Question

Students in a genetics laboratory began an experiment in an attempt to increase heat tolerance in two strains of Drosophila melanogaster, One strain was trapped from the wild six weeks before the experiment was to begin; the other was obtained from a Drosophila repository at a university laboratory, In which strain would you expect to see the most rapid and extensive response to heat-tolerance selection, and why?

Short answer

Answer: The wild strain of Drosophila melanogaster is likely to show the most rapid and extensive response to heat-tolerance selection, due to its higher genetic variation compared to the laboratory strain. Higher genetic variation provides more opportunities for natural selection to take place, leading to faster improvement in heat tolerance.

Step-by-step solution

Identifying the Key Factors

To understand which strain is likely to respond faster to heat tolerance selection, we need to consider the genetic variation in each strain. Genetic variation is crucial for the selection process because it allows for more room for improvement due to differences among individuals that can be passed on to future generations.

Assessing the Genetic Variation

In the wild strain, there's a high chance of having genetic variation because individuals in the wild population are more exposed to various environmental factors, leading to more genetic diversity in the wild population. On the other hand, the strain from the Drosophila repository at the university laboratory is more likely to have experienced controlled conditions and potential inbreeding, reducing the amount of genetic variation present in the population.

Comparing the Effects of Genetic Variation

In order for heat-tolerance selection to occur rapidly and extensively, a higher level of genetic variation is required. This allows for a higher possibility of favorable traits to be selected and passed on to future generations, leading to a quick improvement in heat tolerance.

Concluding the Comparison

Based on the analysis of genetic variation in each strain, we would expect to see the most rapid and extensive response to heat-tolerance selection in the wild strain of Drosophila melanogaster. The higher genetic variation in the wild strain provides more opportunities for natural selection to take place, leading to a faster improvement in heat tolerance compared to the strain obtained from the Drosophila repository at the university laboratory.

Key concepts

Heat Tolerance Selection

When studying how organisms adapt to their environments, scientists may focus on specific traits, such as heat tolerance in fruit flies like Drosophila melanogaster. Heat tolerance selection is a process where, over time, individuals within a population that can withstand higher temperatures survive and reproduce more effectively than those who cannot. This type of selection can be observed both in natural environments and in laboratory settings.

Under a scenario where temperatures gradually increase, flies with genes conferring better heat resistance are more likely to thrive, leading to an accumulation of these heat-tolerant genes in the population. It's a fascinating example of how a single trait can be honed by the pressures of the environment, demonstrating the dynamic nature of life adapting in the face of climatic challenges.

Genetic Diversity

Genetic diversity refers to the total number of genetic characteristics in the genetic makeup of a species. In the case of Drosophila melanogaster, genetic diversity plays a pivotal role, as it influences the potential for a population to adapt to environmental changes such as increased temperature. Populations with greater genetic diversity have a wider variety of genetic combinations and are more likely to contain individuals with traits beneficial for survival under new conditions.

These variations occur due to mutations, gene flow, or sexual reproduction, which generate new combinations of genes. If you compare two groups of flies, such as those from a wild population versus ones that have been bred in a lab, you might find significant differences in genetic diversity, often with the wild group possessing a richer genetic pool. This inherent diversity forms the raw material that natural selection works on.

Natural Selection

Natural selection is a foundational concept in evolutionary biology, articulated by Charles Darwin. It acts on the variation within a population, leading to the survival and reproduction of organisms that are best adapted to their environment. It's akin to a sieve that preserves favorable traits and eliminates those that are less suited.

Imagine a diverse population of Drosophila melanogaster where some individuals can tolerate higher temperatures. As the environment heats up, these individuals are more likely to survive and pass on their heat-tolerant genes. Over generations, the characteristic of heat tolerance could become more common in the population, illustrating natural selection's role in shaping species continuously.

Environmental Adaptation

Environmental adaptation involves changes in organisms that enhance their survival and reproductive success in a specific environment. For Drosophila melanogaster, adapting to hotter environments may require physiological, behavioral, or even genetic changes. Adaptations can happen quickly or over thousands of generations, depending on the pressure of the environmental factors and the genetic variability of the population.

In the context of increasing global temperatures, understanding how species like the fruit fly adapt has practical implications for predicting the future of biodiversity and ecosystem function. Moreover, it provides insights into potential strategies organisms may take to cope with and survive in changing climates. Whether through behavioral strategies like seeking shade or physiological changes, adaptation plays a key role in the long-term survival of species.