No bilateral asymmetry in wild-caught, endangered Poeciliopsis o. occidentalis (Gila topminnows)

Article Abstract:

Support for the hypothesis that some unknown, perhaps unnatural, environmental factor in a given laboratory has been responsible for differences found in bilateral asymmetry in samples of fish taken from two springs is presented. Bilateral asymmetry is not found in wild-caught Poeciliopsis o. occidentalis (Gila topminnows). This fish species, found in Arizona, has been considered a well-known example of positive association between genetic variation level and fitness in endangered species.

Arizona, Statistical Data Included, Environmental aspects, Endangered species, Natural selection, Laboratory animals, Ichthyological research, Ichthyology, Symmetry (Biology), Experimental design, Research design, Killifishes

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Female choice and variation in the major histocompatibility complex

Article Abstract:

Two previous reports have claimed that female mice prefer to mate with males carrying different major histocompatibility complex traits. A symmetrical balancing-selection model describing these apparent preference of female mice is developed and analyzed. Results indicate that female choice reduces the frequency of homozygotes in the population. The model indicates that all homozygotes are non-preferentially selected against and that all heterozygotes are non-preferentially selected for.

Sexual behavior, Models, Physiological aspects, Mice, Mice (Rodents), Major histocompatibility complex, Sexual behavior in animals, Animal sexual behavior

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Factors influencing the extent of inbreeding depression: an example from Scots pine

Article Abstract:

In a study of Scots pine the level of inbreeding depression was much lower in northern than in southern populations in Finland. Population genetic factors might account for the difference, and whether that is so has been studied theoretically. It seems likely stronger selection against heterozygotes or higher selfing in the northern population at biologically reasonable levels in both cases bring changes consistent with observed differences.

United States, Finland, Plants, Plant development, Lethal mutation, Inbreeding, Fertilization of plants, Plant fertilization, Scots pine, Scotch pine

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