Drosophila buzzatii is a fruit fly that feeds on the rotting...

Drosophila buzzatii is a fruit fly that feeds on the rotting fruits of cacti in Australia. Timothy Prout and Stuart Barker calculated the heritabilities of body size, as measured by thorax length, for a natural population of $D .$ buzzatii raised in the wild and for a population of $D .$ buzzatii collected in the wild but raised in the laboratory (T. Prout and J. S. F. Barker. $1989 .$ Genetics $123: 803-813$ ). They found the following heritabilities: Population Wild population Laboratory-reared population Heritability of body size ( $\pm$ standard error) $$0.0595 \pm 0.0123$$ $$0.3770 \pm 0.0203$$ Why do you think that the heritability measured in the laboratory-reared population is higher than that measured in the natural population raised in the wild?

Drosophila buzzatii is a fruit fly that feeds on the rotting fruits of cacti in Australia. Timothy Prout and Stuart Barker calculated the heritabilities of body size, as measured by thorax length, for a natural population of $D .$ buzzatii raised in the wild and for a population of $D .$ buzzatii collected in the wild but raised in the laboratory (T. Prout and J.
S. F. Barker. $1989 .$ Genetics $123: 803-813$ ). They found the following heritabilities:
Population
Wild population Laboratory-reared population
Heritability of body size ( $\pm$ standard error) $$0.0595 \pm 0.0123$$
$$0.3770 \pm 0.0203$$
Why do you think that the heritability measured in the laboratory-reared population is higher than that measured in the natural population raised in the wild?

Key Concepts

Controlled Experimental Conditions

Controlled experimental conditions, such as those in a laboratory setting, reduce environmental noise by standardizing variables that can influence the trait of interest. This reduction in environmental variance allows the genetic variance to represent a larger portion of the overall phenotypic variance, leading to higher and more accurate estimates of heritability.

Environmental Variance

Environmental variance refers to the component of phenotypic variance caused by differences in the external environment. When environmental factors are highly variable, they can obscure the underlying genetic contributions to a trait. In controlled settings like a laboratory, reduced environmental variance enhances the visibility of genetic effects, resulting in higher heritability measurements.

Phenotypic Variance

Phenotypic variance is the total observable variation in a trait within a population, which arises from both genetic differences and environmental influences. In environments where external factors contribute significant noise, the genetic contribution to overall variability is diluted, leading to lower heritability estimates.

Heritability

Heritability is the proportion of the total phenotypic variance in a trait that can be attributed to genetic variance among individuals. It is presented as a ratio that highlights how much genetics, as opposed to the environment, influences a particular trait. Changes in environmental variance can alter the observed heritability, even if the genetic variance remains constant.

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