Evolution Exam 1

What role did the fossil record played in the development of the concept of evolution?

It triggered other naturalists to begin to realize and eplorer the fact that remains of animals and plants were sometimes preserved and transformed into stone which provided a record of life's history

Compare and contrast Darwin's and Lamarck's hypotheses about evolution.

Lamarck thought that organisms changed out of need and after a change in the environment and Darwin thought organisms changed by chance when they were born and before there was a change in the environment.

Stromatolites

Layered rock that results from the activities of prokaryotes that bind thin films of sediment together.

How likely are point mutations?

Point mutations rarely cause a huge change in the underlying organism, which is fortunate as they are by far the most common type of mutation.

Explain the difference between protein coding and non-coding segments of DNA.

Protein-coding: a gene whose sequence codes for a protein non-coding: the vast bulk of non-coding DNA does not have an obvious function, but regulates how genes are expressed

What is the difference between proximate and ultimate causation? Provide examples of each.

Proximate: focus on a mechanistic understanding of how something happened (mechanics of behavior) Ultimate: focus on historical perspectives of how something came to be (advantages of behavior)

Describe how radioactive elements are used to determine the age of rocks.

Radiometric dating is a method of dating geological or archeological specimens by determining the relative proportions of particular radioactive isotopes present in a sample

Describe the hypothetic-deductive method. Explain the potential outcomes.

Scientific inquiry proceeds by formulating a hypothesis that can b falsifiable, using a test on observable data where the outcome is not yet known 1. reject hypothesis 2. modify hypothesis 3. provisionally accept hypothesis

Discuss the complex relationship between genotypes and phenotypes. How are they related?

The sum of an organism's observable characteristics is their phenotype. A key difference between phenotype and genotype is that, whilst genotype is inherited from an organism's parents, the phenotype is not. Whilst a phenotype is influenced the genotype, genotype does not equal phenotype.

In addition to finding fossils in sediments formed by freshwater, what data is also consistent with whales first evolving in freshwater?

Their fossils were found in freshwater deposits, but their teeth also did not show signs of life in saltwater

Jean-Baptiste Lamarck

This man developed the first cohesive theory of evolution after his studies of biology -adaptation occurs through inheritance of acquired changes

Compare and contrast the events that occur in transcription and translation.

Transcription: -produces mRNA -facilitated by RNA polymerase -starts at gene promoter region Translation: -produces proteins -is facilitated by ribosomes and tRNA -reads codons

Tiktaalik

"missing link" thought to be a transitional form between fish and tetrapods

Identify characteristics of viruses that make them difficult to control.

(mutations may be harmful or beneficial) -viral strains with beneficial mutations increase in frequency through natural selection -viral strain is no longer recognized by the immune system which leads to higher production

George Cuvier (1769-1832)

- Recognized that fossils resembled, but were not exactly the same as modern species - Demonstrated that extinction occurred - Was a *Catastrophist:* fossils succession was caused by catastrophic processes

Explain how Darwin's observations of nature lead to the inferences he developed regarding natural selection.

-Darwin was convinced that species changed over time after seeing population of finches on the Galapagos Islands. -Observation 1 -> Members of a population often vary greatly in their traits. Observation 2 -> Traits are inherited from parents to offspring. Observation 3 -> All species are capable of producing more offspring than their environments can support. Inference 1 -> Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment leave more offspring than other individuals. Inference 2 -> This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in a population over time.

Mary Anning

-Discovered several species of extinct marine reptiles -amateur fossil collector who pioneered the discovery of time with her collection; very important in the field of geology. her contributions were slighted and her work was not respected because she was a woman. she discovered the first complete skeleton of an ichthyosaur

Nicholas Steno (1638-1686)

-First to recognize fossils were remains of organisms -father of stratigraphy (study of the layering in rocks)

How did Shubin find Tiktaalik? What does his work teach us about using phylogenies and the fossil record to test evolutionary hypotheses?

-Found in Canada -Tiktaalik is a 375 million year old fishlike tetrapod ancestor. It was an exciting discovery because its anatomy is evidence that the basic form of the human hand emerged from the fins of ancient fish.

Charles Darwin (1800s)

-HMS beagle -five years voyage as naturalist -developed same ideas as wallace -influenced by malthus -Wrote The Origin of Species -the first to propose a correct mechanism for how life changed over time -natural selection

How many times has life evolved on Earth? Describe evidence that supports the inference that all currently forms of life on Earth share a common ancestor.

-Life may have originated more than once -scientists have found biomarkers in ancient zicrons that formed 4.1 bya -the oldest fossils of microbes are up to 3.8 byo

What factors influence the probability that a species will leave a fossil record? Why is the fossil record incomplete for many taxa?

-When an organism is buried quickly, there is less decay and the better the chance for it to be preserved. The hard parts of organisms, such as bones, shells, and teeth have a better chance of becoming fossils than do softer parts. One reason for this is that scavengers generally do not eat these parts. -Most organisms decomposed or were eaten by scavengers after death. Many species lacked hard parts, which are much more likely to fossilize. Some rocks and the fossils they contained have eroded and disappeared.

What are point mutations? How common are point mutations, relative to other types of mutations?

-a single base pair is altered -very common

George Buffon (1707-1788)

-earth formed according to laws of physics and chemistry -life emerged as distinct types but changed when the environment changed

Describe how the fossil record can be used to learn about the evolution of morphology, behavior, and development of extinct species.

-fossils suggest nesting behavior seen in living birds first evolved over 150 mya in feathered dinosaurs -identification of melanosomes in anchiornis suggests they had brightly colored plumage -Fossils are important evidence for evolution because they show that life on earth was once different from life found on earth today.

What are the closest living terrestrial relatives of whales? How was this demonstrated?

-hippos -in the 90's, scientists began comparing DNA from cetaceans and other mammals -the DNA from whales is most closely related to a group called artiodactyls (hippos, camels, cows) -whales and hippos share a more common recent ancestor with each other than with other species of land mammals

What is a genome? What are the characteristics of the human genome?

-includes ALL of the hereditary information of an organism -23 chromosomes (~3,200,000,000 bp) -diploid (containing 2 homologous copies of each chromosome

Explain how the bones of the middle ear can be used to trace the evolution of mammals.

-mammalian ear bones are homologous to to synapsid jaw bones -Over the course of the evolution of mammals, one lower and one upper jaw bone lost their purpose in the jaw joint and were put to new use in the middle ear, connecting to the existing stapes bone and forming a chain of three bones which transmit sounds more efficiently

Define uniformitarianism. How did this concept influence Darwin's thinking about evolution?

-observable processes produce small changes that accumulate over time (The Earth was old) -Darwin thought that a similar process in nature could explain how organisms change over time.

How old did Kelvin say the Earth was and why? Why were his estimates incorrect? How old is the Earth according to radiometric dating?

-the planet was less than 20 million years old -he argued that the earth's rate of heat lost showed that the age of the planet was less than 20 myo -estimates were based on flawed assumptions about the structure of the planet's interior -4.568 byo

What are the two major evolutionary hypotheses that Darwin proposed in The Origin of Species?

1. organisms have descended with modification, from common ancestors 2. the chief cause of modification is natural selection acting on hereditary variation

Identify the components of phylogenies and what they represent.

A VISUAL REPRESENTATION OF THE EVOLUTIONARY HISTORY OF A SPECIES Branches: are lineages evolving through time Nodes: are branch points in a phylogeny where lineages split Internal Node: rerepresent ancestral species Root/Rootnode: represents the most recent common ancestor of all species in the tree Tips/terminal nodes: represent the lineages being compared

synonymous mutation (silent mutation)

A base pair substitution that does not change the amino acid that a codon normally produces

missense mutation

A base-pair substitution that results in a codon that codes for a different amino acid.

silent mutation

A mutation that changes a single nucleotide, but does not change the amino acid created.

non-synonymous mutation

A point mutation (nucleotide substitution) that causes an amino acid replacement.

Burgess Shale

A sedimentary rock formation in British Columbia, Canada, that preserves a remarkable sampling of marine life during the initial diversification of animals.

homoplasy

A similar (analogous) structure or molecular sequence that has evolved independently in two species.

What is the difference between Synapomorphy and Homoplasy?

A synapomorphy implies that a homologous trait, one that is the same in both organisms, was inherited from the same ancestor. A homoplasy, on the other hand, is simply a trait that appeared in different organisms. ... Wings in birds and insects are a homoplasy, a trait which is similar but not from a common ancestor.

We know more about the K-T extinction event (the mass extinction event that causes most species of dinosaurs to go extinct) than the other mass extinction events in Earth's history. What is the leading hypothesis promoted to explain it? What evidence is there to support these claims?

Abundant fossil bones, teeth, trackways, and other hard evidence have revealed that Earth was the domain of the dinosaurs for at least 230 million years. But so far, not a single trace of dinosaur remains has been found in rocks younger than about 66 million years. + climate and geolological changes induced this extinction. HYpothesis: giant astroid and a large volcanic eruption

Cladistics

An approach to systematics in which organisms are placed into groups called clades based primarily on common descent.

Phenotype

An organism's physical appearance, or visible traits.

Autosomes

Any chromosome that is not a sex chromosome

What are the three major branches of life?

Archaea, bacteria, and Eukaryotes

When did feathers evolve? Did they evolve to assist in powered fight?

Based on fossil evidence, we know that the first non-avian theropods with simple, single-filament feathers lived about 190 million years ago, and that non-avian theropods with feathers having a complex branching structure like those of present-day birds (pennaceous feathers) existed about 135 million years ago -insulation or sexual display

Alfred Russel Wallace (1823-1913)

British naturalist who developed the theory of evolution by natural selection in parallel with Charles Darwin

derived character

Characteristic that appears in recent parts of a lineage, but not in its older members

sex chromosomes

Chromosomes that determine the sex of an individual (X and Y)

How far back can we find evidence for life? How far back can we go and still find definitive evidence of life? What is that evidence?

Earliest fossils: Bacteria -3.45 byo stomatolites -2.6 byo cyanobacteria Earliest Fossils:Archaea -3.5 byo methane biomarkers Earliest fossils: Eukarya -2.1 byo -1.8 byo

Ediacaran fauna

Earliest generally accepted animal fossils, dating from about 575 million years ago

Carolus Linnaeus (1707-1778)

specialized in taxonomy, developed a binomial system of naming organisms according to genus and species that is still used today. Also adopted a system for grouping similar species into a hierarchy of increasingly general categories.

Systematics

study of the diversity of life and the evolutionary relationships between organisms

What is the relationship between genome size, gene number, and mutation rate?

that the mutation rate within a genome and its size are inversely correlated. This rule has been found to be approximately correct for simple genomes such as those in DNA viruses and unicellular organisms.

Nodes are branch points in a phylogeny where lineages split.. at each internal node, lies ___

the most common ancestor of all the lineages descended from that branch point

Paleozoic Era

the oldest era (542-251 mya) - immediately after Precambrian; organisms developed hard parts and plants became widespread

Paleontology

the scientific study of fossils

What is the genetic code?

the set of rules that determines how a nucleotide sequence is converted into the amino acid sequence of a protein

horizontal gene transfer (HGT)

transfer of genetic material from one organism to another

Tetrapods

vertebrate animals having four feet, legs or leglike appendages

How old is the universe, the solar system and the Earth?

~14 byo (Big Bang) ~4.6 byo 4.568 byo

Using evidence from fossil whales, demonstrate how lineages change through time.

Whales share similarities with mammals and in 1859 Charles Darwin proposed that cetaceans descended from mammals that lived on land and their lineage evolved into a marine mammal through a process called natural selection

ancestral character

a character that evolved in a common ancestor of both groups

polyphyletic group

a group that does not include the most recent common ancestor (not a legitimate group)

outgroup

a group that one does not belong to or identify with

Describe the organization of DNA within a human cell.

a linear molecule made up of two strands of nucleotides that wind together each nucleotide contains a sugar and a base --> a base: Adenine, Cytosine, Guanine, Thymine

Exaption

a trait co-opted by natural selection for a role incidental to the trait's origin

How big is the human genome?

about 3 billion base pairs

William Smith (1769-1839)

among the first to realize that the relative ages of rocks could be determined by studying the particular assemblage of fossils that occur within different rock layers (Faunal Succession). This also allowed him to correlate rocks from distant locations, helping him produce the world's first thorough geological map.

Define biological evolution

any change in the inherited traits of a population that occurs from one generation to the next

amino acids

building blocks of proteins

Divergence

can occur such that closely related species can no longer resemble each other because they have adapted to different ecological conditions

paraphyletic clade

consists of an ancestral species and some, but not all, of the descendants

Charles Lyell

effectively discredited the long-standing view that the earth's surface had been formed by short-lived cataclysms, such as biblical floods and earthquakes-his principle: uniformitarianism: same geological processes that are at work today slowly formed the earth's surface over an immensely long time

Cenozoic Era

era that began about 66 million years ago, known as the "Age of Mammals"

a hypothesis that has acquired so much supporting evidence that we act as if it is true

fact

James Hutton

father of modern geology observable processes produce small changes that accumulate over time (uniformitarianism)

Describe three lines of evidence that scientists use for understanding evolution.

fossil evidence, biogeographical evidence, and anatomical evidence

Genotype

genetic makeup of an organism

Define taxa

group or level of organization into which organisms are classified

monophyletic group

group that consists of a single ancestral species and all its descendants and excludes any organisms that are not descended from that common ancestor

Synapsids

have single opening in the outer layer of the skull just behind eye socket and give rise to mammals and thier extinct relatives

frameshift mutation

mutation that involves the insertion or deletion of a nucleotide in the DNA sequence

Unifrmitarianism

observable natural processes responsible for events in the past

Allele

one of a number of different forms of a gene

Describe the structure of proteins.

proteins are formed by strands of amino acids. amino acids have an amine group, acid group and a side chain. amines can bond to acids

What does Tiktaalik teach us about the order in which these traits evolved leading up to tetrapods?

provides clues about a key transition in the history of life. Now extinct, this organism was a close relative of one our own ancestors — the first vertebrate to evolve four limbs and crawl out onto dry land. Tiktaalik, for example, had fins with thin ray bones, scales, and gills like most fish.

evolutionary reversal

reversion back to ancestral character state

a comprehensive, coherent body of interconnected statements, based on reasoning and evidence, that explain some aspect of nature

scientific theory

Synapomorphy

shared derived characteristics EX: The Monotremes, such as the platypus, still lay eggs but they feed their young milk which they excrete from glands. While their other features might make them seem more like birds or reptiles, milk production is a clear synapomorphy with the other mammals.

Homology

similarity resulting from common ancestry

What is a Lagerstätten? Why are the particularly valuable resources?

sites with an abundant supply of unusually well-preserved fossils from the same period of time

What type of mutation can cause frameshifts? What are the consequences of frameshifts?

Insertion or deletions; This can result in the incorporation of many incorrect amino acids into the protein.

What adaptations were required before vertebrates could move onto land?

Clearly, the vertebrates that first invaded the land possessed a series of pre-adaptations, such as air-breathing and limb-based locomotion, that allowed them to move about effectively on land; however, other behaviors such as reproduction and swallowing likely tied these vertebrates to the water. Must be able to withstand the effects of gravity. Must be able to breathe air. Must minimize water loss (desiccation) Must adjust its senses so that they are suited for air instead of water

Examples of proximate vs ultimate

Example:

Discuss how a phylogenetic approach can be used to explore the role of feathers in dinosaur evolution.

Feathers originally evolved in other functions. Traits often change their function over the course of evolution. Phylogenies allow us to track this transformation by linking homologous traits in different taxa. The phylogeny of theropods shows that feathers gradually evolved into the complex structure in birds over millions of years. Early theropods obviously couldn't have used feathers for flight, because their arms were too short and their feathers couldn't lift them off the ground. But they used them for things like recognizing other members of their species, to attract mates, insulation, incubating eggs, and protection.

Demonstrate how scientists can determine the timing of branching events using fossils.

Fossils enable us to determine some aspects of the timing of evolution. To constrain the range of time in which branches diverged, we can determine how fossil taxa are related to extant ones. However, while we know the minimum possible age, one fossil alone can't tell us what the maximum age is. We also can't determine from one fossil how old a common ancestor is. With the advent of molecular phylogenetics-using DNA instead of morphological traits to reconstruct phylogenies-scientists have another way to constrain the timing of evolution.

What does monophyly for a taxon imply?

In cladistics for a group of organisms, monophyly is the condition of being monophyletic—that is, a group of taxa that share a common ancestry. The resulting group is called a monophyletic group or clade, composed only of a common ancestor (or more precisely an ancestral population) and its lineal descendants.

What is the difference between how scientists use the word theory and how it is used in everyday language?

In everyday language a theory means a hunch or speculation. In science, the word theory refers to a comprehensive explanation of an important feature of nature supported by facts gathered over time.

Taxonomy

The science of classifying organisms

Explain how phylogenies can be used to develop hypotheses about the evolution of tetrapods.

Scientists predicted where transitional fossils would be found 1. 380-350 mya 2. in coastal wetland or river deltas The tetrapod body plan evolved gradually over 40 million years

homologous traits

Similar in structure, but does not have same function. They are inherited from a common ancestor.

Differentiate between somatic mutations and germ-line mutations and their role in variation within a population.

Somatic: affect all the cells in the body and are NOT heritable Germ-line mutation: affect gametes and are heritable (can be passed to offspring and are sex related)

Homoplasy and Convergent Evolution

Species in similar environments may be selected for similar traits, even without a common ancestor (Convergent evolution creates analogous structures that have similar form or function but were not present in the last common ancestor of those groups. The cladistic term for the same phenomenon is homoplasy. ... The opposite of convergence is divergent evolution, where related species evolve different traits.)

alternative splicing

Splicing of introns in a pre-mRNA that occurs in different ways, leading to different mRNAs that code for different proteins or protein isoforms. Increases the diversity of proteins.

Give three examples of homologies, and explain why they are homologies.

The arm of a human, the wing of a bird or a bat, the leg of a dog and the flipper of a dolphin or whale are homologous structures. They are different and have a different purpose, but they are similar and share common traits.

What happened at the beginning of the Cambrian? Why is this event so important to paleontologists?

The beginning of the Cambrian Period is marked by the evolution of hard body parts such as calcium carbonate shells. These body parts fossilize more easily than soft tissues, and thus the fossil record becomes much more complete after their appearance. The Cambrian Explosion saw an incredible diversity of life emerge, including many major animal groups alive today. Among them were the chordates, to which vertebrates (animals with backbones) such as humans belong.

an informed conjecture or statement of what might be true

hypothesis

Mesozoic Era

middle life (245-144 million years ago); rise of mammals and dinosaurs; the rise of birds; extinction of dinosaurs, rise of flowering plants (age of reptiles)

Teleosts

modern bony fishes