A re-examination of variation associated with environmentally stressed organisms.
نویسندگان
چکیده
Variation is an essential feature of biological systems. Populations adapt to dynamic environments, in part, because of this variation. In this review, we re-examine phenotypic variation, especially in organisms living in polluted environments. A recent goal of ecotoxicology is to understand the sublethal effects of exposure to pollutants, e.g. responses to endocrine-disrupting contaminants. While variation is an inherent quality of organisms, variance is a statistical measure of the variation of a trait. Increased variance has been associated with organisms living at the perimeter of a population's range, introduced into novel environments, or exposed to pollution. Some researchers have proposed increased phenotypic variance in exposed populations as an evolutionary mechanism, and others have suggested its use as a biomarker. While we agree that variance often increases in the exposed population, we also recognize that the opposite phenomenon occurs. That is, variance can decrease from exposure to pollution. Altered variance in the exposed population-leading to heteroscedasticity-could result in erroneous conclusions (Type II errors). We suggest that exposure to endocrine-disrupting contaminants could influence the health of populations in ways that are not always represented by measures of central tendency, and that variance and distribution should also be examined in environmentally stressed wildlife.
منابع مشابه
Genetic variability and identification of markers associated with germination parameters in gamma-irradiation induced mutants of sunflower under water stress condition
The objectives of the present research were to evaluate the variability induced by gamma-irradiation among a population of M8 sunflower mutant lines and to identify molecular markers associated with different seed germination traits. Experiments were carried out under well watered and water-stressed conditions using a randomized blocks design, with three replications. The studied traits consist...
متن کاملA Microhomology-Mediated Break-Induced Replication Model for the Origin of Human Copy Number Variation
Chromosome structural changes with nonrecurrent endpoints associated with genomic disorders offer windows into the mechanism of origin of copy number variation (CNV). A recent report of nonrecurrent duplications associated with Pelizaeus-Merzbacher disease identified three distinctive characteristics. First, the majority of events can be seen to be complex, showing discontinuous duplications mi...
متن کاملPopulation structure between environmentally transmitted vibrios and bobtail squids using nested clade analysis.
Squids from the genus Euprymna (Cephalopoda: Sepiolidae) and their symbiotic bacteria Vibrio fischeri form a mutualism in which vibrios inhabit a complex light organ within the squid host. A host-mediated daily expulsion event seeds surrounding seawater with symbiotically capable V. fischeri that environmentally colonize newly hatched axenic Euprymna juveniles. Competition experiments using nat...
متن کاملDispersion of Torsional Surface Wave in a Pre-Stressed Heterogeneous Layer Sandwiched Between Anisotropic Porous Half-Spaces Under Gravity
The study of surface waves in a layered media has their viable application in geophysical prospecting. This paper presents an analytical study on the dispersion of torsional surface wave in a pre-stressed heterogeneous layer sandwiched between a pre-stressed anisotropic porous semi-infinite medium and gravitating anisotropic porous half-space. The non-homogeneity within the intermediate layer a...
متن کاملA Retroesophageal Right Subclavian Artery as the Last Branch of the Aortic Arch- In Vivo Case Report
Three major arteries normally originate from the aortic arch. Variations of the aortic arch branches are observed in some cases. Rare variation of the aortic arch branches is originated from the retroesophageal right subclavian (RRS) artery as the last branch of the aortic arch. Variation of artery is possibly associated with the variation of the recurrent laryngeal nerve. This research p...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- Human reproduction update
دوره 7 3 شماره
صفحات -
تاریخ انتشار 2001