Chapter 9 Test Review Natural Selection, Selective Breeding & Dichotomous Keys
Charles Darwin Studied birds called finches on the Galapagos Islands The finches had different beaks due to their different food sources Organisms produce more offspring than can survive. There is competition among offspring for food, space, and other resources. ● Theory of natural selection: organisms that survive have variations best suited for their environment. ● ● ● ●
Can organisms vary? Variations in organisms can be: 1. External 2. Behavioral 3. Physiological
Darwin’s theory of natural selection: ● Organisms that survive have variations best suited for their environment.
Can you adapt to survive? Adaptations for avoiding predators: ● Camouflage ● Living in groups ● Sensitive hearing
Example of adaptations: ● Camouflage ● Camel producing little sweat ● Penguins having wings that look like flippers ● Cheetahs having long, powerful legs ● The Arctic snow hare having white fur to blend in with snow
Vocab, anyone? ● Adaptation: a trait in an organism that helps it survive in its environment ● Selective breeding: the process of choosing parent organisms for the characteristics we want in their offspring ● Natural selection: the survival of the organisms that are genetically best adapted to the environment
The Peppered Moth ● The peppered moths experienced a population shift in England during the Industrial Revolution because: ○ ○
Soot-covered trees camouflaged the dark moths The light colored moths became more visible
● This is an example of natural selection at work.
Adaptations, Adaptations, Adaptations ● The plant below has seeds attached by light, fluffy threads. This is an adaptation for seed dispersal.
● To survive in the desert, some plants have a waxy coat on their leaves to avoid water loss. ● Your teeth are an adaptation! Some animals, like sharks have very sharp teeth to eat meat. Deer are herbivores, so their teeth are more flat to chew plants.
Dichotomous Keys ● The purpose of a dichotomous key is to identify an organism. ● If trying to identify leaves using a dichotomous key, you might observe if the leave is compound or simple.
Classification Systems ● As you move from the species to kingdom level in the classification hierarchy organisms become less closely related. ● As you move from the kingdom to species level in the classification hierarchy, organisms become more closely related. ● There are several different types of bears that have been identified-Selenarctos thibetanus, Ursus americanus, Ursus arctos, and Ailuropoda melanoluca. Which two species are more closely related? ○
Ursus americanus and Ursus arctos
Selective Breeding ● Humans control selective breeding. ● Examples: ○ Breeding race horses ○ Breeding “designer” mutts like a Malti-poo, Puggle, or Yorkiepoo. ○ Breeding corn for a specific trait
An adaptation... ●
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An adaptation occurs when all members of the population have the favorable trait. An adaptation helps a population of species survive and reproduce in their environment. An adaption evolves from a mutation and gives an advantage that becomes common throughout the population.
Natural Selection vs. Selective Breeding A farmer notices that one of his cattle and their offspring are eating weeds more often than grasses. The farmer wants to kill the weeds, but doesn’t want to use dangerous chemicals to do so. What should the farmer to do reduce the weeds? The farmer should breed the cattle eating weeds to produce more offspring with this desirable trait.
One species of lizards have have spikes on their backs to defend themselves from predators. In a population of lizards, a few lizards do not have these spikes. Why are the lizards that have spikes more likely to produce offspring than the spikeless lizards? Lizards with the spikes will be better to defend themselves.
Carolus Linnaeus ● In the 1700’s Carolus Linnaeus created a different classification system based on similarities in structures. ● Called “the father of taxonomy” ● Latinized his own name from Carl Linne’ ● Came up with a way to classify organisms with a two name naming system (binomial nomenclature) that would be universal to scientist all over the world.
