Morphological and Osteological Variation in Cichlids (Perciformes: Cichlidae)

• Author / Creator

  Kaur, Jasdeep

• The family Cichlidae is a species-rich family in the order Perciformes, with estimates of about 1,703 validly described species, which inhabit freshwater and marginal marine environments in Central and South America, Africa, Madagascar, the West Indies, Sri Lanka, and coastal areas of India and Iran. Cichlids are the classical examples of adaptive radiation which has led to an outstanding diversity of body shapes, color patterns, behavior, and an enormous variety of trophic and ecological specializations. Most of the recent work to determine phylogenetic relationships within this family are based on molecular data and neglect morphological characters, which are very important specifically for including fossils in phylogenies, and play a crucial role in identifying cichlid species in the field. My project is in part to rectify this situation, and will include morphological (including osteological) studies. An assessment of the variability of skeletons of extant cichlids within a single population and the variation of the skeleton that might occur with growth, will provide a baseline of the amount of variation that might be expected in a single species of extinct cichlid. This baseline would then allow us to indicate whether or not a sample of fossil cichlids is likely to represent more than a single species. I conducted the morphological and osteological studies within a sample (n=22) of a single population of Mesonauta festivus. The measurements and meristics for specimens are found to be normally distributed with the standard deviation ranges from 0.01-0.07. In the current study, the osteology of Mesonauta festivus has been described for the first time. I cleared and stained five specimens of Mesonauta festivus and used CT scans of the rest of the specimens for the analyses. All the bones examined were found to be morphological similar within the specimens. I reported the morphological analyses and osteological descriptions for a size series of Iranocichla hormuzensis (n=107). The standard deviation ranges from 0.01-0.09 among the measurements of the specimens. I documented isometric growth among the Iranocichla hormuzensis specimens Among the variable sized specimens of Iranocichla hormuzensis, the bones were found to be similar with the exception of cartilage being more in the juvenile samples. The osteology of the cichlid species in this thesis is found to be conserved. Consequently, if a sample of fossils shows any osteological variation, it is likely that the sample includes more than one different species. For future research, studies in my thesis can be combined with genetic data to determine if there is any variation among the DNA sequences in the individuals of the same species. Further, these morphological and osteological analysis can be included with the molecular studies along with the fossils to better understand the phylogenetic relationships of cichlids.

• Subjects / Keywords

  • Cichlids
  • Intraspecific Variation
  • Morphological Studies

• Graduation date

  Spring 2022

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-n154-hn73

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.