Chapter 2 Section 1 discussed the effect of the environment on the phenotype of individuals light, population ratio, type of soil, temperature )

Transcription

1 Chapter 2 Section 1 discussed the effect of the environment on the phenotype of individuals light, population ratio, type of soil, temperature ) Chapter 2 Section 2: how traits are passed from the parents to the offspring

2 Chapter 2 Section 3: Environmental impact on a whole population over time ( or: the effect of the environment on the inherited traits of a species as a whole, not only individuals) We will study Evolution

3 What is Evolution? It is the change in the genetics of a species over time ( if the genotype changes, also the phenotype will change)

4 Old ideas about Evolution Beginning of the 1800 s : all known species were created at the same time and remained unchanged throughout history. Creationism is the name of the theory that explains that all creatures were created by God.

5 Old ideas about Evolution There are 2 main initial Evolution Theories Lamarck s theory Darwin s theory

6 Lamarckism Acquired traits could be passed onto the offspring. Ex: The ancestors of giraffes had only short necks. Giraffes had to compete to obtain food, had stretch their necks to get food and passed this trait to the offspring. WHY WAS LAMARCK WRONG????????????????????????

7 Lamarck was wrong because inherited traits are not in an organism s genotype, so cannot be passed to the offspring!!!!!!!

8 Darwin 1850 s explained Evolution through his Theory of Natural Selection handout page 190

9 Evolution through Natural Selection Giraffe s neck according to Darwin Initially, there were giraffes with long neck and short neck ( important) The giraffes with long neck had an advantage. They could feed themselves better than the ones with the short neck The giraffe s with long neck survived better and reproduced more, generating more offspring With time, all giraffes had long necks because the short neck ones could not survive and went extinct.

10 Natural Selection also called Survival of the Fittest This theory explains that organisms with traits best suited to the environment they inhabit, are more likely to survive and reproduce, generating more offspring. ** These traits, that give survival advantage to certain individuals, are called FAVORABLE

11 **Modern Theory: Neo-Darwinism Neo - Darwinism adds knowledge of genetic inheritance to the Theory of Natural Selection. Today we know that the gene pool of a population can change due to mutations and sexual reproduction. These changes will pass from parent to offspring and the whole population will change over time. Imp: The ultimate goal of any organism is to reproduce and pass the genes to the offspring.

12 Charles Darwin The Theory Of Natural Selection

13 Darwin s Theory of Natural Selection Important principles that led to this theory: mentioned in the video and written in the handout page 191

14 Darwin s Theory of Natural Selection - Important principles that led to this theory: ( video and also in the handout page 191) Number 1: Organisms produce more offspring than the amount that can or will survive

15 Darwin s Theory of Natural Selection - Important conclusions that led to this theory: (see handout page 191) Number 2: Individuals within a population have different traits, so there is variation of traits among individuals of a species (There were giraffes with long neck and short neck)

16 Darwin s Theory of Natural Selection Number 3: The different traits are passed from parent to offspring (If there are more giraffes with long neck surviving, the percentage of this trait in the population will be higher)

17 Darwin s Theory of Natural Selection Number 4: Individuals with favorable traits are more successful at surviving and reproducing Long neck is a trait that represents an advantage and will help giraffes survive and reproduce

18 Darwin s Theory of Natural Selection Over time, this process can result in populations that are specialized to live in certain environments These populations have traits that will help them survive in the environment better than other populations without the trait this trait will become DOMINANT in the population This process can lead to the appearance of new species

19 Concept Review: Underline in your printout the following terms: - Species - Evolution - Natural Selection - Variation - Adaptation

20 Adaptation any trait (structural or behavioral) that helps an organism survive and reproduce in a particular environment Variation inherited trait that makes an individual different from other members of the same species Variations can be a result of sexual reproduction or mutations. Read handout page 191

21 Vocabulary: **Speciation - is the process of forming a new species through evolution Species a group of organisms with similar characteristics that can reproduce and generate fertile offspring

22 Speciation can happen due to: Geographic Isolation and Changes in the environment read printout page 192

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24 Speciation due to changes in the environment Speciation can happen if there is a change in the environment. Organisms better equipped to the new conditions will survive, others will disappear. Survivors will reproduce, increasing the presence of the favorable trait in the population and can also suffer mutations generating new species, over time

25 Adaptive Radiation: During his trip to South America, Darwin observed a process called Adaptive Radiation, due to geographical isolation **Adaptive Radiation is the production of several species from one ancestral species Case of the finches in the Galapagos Islands Read handout page 190

26 Ancestral finch The ancestral finch migrated from the mainland to nearby islands and had to adapt to survive. The type of beak that helped the bird survive in a certain area, is the trait that will remain in the population.

27 Section 3 in the textbook: Environmental Impact over Time Factors in the environment that will affect entire populations over time The factors can be: Non-living and Living

28 *Nonliving = ABIOTIC *Amount of water *Temperature *Food availability *Air pollution *Type of soil for plants *Light *Availability of space to live

29 *Living = BIOTIC *The presence of predators *The presence of other species that will compete for the space, food, water *For Plants the presence of species that will compete for light

30 **Mutation Is a change in the DNA resulting in new alleles and in variations in traits A mutation can be the result of exposure to chemicals, radiation, or mistakes during the DNA replication A mutation can be good, bad or neutral for the population

31 **Mutation The variations that results in favorable traits for the species tend to remain in the population and be passed to other generations. The variations that do not help an organism survive and reproduce tend to disappear from the population.

32 **Selective Breeding Artificial process of natural selection Selective breeding is the process by which humans breed animals and plants to develop an offspring that will possess desirable traits 1) Breeders observe which traits are desirable in a certain population 2) Breeders cross animals or plants that show the desirable traits to obtain offspring that have that certain trait EX: Animals faster or stronger Plants more resistant to illnesses, parasites or cold.

33 **Extinction of Species Extinction occurs when the last individual of a species dies. Reasons: 1)**Overharvesting, Hunting (reducing natural stocks) 2)Pollution and habitat destruction 3)Introduction of new species (such as new predators and food competitors that will affect the ecological balance to the community of a certain area)

34 ** Diversity - is the variability of traits among all living organisms ** Environment - Everything that surrounds an organism and can affect its development and survival. Physical environment non living - abiotic Biological environment living biotic Examples can be found in pages 49 and 50 of the textbook