Question

freeze tolerance
use the information and your knowledge of science to answer the questions.
doug schemske is a biologist who studies plants from around the world. doug and his research team carry out experiments with the plant species mouse - ear cress, or arabidopsis thaliana. they like this species because it is easy to grow in both the lab and field. arabidopsis is very small and lives for just one year. it grows across most of the globe and in a wide range of latitudes and climates. arabidopsis is also able to pollinate itself and produce many seeds, making it possible for researchers to grow many individuals to use in their experiments.
doug chose arabidopsis populations in scandinavia and the mediterranean for his research on local adaptation because those two locations have very different climates. the populations may have adapted to have the highest survival and reproduction based on the climate of their home location.
to deal with sudden freezes and cold winters in scandinavia, plants may have evolved freeze tolerance traits, which produces chemicals that act like antifreeze. these chemicals accumulate in their tissues to keep the water from turning into ice and forming crystals. to see whether freeze tolerance was driving local adaptation, doug set up an experiment to identify which plants survived after freezing. doug collected seeds from several different populations across scandinavia and the mediterranean.
doug noticed the scandinavian plant populations had the highest rate of survival in the deep freeze.

• using chart 1, explain how the genetic information in the scandinavian plant populations increased their rate of survival in their environment.
• describe an additional factor that causes populations to change over time

Explanation:

1. For the first question: Scandinavian Arabidopsis populations have genetic variation for freeze tolerance traits. Individuals with genes that produce more effective antifreeze-like chemicals had higher survival in deep freezes. Through natural selection, these favorable genes became more common in the population over generations, increasing the overall survival rate in their cold environment.
2. For the second question: Gene flow (movement of genes between populations) is an additional factor. When individuals from different populations breed, they introduce new genetic material, which can change the genetic makeup of a population over time. Other valid factors include genetic drift (random changes in gene frequencies) or mutation (new genetic variations arising randomly).

Answer:

1. Scandinavian plant populations have genetic variation for freeze tolerance. Natural selection favored individuals with genes that produce antifreeze-like chemicals, as these plants survived deep freezes better. Over generations, these beneficial genes became more prevalent in the population, raising the overall survival rate in their cold native environment.
2. One additional factor is genetic drift: random, chance events that change the frequency of genes in a population over time, especially impactful in small populations. Alternatively, gene flow (the transfer of genetic material between different populations via mating or seed dispersal) can also alter population traits over time.