Rapid Body Size Shifts Of Animals In Fragmented Habitats Of The Thousand Island Lake

Background Habitat fragmentation is one of the important factors leading to the loss of biodiversity,the body size of various groups of animal is one of the vital morphological features that impact life cycle characteristics,intraspecific and interspecific relationship and other ecological process.The change of body size in space and time is a universal phenomenon of evolution and environmental adaptation.Compared with the mainland population,island populations of many animal groups often show very significant changes in morphology and body size.Aim This article focused on the body size shifts of Niviventer confucianus,Nebria chinensis and Loxoblemmus aomoriensis on artificial land-bridge islands with short history of isolation in the Thousand Island Lake(TIL).By testing the ’island rule’ of different animals,analyzing the relationship between selective pressure,islands variables,dispersal effectiveness and body size adaptions,we investigated the underlying mechanisms of adaptions for animals on islands within a pretty short time scale.Location Thousand Island Lake,Zhejiang,China.Methods In this paper,line transect method,mark-recapture method,ground trap method and other field survey sampling methods and indoor measurement methods are used to analyse the body size differences between mainland and island samples as well as between islands and the effects of island size and isolation,predation and competition on rapid adaptation to body size.Results There was a significant difference of body size in Niviventer confucianus and Nebria chinensis samples between the mainland and island sites,and there was an"island rule" between the islands.There was a significant negative correlation between the body size parameters and the island area,that is,the smaller the island area was,the larger the body size was,while the island isolation degree had no significant effect on the body size of both.Predation is the most important biological factor affecting the body size of Niviventer confucianus.However,there was no significant difference in body size between mainland and island Loxoblemmus aomoriensis samples,nor was there an "island rule" between islands,while allometry phenomenon and different responses of individual body size between male and female were observed,also its genetic diversity varies from island to island.Main conclusions Our findings suggest that rapid shifts of Niviventer confucianus and Nebria chinensis body size has occurred on the islands in the past 60 years after habitat fragmentation occurred in Thousand Island Lake,which may be a life-history strategy for animals to adapt to the rapidly changing environment.The variation of body size of Niviventer confucianus and Nebria chinensis in the artificial land bridge island system of TIL also conforms to the "island rule" of animal body size,which proves that the "island rule" is universal.More diffuse animals,however,such as the cricket Loxoblemmus aomoriensis were not significantly affected by habitat fragmentation in body size.However,allometry phenomenon and gender differences in body size response to habitat fragmentation have emerged.Theoretical and practical significance The above research results are of great scientific value to enrich the theories of island species evolution,island biogeography and biodiversity maintenance mechanism,and can provide scientific basis for the formulation and implementation of biodiversity conservation strategies in China and the world.