NCEA Level 3 Biology Achievement Standard 3.5 ‘Describe processes and patterns of evolution by; Discussing ways in which speciation occurs (sympatric and allopatric )
“Father of Evolution”
Maori of human beings and other living things on earth. Cultures, groups of people and individuals have various ideas about how life, earth and humans came about and what it means.
Have the story that Papa, the earth goddess and Rangi the god of the sky, where joined so tightly that no light could come into the world and their children could not escape from between them. Tane, managed to separate them, which allowed light into the world meaning plants could grow and animals survive.
The of human beings and other living things on earth. Cultures, groups of people and individuals have various ideas about how life, earth and humans came about and what it means.Boshongo Tribe
This is a tribe in central Africa. They believed that in the beginning there was only darkness, water and the god Bumba. One day Bumba had a bad stomach ache and vomited up the sun, moon, stars, animals and finally man.
Christian Story of human beings and other living things on earth. Cultures, groups of people and individuals have various ideas about how life, earth and humans came about and what it means.
God made the world in 6 days and rested on the seventh. This comes from the old Testament and has been passed on through generations.
Thoughts from Scientists of human beings and other living things on earth. Cultures, groups of people and individuals have various ideas about how life, earth and humans came about and what it means.
1. Organisms differ; variation is inherited
2. Organisms produce more offspring than survive
3. Organisms compete for resources
4. Organisms with advantages survive to pass those advantages to their children
5. Species alive today are descended with modifications from common ancestors
Fossil Record provides evidence that living things have evolved
Fossils show the history of life on earth and how different groups of organisms have changed over time
Australopithecus Homo erectus Homo sapien
Similar animals in different locations were the product of different lines of descent
Geographic distribution- the distribution of related species, especially on isolated islands, provides evidence of how new species have evolved.
Homologous Body Structures
e.g. Wing of bat, human arm, leg of turtle
e.g. Appendix, horse chestnut, dog claw…
Similarities in Embryology
NZ Fur Seal (Arctocephalus forsteri)
Divergent Evolution organisms descended from ancient ones
Adaptive radiation organisms descended from ancient ones
Blue-black grassquit finch (seed eating ground finch) organisms descended from ancient ones
from South American mainland
The most famous example of adaptive radiation. organisms descended from ancient ones
http://home.earthlink.net/~snailstales/parallelism.JPG organisms descended from ancient ones
Which one’s which?!!
Punctuated equilibrium: organisms descended from ancient onesevolutionary model in which there is long periods of little change in the species punctuated by short bursts of rapid change most often associated with speciation. Ancestor is still present.
Gradualism: evolutionary model for the rate of evolution where the accumulation of changes resulting in speciation occurs slowly and steadily over millions of years. Ancestor is extinct.
(Phenotype is the expression of the coding- genotype, that we usually see)
1. Present day species have evolved from ancestral forms.
2. Organisms produce more offspring than survive. The offspring compete for food and other essentials for survival.
3. Offspring produce by sexual reproduction will show variation; some characteristics that are more suited to their environment than others.
4. Those individuals of a species with favourable characteristics will survive longer and produce more offspring to pass their favourable characteristics on. Those with unfavourable characteristics will not survive as long or reproduce as frequently. This is called ‘survival of the fittest’.
5. Successive generations will become modified over time, particularly if their environment is changing. Gradually the species will change sufficiently to be recognised as a new species.
Adaptation and natural selection by genotype
In all populations there is a large range of phenotypes that usually fall into the normal bell-shaped pattern of distribution.
Variation is caused by
This is when a population becomes separated by a geological barrier.
This eventually leads to different species with completely different gene pools.
Mountains selection to work against.
Canyons and Deserts
Black Robin selection to work against.
Chatham Island Robin
South Island Robin
American Squirrels selection to work against.
Once the population has been separated by geological barriers, they become so different they are not able to interbreed if the physical barrier separating them were removed. There can be no exchange between their gene pools because of reproductive isolating mechanisms.
Prezygotic then the isolating mechanism must be biological. There are two types of biological mechanisms Mechanisms
Postzygotic then the isolating mechanism must be biological. There are two types of biological mechanisms Mechanisms
Describe the Key ideas that underpin the theory of evolution: genetic variation, competition, differential reproductive success (natural selection)
http://www.offthemarkcartoons.com/cartoons/1999-10-05.gif evolution: genetic variation, competition, differential reproductive success (natural selection)
Figure 7.7 Concept of genetic drift. In a large population with random mating, large fluctuations of gene frequency are unlikely. In a small population, however, gene frequency can change dramatically from one generation to the next, if, for example, only the AA individuals participate in mating by chance.
Genetic drift neck effect.
This is a change in the allele frequencies of a population as a result of chance processes. This has a big influence in small populations where chance alone may play a considerable role.
Two examples of these chance events are the genetic bottleneck and similarly the Founders effect.
1. Double disaster: The island fruit flies are now geographically isolated from their mainland relatives, but only a few larvae have survived the harrowing journey to end up colonizing the island.
2. Rare genes survive: These few survivors just by chance carry some genes that are rare in the mainland population. One of these rare genes happens to cause a slight variation in the mating dance. Another causes a slight difference in the shape of male genitalia. This is an example of the founder effect.
3. Gene frequencies drift: These small differences, which are rare on the mainland, drift to fixation in the small population on the island over the course of a few generations (i.e., the entire island population ends up having these genes).
www.brooklyn.cuny.edu/.../C21_Bottleneck_2.GIF as a result of small group of founders become isolated from the main population.
Bottleneck effect- Period in which a population becomes temporarily reduced to very small numbers, as a result of which its genetic diversity becomes reduced.
An example of a bottleneck:Northern elephant seals have reduced genetic variation probably because of a population bottleneck humans inflicted on them in the 1890s. Hunting reduced their population size to as few as 20 individuals at the end of the 19th century. Their population has since rebounded to over 30,000—but their genes still carry the marks of this bottleneck: they have much less genetic variation than a population of southern elephant seals that was not so intensely hunted.
http:// as a result of small group of founders become isolated from the main population.nationalzoo.si.edu/Animals/ZooAnimalWallpaper/images/cheetah.jpg
http://www.biology-online.org/images/darwin_finches.jpg as a result of small group of founders become isolated from the main population.
Macro and Micro evolution as a result of small group of founders become isolated from the main population.
A change in the frequencies of certain alleles in a gene pool over successive generations is called microevolution. This term is often used to refer to small, reversible changes within a species.
Large, irreversible changes in a gene pool, such as those involved in the formation of a new species (speciation) or in adaptive radiation is called macroevolution.
Agents that change gene frequencies as a result of small group of founders become isolated from the main population.
The following agents change the frequency of genes in the gene pool of the population:
Non-random mating as a result of small group of founders become isolated from the main population.
This occurs when a certain phenotype is preferred over others. This eventually leads to the decrease in the un-preferred phenotypes.
Mutation as a result of small group of founders become isolated from the main population.
Mutation is the ultimate source of variation that can change the equilibrium within a population.
Geneflow as a result of small group of founders become isolated from the main population.
This is caused by the immigration and emigration of individuals into a population. This increases and decreased the genes within the population.
Natural Selection as a result of small group of founders become isolated from the main population.
Some combinations of alleles are more likely to help survival and reproduction than others. This means that the frequency of these alleles in the population will increase. This is what is meant by the ‘survival of the fittest’.
Different forces such as predation, competition, disease, lack of food, water, climate etc. act on the different phenotypes causing the normal distribution to change.
Stabilising selection: is when the average is favoured over the other extremes.
Directional selection- favours one extreme over the average or the other extremes.
Disruptive selection- favours both extremes over the average.
Dark forms of the British peppered moth (Biston betularia), as well as many other species of moth, became common in the middle of the 19th century near centres of industrial pollution. Soot coated the trunks and branches of trees, and killed lichens. In the photos, a pale form (typica) and a dark form (carbonaria) rest side-by-side on an unpolluted lichen covered trunk in Dorset (above), and a soot-covered trunk near Birmingham. (From HBD Kettlewell, 1956, Heredity 10: 300).