Biology Exam 2 Prep

A smooth line graph

"line of best fit."; represents a mathematical function that summarizes the relationship between the x and y variables.

Natural Selection Is Not "Lamarckian" Inheritance, Define Lamarckian Inheritance

(1) individuals change in response to challenges posed by the environment (such as giraffes stretching their necks to reach leaves high in the treetops), and (2) the changed traits are then passed on to offspring

In describing a dataset, what does the mean represent?

(Usually) The arithmetic average.

Hardy-Weinberg Principle with three alleles?

(p^2 + 2pq + q^2 + 2pr + 2qr + r^2)^2 = 1

What are moving in Gene Flow?

Alleles

Dogs and humans mostly share

Ancestral traits

Adaptation

Any heritable trait that increases the fitness of an individual with that trait, compared with individuals without that trait, in a particular environment.

Which is more common Autopolyploid or Allopolyploid

Autopolyploid

phylogenetic species concept

Based on the evolutionary history of populations

How does gene flow ruin speciation?

Because the constant migration of alleles causes populations to be very simialr

Imagine a gene pool in a random-mating population. If the frequency of allele A1 is p and the frequency of allele A2 is q, why is the predicted frequency of heterozygotes among the offspring 2pq instead of just pq?

Because there are two ways to get a heterozygote: A1 egg + A2 sperm or A2 egg + A1 sperm.

Why have polyploids been so successful?

Because they have a greater chance at obtaining more genetic diversity.

Why is non-random mating not a form of evolution?

Because this is essentially natural selection, which is a influencer of evolution

What is probability used for in biology?

to evaluate the significance of experimental results and to predict the outcome of genetic crosses

Gene Flow does what to genetic diversity?

Increases it via immigration and decreases it via emigration

Advantage to the biological species concept

clear evidence of evolutionary independence.

Analysis of variance

compares the means of two or more sets of data by calculating how widely individual values in each data set vary

Imagine a population composed of 4 individuals with genotype QQ, 8 with QR, and 8 with RR. What is the frequency of allele Q?

0.4

fundamental asymmetry of sex

1. Because eggs are large and energetically expensive, females produce relatively few young over the course of a lifetime. A female's fitness is limited not by her ability to find a mate but primarily by her ability to gain the resources needed to produce more eggs and healthier young 2. Because sperm are so energetically inexpensive to produce, a male can father an almost limitless number of offspring. Thus, a male's fitness is limited not by the ability to acquire the resources needed to produce sperm but by the number of females he can mate with.

4 different patterns of natural selection

1. Directional selection changes the average value of a trait 2. Stabilizing selection reduces variation in a trait 3. Disruptive selection increases variation in a trait 4. Balancing selection maintains variation in a trait

Sympatric Speciation by disruptive Selection examples

1. Flies preference for a certain fruit 2. Cricket's preference for a mate vs ability to survive (trade-off fitness)

Allopatric Speciation by Vicariance

1. Geographic isolation: Chance event physically separates population into subgroups. 2. Divergence: Isolated populations begin to diverge due to mutation, genetic drift, and selection. 3. Genetic isolation: Eventually the two populations are genetically isolated from one another.

Allopatric Speciation by dispersal

1. Geographic isolation: Some individuals disperse from their population and colonize a new habitat. 2. Divergence: New population begins to diverge due to mutation, genetic drift, and selection. 3. Genetic isolation: Eventually the two populations are genetically isolated from one another.

Bateman-Trivers hypothesis Predicts

1. If females invest a great deal in each egg, then they should protect that investment by being choosy about their mates and males will mate anyone 2. If there are an equal number of males and females in the population, and if males are trying to mate with any female possible, then males will compete with each other for mates 3. If male fitness is limited by access to mates, then any allele that increases a male's attractiveness to females or success in male- male competition should increase rapidly in the population (sexual selection acts more on males than females)

Bateman-Trivers hypothesis of sexual selection

1. If females invest a great deal in each egg, then they should protect that investment by being choosy about their mates. Conversely, if males invest little in each sperm, then they should be willing to mate with almost any female. 2. If there are an equal number of males and females in the population, and if males are trying to mate with any female possible, then males will compete with each other for mates 3. If male fitness is limited by access to mates, then any allele that increases a male's attractiveness to females or success in male- male competition should increase rapidly in the population, violating the assumptions of Hardy-Weinberg. Thus, sexual selection should act more strongly on males than on females.

Advantages to the phylogenetic species concept

1. It can be applied to any population (fossil, asexual, or sexual) 2. It is logical because different species have different synapomorphies only if they are isolated from gene flow and have evolved independently

Cons of the morphospecies concept

1. It may lead to the naming of two or more species 2. It cannot identify cryptic species 3. It is subjective

inbreeding depression

1. Many recessive alleles represent loss-of-function mutations. Inbreeding increases the frequency of homozygous recessive individuals. Loss-of-function mutations are usually deleterious and are quickly eliminated by selection. 2. Many genes—especially those involved in fighting disease—are under intense natural selection for heterozygote advantage, a selection process that favors genetic diversity. If an individual is homozygous at these genes, then fitness declines.

What four processes drive Evolution?

1. Natural selection (increases the frequency of certain alleles—the ones that contribute to reproductive success in a particular environment.) 2. Genetic drift (causes allele frequencies to change randomly. In some cases, drift may cause alleles that decrease fitness to increase in frequency.) 3. Gene flow (occurs when individuals leave one population, join another, and breed. Allele frequencies may change when gene flow occurs, because arriving individuals introduce alleles to their new population and departing individuals remove alleles from their old population.) 4. modifies allele frequencies by continually introducing new alleles. The alleles created by mutation may be beneficial, deleterious (detrimental), or neutral in their effects on fitness.

For determining whether similar species are homologous or convergent

1. Phylogenetic evidence 2. Structural evidence 3. Genetic and developmental evidence

What are the five important assumptions about how populations and alleles behave in the Hardy-Weinberg Principle

1. Random mating The model assumes that gametes from the gene pool combine at random. Individuals are not allowed to choose a mate. 2. No natural selection The model assumes that all members of the parental generation survive and contribute equal numbers of gametes to the gene pool, no matter what their genotype. 3. No genetic drift (random allele frequency changes) The model assumes that alleles are picked in their exact frequencies p and q, and not at different frequencies caused by chance— that is, the model behaves as though the population is infinitely large. In the example in Figures 23.1 and 23.2, allele A2 did not "get lucky" and get drawn more than 70 percent of the time. 4. No gene flow The model assumes that no new alleles are added by immigration or lost through emigration. As a result, all of the alleles in the offspring population come from the original population's gene pool. 5. No mutation The model assumes that no new alleles, such as A 3 or A 4 , are introduced into the gene pool.

How do you use a statistical test to determine if differences are significant?

1. Specify the null hypothesis, which is that reactant concentration has no effect on reaction rate 2. Calculate a test statistic 3. Determine the probability of getting by chance a test statistic at least as large as the one calculated.

Flaws in the Biological Species Concept

1. You can't apply this concept to fossils or asexual organisms 2. Some species are too far away from each other to test 3. Ligers that reproduce successfully suggest that tigers and lions are the same species.

Three criteria for identifying species

1. biological species concept 2. the morphospecies concept 3. phylogenetic species concept

What triggers sympatric speciation

1. external events, such as disruptive selection for extreme phenotypes based on different ecological niches and/or mate preference 2. internal events, such as chromosomal mutations

Consequences of the fundamental asymmetry of sex

1. female's fitness is limited not by her ability to find a mate but primarily by her ability to gain the resources needed to produce more eggs and healthier young 2. a male's fitness is limited not by the ability to acquire the resources needed to produce sperm but by the number of females he can mate with.

Balancing selection occurs when

1. heterozygote advantage is present 2. The environment varies over time or in different geographic areas occupied by a population 3. frequency- dependent selection

females may choose mates on the basis of

1. physical characteristics that signal male genetic quality 2. behavioral characteristics of the males that indicate their ability to provide parental care 3. or both (all of this can be summarized as Female Choice for "Good Alleles")

Reproductive Isolation

1. prezygotic isolation 2. postzygotic isolation

Point mutation

A change in a single base pair in DNA

Chromosome-level mutation

A change in the number or composition of chromosomes

Branch

A line representing a population through time

In describing a dataset, what does the standard deviation or standard error represent?

A measure of the variation around the estimate of the mean.

Polytomy

A node that depicts an ancestral branch dividing into three or more (rather than two) descendant branches

Hardy-Weinberg principle

A principle of population genetics stating that genotype frequencies in a large population do not change from generation to generation in the absence of evolutionary processes (e.g., mutation, gene flow, genetic drift, and selection), and nonrandom mating.

If the frequencies of alleles A1 and A2 in a population are given by p and q, then the frequencies of genotypes A1A1, A1A2, and A2A2 will be given by p2, 2pq, and q2, respectively, for generation after generation. That is:

Allele frequencies : p + q = 1 Genotype frequencies : p2 + 2pq + q2 = 1

When gene flow occurred between populations of wild and captive-bred salmon, what was the most important result?

Allele frequencies became more similar among populations; fitness of wild salmon decreased.

Natural Selection does what to genetic diversity?

Can maintain, increase,or reduce genetic variation, but normally reduces it

Natural selection Effect on Average Fitness

Can produce adaptation, increasing fitness

What is the difference between a categorical and continuous variable?

Categorical are assigned to discrete categories; continuous can take any value in a range.

Mutation's influence over fitness?

Changes affect fitness randomly

A common cause of homoplasy is

Convergent evolution

Mutation does what to genetic diversity?

Creates entirely new alleles

Crossing over and independent assortment of chromosomes shuffle existing alleles into new combinations, but only mutation...

Creates new alleles

What's more common deleterious or beneficial alleles?

Deleterious; most mutations in sequences that code for a functional protein or RNA result in deleterious alleles (luckily Deleterious alleles tend to be eliminated by purifying selection)

How does geographical isolation occur

Dispersal or vicariance

Inbreeding reduces heterozygosity and increases homozygosity. This sometimes results in a decline in the mean fitness of a population—a phenomenon known as inbreeding depression. Why does inbreeding depression occur?

Either deleterious recessives are homozygous, or fewer individuals enjoy the benefits of heterozygote advantage, or both.

What is the difference between an explanatory (or independent) variable and a response (or dependent) variable?

Explanatory is the factor that varies in an experiment; response is measured as the explanatory variable varies.

intersexual selection

Female Chooses males

Frequency - dependent selection

For example, rare alleles responsible for coloration in guppies are favored because predators learn to recognize common color patterns. Alleles for common colors get eliminated; alleles for rare colors increase in frequency. As a result, allele frequencies shift over the short term, but overall genetic variation in the population is maintained in the long term.

Expanding human populations are forcing many organisms into small, isolated, fragments of habitat. In general, how will this affect levels of gene flow and inbreeding in these organisms?

Gene flow down; inbreeding up

Genetic correlation.

Genetic correlations occur because of pleiotropy, in which a single gene affects multiple traits

Frequencies that conform to the Hardy-Weinberg Principle are frequencies said to be in the

Hardy-Weinberg equilibrium

heterozygote advantage in balancing selection

Heterozygous individuals have higher fitness than homozygous individuals do

If we want to plot the distribution of scores on Exam 1, we should use a

Histogram

How Can Biologists Distinguish Homology from Homoplasy?

Homology (literally, "same-source"), homoplasy ("same-form")

Sympatric Speciation by disruptive Selection

Hybrid genotypes having a lower fitness suggests that Sympatric Speciation by disruptive Selection is occurring.

Genetic bottleneck

If a large population experiences a sudden reduction in size, a population bottleneck is said to occur; leaves only a few individuals to establish the next generation (a sudden reduction in the diversity of alleles in a population)

when has vicariance has taken place

If a new physical barrier such as a mountain range or river splits the geographic range of a species

Why is Lack of genetic variation in a population is usually a bad thing

If genetic variation is low and the environment changes— perhaps due to the emergence of a new disease-causing virus or a rapid change in climate—there is a good chance that none of the available alleles will enable individuals to survive and reproduce under the new conditions

founder effect

If the new population is small enough, the allele frequencies in the new population are almost guaranteed to be different from those in the source population; A change in allele frequencies that occurs

Fitness trade-off

Is a compromise between two traits that cannot be optimized simultaneously

Regression and correlation analyses

Is there a relationship between two variables and is it positive or negative.

Which of the following is one of the most important effects of mutation?

It increases genetic diversity.

Male-Male Competition

Males fight each other and the winner gets to have to female to use to pass alleles onto the next generation

In most species, why does sexual selection act more strongly on males than females?

Males have higher variation in RS. Traits that confer an advantage in courtship have a huge effect on fitness.

Inbreeding

Mating between relatives

Does Genetic Drift increases genetic variation in populations

No

Does mutation alone occur often enough to make it an important factor in changing allele frequencies?

No

Does Inbreed mating cause evolution?

No, but it can speed up the process. It increases the rate at which natural selection eliminates recessive deleterious alleles.

Does Nonrandom mating change allele frequencies?

No, but it does change genotype frequencies

In many or most animals, females are larger than males. Most animals are insects and in many insects, females tend to be much larger than males because they are under strong selection for producing large numbers of eggs, and larger females can produce more eggs. Is this an example of sexual selection?

No--sexual selection is about differential success in acquiring mates.

P > 0.05

Not significant

Isolated Populations

Occurs after a piece of a population breaks off from another. Gene drift will differ from the two with the assumptions that they have different environments

Why are environmental cues and bobbing dewlaps important to mating lizards?

One reason is that lizards that succeed in synchronizing their sexual readiness will likely bear more offspring and have higher fitness than those that do not

When stabilizing selection occurs, which of the following is NOT true?

Overall genetic variation, measured as the diversity and relative frequency of alleles, increases.

allopatry

Populations that are geographically separated

Mutation in Eukaryota vs Prokaryotic cells

Prokaryotic cells tend to be affected by mutation more often due to short life spans and more errors in gene replication.

Gene Flow Effect on Average Fitness

Random with respect to fitness; may increase, decrease, or have no effect on average fitness, depending on the alleles

Mutation Effect on Average Fitness

Random with respect to fitness; most mutations in coding sequences lower fitness

Gene Drift Effect on Average Fitness

Random with respect to fitness; usually reduces average fitness

Homology

Similarity in organisms due to common ancestry

Homoplasy

Similarity in organisms due to reasons other than common ancestry

What kind of graph do natural selection and mutation create together?

Stair case, When rare beneficial mutations occur there is a rapid increase in frequency.

If the expected frequencies match the observed frequencies then

The Hardy-Weinberg principle functions as the null hypothesis

The text claims that when natural selection occurs, the characteristics of the selected individuals do not change--only the characteristics of the population change. Why is this so?

The alleles in the "selected" individuals do not change during the process.

Chi Square Test

The chi-square test always tests the null hypothesis

phylogeny

The evolutionary history of a group of organisms

parsimony

The most likely explanation for a pattern is the one that assumes the fewest steps to reach a particular result; limbs evolved once in an ancestor and were inherited by all descendants, rather than to assume that limbs evolved multiple times independently in the descendants

What is stable during stabilizing selection?

The population mean phenotype.

What does it mean to say that inbreeding increases homozygosity?

The proportion of homozygous genotypes increases.

Does non-Random mating occur in nature?

The short answer is No

Lateral gene transfer

The transfer of genes from one species to another

What does "homogenize" mean?

To mix together, into a single entity.

What are additive traits in Poly genetics

Traits that add up together to create a phenotype

If the expected frequencies don't match the observed frequencies then

We can expect that at least one of the 5 assumptions of the Hardy-Weinberg principle have been violated, the question is which one?

When can you rule out Gene Drift and Gene Flow?

When both populations are very large and populations are isolated.

purifying selection

When disadvantageous alleles decline in frequency

Why does convergent evolution occur?

When natural selection favors similar traits in similar environments.

Sympatry

When populations or species live in the same geographic area, or close enough to one another to make interbreeding possible

Difference between monophyletic and paraphyletic groups?

Whether they share a direct common ancestor or not

Can branches be added or removed without changing the relationships of other branches?

Yes

Can branches can rotate at each node in a phylogenetic tree?

Yes

Does sexual selection lead to a change in allele frequency?

Yes, because sexual selection is non-random

In a statistical test, by increasing the sample size

You are less likely to reject the null hypothesis if it is true

How does the law of large numbers affect Gene Drift

You get less drift

Acclimatization

a change in an individual's phenotype that occurs in response to a change in natural environmental conditions

genetic marker

a specific allele that causes a distinctive phenotype

outgroup

a taxon that is known to have diverged before the rest of the taxa shown in the tree; fish are outgroups to humans and dogs aren't

sampling error

allele frequencies of a chosen sub- set of a population (the sample) are different from those in the total population, by chance

gene pool

alleles from all the gametes produced in each generation go into a single group then combine at random to form offspring (occurs in clams and sea stars)

beneficial allele

an allele that allows individuals to produce more surviving offspring, increasing fitness; tend to increase in frequency in the population due to natural selection

neutral allele

an allele with no effect on fitness; when a point mutation is silent

Paraphyletic group

an ancestral population and some of its descendants, but not all

Mutation-Selection Balence

an equilibrium in the number of deleterious alleles in a population that occurs when the rate at which deleterious alleles are created by mutation equals the rate at which deleterious alleles are eliminated by selection

Species

an evolutionarily independent population or group of populations

Genetic drift

any change in allele frequencies in a population that is due to chance; allele frequencies change due to blind luck

taxon

any named group of organisms, such as a population, a species, or a larger group

Pros of the morphospecies concept

applicable to sexual, asexual, or fossil species

Phylogenetic Tips (terminal nodes)

are the tree's endpoints

cladistic approach

based on the principle that relationships among species can be reconstructed by identifying shared derived traits, called synapomorphies

How rare are beneficial alleles?

because most organisms are well adapted to their current habitat, random changes in genes usually result in products that do not work as well as the products of alleles that currently exist; so pretty rare

Bar charts plot data that have

categorical values instead of a continuous range of values

Evolution

change in allele frequencies, and thus heritable traits, in a population over time

Mutation alone is usually inconsequential in...

changing allele frequencies at a particular gene; it needs to be paired with natural selection, genetic drift, and gene flow to become an evolutionary process.

ancestral trait

character that existed in an ancestor

monophyletic group

consists of an ancestral species and all of its descendants

Scatterplots, or line-of-best-fit graphs, are the most appropriate type of graph when the data have a

continuous range of values

Genetic Drift tends to

decrease genetic variation within populations and increase genetic differences among populations.

Mammals and Fish mostly share

derived traits

When alleles are transmitted via meiosis and random combinations of gametes, their frequencies

do not change over time.

Name a type of natural selection other than sexual selection

ecological selection

ecological selection

favor traits that enable organisms to do things other than obtain mates—such as survive in their physical and biological environments.

Genetic drift is random with respect to

fitness. The changes in allele frequency that it produces are not adaptive

How does speciation occur?

genetic isolation followed by genetic divergence

nonrandom mating can cause only

genotype frequencies to change, not allele frequencies, unless it occurs in concert with other processes such as natural selection

Visual Cues from Males Trigger female

hormone production and the onset of sexual behavior

Pattern component of speciation

how can we define and identify species 1. biological species concept 2. morphospecies concept 2. Phylogenetic species concept

Process component of speciation

how do new species form Isolation and Divergence in Allopatry Isolation and Divergence in Sympatry

postzygotic isolation

hybrid offspring of matings between members of different species either do not survive or do not reproduce

Histograms

illustrate frequency data and can be plotted as numbers or percentages

When disruptive selection occurs, the overall amount of genetic variation

increases in a population

Allopolyploid

individuals are created when parents of different species mate, and then an error in mitosis occurs, resulting in viable, nonsterile offspring with two full sets of chromosomes

Autopolyploid

individuals are produced when a mutation results in a doubling of chromosome number and the chromosomes all come from the same species

intrasexual selection

individuals sometimes compete with one another to obtain mates

cryptic species

individuals that are morpholigically identical to each other but belong to different species

derived trait

is one that is a modified form of the ancestral trait, found in a descendant

Prezygotic isolation

isolation, which prevents individuals of different species from mating successfully

The tree that assumes the fewest overall character changes is hypothesized to be the one that...

most accurately reflects what really happened during evolution.

How does speciation occur in a phylogenetic tree?

mutation, natural selection, and genetic drift

Why are traits similar in two species

not because those traits were present in a common ancestor, but because similar traits evolved independently in two different lineages

Phylogenetic Nodes (forks)

occur where a hypothetical ances- tral group splits into two or more descendant groups

Directional selection tends to reduce the genetic diversity of populations. If directional selection continues over time, the favored alleles will eventually approach a frequency

of 1.0 while disadvantageous alleles will approach a frequency of 0.0

Over time, genetic drift can lead to the random loss

or fixation of alleles. When random loss or fixation occurs, genetic variation in the population declines.

Genetic drift is most pronounced in small

populations

Sexual Dimorphism

refers to any trait that differs between males and females

Disadvantages to the phylogenetic species concept

relatively few well-estimated phylogenies are currently available.

Phylogenetic branch

represents populations through time

biological species concept

reproductive isolation; This is a logical yardstick because no gene flow occurs between populations that are reproductively isolated from each other

morphospecies ("form-species") concept

researchers identify evolutionarily independent lineages by differences in size, shape, or other morphological features

Box-and-whisker

see where most ofthe data fall

What causes the onset of sexual behavior

sex hormones, testosterone in males testes and estradiol in females ovaries

Why is mating mostly non-random in nature?

sexual selection

How can ecological selection and sexual selection conflict

sexual selection may favor long trains in peacocks, while ecological selec- tion may favor shorter trains that make the peacocks better able to maneuver and less vulnerable to predators

Phylogenetic trees

show the hypothesized evolutionary relationships among species or other taxa

Phylogenetic species

smallest monophyletic groups

Disruptive selection is important because it sometimes plays a part in

speciation

allopatric speciation

speciation that begins with geographic isolation

Sympatric speciation

speciation that occurs even though populations live within the same geographical area

Speciation

splitting event that forms two or more distinct species from a single ancestral species

A Curved line graph

takes on characteristic shapes depending on the relationships between the x and y variable

Genetic Drift does what to genetic diversity?

tends to reduce genetic variation via loss or fixation of alleles

What is probability?

the chance or likelihood that an event will occur or that a hypothesis or scientific prediction is correct

Convergent evolution

the independent evolution of similar traits in distantly related organisms due to adaptation to similar environments and lifestyles

genetic variation

the number and relative frequency of alleles that are present in a particular population

P value

the probability of getting various values of the test statistic if the null hypothesis is correct

niche

the range of ecological resources that a species can use and the range of conditions that it can tolerate

biogeography

the study of how species and populations are distributed geographically

If P is 0.01

there is a 1 percent chance that the null hypothesis has been rejected when it is actually correct

In stabilizing selection genetic variation in the population is reduced but,

there is no change in the average value of a trait over time

Null hypothesis of Chi square test

there is no significant difference between the observed and expected results

Null hypothesis of T-tests

there is no significant difference between the means of the two data sets

If certain alleles are associated with the favored phenotypes

they increase in frequency while other alleles decrease in frequency

Evolution can cause allele frequencies in a population

to change over time

synapomorphy

trait found in two or more taxa that is present in their most recent common ancestor but is missing in more distant ancestors; a trait that is derived from an ancestor and identifies a monophyletic group

Light and Social Stimulation

triggers sex hormones to develop 1. Females that were exposed to springlike conditions began producing eggs; females in the field that were not exposed to springlike conditions did not. 2. Females that were exposed to breeding males began producing eggs much earlier than did females that were alone, with other females, or with castrated males

T-tests

used to determine if there is a significant difference between the mean values of two groups

The Hardy-Weinberg principle can function as a null hypothesis when

we test a hypothesis that nonrandom mating is occurring, or that natural selection or one of the other evolutionary processes is affecting a particular trait in a population

What does the Hardy-Weinberg Principle predict?

what genotype frequencies and allele frequencies will occur in the next generation

The both-and rule

when you want to know the probability of two or more independent events occurring together [The probability of rolling a six on both dice, then, is 1/6 * 1/6 = 1/36]

The Either-Or Rule

when you want to know the probability of an event happening when there are two or more alternative ways for that event to occur [suppose you wanted to know the probability of rolling either a one or a six when you toss a die. The probability of rolling each number is 1/6, so the probability of rolling one or the other is 1/6 + 1/6 = 1/3]

Phylogenetic root

where the tree originates

Homology and homoplasy produce similar traits. What is the key difference?

whether or not the similar traits were inherited from a common ancestor

Regression and correlation

whether there is a relationship or correlation between two variables and, if so, is it positive (positive slope) or negative (negative slope).

If mutation did not occur, evolution...

would eventually stop; natural selection and gene drift tend to eliminate alleles

Correct the Phrase "Evolution is goal directed"

• Adaptations do not occur because organisms want or need them • Mutation, the source of new alleles, occurs by chance • Evolution is not progressive • Loss of traits can be adaptive • There is no such thing as a higher or lower organism

Correct the phrase "Evolutionary change occurs in organisms"

• Natural selection just sorts existing variants in organisms; it doesn't change them • Evolutionary change occurs only in populations • Acclimatization does not equal adaptation

Correct the Phrase "Evolution perfects organisms"

• Not all traits are adaptive • Some traits cannot be optimized due to fitness trade-offs • Some traits are limited by genetic, historical, or environmental constraints