10 days after hatching, and began to migrate to mussels’ suprabranchial cavity 11 days after hatching. At this time, the larvae had clear components of heart rate and caudal fin began to develop. At 24 days after hatching, the minute tubercles had almost disappeared, and some individuals were observed swimming out of the mussels. 4. The experiment results herein presented prove that the minute tubercles are a first direct evidence that the bitterling larvae are morphologically adapted to prevent premature ejection from the mussel.

Peer review status:ACCEPTED

06 Feb 2020Submitted to Ecology and Evolution
10 Feb 2020Assigned to Editor
10 Feb 2020Submission Checks Completed
19 Feb 2020Reviewer(s) Assigned
12 Mar 2020Review(s) Completed, Editorial Evaluation Pending
12 Mar 2020Editorial Decision: Revise Minor
24 Mar 20201st Revision Received
27 Mar 2020Review(s) Completed, Editorial Evaluation Pending
27 Mar 2020Assigned to Editor
27 Mar 2020Submission Checks Completed
30 Mar 2020Editorial Decision: Revise Minor
01 Apr 20202nd Revision Received
02 Apr 2020Submission Checks Completed
02 Apr 2020Assigned to Editor
02 Apr 2020Review(s) Completed, Editorial Evaluation Pending
02 Apr 2020Editorial Decision: Accept