Novel physiological challenges in different environments can promote the evolution of divergent phenotypes, either through plastic or genetic changes. Environmental salinity serves as a key barrier to the distribution of nearly all aquatic organisms, and species diversification is likely to be enabled by adaptation to alternative osmotic environments. The threespine stickleback (Gasterosteus aculeatus) is a euryhaline species with populations found both in marine and freshwater environments. It has evolved both highly plastic and locally adapted phenotypes due to salinity-derived selection, but the physiological and genetic basis of adaptation to salinity is not fully understood. We integrated comparative cellular morphology of the kidney, a key organ for osmoregulation, and candidate gene expression to explore the underpinnings of evolved variation in osmotic plasticity within two populations of sticklebacks from distinct salinity zones in the Baltic Sea: the high salinity Kattegat, representative of the ancestral marine habitat; and the low salinity Bay of Bothnia. A common-garden experiment revealed that kidney morphology in the ancestral high-salinity population had a highly plastic response to salinity conditions whereas this plastic response was reduced in the low-salinity population. Candidate gene expression in kidney tissue revealed a similar pattern of populationspecific differences, with a higher degree of plasticity in the native high-salinity population. Together these results suggest that renal cellular morphology has become canalized to low salinity, and that these structural differences may have functional implications for osmoregulation.

Abstract:The people fall in low income group is generally migrants and the local poor. Majority of slum people are living in poor quality housing where the absence of basic services and facilities is significant. The aim of the study is to evaluate the existing housing condition, to identify the present condition of sanitary facilities & drainage facilities, to evaluate the present condition of drinking water quality (lab analysis) & to determine the level of noise as this area is near to the main bus station & health services. To collect the required information random sampling method was used and questionnaire survey was done with slum dwellers. Lab analysis was made to find out the water quality. The noise level was measured using Noise Level meter. The study has tried to analyze the problem and advantages for living in the slum settlements, the slum settlements consequences on surroundings with a special reference of Khora Slum of Khulna City Corporation. The housing condition of the study area is not good. About 80% houses are in such a condition that it is very hard to live in there. The main problem is that these people are not aware of the environment where they are living as it is not their permanent living place. It was found that responsible authorities are not doing anything for the slum people. There is no qualified doctor in that area. Though the sadar hospital is nearer but they don't have enough money to go there. Mosquito is main problem here as there is no fixed place for throwing their household waste. Sanitation facilities are very poor here. There is only one community sanitary latrine with three chambers but it is not sufficient for all the people of the slum. Drinking water is another problem here as there exists only five tube wells of three are used by most of the people and the quality of water of the tube wells were analyzed in the lab. It was found that salinity level is very high (10 ppt) & color is dark of the water of the tube wells. By this study it will be easy to get the idea about house rent structure of the slums, getting services and facilities of the slums, distance of the services and facilities from the settlements, water supply and other utility services conditions of the slums.

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