Convergent evolution is defined as the independent
development of specific similar traits and structures, among species. Typically,
a characteristic is considered to be convergent if the previous ancestor in the
lineage did not possess the same traits. In this study, the hypothesis explores
the wide variety of karyotypes in chameleons. Species in the Chamaeleonidae
family can have anywhere between 20 and
62 chromosomes, which, given their similar phenotype, prompted researchers to
investigate what was driving the convergent evolution. The study explored microchromosome
fusions, and found this to be the predominant cause for reduced evolutionary
change.
Research was gathered from 57 species of chameleons, and PCR
was utilized to amplify markers in the specimens. Chromosome samples were analyzed
and separated into separate categories: haploid, diploid, arm number, macrochromosome,
microchromosome and position of NOR loci. Sex chromosomes were not researched,
due to their independence from autosomal chromosomes and different arrangements
in various species. Loss and gain of
chromosomes was tracked on ChromEvol system. Estimates of chromosome numbers
were generated for the chameleon genuses, as shown below, with the color and
number indicating the number of chromosome pairs (haploid value). It is extremely
interesting to see the convergence of traits, given the diversity of the Chamaeleonidae
family. Many of these species have had
little to none research, so there is a significant amount of information we
have yet to learn from these beautiful creatures.
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