Morphology and development of the axial and appendicular systems in fishes

2005 2005

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Abstract (summary)

The newly resurgent field of evolutionary developmental biology integrates the study of evolutionarily important anatomical changes and developmental biology to describe the genetic and developmental changes that have led to anatomical changes. In this dissertation I describe candidate developmental mechanisms in the context of axial elongation and pectoral fin musculature evolution in fishes. Both axial elongation and increase in pectoral fin muscle subdivisions have important ecological correlates. Elongate fishes tend to be found in highly structured environments and fishes with an increased number of fin muscles tend to use fin-based locomotion to swim. Both of these morphologies have evolved multiple times within the ray-finned fish radiation.

In Chapter 1 I focus on a specific predator avoidance behavior that is only seen in elongate fishes. Deeper-bodied fish tend to perform a unilateral bend of the body and swim away whereas elongate fish, when startled, bend bilaterally and hide. Although all elongate fishes perform head retraction, their specific anatomy indicates multiple explanations for how elongation occurs. In Chapter 2, I describe changes in the vertebral column in lineages of actinopterygian fishes that have elongate members. Elongation occurs through three different mechanisms: addition of abdominal vertebrae, addition of caudal vertebrae, and lengthening of all the vertebral cents. This study suggests that the number of abdominal vertebrae, number of caudal vertebrae, and length of the vertebral cents are controlled by separate developmental modules.

Fin-based locomotion has evolved multiple times independently within actinopterygian fishes and is correlated with a modification of the pectoral fin musculature. In order to increase the understanding of fin muscle development, in Chapter 3 I describe the wildtype anatomy and embryology of the pectoral fin musculature in the zebrafish, Danio rerio. Zebrafish have six muscles in the pectoral fin. Early in development, the fin musculature consists of two muscle masses, one on each side of the fin. The arrector ventralis is the first muscle to individuate from the initial abductor muscle mass, and the adult musculature is present by 3 weeks postfertilization. This study provides a basic understanding of the embryology of the fin muscles and will provide a baseline for examining mutant fin muscle morphologies in zebrafish and diverse fin muscle morphologies in other species.

Indexing (details)

Anatomy & physiology;
0472: Zoology
0433: Anatomy & physiology
0433: Animals
Identifier / keyword
Biological sciences; Actinopterygii; Appendicular; Axial; Fishes
Morphology and development of the axial and appendicular systems in fishes
Ward, Andrea B.
Number of pages
Publication year
Degree date
School code
DAI-B 66/06, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
9780542198335, 0542198339
Brainerd, Elizabeth L.
University of Massachusetts Amherst
University location
United States -- Massachusetts
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
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