BIO 103 instructions can be found in the introduction to scientific method attachment.
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BIO 103 Chapter 1
Overview
Overview
Zoology and Evolutionary Theory
Biology is the scientific study of life. Zoology, a branch of biology, is the scientific study of animals. One theme in biology is the scientific Theory of Evolution. Evolutionary Theory states that populations genetically change over time. Natural selection is a mechanism that causes or drives evolution. Natural selection is the idea that individuals in a population show differential survival and reproduction due to environmental influences that act on that population. In accordance with natural selection, those individuals that have traits that provide advantages for survival and reproduction will survive the longest and reproduce the most, and therefore contribute more offspring with their traits for future generations. That is what causes a change in the genetics of the population over time (evolution). Remember, according to Evolutionary Theory, the population evolves not the individual.
Charles Robert Darwin and Alfred Russell Wallace are credited with independently developing the Theory of Evolution. Contributing to their ideas of evolutionary change were concepts developed by others. Examples include the idea that fossils were evidence of past life and that the earth was potentially hundreds of millions of years old with processes that have occurred over long periods of geologic time. Some of Darwin’s ideas were also influenced by his time aboard the Beagle. Darwin’s Theory of Evolution is often presented as five major components: perpetual change of the living world, common decent among life, multiplication of species as populations change over time, gradualism relative to changes in species, and natural selection. The scientific discipline must use evidence to support ideas. The following are considered some of the scientific evidences supporting evolution: fossils and the fossil record, comparative morphology including homology (i.e. example of vertebrate limb bones) and adaptive radiation, and DNA. Additionally, although gradualism is considered one of Darwin’s five components of evolution, sometimes evolution can occur more rapidly, relatively speaking for a geologic time scale. Examples may potentially include some insects’ resistances to pesticides, industrial melanism in peppered moths, and antibiotic resistant bacterial strains. Darwin was unable to accurately identify the mechanism for generational inheritance of traits. However, Gregor Mendel’s work provided the genetic basis for the chromosomal theory of inheritance. Microevolution and macroevolution play a role in how a population changes over time. Genetic drift, migration, mutations, and natural selection pressures interact as factors of evolutionary change in allelic frequencies in populations.
Macroevolution and microevolution also affect speciation. Speciation and extinction processes have occurred throughout geologic time. Scientists have identified at least five major mass extinction events throughout earth’s history. The fossil record suggests that adaptive radiation of species that survive mass extinctions is not uncommon. (This will be addressed again in chapter 2.)
Scientific Method
The process of “doing science” as certain requirements, and zoology is a scientific discipline. Sciences must use the scientific method. The steps of the scientific method include an observation, formation of a question from that observation, formation of a hypothesis related to the observation (including a null hypothesis), an experiment to test the hypothesis, and formation of a conclusion based on the data collected from the experiment that will support or negate the hypothesis. Experimental results can then be published in peer reviewed scientific journals. Repeated sampling and testing are important in science, and sometimes hypotheses may eventually lead to scientific theories or laws.
Controlled experiments typically include at least one control group and at least one experimental group. A control group lacks the variable being tested (i.e. lacks the experimental or independent variable). The experimental group has the experimental variable. The dependent variable will be the result measured in the experiment. The experimental data will determine whether or not the hypothesis will be rejected or supported. Sometimes comparative methods are also utilized in science.
Reference: Hickman, C.P. Jr., et al., Animal Diversity
Chapter 1
Science of Zoology and Evolution of animal diversity
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A Legacy of Change
Evolutionary diversification of Hawaiian honeycreepers
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Science of Zoology (1)
Zoology:
The scientific study of animals
Phylogeny or phylogenetic tree:
A diagram depicting the history of animal life
Branches represent evolutionary lineages
Each branching event represents the historical splitting of an ancestral species to form new ones
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Science of Zoology (2)
One major goal of studying animal diversity is to locate the origins of certain key developments such as multicellularity, a coelom, spiral cleavage, vertebrae, and homeothermy
Another goal is to understand historical processes that generate and maintain diverse species and adaptations
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Essential Characteristics of Science
Science is guided by natural law
Science must be explanatory by reference to natural law
The conjectures of science are testable against the observable world
The conclusions of science are tentative and therefore not necessarily the final word
Science is falsifiable
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Scientific Method
Hypothetic-deductive Method:
Scientific process of making a conjecture and then seeking empirical tests that potentially lead to its rejection
One begins this process by generating hypotheses, or potential explanations of a phenomenon of nature
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Hypotheses
Potential answers to questions being asked
Derived from prior observations of nature or from theories derived on such observations
Often constitute general statements about nature that may explain a large number of diverse observations
A scientist must say “If my hypothesis correctly explains past observations, then future observations must match specific expectations.”
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Steps of the Scientific Method
Observation
Question
Hypothesis Formation
Empirical Test
Controlled experiment including at least 2 groups
Test Group and Control Group
Conclusions
Accept or reject your hypothesis
Publication
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Founders of Theory of Evolution by Natural Selection
Charles Robert Darwin and Alfred Russel Wallace were the first to establish evolution as a powerful scientific theory. Darwin and Wallace independently developed the same theory. A letter and essay from Wallace written to Darwin in 1858 spurred Darwin into writing On the Origin of Species, published in 1859.
Source: Thomas Herbert Maguire/National Library of Medicine
©New York Public Library/Science Source
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Pre-Darwinian Evolutionary Ideas
Early Greek philosophers Xenophanes, Empedocles, and Aristotle
Recorded idea that life has a long history of evolutionary change
Recognized fossils as evidence of former life
However, they failed to establish an evolutionary concept that could guide a meaningful study of life’s history
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Lamarckism
Jean Baptiste de Lamarck (1744 to 1829)
Authored 1st complete hypothesis of evolution in 1809
Made convincing case that fossils were remains of extinct animals
Proposed an evolutionary mechanism, inheritance of acquired characteristics
Lamarck’s concept of evolution was transformational
We now reject transformational theories because genetic studies show that traits acquired during an organism’s lifetime are not transmitted to offspring
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Transformational versus Variational
Darwin’s evolutionary theory
Differs from Lamarck’s in being a variational not a transformational theory
According to Darwin, evolutionary change is based in differences that occur among organisms within a population
Evolution occurs at the level of the population, with the frequency of favorable traits increasing over generations
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Uniformitarianism
Charles Lyell (1797 to 1875) – Geologist
Principle of Uniformitarianism
Guides scientific study of the history of nature
Laws of physics and chemistry have not changed throughout earth’s history
Past geological events occurred by natural processes similar to those observed today
Lyell’s studies led him to conclude that the earth’s age must be measured in millions of years
Claims left important marks on Darwin’s evolutionary theory
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Darwin’s Great Voyage of Discovery
Darwin made extensive collections and observations on a 5 year voyage (1831 to 1836) on the H.M.S Beagle
1-‹#›
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Galapagos Islands
The Galapagos Islands viewed from the rim of a volcano, with a giant tortoise in the foreground.
©Cleveland P. Hickman, Jr.
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Down House
Darwin’s study at Down House in Kent, England is preserved today much as it was when Darwin wrote On the Origin of Species.
©Cleveland P. Hickman, Jr.
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Theories of Evolution and Heredity (1)
Ernst Mayr (Harvard University) proposed that Darwinism should be viewed as five major theories:
Perpetual Change
Common Descent
Multiplication of the Species
Gradualism
Natural Selection
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Theories of Evolution and Heredity (2)
Perpetual Change
The living world is neither constant nor perpetually cycling, but is always changing
The varying forms of organisms undergo measurable change across generations throughout time
Documented by the fossil record
Theory upon which the remaining 4 are based
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Theories of Evolution and Heredity (3)
Common Descent
All forms of life propagated from a common ancestor through a branching of lineages
Life’s history has the structure of a branching evolutionary tree, known as a phylogeny
Serves as the basis for our taxonomic classification of animals
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The Tree of Life
An early tree of life drawn in 1874 by the German biologist Ernst Haeckel, who was strongly influenced by Darwin’s theory of common descent. Some hypotheses shown here have been verified, while others have been rejected in favor of other groupings.
Source: Haeckel, Ernst, The Evolution of Man, New York, NY: D. Appleton, 1886.
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Theories of Evolution and Heredity (4)
Multiplication of Species
The evolutionary process produces new species by splitting and transforming older ones
When populations of a species become isolated from each other, the isolated populations undergo separate evolutionary change and can diverge from each other
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Theories of Evolution and Heredity (5)
Gradualism
Large differences in anatomic traits that characterize disparate species originate through the accumulation of many small incremental changes over very long periods of time
This theory opposes the notion that large anatomical differences arise by sudden genetic changes within a generation
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Theories of Evolution and Heredity (6)
Natural Selection
A natural process by which populations accumulate favorable characteristics throughout long periods of evolutionary time
Adaptations are anatomical structures, physiological processes, or behavioral traits that improve an organism’s ability to survive and leave descendants
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Theory of Natural Selection
Darwin developed his theory of natural selection as a series of five observations
He made three inferences based on these observations
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Evolution by Natural Selection
Observation 1
Organisms have great potential fertility, which permits exponential growth of populations. (Source: Thomas Malthus)
Observation 2
Natural populations normally do not increase exponentially but remain fairly constant in size. (Source: Charles Darwin and many others)
Observation 3
Natural resources are limited. (Source: Thomas Malthus)
Inference 1
A struggle for existence occurs among organisms in a population. (Source: Thomas Malthus)
Observation 4
Variation occurs among organisms within populations. (Source: animal breeding and systematics)
Observation 5
Variation is heritable. (Source: animal breeding)
Inference 2
Varying organisms show differential survival and reproduction, favoring advantageous traits (natural selection). (Source: Charles Darwin)
Inference 3
Natural selection, acting over many generations, gradually produces new adaptations and new species. (Source: Charles Darwin)
Source: E. Mayr, One Long Argument, 1991, Harvard University Press, Cambridge, MA.
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A Two-Step Process
Natural selection can be considered a two-step process with a random component and a nonrandom component
Production of variation by mutation is the random part
Differential persistence of adaptations is nonrandom
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Evidence for Perpetual Change
Perpetual Change
Evidenced by the fossil record
Fossil: remnant of past life uncovered from the crust of the earth
Many organisms left no fossils
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Examples of Fossil Material – Crinoids
This example of fossilized material shows stalked crinoids (sea lilies, class Crinoidea, phylum Echinodermata) from Devonian rocks. The fossil record shows that these echinoderms reached their greatest diversity millions of years earlier and began a slow decline to the present.
©Alan Morgan RF
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Examples of Fossil Material – Insect in Amber
This example of fossilized material shows an insect that got stuck in the resin of a tree approximately 25 million years ago, after which the resin hardened into amber.
©McGraw-Hill Education/Carlyn lverson, photographer
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Examples of Fossil Material – Fish
This example of fossilized material shows a fish of the perciform genus Priscacara from rocks of the Green River Formation, Wyoming. Such fish swam here during the Eocene epoch approximately 50 million years ago.
©Alan Morgan RF
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Interpreting the Fossil Record
The fossil record is biased because preservation is selective
Vertebrate skeletons and invertebrates with shells provide more records
Soft-bodied animals leave fossils only in exceptional conditions
Fossils form in stratified layers
New deposits are on top of older material
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Animals of the Cambrian Period
The major body plans of living animals appear rather abruptly in fossils dated approximately 540 million years old, as reconstructed from fossils preserved in the Burgess Shale of British Columbia, Canada.
©Kevin Schafer/Alamy Stock Photo
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Index Fossils
“Index” or “guide” fossils are “indicators” of specific geological periods
Layers often tilt and crack, and can erode or be covered with new deposits
Under heat and pressure, rock becomes metamorphic and fossils are destroyed
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A Fossil Skeleton
Shown here is a fossil skeleton from Dinosaur Provincial Park, Alberta, Canada.
©Cleveland P. Hickman, Jr.
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Inferred Evolutionary Relationships
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Geological Time
Geologists divided Earth’s history into a table of succeeding events based on ordered layers of sedimentary rock
The Law of Stratigraphy
Produces sequence of dates with the oldest layers at the bottom
Radiometric Dating (late 1940s)
Method for determining the absolute age of rocks
Radioactive decay of naturally occurring elements is independent of heat and pressure
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Potassium-Argon Dating
Potassium-40 decays to argon-40 and calcium-40
Half-life of potassium-40 is 1.3 billion years
Half of a sample will be gone at end of 1.3 billion years
Half of the remaining potassium-40 will be gone at end of next 1.3 billion years
Calculating the ratio of remaining potassium-40 to amount originally there provides mathematically close estimate of age of deposit
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Uranium-Lead Dating
One of the most useful radioactive clocks depends on decay of uranium into lead
Can date age of earth
Error is less than 1% over 2 billion years
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Evolutionary Trends
Trends are directional changes in features and diversity of organisms
Fossil record allows observation of evolutionary change over broad periods of time.
Animals species arise and become repeatedly extinct.
Animal species typically survive 1 to 10 million years
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Trends in Horse Evolution
Horse evolution shows clear trend
Change occurred in both features of horses and numbers of species
Trends in fossil diversity are due to different rates of species formation and extinction
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Stratigraphy of Genera of Horses
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Diversity Profile of Animal Groups
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Evidence for Common Descent
Darwin proposed that all plants and animals descended from a common ancestor
Life’s history forms a branching tree called a phylogeny
All forms of life, including extinct branches, connect to this tree
Phylogenetic research is successful at reconstructing the history of life
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Homology
Darwin saw homology as major evidence for common descent
Richard Owen described homology as “the same organ in different organisms under every variety of form and function”
Vertebrate limbs show the same basic structures modified for different functions
Darwin’s central idea that apes and humans have a common ancestor was explained by anatomical homologies
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Homologous Forelimbs
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Public Perception of Common Descent
This 1873 advertisement for Merchant’s Gargling Oil ridicules Darwin’s theory of the common descent of humans and apes, which was widely doubted by the general public during Darwin’s lifetime. Darwin devoted an entire book, The Descent of Man and Selection in Relation to Sex, largely to the idea that humans share common descent with apes and other animals. Darwin built his case mostly on homologies between humans and apes.
Source: Library of Congress Prints and Photographs Division, [LC-USZ62-48534]
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Reconstruction of Phylogeny
The sharing of homologies among species provides evidence for common descent
We can use homologies to reconstruct a branching evolutionary history of life
We illustrate such evidence using a phylogenetic tree
Different groups of species located at the tips of branches contain different combinations of homologies
Branching points show common ancestry
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Phylogeny of Flightless Birds
The tree on the left shows the pattern specified by 15 homologous structures in the skeletons of a group of flightless birds
On the right, the molecular data suggest a different pattern of relationships
Jump to
Phylogeny of Flightless Birds
Long Description
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Ontogeny
Ontogeny is the development of an organism through its entire life
From its origin as a fertilized egg or bud through adulthood to death
Homologous genes may guide developmental differentiation
For example, homeotic genes provide an evolutionary “tool kit” that can be used to construct new body parts by relocating patterns of gene expression to different parts of a developing embryo
Mutations in such genes in fruit flies can cause developmental changes such as legs in place of antennae or an extra pair of wings
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Recapitulation
The false notion of recapitulation, also called the biogenetic law, was proposed by the German zoologist Ernst Haeckel
It stated that each successive stage in an organism’s development represented an adult form present in the evolutionary history
Embryologist K.E. von Baer gave an alternative explanation that early developmental features were simply more widely shared among different animal groups than were later ones
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Comparison of Vertebrate Embryos
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Heterochrony
Evolutionary change in timing of development
Characteristics can be added late in development and features are then moved to an earlier stage
Ontogeny can be shortened or lengthened in evolution
Leads to mosaic of different kinds of developmental evolutionary change in a single lineage
Therefore, cases in which an entire ontogeny recapitulates phylogeny are rare
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Multiplication of Species
A branch point in the evolutionary tree occurs where an ancestral species splits into two different species
Total number of species increases in time
Most species eventually become extinct
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Definition of “Species”
No consensus exists regarding the definition of species
Most biologists would agree on three important criteria for recognizing a species
Members descend from a common ancestral population
Interbreeding occurs within a species but not among different species
Genotype and phenotype within a species is similar
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Reproductive Barriers
Central to forming new species
If diverging populations reunite, before they are isolated, interbreeding maintains one species
Evolution of diverging populations requires they be kept physically separate for a long time
Geographical isolation with gradual divergence provides chance for reproductive barriers to form
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Geographic Isolation
Formation of the Isthmus of Panama separated an ancestral population of the sea urchin Eucidaris into two geographically isolated populations. This lead to evolution of separate Caribbean (E. tribuloides) and Pacific (E. thouarsi) species.
(Bottom) ©Sami Sarkis (5)/Alamy Stock Photo (Top) ©Roberto Nistri/Alamy Stock Photo
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Allopatric Speciation
Allopatric populations occupy separate geographical areas
Cannot interbreed because they are separated, but could do so if barriers were removed
Separated populations evolve independently and adapt to different environments
Eventually they become distinct enough they cannot interbreed when reunited
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Sympatric Speciation
Hypothesis that individuals can speciate while living in different components of the environment
Individuals within a species become specialized for occupying different components of the environment
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Parapatric Speciation
Geographically intermediate between allopatric and sympatric speciation
Two species are parapatric if their geographic ranges are primarily allopatric but make contact along a borderline that neither species successfully crosses
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Adaptive Radiation
Evolution of several ecologically diverse species from a common ancestral species
Galapagos finches clearly illustrate adaptive radiation on an oceanic archipelago
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Speciation in Progress
Populations of Ensatina eschscholtzii form a geographic ring around the Central Valley of California
Adjacent differentiated populations throughout the ring can exchange genes except at the bottom of the ring, where the subspecies E. e. eschscholtzii and E. e. klauberi overlap without interbreeding.
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Tentative Model for Evolution of Darwin’s Finches
This model postulates three steps: (1) immigrant finches from South America reach the Galapagos and colonize an island; (2) after a population becomes established, finches disperse to other islands where they adapt to new conditions and change genetically; (3) after a period of isolation, secondary contact is established between different populations. Different populations would be recognized as different species if they cannot interbreed successfully.
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Adaptive Radiation of Darwin’s Finches
This figure shows the differences in beaks and feeding habitats of 10 contrasting forms of finches from Santa Cruz, one of the Galapagos Islands. All apparently descended from a single common ancestral finch from South America.
Jump to
Adaptive Radiation of Darwin’s Finches
Long Description
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Gradualism
Darwin’s theory of gradualism
Based on accumulation of small changes over time
Agreed with Lyell that past changes do not depend on catastrophic events not seen today
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Evidence for Gradualism
In natural populations
Usually observe small, continuous changes in phenotypes
Under such conditions, major differences among species would require thousands to millions of years
Accumulation of quantitative changes leads to qualitative change
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Punctuated Equilibrium
Phyletic Gradualism
If the rule, we would expect to find in the fossil record a long series of intermediate forms bridging phenotypes of ancestral and descendant populations
Instead, we find discontinuous evolutionary changes observed through geological time
Punctuated Equilibrium
Niles Eldridge and Stephen Jay Gould proposed as an explanation for this discontinuity
Theory that phenotypic evolution is concentrated in brief events of speciation followed by long intervals of morphological evolutionary stasis
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A Gradualist Model
Changes in morphology on this tree are shown as proceeding more or less steadily through geological time (over millions of years). Bifurcations followed by gradual divergence led to speciation.
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A Punctuated Equilibrium Model
This tree shows evolutionary change concentrated in relatively rapid bursts of branching speciation (lateral lines) followed by prolonged periods of little change throughout geological time (millions of years).
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Speciation is Episodic
Punctuated equilibrium predicts that speciation is an episodic event occurring over a period of 10,000 to 100,000 years
Species survive for 5 to 10 million years
Thus a speciation event occurs in a “geological instant”, since speciation may account for less than 1% of species life span
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Natural Selection (1)
Natural selection provides a natural explanation for origins of adaptation
Rapid evolution by natural selection of industrial melanism in the peppered moths of England
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Neo-Darwinism
Darwin did not know the mechanism of inheritance
Saw inheritance as a blending of parental traits
Believed an organism could alter its heredity through use and disuse of parts
August Weismann’s experiments showed an organism could not modify its heredity
Modifications known as neo-Darwinism
Genetic basis of neo-Darwinism eventually became what is now called the chromosomal theory of inheritance
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Modern Darwinism
In the 1930s geneticists reevaluated Darwin’s theory mathematically
Population geneticists: scientists who studied variation in natural populations using statistical methods
A new comprehensive theory emerged that brought together population genetics, paleontology, biogeography, embryology, systematics, and animal behavior
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Population Genetics
Population Genetics studies evolution as change in gene frequencies in populations
Microevolution
Evolutionary changes in frequencies of different allelic forms of genes
Macroevolution
Origins of new structures and designs, trends, mass extinctions, etc.
The synthesis theory combines micro- and macroevolution and expands Darwinian theory
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Microevolution
Genetic variation and change within species
Gene pool
All alleles of all genes that exist in a population
Polymorphism
Different allelic forms of a gene
Allelic frequency
Frequency of a particular allelic form in a population
Since each person carries two alleles, the total numbers of alleles is twice the population size
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Frequencies of Blood-Type B Allele
The blood-type B allele () is more common in eastern Europe than in the west. The allele may have arisen in eastern Europe and gradually diffused westward through genetically continuous populations. This allele has no known selective advantage, and its changing frequency probably represents random genetic drift.
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Genetic Equilibrium
Whether a gene is dominant or recessive does not affect its frequency
Dominant genes do not supplant recessive genes
Hardy-Weinberg equilibrium
In large two-parent populations, genotypic ratios remain in balance unless disturbed
Accounts for the persistence of rare traits caused by recessive alleles
Recessive conditions in humans include albinism and cystic fibrosis
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Genotype Frequency
Genotype frequency can be calculated by expanding the binomial where p and q are allele frequencies
For example, an albino is homozygous recessive
Trait is represented by in the formula:
Albinos occur in one in 20,000 individuals
and
Non-albino, p, is
Carriers would be 2pq
, so one person in 70 is a carrier
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Eliminating Recessive Alleles
Eliminating a “bad” recessive allele is nearly impossible
Selection can only act when it is expressed
Recessive allele will persist through heterozygous carriers
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Nonrandom Mating
If mating is nonrandom, genotypic frequencies deviate from Hardy-Weinberg expectations.
Positive assortative mating
Individuals mate preferentially with others of the same genotype
Matings among homozygous parents generate offspring that are homozygous like themselves
Increases homozygous genotypes, but does not change allelic frequencies
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Inbreeding
Preferential mating among close relatives
Like positive assortative mating, inbreeding increases homozygosity
However, positive assortative mating usually affects one or a few traits
The traits used to select mates
Inbreeding simultaneously affects all variable traits
Greatly increases the chances that rare recessive alleles become homozygous and thereby expressed
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Forces of Evolutionary Change
Population geneticists measure evolutionary change as a change in the frequency of an allele in the gene pool
Force of evolutionary change capable of altering allelic frequencies include:
Recurring mutation
Genetic drift
Migration
Natural Selection
Interactions among these factors
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Recurring Mutation
Ultimate source of variability in all population
Usually requires interaction with one or more of the other factors to cause noteworthy change in allelic frequencies
The total change in allelic frequencies caused by a single mutation in one individual is vanishingly small
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Genetic Drift
Each individual in a population contains at most 2 different alleles at a single locus
Mating pair may have 4 alleles
By chance alone, some of the alleles may not be passed on
Genetic Drift
Chance fluctuation from generation to generation, including loss of alleles
The smaller the population, the greater the effect of drift
Response to change is restricted.
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Population Bottlenecks
A large reduction in the size of the population can lead to a loss of genetic variation
Genetic drift takes on increased prominence in the small population
The loss of variation is proportional to the number of generations that population size remains small before the population expands
A bottleneck associated with the formation of a new geographic population is called a founder effect
May lead to speciation
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Genetic Drift in Small Populations
Cheetahs are an example of a species whose genetic variability has been depleted to very low levels because of small population size in the past.
©Jack Hollingsworth/Getty Images
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Migration
Migration is the movement of individuals from one population to another one prior to mating
Prevents different populations from diverging
If a large species is divided into many small populations genetic drift and selection acting separately in the different populations can produce evolutionary divergence among them
Small amount of migration each generation prevents the different populations from becoming too distinct genetically
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Natural Selection (2)
Changes both allelic frequencies and genotypic frequencies
An organism that possesses a superior combination of traits is favored
Sexual selection
Selection for traits that obtain a mate but not for survival
Environmental change alters selective value of traits
Makes fitness a complex problem
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Types of Natural Selection
Selection acting on quantitative traits produces 3 evolutionary responses
Stabilizing selection selects against extreme phenotypes
Directional selection phenotypic character shifts in one direction
Disruptive selection selects against average phenotypes
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Examples of Types of Selection
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Examples of Types of Selection Long Description
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Interactions of Factors
Subdivision of a species into small populations that exchange migrants promotes rapid evolution
Genetic drift and Selection allow many combinations of many genes to be tested
Migration allows favorable new combinations to spread
Interactions of all factors produce change different from what would result from one alone
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Major Evolutionary Events
Speciation and Extinction Through Geological Time
A species has two possible fates
Become extinct or
Give rise to new species
Speciation and extinction rates vary among species
Lineages with high speciation and low extinction
Produce the greatest diversity
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Species Selection
Differential survival and multiplication of species based on variation among lineages
Species-level properties include mating rituals, social structuring, migration patterns, geographic distribution, etc.
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Mass Extinctions
Periodic events where huge numbers of taxa go extinct
Catastrophic species selection may follow these events
Mass extinctions appear to occur at intervals of 26 million years.
The Permian Extinction (225 million years ago)
Half of the families of shallow water invertebrates and 90% of marine invertebrates disappeared
The Cretaceous Extinction (65 million years ago)
Marked the end of the dinosaurs and many other taxa
Mammals were able to use resources due to dinosaur extinction, resulting in adaptive radiation
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Five Major Mass Extinctions
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Appendix of Image Long Description
Phylogeny of Flightless Birds Long Description
A phylogenetic analysis of molecular data suggests skeletal structures were lost or arose independently. Multiple origins and losses complicate phylogenetic analysis.
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Phylogeny of Flightless Birds
Adaptive Radiation of Darwin’s Finches Long Description
Tree finches that eat fruit or insects have grasping bills, certain insect eaters and cactus eaters have probing bills, including the warbler finch that has a very slender bill. The ground finches are seed eaters and have stronger crushing bills.
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Adaptive Radiation of Darwin’s Finches
Examples of Types of Selection Long Description
An ancestral snail population is shown with a normal distribution in coloration. An example of stabilizing selection would favor medium coloration, with more snails in the center of the distribution and both very light and very dark coloration disappearing from the population. An example of directional selection would be a favoring of very dark snails at the detriment of light coloration. An example of disruptive selection would be increases in both very light and very dark snails, but a decrease in medium colored snails.
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BIO103 Introduction to Scientific Method and
Graphing
Activity
35 points
Due by 11:59 on due date noted on syllabus and D2L
Purpose
· Formulate null and alternative hypotheses
· Determine the appropriate type of graph to be used for different types of data sets
· Graph data
· Make a conclusion concerning the hypotheses
Background
As discussed in chapter 1 in the textbook, scientific disciplines use the scientific method. Hypothesis formation is part of the scientific method. Graphing is also an important component for the presentation of scientific data.
Assignment
· Read the following scenario.
· Then write null and alternative hypotheses comparing the number of flying insects observed on the three different data collection days as a function of temperature. (You may need to research what a ‘null’ and ‘alternative’ hypothesis are and how they are written or see my example that is uploaded by this document.)
· Make a graph comparing the number of flying insects observed on the five different data collection days, as a function of temperature. Graph paper is provided at the end of this packet.
· Make conclusions based on your hypotheses and what you found.
Scenario
An entomologist was curious if temperature affected the number of individuals of flying insects that could be observed. After all, insects are ectotherms. The entomologist collected data for a period of 3 hours on each of five different days. The average temperature for the 3-hour data collection window on the first day was 22°C. On this day, the researcher recorded 11 flying insects. On the second day of data collection, the average temperature during the 3-hour data collection period was 28 °C. On this day, the entomologist observed a total of 36 flying insects. On day 3, the temperature was 26 °C and 29 flying insects were observed. On day 4, the average temperature was 23 °C and 15 flying insects were observed. On day 5, the average temperature was 25 °C and 22 flying insects were observed.
Hypothesis Formation
· A null hypothesis (Ho) is written in a “negative form”. It basically states that there is no difference in the measured result between the groups being tested. The alternate option to the null hypothesis is an alternative hypothesis. An alternative hypothesis (HA) is basically the opposite of the null hypothesis and therefore states that there is a difference in the measurable result between the groups being compared. Remember to include an explanation in your alternative hypothesis, and how you would measure the outcome.
· Statistical analyses are typically used to determine if the null hypothesis will be rejected or accepted.
· Write a clear null hypothesis and alternative hypothesis addressing the possible relationship between the number of flying insects observed for the two data collection days as a function of temperature.
HO:
HA:
· Does the data suggest that the null hypothesis is accepted or rejected? (You do not have to run a statistical analysis.)
Graphing
The type of graph used to present data depends on the type of data depicted on the graph.
After reading the following information about different types of graphs, make a graph for the data provided in this assignment scenario comparing the number of flying insects observed each day.
· Pie charts are used to illustrate the percentages of the total number of measurements that fall into specific categories. They are often used to contrast the percentage of measurements in each category relative to 100%.
· Bar graphs are used to show data measurements for descriptive (qualitative) categories. The bars on the graph are separated by a space between each bar.
· Histograms are similar to bar graphs. However, histograms show quantitative data represented as numerical intervals on the x-axis rather than descriptive categories on the x-axis. The bars representing the plotted data are not separated.
· Line graphs are used to show continuous, quantitative data. For example, data that are recorded continuously over a period of time.
· Components of a graph
· The independent (experimental) variable should be plotted on the x axis and the dependent variable should be plotted on the y axis of the graph. In a controlled experiment, the independent variable is lacking in the control group but present in the experimental group. Independent variables often cause the results of the experiment. A dependent variable is the result being measured in the experiment. Dependent variables are “dependent” on the independent variables.
· A graph should have a title specific to the data represented on the graph, appropriately labeled axes, including units, and if applicable, a legend (key).
Conclusion:
Things to include: errors, what would you do differently, summary of data, what did the graph show, further studies, etc. (Should be 4-5 sentences (at least) discussing the findings.)
Science of Zoology, Evolution, and the Scientific Method
BIO 103: Chapter 1
Objectives
Vocabulary
biology, zoology, evolution, microevolution, macroevolution, natural selection, artificial selection, phylogeny, ontogeny, sorting, scientific method, hypothesis, null hypothesis, controlled experiment, control group, experimental group, experimental (independent) variable, dependent variable, scientific theory, scientific law, experimental method, comparative method, biological species, speciation, fossil, homology, adaptive radiation, speciation, extinction, mass extinction
Objectives
After attending lectures and studying the chapter, the student should be able to:
1. Define zoology and be able to apply the term correctly
2. Provide examples of animal diversity
3. Identify and apply Evolutionary Theory
4. Identify the concepts and provide examples of microevolution and macroevolution
5. Explain natural selection and how it causes evolution
6. Explain artificial selection and how it can cause evolution
7. Explain why evolution occurs at the population level
8. Explain the basic contributions and importance of Lamarck with respect to evolution. Also explain transformational evolution and any potential fallacies with that concept
9. Explain and identify the basic concepts, importance and contributions of Lyell (as related to age of earth)
10. Explain Darwinism and apply the five individual components in Darwin’s Theory of Evolution
11. Explain and identify any current modifications to Darwin’s Theory of Evolution
12. Explain the importance of the Galapagos Islands (i.e. finches) with respect to Darwin’s ideas on natural selection
13. Explain Wallace’s contribution to evolution
14. Explain and apply the five factors or “forces” of evolutionary change: recurring mutation, genetic drift, migration, natural selection, and interactions of these factors
15. Explain a mass extinction and identify the number of mass extinctions thought to have occurred on earth
16. Explain the relationship between speciation and extinction
17. Explain the relationship between mass extinctions and adaptive radiation
18. Explain the relationship between ontogeny and phylogeny
19. Identify and provide examples of homology
20. Identify the evidences of evolution: fossil record, biogeography (adaptive radiation and parallel adaptation, comparative embryology and anatomy (homologous and vestigial structures), comparative molecular biology
21. Explain why the scientific method is used in science.
22. Identify the major steps of the scientific method (in order) and be able to recognize and apply the steps of the scientific method.
1)
Identify the following groups in an experimental design: control group and experimental group
2) Identify controlled variables, experimental variables and dependent variables in an experiment
3) Explain why controlled experiments are so important in science and how field work can impact controlled experiments.
4) Identify and write a hypothesis
5) Identify and formulate a conclusion from experimental data and explain how that conclusion relates to a hypothesis
6) List a scientific theory
7) List a scientific law
8) Explain the difference between a scientific hypothesis, theory, and law
9) Explain why a hypothesis is either supported or disproven, rather than proven or disproven.
10) Explain the difference between qualitative data and quantitative data, including which is more appropriate in science, and recognize examples of each category of data
23. Explain why it is important for science to be dynamic
WILLS 1
SCIENTIFIC METHODS AND GRAPHING ACTIVITY
Susie Wills
BIO 103
Professor Sackuvich
1/30/2022
5 10 15 20 25 30 35 40
0
5
10
15
20
25
30
Graph of Flying Insect over Temperature
flying insects
te
m
pe
ra
tu
re
These should be reversed.
WILLS 2
Null hypothesis: increase in temperature have no effect on the frequency of flying insects
Alternative hypothesis: increase in temperature have effect on the frequency of flying insects
A hypothesis is a statement that explains the prediction and reasoning of your research and education
guess about how scientific experiment will end
Null hypothesis suggests that there is no relationship between variables and is abbreviated as H0
Alternative hypothesis suggests that what is opposite of the null hypothesis, and is abbreviated as H1
According to the hypothesis it is true that the increase in temperature increase the number of flying
insects. This is because, when the temperature is 220 the number of insects flying is 11, but when the
temperature increases the number of flying insects increase also, until the last temperature, which is 280 to
flying insect number of 36.
The reason of increase in temperature causes increase in flying insect is because, insects are cold
blooded, and their metabolism and activity is very greatly influenced by the temperature of their bodies, when
temperature is almost entirely dependent to that of the surrounding environment. The lower temperature inhibits
the activity of the insects, and high temperature usually stimulates the animal. This explains the results
You should use headings or label this. I’m not sure what is what here.
WILLS 3
Work Citation
Adams. H, (2021). Null Hypothesis.
Bellhouse. P (2001). Statisticians of the centuries.
Kendra c,(2020). Hypothesis for Scientific Research.
Raymond. H, (September 2013). Values are not Error Probabilities
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