The Assessment of Current Biogeographic Patterns of Coral Reef Fishes in the Red Sea by Incorporating Their Evolutionary and Ecological Background

  • Vanessa S. N. Robitzch Sierra

Student thesis: Doctoral Thesis


The exceptional environment of the Red Sea has lead to high rates of endemism and biodiversity. Located at the periphery of the world’s coral reefs distribution, its relatively young reefs offer an ideal opportunity to study biogeography and underlying evolutionary and ecological triggers. Here, I provide baseline information on putative seasonal recruitment patterns of reef fishes along a cross shelf gradient at an inshore, mid-shelf, and shelf-edge reef in the central Saudi Arabian Red Sea. I propose a basic comparative model to resolve biogeographic patterns in endemic and cosmopolitan reef fishes. Therefore, I chose the genetically, biologically, and ecologically similar coral-dwelling damselfishes Dascyllus aruanus and D. marginatus as a model species-group. As a first step, basic information on the distribution, population structure, and genetic diversity is evaluated within and outside the Red Sea along most of their global distribution. Second, pelagic larval durations (PLDs) within the Red Sea environmental gradient are explored. For the aforementioned, PLDs of the only other Red Sea Dascyllus, D. trimaculatus, are included for a more comprehensive comparison. Third, to further assess ongoing pathways of connectivity and geneflow related to larval behavior and dispersal in Red Sea reef fishes, the genetic composition and kinship of a single recruitment cohort of D. aruanus arriving together at one single reef is quantified using single nuclear polymorphisms (SNPs). Genetic diversity and relatedness of the recruits are compared to that of the standing population at the settlement reef, providing insight into putative dispersal strategies and behavior of coral reef fish larvae. As a fourth component to study traits shaping biogeography, the ecology and adaptive potential of the cosmopolitan D. aruanus is described by studying morphometric-geometrics of the body structure in relation to the stomach content and prey type from specimen along the cross-shelf of the central Red Sea and at a site outside the Red Sea, in Madagascar, and approach whether foraging strategies change depending on geographic location and environment, and if differences in diet are followed by phenotypic plasticity. Jointly, results suggest that biological responses and putative adaptive strategies are correlated with different biogeographic ranges and habitat preferences.
Date of AwardMar 2017
Original languageEnglish (US)
Awarding Institution
  • Biological, Environmental Sciences and Engineering
SupervisorMichael Berumen (Supervisor)


  • Biogeography
  • Coral reef fishes
  • Red Sea
  • Recruitment
  • Adaptation
  • Genetics

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