Exam 1 Review Questions

BISC 104 Exam 1 Review Questions Chapter 12 What is evolution? Change over time, change in a population over time, descent with modification. - What do we mean by a change in allele frequencies? - What are micro and macro evolution? microevolution - how population change from generation to generation, most often through the process of natural selection Macroevolution - refers to larger changes over a longer time frame, how one population divides into two and how life evolved from a common ancestor to the diversity of species we see today What is the history of evolutionary thought, prior to Darwin? - Be ready to answer questions about Aristotle, Buffon, Lamark and Lyell Aristotle- had students collect living things which he categorized - Saw that there were simpler to more complex forms, but assumed life was static and had originated in its current forms Buffon- saw that different regions with similar environment had different species - He argues that they had descended from common ancestors Lemark - credited with the first hypothesis for how life evolved - Argues (incorrectly) that individuals acquire traits over the course of their lives that are then passed down to their offspring Lyell- was a geologist who used measurement of ongoing process to estimate the ages of preexisting geologic formations - Leading him to the conclusion that the earth is very old Who was Charles Darwin and what led him to his ideas about evolution? Developed his theory of evolution to explain how species evolve and how all life evolved from a common ancestor - On the Galapagos island, he collected specimens of closely related finch species which he hypothesized has all evolved from a mainland species. Darwin hypothesized that species evolved by natural selection How does natural selection occur? The concept of natural selection is based on 3 observations: - Within each population, there is a variation in heritable traits. Every habitat contains limited resources for a population more individuals are born than will survive to reproduce. - What are the observations and inferences? - There will be competition for limited resources. Individuals with more favorable traits will be more likely to obtain resources, survive and reproduce. Populations will change to resemble those better suited individuals. What are adaptations? Inherited traits that confer an advantage and have evolved through natural selection - Be ready to answer questions about how they arise through natural selection What is the Hardy Wienberg Equilibrium Model? A model used to represent a population which is not evolving - Its predictions can then be compared to the existing population to determine the source and direction of change - What do p, q , p2, 2pq and q2 represent in the model? P - frequency of dominant allele Q - frequency of recessive allele p^2 - frequency of DD genotype 2pq- frequency of Dd genotype q^2 - frequency of dd genotype - What does it mean when a population is not at HWE? If the allele frequencies change from the original frequencies after one cycle of random mating, the population is not in HWE and evolution has occurred within the population - What causes populations to deviate from HWE? Populations deviate from HWE if any of the following occur: non-random mating, mutation, immigration/emigration, small populations, natural selection What forms can natural selection take when applied to continuous traits like height? Natural selection on traits determined by multiple genes may take the from of stabilizing selection, directional selection, or disruptive selection - Be ready to answer questions about direction, disruptive and stabilizing selection Directional selection- happens when natural selection favors one extreme and the allele frequencies for the entire set of genes shifts Disruptive selection- occurs when phenotypes at either extreme are favored over intermediate forms. Can contribute to the formation of new species. Stabilizing selection- occurs when an intermediate phenotype is favored. Variation within the population decreases. What is sexual selection? The result of non-random mating. Reproductive success is the ultimate decider of allele frequencies in future generations. If every individual is not equally likely to mate, then the population will evolve to resemble those who are successful.two factors make an individual more likely to succeed than others, which are; access to makes and the choice of mates by others - What are secondary sexual characteristics?\ Differences between the sexes that were not directly associated with reproduction. Examples: antlers on male deer, horns on male sheep. - What is sexual dimorphism? In cases where male and female appear different, that species is considered sexually dimorphic - What happens when males compete for access to females? The male has features that the female lacks, which made their ancestors more likely to mate - What happens when female choose mates based on some trait? The direction of evolution is then dependent on the choosers' preferences Chapter 13 What are fossils? Fossils come from organisms that lived at least 10,000 years ago, and therefore provide us our only direct evidence of organisms that preceded human history - How are they formed? Fossil formation requires mineralization of the fossilized organism and incorporation into the surrounding rock - Why is the fossil record incomplete? The fossil record is incomplete because the vast majority of organism never left any What is relative dating? Using vertical locations of fossils. This vertical location puts their existence in a historical context. Does Not provide the exact timeframe in which they lived. - Where does that information come from? Our knowledge of the ages of the geological structures they are found in, and the location of different fossils in relation to each other. What is absolute dating? (radiometric dating) uses radioactive isotopes of common elements to make precise estimates of when something lived - What are radioactive isotopes and how do we use them? Isotopes are versions of elements with more neutrons than protons. To make precise estimates of when something lived What are plate tectonics? The earth’s continents sit on plates that have moved over the earth’s history, taking their species with them. - How has our knowledge of them contributed to our understanding of life’s history? North America and purpose were once connected and they have species that appear closely related, and fossil evidence of those species' common ancestors are often found in both places. - How is the modern day distribution of marsupials related to plate tectonics? Marsupials dominate Australia today, which disconnected from the other continents early on. There is fossil evidence of a diversity of marsupials in south América as recently as 2 million years ago. What are jj b? Structures that have a common origin. - What are they evidence of? Evidence of shared ancestry. - Be ready to identify some examples EX: the forelimbs of all tetrapods (terrestrial vertebrates) share a common origin but have diversified into different forms (legs, arms, wings) the same bones make up all forelimbs EX2: the flowers of flowering plants all come from an ancestral flower form and have also diversified. All flowers develop from the same type of plant tissues and have common components. What are vestigial structures? Also considered evidence of shared ancestry, occur when a once functional structure persists even after losing its function. - What are they evidence of? Shared ancestry. - Be ready to identify some examples EX: non-functioning eyes are found in a diverse group of animals that live in caves, blind salamanders inherited their eyes from a common ancestor that possessed them. What are analogous structures? Structures which appear similar and may have a similar structure but do not have a common origin. They are typically found in species which occur in similar environments but are not closely related. - What are they evidence of? Convergent evolution through natural selection, because the two organisms possessing them presumably evolved them independently in response to their environment. - Be ready to identify some examples EX: the wings of birds and bats, which look similar and have the same function (flight) but are structured differently and have independent origins. EX2: The legs of insects and tetrapods do similar things, but insect legs are made of exoskeleton while tetrapods have an endoskeleton. Both groups evolved legs as their ancestors moved onto land. How do developmental patterns of different species help us understand their relationship? A lot of evidence of evolutionary relationships comes from the development of organisms. Many organisms that appear very different go through similar sequences of developmental events. - Be ready to answer questions about specific examples. Major differences between the skulls of chimps and humans that appear later in development. They are attributable to different growth rates of different parts of their skull. Bird, mouse and human embryos all look similar at some stage. How has modern biotechnology helped us study evolution? Technological advances over the last several decades have passed to our evidence for evolutionary relationships, while correcting some of our erroneous assumptions that were based on convergent evolution. - Comparing the sequences of DNA (genomoes) and proteins (proteomes) tells us a lot about life's history. More closely related species will have fewer differences in sequences for related proteins. Molecular clocks also provide valuable information. DNA mutates at a predictable rate, so the numbers of differences can be used to tell the length of time since separation.