NCSU Biology 181 Final Exam

The seven characteristics of life include: responsiveness to the environment; growth and change; ability to reproduce; have a metabolism and breathe; maintain homeostasis; being made of cells; passing traits onto offspring

-is a scientific methodology which emphasizes analysis of large volumes of experimental data with the goal of finding new patterns or correlations, leading to hypothesis formation and other scientific methodologies

-Collect and analyze data, not hypothesis driven.

-Ex: Testing drugs to determine usefulness in various diseases

- Discovery based science is results that have been found from actually having carried out the experiment or investigation.

-Hypothesis based science is an educated guess by a scientist of what will happen during an experiment or investigation. (Prove long before the discovery)

-Scientific Method: Series of steps used to answer questions logically

-Hypothesis driven

-Usually tested with a controlled experiment

-Results should be repeatable

1. Make observations - question things!

2. Formulate a hypothesis

3. Design and perform a controlled experiment

4. Analyze Results

5. Draw conclusions (accept or reject hypothesis), present results

-Question: Does the color of light affect plant growth?

-Conditional Statement: The color of light may affect plant growth.

-If . . . then Statement: If plant growth is related to the color of light, then some colors of light will produce greater growth than others

-Hypotheses must state a relationship in order to not just be a prediction

-Hypotheses must also be falsifiable

-The real strength of a hypothesis is not evidence in favor of it, but situations which could falsify it, not doing so!

-Both a control and a variable

-Control: Used as a baseline measure, identical to variable group except does NOT receive treatment in question

-Variable: What is altered, measured, or manipulated in an experiment

In an experiment, the independent variable is the variable that is varied or manipulated by the researcher, and the dependent variable is the response that is measured. An independent variable is the presumed cause, whereas the dependent variable is the presumed effect.

-Can be more than one dependent variable but only one independent variable per experiment

-Could not control all variables

Deductive reasoning is a logical process in which a conclusion is based on the concordance of multiple premises that are generally assumed to be true. Deductive reasoning is sometimes referred to as top-down logic. Its counterpart, inductive reasoning, is sometimes referred to as bottom-up logic.

Inductive reasoning is a logical process in which multiple premises, all believed true or found true most of the time, are combined to obtain a specific conclusion. Inductive reasoning is often used in applications that involve prediction, forecasting, or behavior.

- The first part of the scientific method is inductive, the rest is deductive.

-Evolution is change in heritable traits of biological populations over successive generations.

-Evolutionary processes give rise to diversity at every level of biological organisation, including the level of species, individual organisms, and at the level of molecular evolution.

Lamarck was struck by the similarities of many of the animals he studied, and was impressed too by the burgeoning fossil record. It led him to argue that life was not fixed. When environments changed, organisms had to change their behavior to survive. If they began to use an organ more than they had in the past, it would increase in its lifetime. If a giraffe stretched its neck for leaves, for example, make it longer. Its offspring would inherit the longer neck, and continued stretching would make it longer still over several generations. Meanwhile organs that organisms stopped using would shrink.

It was Darwin's genius both to show how all this evidence favored the evolution of species from a common ancestor and to offer a plausible mechanism by which life might evolve . . . Natural Selection

-Wallace came to similar conclusions

-Wallace and Darwin together presented their ideas on natural selection and adaptation in 1858 in London

Organisms over-reproduce:

1. Individuals vary, some variations are heritable

2. Resources are limited

3. Organisms with most favorable traits for a given environment have the most reproductive success, and those traits are passed on to next generation

-The theory of evolution is known as "descent with modification," through variation and natural selection

-Environment, forces of nature that "select" individuals with traits that favor reproductive success

--Process that causes evolutionary change is natural

-Over long period of time, this process of natural selection leads to adaptation

--A population's characteristic change

--Better able to survive and/or reproduce=affects evolution of populations and species

FACT!!

-Mechanisms for how evolution occurs is strongly supported theory

-As one looks farther up, at younger and younger rock layers, the fossilized plants and animals become more and more familiar until they are a lot like organisms that are around now. The organisms also tend to become more and more complex.

-From this, Darwin concluded that organisms have not remained the same since earth's beginning, and that they have changed a lot, gradually becoming more and more complex. He also realized that as new species arise, other ones become extinct.

-Darwin and scientists today have discovered that the ancient organisms whose remains they find look like organisms alive today because they are the living organisms' ancestors or evolved from a common ancestor

-Today, fossils are still being studied to find out more about life in the past and its relation to life in the present. They provide valuable information about evolution and how life formed. Unlike in Darwin's time, now scientists can date these fossils and remains to get a more exact picture of when different organisms evolved.

Vestigiality refers to genetically determined structures or attributes that have apparently lost most or all of their ancestral function in a given species, but have been retained through evolution.

Long before Darwin and Wallace, farmers and breeders were using the idea of selection to cause major changes in the features of their plants and animals over the course of decades. Farmers and breeders allowed only the plants and animals with desirable characteristics to reproduce, causing the evolution of farm stock. This process is called artificial selection because people (instead of nature) select which organisms get to reproduce.

the study of similarities and differences in the anatomy of different species. It is closely related to evolutionary biology and phylogeny (the evolution of species). Comparative anatomy has long served as evidence for evolution; it indicates that various organisms share a common ancestor.

structures (body parts/anatomy) which are similar in different species because the species have common descent. They may or may not perform the same function. An example is the forelimb structure shared by cats and whales.

structures similar in different organisms because they evolved in a similar environment, rather than were inherited from a recent common ancestor. They usually serve the same or similar purposes. An example is the streamlined torpedo body shape of porpoises and sharks.

-Convergent Evolution!

By studying the basic biochemistry shared by many organisms, we can begin to piece together how biochemical systems evolved near the root of the tree of life.

Embryos of many different kinds of animals: mammals, birds, reptiles, fish, etc. look very similar and it is often difficult to tell them apart. Many traits of one type of animal appear in the embryo of another type of animal. For example, fish embryos and human embryos both have gill slits. In fish they develop into gills, but in humans they disappear before birth.

This shows that the animals are similar and that they develop similarly, implying that they are related, have common ancestors and that they started out the same, gradually evolving different traits, but that the basic plan for a creature's beginning remains the same.

study of how species are scattered across the planet, and how they got that way

Can breed and produce fertile offspring

Same species, same place, same time

-Natural selection works on individuals, yet populations evolve

The phenotype of an organism depends on which genes are dominant and on the interaction between genes and environment. Compare genotype. The outward appearance of an organism; the expression of a genotype in the form of traits that can be seen and measured, such as hair or eye color.

The genotype is the genetic makeup of a cell, an organism, or an individual usually with reference to a specific characteristic under consideration.

An allele is a variant form of a gene. Some genes have a variety of different forms, which are located at the same position, or genetic locus, on a chromosome. Humans are called diploid organisms because they have two alleles at each genetic locus, with one allele inherited from each parent.

-Is the change in allele frequencies that occur over time within a population.

-This change is due to four different processes: mutation, selection (natural and artificial), gene flow, and genetic drift.

-Microevolution over time may lead to speciation or the appearance of novel structure, sometimes classified as macroevolution. Macro and microevolution describe fundamentally identical processes on different scales

-Mutations are changes in the DNA sequence of a cell's genome and are caused by viruses, radiation, mutagenic chemicals, as well as errors that occur during meiosis or DNA replication.

*** Each human has at least 100 new mutations in their DNA

-The term epigenetics refers to heritable changes in gene expression (active versus inactive genes) that does not involve changes to the underlying DNA sequence; a change in phenotype without a change in genotype. Epigenetic change is a regular and natural occurrence but can also be influenced by several factors including age, the environment/lifestyle, and disease state.

-can turn a gene on or off, but NOT a mutation!

***Lick your rats example

is the process by which humans breed other animals and plants for particular traits.

-The theory holding that competition exists within species, determining which species live to have offspring, and pass their traits on to those offspring.

-Natural selection works on individuals yet populations evolve

-natural selection selects for or against some traits.

*** In measuring the effects of selection, an individual with higher fitness has greater reproductive success than those with lower fitness.

1. Stabilizing

2. Directional

3. Disruptive

-The "average" trait is selected

-This is thought to be the most common mechanism of action for natural selection because most traits do not appear to change drastically over time.

-A classic example of this is the human birth weight.

-An extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype.

-Directional selection occurs most often under environmental changes and when populations migrate to new areas with different environmental pressures. Directional selection allows for fast changes in allele frequency, and plays a major role in speciation.

-Opposites, extremes are selected (often results in balanced polymorphism

-In this case, the variance of the trait increases and the population is divided into two distinct groups.

Suppose there is a population of rabbits. The color of the rabbits is governed by two incompletely dominant traits: black fur, represented by "B", and white fur, represented by "b". A rabbit in this population with a genotype of "BB" would have a phenotype of black fur, a genotype of "Bb" would have grey fur (a display of both black and white), and a genotype of "bb" would have white fur.

If this population of rabbits occurred in an environment that had areas of black rocks as well as areas of white rocks, the rabbits with black fur would be able to hide from predators amongst the black rocks, and the rabbits with white fur likewise amongst the white rocks. The rabbits with grey fur, however, would stand out in all areas of the habitat, and would thereby suffer greater predation

-maintains diversity in a population, doesn't favor one form of a gene over another

-can result in balanced polymorphism

-opposite forms of a gene exist equally in a populationThis usually happens when the heterozygotes for the alleles under consideration have a higher adaptive value than the homozygote

***Sickle-cell anemia in regions where malaria is prevalent!

***The heterozygote is resistant to the malarial parasite which kills a large number of people each year

-Genes are the hereditary factors that produce traits.

-Small, random changes in allelic frequencies due to chance rather than selection.

-When there are few copies of an allele, the effect of genetic drift is larger, and when there are many copies the effect is smaller

-Both bottlenecks and founder effects provide perfect opportunities for genetic drift to take over, as they both involve small populations.

a) Founder effect: new habitat, few individuals

b) Bottlenecks: drastic population reduction

***Unlike bottlenecks, which persist as long as the effective population size remains low, a founder effect is an instant event

-The founder effect occurs when there is a lack of genetic variation due to a small mating population. The Founder Effect happens when there is a dramatic decrease in genetic diversity caused by the development of small colonies of individuals, from the original population, that remain isolated to other colonies.

-Examples of this showing up in human populations is polydactyly(more than five fingers) among Amish communities or the Blue people of Kentucky

-Another example is when Afrikaner population of Dutch settled in South Africa

-The Bottleneck Effect occurs when there is a disaster of some sort that reduces a population to a small handful, which rarely represents the actual genetic makeup of the initial population.

-This can have an extreme effect on the genetic diversity of the population

Genotype frequencies are the frequencies of the homozygous dominant (AA) heterozygous (Aa) and homozygous recessive (aa).

Allele frequencies are the frequencies of each allele, dominant (A) and recessive (a)

-Northern elephant seals have reduced genetic variation most likely due to being hunted. Hunting reduced their population size to as few as 20 individuals at the end if the 19th century. Since then their population has rebounded to over 30,000 but the genes still carry the marks of their bottleneck. They have much less variation than a population of Southern Elephant seals that have not been hunted.

-The movement of genes through a population or between two populations through mating

-Also called migration

-If gene versions are carried to a population where those gene versions previously did not exist, gene flow can be a very important source of genetic variation.

-Nonrandom mating occurs when the probability that two individuals in a population will mate is not the same for all possible pairs of individuals.

-When the probability is the same, then individuals are just as likely to mate with distant relatives as with close relatives -- this is random mating.

-Nonrandom mating can take two forms:

1. Inbreeding - individuals are more likely to mate with close relatives (e.g. their neighbors) than with distant relatives. This is common.

2. Outbreeding - individuals are more likely to mate with distant relatives than with close relatives. This is less common.

***Inbreeding changes genotype frequencies, not allele frequencies: Homozygotes increase in frequency, heterozygotes decrease in frequency.

-certain traits make an individual more attractive to the opposite sex, and thus more likely to reproduce

-first recognized by Darwin

-typically, female choosing "best" male

- Sexual selection acts on males more strongly than on females

- "Eggs are expensive, but sperm are cheap"

*** Fundamental asymmetry of sex

- Females are limited by resources to produce eggs

- Males are limited by number of females they can mate with

-Males display their genetic quality to females

- Results in sexual dimorphism

1) Intrasexual: individuals of one sex compete

- Precopulatory: dominance, territories, etc.

- Postcopulatory: sperm competition

- Post-zygotic: induced abortion or infanticide

For example, intrasexual selection would operate on physical and behavioral features which helped to determine the outcome of aggressive encounters among males over territories, if possession of or the quality of a territory affected subsequent mating success

2) Intersexual/Mate Choice

- For resources, protection, or aid to offspring

- For genetic quality of offspring

Intersexual Selection would influence the evolution of secondary sexual characteristics which determine the relative "attractiveness" of members of one sex to the other sex. Such items as courtship displays and male plumage in birds (e. g., the male peacock)

***Both result in Sexual Dimorphism

The differences in appearance between males and females of the same species, such as in colour, shape, size, and structure, that are caused by the inheritance of one or the other sexual pattern in the genetic material.

The differences may be extreme, as in the adaptations for sexual selection seen in the exotic plumes and colours of the male bird-of-paradise

-Macroevolution is evolution on a grand scale — what we see when we look at the over-arching history of life: stability, change, lineages arising, and extinction.

-Macroevolutionary studies focus on change that occurs at or above the level of species, in contrast with microevolution,which refers to smaller evolutionary changes (typically described as changes in allele frequencies) within a species or population.

*** (Mutation + Gene Flow + Genetic Drift + Natural Selection) + 3.8 Billion Years = Macroevolution

***Speciation bridges microevolution to macroevolution

1.) Phylogenetic

-Characteristics (Not very accurate)

2.)Biological What we most often use in class

-A group of individuals whose members have the potential to interbreed with one another in nature to produce viable, fertile offspring but cannot successfully interbreed with members of other species

3.)Evolutionary

-A species is derived from a single lineage that is distinct from other lineages and has its own evolutionary tendencies and historical fate; more theoretical - can be applied to formation of all species

4.) Ecological

- Each species occupies an ecological niche

-If two organisms are very similar, their needs will overlap, which will result in competition

-Such competition individuals are very likely to be of the same species

-useful for bacterial species

-Identify whether geographically isolated populations belong to the same species

-Classify species in extinct populations

-Account for asexually reproducing organisms

-Clearly define species when barriers to reproduction are incomplete

A ring species is a situation in which two populations which do not interbreed are living in the same region and connected by a geographic ring of populations that can interbreed.

Famous examples of ring species are the herring and lesser black-backed gulls in northern Europe and the Ensatina salamanders of California.

A ring species can be best imagined like this:

Consider a species that is geographically distributed in a straight line from east to west across America: it is possible that the forms in the east and west are so different that they could not interbreed. Now imagine taking the line and bending it into a circle, such that the end points (formerly in the east and west) come to overlap in space.

If they do not interbreed then the geographic distribution of the species will be in the shape of a ring, and they will be 'ring species': the extreme forms do not interbreed in the region of overlap. A ring species has an almost continuous set of intermediates between two distinct species, and these intermediates happen to be arranged in a ring. At most points in the ring, there is only one species; but there are two where the end-points meet.

One major type is called prezygotic isolation and it happens before fertilization occurs between gametes. Basically, prezygotic isolation keeps different species from sexually reproducing. If individuals cannot reproduce, they are considered to be different species and diverge on the tree of life.

1.) Mechanical Isolation

- Simply put, mechanical isolation is the incompatibility of sexual organs. They just do not fit together.

-For instance, a plant that is structured so a bee can pollinate it will not be compatible with a flower that relies on hummingbirds to spread its pollen.

2.) Gametic Isolation

-Gametic isolation ensures that only sperm of the same species can penetrate the egg of that species and no others.

-This type of reproductive isolation is especially important for species that reproduce externally in the water.

3.) Temporal Isolation

-"He works the night shift and she works the day shift"

-Different species tend to have different breeding seasons

4.) Behavioral Isolation

- Has to do with the behaviors of the individuals, and in particular the behaviors around mating time

-For instance, the blue footed booby bird has a very elaborate mating "dance" the males must do to woo the female. The female can either then accept or reject the advances of the male. Other species of birds do not have the same mating dance and will be fully ignored by the female meaning they have no chance at reproducing with a female blue footed booby.

5.)Ecological/Habitat Isolation

-Obviously, if individuals of two different species live nowhere near each other, there will be no opportunity to reproduce

-even different species that live in the same area may not be compatible due to their preferred place of reproduction. There are some types of birds that prefer different types of trees, or even different parts of the same tree, to lay their eggs and make their nests.

-A number of mechanisms which act after fertilisation preventing successful inter-population crossing are discussed below.

1.) Zygotic Mortality

-Even if the sperm and the egg from the two separate species are able to fuse during fertilization, that does not mean the zygote will survive

2.)Hybrid Sterility

-A hybrid has normal viability but is deficient in terms of reproduction or is sterile. This is demonstrated by the mule and in many other well known hybrids.

3.)Hybrid Breakdown

-Hybrids are often not suited for their environment the way a pure species would be

-Weak, low fitness, high mortality rates among offspring (Liger)

-There are many different isolating mechanisms, called prezygotic isolations, that prevent species from interbreeding with each other. If they do manage to produce offspring, there are more isolating mechanisms in place, called postzygotic isolations, that ensure the hybrid offspring are not selected for by natural selection. In the end, both types of isolations are designed to drive evolution and make sure that speciation is desired outcome

-How microevolution (changes within species) results in macroevolution (changes in types of speciations)

-Anagenesis vs cladogenesis (Most Common)

-Also known as "phyletic change", is speciation wherein the ancestor species wholly morphs into the new species, such that there are no remaining other populations of the ancestor species and the species can be considered extinct

-Sequence of species, no increase in # of species.

-is an evolutionary splitting event where a parent species splits into two distinct species, forming a clade.

-Cluster of all species derived from a common ancestor (Darwin's Finches)

-Allopatric vs. parapatric vs. sympatric speciation

-Allopatric=Most common way cladogenesic occurs

-Geographical Isolation results in new species; gene flow between populations slows or stops

-Examples can be highways (barriers to species such as turtles)

-Geographic separation often leads to adaptive radiation (one group spreads out into new areas, undergoes new adaptations)

-Reproductive isolation evolves in neighboring populations that share small zones of contact and exhibit modest gene exchange

-Genetic divergence arises largely through natural selection

-Often differences in mating habits due to different ecological conditions (nonrandom mating)

New species evolve in same areas as parental species (more common in plants)

-change in chromosome #; often abrupt genetic changes that lead to reproductive isolation of a group

-change in ecology

A theory of evolution, supported by Darwin, which states that evolution is a gradual process that proceeds slowly but constantly through a series of small changes.

A theory of evolution, proposed by Niles Eldredge and Stephen J. Gould, which disagrees with phyletic gradualism and states that evolution is not gradual, but rather proceeds by means of bursts of change separated by long periods of relative stasis.

-Most likely a blending off the two

Approximately 700 species of dinosaurs have been named. Recent estimates suggest that about 700 to 900 more dinosaur genera may remain to be discovered.

Dinosaurs ate lizards, turtles, eggs, or early mammals. Some hunted other dinosaurs or scavenged dead animals. Most, however, ate plants

Extinction: inability to change/adapt= disappearance of species

Of all species that have existed on Earth, 99.9% are now extinct

-five major mass extinctions (in which 20-90% species become extinct) have occurred since life began on Earth

-70% of scientists believe we are in a sixth major mass extinction currently

-Extinction often accelerates evolution for remaining species, allows a new species or to become dominant (ex. mammals following extinction of dinosaurs)

- Massive volcanic eruptions

- Massive land formations

- Falls in sea level

- Asteroid or comet impact

- Sustained global cooling (ice age)

- Sustained global warming

-Dodo Bird, Mammoths (Mastodon), and Tasmanian Tiger

- Humans are contributing greatly to extinctions in our current era

-Red Wolf

-Monk Seal

>80 Bird Species in past year

-Red-cockaded woodpecker

-Passenger Pigeon

-Carolina Parakeet

-->12 MONTH VIEW

Formation of Earth- January 1; Bacteria appeared- March 26;

Green algae- mid October; Mesozoic era began- December 14; Mammals adaptive radiation (after dinosaur extinction)- December 24; Genus Homo appears- 5pm December 31.

-->24-HOUR VIEW

Look at picture

is the variety of different types of life found on earth. It is a measure of the variety of organisms present in different ecosystems. This can refer to genetic variation, ecosystem variation, or species variation (number of species) within an area, biome, or planet.

study of the diversity of organisms and their evolutionary relationships

-Naming, describing, classifying organisms

-The field of taxonomy, or classification, originated with Carolus von Linnaeus, in 1750s

‐Attempted to place each species into unchangeable categories, based on similarities and differences

‐Today, evolution is the underlying thought concept of taxonomy, not the immutability of species

each level more inclusive (specific) than one below it

"Dear King Philip Came Over For Good Soup"

Domain

Kingdom

Phylum

Class

Order

Family

Genus

Species/Specific Epithet

-Using Linnaeus' binomial system of nomenclature, each species is assigned two-part name="scientific name"

-Genus (capitalized) + specific epithet (lower case) = species name

-Both always italicized or underlined

-the history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms

-Used to build classifications based on common ancestries

-Summarized by a phylogenetic tree

A phylogenetic tree or evolutionary tree is a branching diagram or "tree" showing the inferred evolutionary relationships among various biological species or other entities—their phylogeny—based upon similarities and differences in their physical or genetic characteristics.

Evolutionary trees depict clades. A clade is a group of organisms that includes an ancestor and all descendants of that ancestor. You can think of a clade as a branch on the tree of life. Some examples of clades are shown on the tree below.

(Monophyletic -- used most frequently)

-Interchangeable with clade

defined as one that includes the most recent common ancestor of a group of organisms, and all of its descendants

a group that includes the most recent common ancestor, but not all of its descendants

defined as one that does not include the common ancestor of all members of the group

A branching diagram depicting the successive points of species divergence from common ancestral lines without regard to the degree of deviation.

-Length of branches unimportant

-Phylogenetic tree often gives specific time so more info than cladograms

-Both cladograms and phylogenetic trees are "phylogenetic maps", showing evolutionary relationships

1.) Archaea

-prokaryotes, hostile environments, closer relatives to eukaryotes

2.) Bacteria

-prokaryotes, cyanobacteria

3.) Eukaryote.

-Protists, Fungi, Plants, Animals

The first two are all prokaryotic microorganisms, or single-celled microbes whose cells have no nucleus.

1.) Bacteria

2.) Archaea

-Both prokaryotes

-Everything else is eukaryotic

3.) Protists

- Bacteria, Archaea, and Protists (sometimes multicellular) are all unicellular

4.) Plantae

5.) Fungai

6.) Animalia

- Smaller than the cells of eukaryotes

• Ring of DNA—0.001 times as much as eukaryotes

• More abundant than eukaryotes‐ diverse habitats and nutritional requirements

• Important in medicine,industry, and quality of the environment

• Bacteria can be pathogenic, but no archaea are known to cause disease in humans

It is estimated that over 200 different species of microorganisms (bacteria, mainly) inhabit a healthy human body... (about 80 species in the mouth alone)

- Common name: Bacteria

- No introns in genome

- Peptidoglycan in cell walls

Gram-positive bacteria have a thicker peptidoglycan layer in their cell wall outside the cell membrane (Gram-Negative = thinner)

- Basic shapes are cocci, bacilli, and spirilli

- Diverse nutrition and respiration

- Reproduce by binary fission, conjugation, transformation, and transduction