Chatham Islands skink
Encyclopedia
The Chatham Island skink, Oligosoma nigriplantare, is a species of skink
in the family
Scincidae.
It is the sole reptile species found on the Chatham Islands
of New Zealand
where it occurs on all the major islands except Chatham Island itself. Given the geological history of the Chatham Islands, it is assumed that O. n. nigriplantare previously occurred on Chatham Island; however, there are no fossil records or historical reports of O. n. nigriplantare on Chatham Island . Since O. n. nigriplantare is almost locally extinct on Pitt Island as a result of introduced mammals , the presence of introduced mammals on Chatham Island might have resulted in the local extinction of O. n. nigriplantare . On vegetated islands, O. n. nigriplantare inhabits grassland and shrub habitat, but it also occurs on marine rock stacks with sparse vegetation . Substantial morphological variation (body size, colour and colour pattern) is evident within O. n. nigriplantare , potentially indicating morphological evolution following its colonization of the Chatham Islands. Indeed, O. n. nigriplantare (up to 91 mm Snout to Vent Length; SVL) has a substantially larger body size than O. n. polychroma (up to 77 mm SVL) .
Recent genetic studies indicate that O. n. nigriplantare diverged from Oligosoma nigriplantare polychroma (its nearest relative) 5.86–7.29 million years ago. This pre-dates the emergence date for the Chatham Islands, but indicates that O. n. nigriplantare colonized the Chatham Islands via overwater dispersal on a single occasion. There is substantial morphological variability evident in O. n. nigriplantare, and a shallow level of genetic differential between islands within the Chatham Islands indicating low gene flow between islands, but not speciation between islands. The level of genetic and morphological divergence between O. n. nigriplantare and Oligosoma nigriplantare polychroma might warrant their recognition as distinct species.
Skink
Skinks are lizards belonging to the family Scincidae. Together with several other lizard families, including Lacertidae , they comprise the superfamily or infraorder Scincomorpha...
in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Scincidae.
It is the sole reptile species found on the Chatham Islands
Chatham Islands
The Chatham Islands are an archipelago and New Zealand territory in the Pacific Ocean consisting of about ten islands within a radius, the largest of which are Chatham Island and Pitt Island. Their name in the indigenous language, Moriori, means Misty Sun...
of New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
where it occurs on all the major islands except Chatham Island itself. Given the geological history of the Chatham Islands, it is assumed that O. n. nigriplantare previously occurred on Chatham Island; however, there are no fossil records or historical reports of O. n. nigriplantare on Chatham Island . Since O. n. nigriplantare is almost locally extinct on Pitt Island as a result of introduced mammals , the presence of introduced mammals on Chatham Island might have resulted in the local extinction of O. n. nigriplantare . On vegetated islands, O. n. nigriplantare inhabits grassland and shrub habitat, but it also occurs on marine rock stacks with sparse vegetation . Substantial morphological variation (body size, colour and colour pattern) is evident within O. n. nigriplantare , potentially indicating morphological evolution following its colonization of the Chatham Islands. Indeed, O. n. nigriplantare (up to 91 mm Snout to Vent Length; SVL) has a substantially larger body size than O. n. polychroma (up to 77 mm SVL) .
Recent genetic studies indicate that O. n. nigriplantare diverged from Oligosoma nigriplantare polychroma (its nearest relative) 5.86–7.29 million years ago. This pre-dates the emergence date for the Chatham Islands, but indicates that O. n. nigriplantare colonized the Chatham Islands via overwater dispersal on a single occasion. There is substantial morphological variability evident in O. n. nigriplantare, and a shallow level of genetic differential between islands within the Chatham Islands indicating low gene flow between islands, but not speciation between islands. The level of genetic and morphological divergence between O. n. nigriplantare and Oligosoma nigriplantare polychroma might warrant their recognition as distinct species.