Populations of larus gulls around the north pole show an unusual pattern of reproductive isolation: each population is able to i
nterbreed with its neighboring populations, but populations separated by larger geographic distances are not able to interbreed. this type of species complex is known as a:
When there are neighbouring populations that can interbreed with each other while only two of those populations cannot breed between them, we are standing before a ring species. In the case of Larus gulls what is observed is that several of these species can interbreed, but it comes to two of them that are incompatible - they are probably to<span> distantly related to interbreed. It is considered, that this species may be connected to each other in a line of derivation and is both ends on that line that are incompatible.</span>
If I c<span>onsider this northern site of primary succession following the retreat of a glacier, the characteristics that I would expect to see among the plant comprising the pioneer species are the processes of ecological succession and the primary succession.</span>
