Ideas that Influenced Darwin

Transcription

1 Evolution

2 Ideas that Influenced Darwin Reproduction is usually exponential, but many populations remain constant. The difference between reproduction rates and population growth shows Exponential Growth Potential Typical Growth Pattern of Many Populations

3 In that struggle for survival, some individuals may have traits that make them.

4 Ideas that Influenced Darwin Cont. Selective Breeding (Artificial Selection): Change in a population through.

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6 Ideas that Influenced Darwin Cont. Darwin collected fossils during his expedition on the Beagle, finding fossils of.

7 Discuss with your table partner: Review with your table partner what you already know about why the Galapagos Islands were one of the important inspirations for Darwin s Theory of Adaptation through Natural Selection. Also review what you know about natural selection and how it works.

8 Galapagos Islands are far from the main land (700 miles) of Ecuador with diverse locations in a small region.

9 Ideas that Influenced Darwin Cont. Many species on the Galapagos Islands are unique, yet similarities to species found in similar environments. Different species on different island. Example: Finches

10 Beak Adaptations

11 Theory of Evolution by Natural Selection Prerequisites for Natural Selection Overproduction of organisms Variation exists in population and the variation must be. -variation produced by random in genes Some variations are favorable, some are not which leads to differential reproduction (differences in which organisms ).

12 Theory of Evolution by Natural Selection Process of Natural Selection Individuals with favorable traits are more likely to survive and Gene pool of population changes over time (increase in favorable genes).

13 Natural Selection Leads to Adaptations A change in a population due to natural selection is called an adaptation. Adaptations make the population. Example: The peppered moth population in Britain saw an increase in darker coloration when the Industrial Revolution changed the environment (soot).

14 Examples of Adaptations Camouflage: Blending in with the surrounding environment. Example: arctic foxes Mimicry: copying the appearance of another organism. Examples: orchid flower which mimics the shape of wasp species that pollinates it. viceroy butterfly mimics appearance of monarch (which is poisonous).

15 Evolution Simulation

16 Geographic Isolation: A physical barrier between two populations of a species can allow each population to adapt separately to their different environments. Over time this can lead to speciation ( ). Kaibab squirrel on the northern rim of the Grand Canyon. Abert s squirrel on the southern rim of the Grand Canyon. 2 subspecies of tufted-ear squirrels on either side of the grand canyon.

17 Keep in Mind Individuals can t evolve, only can. Survival of the Fittest doesn t always mean survival of the strongest. It means most likely to.

18 Discuss with your table partner: Example of Natural Selection Scientists have documented a decrease in the average size of antlers/tusks for many species. For example, 30% of elephants are now tuskless (genetically). What natural selection pressure is likely driving this change in the gene pool of these species?.

19 Natural Selection is Situational The previous example of natural selection illustrates that natural selection is. If there are any changes to the environment, such as a new predator or new food source, the characteristics that are advantageous may also change.

20 Why do you think that some bacteria strains have adapted quickly to antibiotics, developing antibiotic resistance? Because bacteria have a and. (Remember, favorable genes must be present for the process to occur. )