Many individuals of the platyfish, Xiphophorus maculatus, have spots on their dorsal fins. A closely related species, the swordtail, X. helleri, lacks spots. In some backcross hybrids of these species, enlarged spots develop into malignant tumors, which reduce the organisms' life spans. This could be an example of .a. the Dobzhansky-Muller model of speciation.
b. beneficial hybridization.
c. the morphological species concept.
d. gene flow.
e. genetic compatibility.

answer:

sequence 1- deletion

                  2- duplication

                  3- insertion

                  4- substitute

                  5- inversion

the circled areas are referred to   as sunspots.   the sunspots are cooler than the   surrounding area.

sunspots are temporary phenomena on the photosphere of the sun that appear visibly as dark spots compared to surrounding regions. they correspond to concentrations of magnetic field flux that inhibit convection and result in reduced surface temperature compared to the surrounding photosphere.

actually the answer is c