In contrast, individuals with beneficial genes are more likely to survive and reproduce. Model how variation in prey color and predator foraging affects survival and reproduction of a prey population. This document may be freely reproduced and distributed for non-profit educational purposes. Skip to main content. Search form Search. Join The Community Request new password.
Main menu About this Site Table of Contents. Evolution by Natural Selection. HS-LS Ask questions to clarify relationships about the role of DNA and chromosomes in coding the instructions for characteristic traits passed from parents to offspring.
HS-LS Communicate scientific information that common ancestry and biological evolution are supported by multiple lines of empirical evidence. HS-LS Construct an explanation based on evidence that the process of evolution primarily results from four factors: 1 the potential for a species to increase in number, 2 the heritable genetic variation of individuals in a species due to mutation and sexual reproduction, 3 competition for limited resources, and 4 the proliferation of those organisms that are better able to survive and reproduce in the environment.
HS-LS Construct an explanation based on evidence for how natural selection leads to adaptation of populations. The content and activities in this topic will work towards building an understanding of how all living organisms on Earth adapt to their environments through evolution by natural selection.
Introduction to Evolution by Natural Selection Without physically counting bacteria or viruses, scientists estimate that there are more than 8. Weird Science. Model natural selection in a population of bacteria. Practices of Science. Further Investigations. Table of Contents: Evolution by Natural Selection. Activity: Modeling Evolution. Activity: Simulate Natural Selection. Special Features:.
Representative Image:. Further Investigations: What is an Invertebrate? Question Set: What is a Mammal? Further Investigations: What is a Mammal? Share and Connect. We invite you to share your thoughts, ask for help or read what other educators have to say by joining our community.
Partner Organizations. The gene pool is all the genes contained within a population. The gene pool is affected by selective pressures which are environmental challenges that cause one genetically determined trait to be favoured over another.
Lets go back a little. In a population there is variation, meaning that not everyone is a clone of one another but some genes are found in some and not in others. New genes arise by mutation. Mutation is happening all the time, and it is necessary for the continued survival of a species.
The mutated gene will most likely decrease the fitness of the individual we can discuss why this is but in very rare cases it might confer an advantage to the organism. Increased fitness means the individual is more likely to survive and breed successfully, meaning that it is more likely to pass on its genes to the next generation.
Mutations are changes in the structure of the molecules that make up genes, called DNA. The mutation of genes is an important source of genetic variation within a population. Mutations can be random for example, when replicating cells make an error while copying DNA , or happen as a result of exposure to something in the environment, like harmful chemicals or radiation. Mutations can be harmful, neutral, or sometimes helpful, resulting in a new, advantageous trait. When mutations occur in germ cells eggs and sperm , they can be passed on to offspring.
If the environment changes rapidly, some species may not be able to adapt fast enough through natural selection. Through studying the fossil record, we know that many of the organisms that once lived on Earth are now extinct. Dinosaurs are one example. An invasive species , a disease organism, a catastrophic environmental change, or a highly successful predator can all contribute to the extinction of species.
Today, human actions such as overhunting and the destruction of habitats are the main cause of extinctions. Extinctions seem to be occurring at a much faster rate today than they did in the past, as shown in the fossil record.
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