Speciation And Evolution Of Cichlids

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Speciation and Evolution of Cichlids in East Africa
Dr. Hoeh WIC
Matthew S. Holcomb
March 2, 2015 Introduction
The East-African cichlids are a rather interesting and diverse group of fish, and have caught the eye of many scientists particularly because of the speed, diversity, and convergent patterns of their radiation (Yong-Hwee et al. 2012). For instance, there are 500+ species in just one lake, Lake Victoria, and an estimated 2,000+ species in total. The fish in lake Victoria, which is estimated to be 100,000-400,000 years old or less and to have suffered a complete drought only 14,600 years ago, are an amazing example of just how quickly these fish have diversified (Rijssel et al. 2014). And on an evolutionary time scale, 14,600
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2009). And also, as can be seen from the figure below, Schwarzer and his team were able to determine that the ancestral lineage of the EAR’s have spread from the lakes in Central Africa. However their research does not determine how the EAR’s came into existence. Figure 1: Consensus BI Tree of the African Cichlid Phylogeny.
Consensus tree (50% majority rule) of the African cichlid phylogeny based on the concatenated dataset. The dataset comprises mitochondrial and nuclear sequences of nine independent markers. Green numbers at nodes refer to bootstrap-values (BS, 1000 replicates) of the ML run and black numbers to Bayesian poste- rior probabilities (BPP). Filled circles represent a 100% BS support and 1.00 BPP and empty circles 1.00 BPP and lower BS val- ues. Major groups within the phylogeny were named based on either their center of geographic distribution (Austrotilapiini and Boreotilapiini) or based on taxonomic aspects (Oreochromini). The asterisk (*) in the tree marks the type species of the genus Tilapia. The leaf stability index exceeded 0.95 for all specimens, except for clade AI (all taxa 0.90). Note that for clade AI only representatives of the EAR are included. The results presented here were verified using a more detailed taxon sampling based on ND2 (see additional file 3). The map in
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