Diversity and sexual dimorphism in the head lateral line system in North Sea populations of threespine sticklebacks, Gasterosteus aculeatus (Teleostei: Gasterosteidae)

Harald Ahnelt, David Ramler, Maria Ø. Madsen, Lasse F. Jensen, Sonja Windhager

Publications: Contribution to journalArticlePeer Reviewed

Abstract

The mechanosensory lateral line of fishes is a flow sensing system and supports a number of behaviors, e.g. prey detection, schooling or position holding in water currents. Differences in the neuromast pattern of this sensory system reflect adaptation to divergent ecological constraints. The threespine stickleback, Gasterosteus aculeatus, is known for its ecological plasticity resulting in three major ecotypes, a marine type, a migrating anadromous type and a resident freshwater type. We provide the first comparative study of the pattern of the head lateral line system of North Sea populations representing these three ecotypes including a brackish spawning population. We found no distinct difference in the pattern of the head lateral line system between the three ecotypes but significant differences in neuromast numbers. The anadromous and the brackish populations had distinctly less neuromasts than their freshwater and marine conspecifics. This difference in neuromast number between marine and anadromous threespine stickleback points to differences in swimming behavior. We also found sexual dimorphism in neuromast number with males having more neuromasts than females in the anadromous, brackish and the freshwater populations. But no such dimorphism occurred in the marine population. Our results suggest that the head lateral line of the three ecotypes is under divergent hydrodynamic constraints. Additionally, sexual dimorphism points to divergent niche partitioning of males and females in the anadromous and freshwater but not in the marine populations. Our findings imply careful sampling as an important prerequisite to discern especially between anadromous and marine threespine sticklebacks.
Original languageEnglish
Pages (from-to)103 - 117
Number of pages15
JournalZoomorphology
Volume140
Issue number1
DOIs
Publication statusPublished - 2021

Austrian Fields of Science 2012

  • 106018 Human biology
  • 106012 Evolutionary research
  • 106056 Biological anthropology

Keywords

  • 3-SPINED STICKLEBACK
  • ADAPTATION
  • Anadromous
  • BODY SHAPE EVOLUTION
  • DIVERGENCE
  • LAKE
  • Lateral line
  • MORPHOLOGY
  • Marine
  • PACIFIC GOBIID FISHES
  • POSTEMBRYONIC DEVELOPMENT
  • SUPERFICIAL NEUROMASTS
  • Sexual dimorphism
  • Threespine stickleback
  • WATER

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