Paradigms & Darwin's Theory
1) ________________ is the change that takes place in a populations gene frequencies. It is the process by which modern organisms have descended from ancient organisms.
Over the years, science and other truth-finding systems such as religion have clashed. 2) _________________ bases truth on data that are standardized measurements accepted by scientists worldwide. Religion bases truth on beliefs and faith coming from ancient writings, cultural teachings, prayer, and meditation. When people consider where life and the universe came from they generally fit into three paradigms. The 3)______________ _______________ believes that the universe and life were made in special creation events by a supernatural being. A 4)________________ _________________ believes that the laws of the universe were made by the supernatural and that evolution follows those laws in producing new species. A person believing that no supernatural exists and that evolution has occurred would be an 5) _______________ ______________________.
Charles Darwin was the first to publish the idea that 6) _______________ __________________ could account for change in populations to make new species over long expanses of time. He believed the Earth was ancient and that all life descended from a common ancestor. He thought that populations 7)___________________ offspring beyond what can survive. Within that population there is 8) _________________ which are differences in individuals' traits or phenotypes. There is always a 9)_________________ to survive because there are limited resources such as food, water, shelter, mates, and living space. The individuals MOST suited to the environment 10)_________________ because they are the most fit. Survivors are then able to 11) ______________________ and pass their successful genes on to their offspring.
Modern Ideas of Evolution
Today scientists continue to be convinced that Darwin's 5 ideas are true. The process of natural selection has been repeatedly observed in modern populations of organisms. Fossils show that giraffes necks have increased in length by a type of natural selection called 12) ______________ selection over the past several million years. It has been observed in clam populations where predators have eaten only the middle-sized clams leaving the larger and smaller causing 13)____________________ selection. It has been observed that cottontail rabbits tend to be colored very similar to the soil in their habitat by 14) ______________________ selection. For natural selection to take place, there must be 15)___________________ in a population. A population without this is likely to become 16) ____________________ if the environment changes. Variation is increased in populations by three things. First there are 17) _____________________ which are genetic mistakes in DNA and chromosomes. A change in the genotype of an organism's sperm or eggs may result in the change of its offspring's 18)______________________. Over the last billion years, 19)____________________ reproduction has help to cause an "explosion" of variety because offspring are the result of two parents and the genetic material is shuffled during meiosis and gamete production. Before this, organisms only made clones of themselves by 20)_______________________ reproduction. Finally, if new individuals move into the population, this is called 21)_______________________.
Darwin noticed that finches on the Galapagos Islands were different than any species found on the mainland. This resulted from 22) ___________________ _____________________ in which they were cut-off from the mainland populations by the ocean. Finches changed so much that they could no longer get together, mate, and produce fertile offspring, so they had become different 23)__________________. This reproductive 24)___________________ will occur when there are changes in behavior (such as mating at different times), changes in size, changes in color, or changes in structures that no longer allow them to mate.
Rapid 25) __________________ occurs when a population is isolated and many new niches are available. This process is called 26)_____________ ________________. 65 million years ago, the small mammals that survived the large asteroid strike that killed the dinosaurs did this and evolved to fill the many niches left empty.
Sometimes population gene frequencies seem to randomly change by the process called 27)________________ ______________. There is no obvious reason for this. For example, the frequencies of the blue eye allele may be greater than the rest of the US population in a community like Lindsburg, KS where people from Scandinavia have tended to settle in and make their homes.
uranium to lead
Evidences for Evolution
Evidences for evolution of organisms and relationships to common ancestors is scientifically overwhelming. The 28)__________________ record is recorded in the sedimentary rocks showing that species today are different from the species that once lived on the Earth 10,000, a million, 100 million, or a billion years ago. The age of the earth can be estimated using the breakdown of radiactive 29)_____________ to _____________. Earth crust rocks have been dated to over 3.8 billion years, moon rocks up to 4 billion years, and meteorites over 4.5 billion years. 30)___________ breaking down to Argon can be used to date sedimentary fossils over 1 million years old because its crystals are spewed from volcanoes and falls into sediments. 31) _________________ can be used to date organic fossils less than 60,000 years old.
Organisms show relationship to each other by 32) __________________ DNA evidence showing that organisms most closely related to each other have similar sequences of A,C,T, and G in their genes. Organisms show relationship to each other with 33) _________________ organs that have similar structure but different functions. Organisms show relationship to each other by having 34)____________________ organs that seem to be leftovers and have no apparent function. 35) __________________ breeding in animals such as dogs and livestock indicate that the amount of variation needed for evolution of populations does exist in nature. We have been able in a few thousand years to select the wide variety of dogs today from genes that were in wolf populations on 10,000 years ago.