Biology Exam 3: Chapter 11

Evolutionary Fitness

Ability to Produce Offspring

Evolution & Natural Selection

This evolution is the result of natural selection.

Comparative Anatomy: Vestigial Structures

"Evolutionary leftovers". Structures that related species also have, but no longer play a role. Ex: Molars in vampire bats Ear muscles and tail bones in humans

Natural Selection is NOT exactly "Survival of the Fittest"

"Survival of the fittest" is a misleading phrase since it is the individuals that have the greatest reproductive output that are the most fit in any population. It becomes a more meaningful phrase if we consider it a description of the fact that the alleles that increase an individual's fitness will "survive" in a population more than the alleles that decrease an individual's fitness.

If this beetle population were placed on the side of a white-painted house, what do you think would happen? There are two correct answers.

- A decrease in the allele for dark exoskelton. - An increase in the allele for light exoskelton.

Kin Selection

- Altruistic-appearing behavior will occur when the benefits to close relatives are greater than the cost to the individual performing the behavior. - They are really acting in their own genes' best interests.

Feeding behavior

- Feeding choices directly influence fitness. - Natural selection can shape feeding behavior. - When a heritable trait increases an individual's reproductive success relative to that of other individuals, that trait tends to increase in frequency in the population.

Honesty, Deception and Language

- Honest signals cannot be faked - Given when both the individual making the signal and the individual responding to it have the same interests - Carries the most accurate information about an individual or situation -Begging "allele": Baby birds exaggerating its need for food leads to faster growth and better health for that individual. -Evolutionary "arms race" •Increasing Unambiguous signals •Increasing more sophisticated patterns of deception

Fixed Action Pattern

- Triggered under certain conditions - Requires no learning - Does not vary - Once started, runs to completion

comparative anatomy and embryology

- Vertebrate embryos from very different species look very similar to each other during early development - evidence of common ancestry common mammal ancestor Ex: bats, humans, whales, and cats have similar wrist structures

Astronomy/Geology

-Earth is MUCH older than 6,000 years old

Fossil Record

-Extinction occurred -Animals looked different than current ones living today -Animals can change through generations

Geology

-Geological forces changed the Earth gradually over time -Continuing to do so

Body Size and Behavior

-Selection for larger and larger body size when competition is high -Coloration can also be a clue to behavior Ex: Male-male competition sometimes results in differences in physical appearance between the sexes

Innate Behaviors

-The degree to which a behavior depends upon the environment varies a great deal. -Also called instincts Fixed action pattern Ex: When a goose sees an egg outside its next it will pull it into the nest. Whether its hers or not

Which choice below would explain why an entire population of weeds can become resistant to weed killer?

1.Some individuals within the population were already resistant to weed killer application. 2.Weed killer resistance is heritable. 3.Weeds with weed-killer resistance had a greater survival rate than those without. 4.All of the above.

Conditions for Reciprocal Altruism

1)Repeated interactions among individuals 2)The benefits to the recipient must be significantly greater than the costs to the donor. 3)The ability to recognize and punish cheaters

3 Elements to an Individual's Fitness

1. An individual's fitness is measured relative to other genotypes or phenotypes in the population. 2. Fitness depends on the specific environment in which the organism lives. 3. Fitness depends on an organism's reproductive success compared to other organisms in the population.

The 4 evolutionary mechanisms are:

1. Mutation 2. Genetic drift 3. Migration 4. Natural selection

Evidence for evolution

1. The fossil record 2. Biogeography 3. Comparative anatomy and embryology 4. Molecular biology 5. Laboratory and field experiments

Use the graph below to predict which food people would prefer to eat at a picnic if they could only choose one item?

1.Fresh vegetable salad with low-fat dressing 2.Watermelon 3.Corn 4.Grilled chicken 5.Apple pie

Bacillus thuringienses (Bt) bacteria produce a natural insecticide. Widespread use of spraying the bacteria on corn plants has lead to Bt resistance among insects. Why is this occurring? A.Individual insects that have mutations providing resistance to Bt can survive in the presence of Bt. The survivors pass this Bt resistance on to their offspring. B.Bt-resistant insects increase in the population by chance. There are so many insects that some of them are resistant to each type of insecticide. C.In the presence of Bt, individual insects evolve to become Bt resistant. D.Natural selection causes insects to generate genes providing resistance to Bt.

A - Correct B - Evolution is not random. Mutation and genetic drift are random, but natural selection is due to environment. C - In most cases, the environmental change does not cause a mutation. And if it does cause mutation, its mostly likely NOT going to be the exact mutation needed for resistance D - Natural selection doesn't cause new alleles to be created. It only acts on alleles that are already present in the population.

Male deer (bucks) in a given population are reaching sexual maturity with smaller antlers than they did in the past because antler growth rate has decreased. Some biologists suggest that this change is related to hunting because bucks with larger antlers are most prized and therefore taken by hunters more often than bucks with smaller antlers. Which statement best explains the decreased antler size of the buck population? A.The bucks know that if they grow big antlers, they will be hunted before they can reproduce, so they grow their antlers slowly and reproduce as quickly as they can. B.Because bucks with large antlers are taken most often, more mutations occur to help the deer population reproduce before growing large antlers. C.Bucks that reproduce with smaller antlers are likely to have more chances to reproduce because they are not as likely to be taken by hunters. They then pass on their slower antler growth rate to their offspring. D.All bucks in the population reduce their antler growth rate so that the entire population has smaller antlers.

A - Evolution is not intentional. It cannot be willed by an individual or population B - Selection does NOT cause mutations. It only acts on mutations/variation that are already present in a population C - Correct D - Evolution is not intentional. It cannot be willed by an individual or populatio

Why do Males Compete for Females

A male has more gametes than females. Males increases reproductive output by mating. -Increased mating = more successful offspring A female does not increase reproductive output by additional mating. -Increased resources in parenting = more successful offspring

Genetic Drift: Bottleneck Effect

A rapid decrease in population size due to a disturbance or natural disaster reduces the abundance of a species and removes individuals with some alleles from the population, altering gene frequencies through drift.

heritable traits

A trait that can be passed on genetically from parent to offspring.

Comunication

An action or signal on the part of one organism that alters the behavior of another organism.

Natural Selection Does Not Lead To Perfect Organisms.

As Darwin noted over and over again during his travels, the organisms that possess traits that allow them to better exploit the environment in which they live will tend to produce more offspring than the organisms with alternative traits. With passing generations, a population will be made up of more and more of these more fit organisms. And, as a consequence, organisms will tend to be increasingly well-matched or adapted to their environment. Adaptation refers to both the process by which organisms become better matched to their environment and the specific features that make an organism more fit. Examples of adaptations abound. Bats have an extremely accurate type of hearing (called echolocation) for navigating and finding food, even in complete darkness. Porcupine quills make porcupines almost impervious to predation. If the environment changes, the alleles causing the traits favored by natural selection may change, too.

Differences in Male/Female Behavior

Because the extent of reproductive investment is different among species, mating behavior also differs among species. These physical differences have led to the evolution of differences in male and female reproductive behavior.

prepared learning

Behaviors that are learned easily and by all (or nearly all) individuals •Snake-fearing behavior of monkeys •Acquisition of language in humans •Organisms are well-prepared to learn behaviors that were important to the reproductive success of their ancestors. •Organisms are less prepared to learn behaviors irrelevant to their evolutionary success.

Reciprocal Altruism..."Karma"

Between unrelated individuals. Both individuals give up something of relatively low value in exchange for getting something of great value at a later time when they need it most. "Storing Goodwill"

Evolution

Change over time

Types of Communication

Chemical Acoustical Visual

Scope of Animal Behavior

Conflict, aggression, and territoriality Cooperation, alliance building, and sociality Competing for food and avoiding predators Migration and navigation Behavioral control of body temperature Courtship and mate choice Pair bonding and fidelity Breeding and parental behavior Communication Learning and tool use

Darwin's Trip to the Galapagos Islands

Darwin observed that: •individuals in a population vary in their traits, many of which are heritable •more offspring are produced than survive, and competition is inevitable •In each generation, only some individuals survive long enough to reproduce and some produce more offspring than others, which is dictated by their traits. •species generally suit their environment

A plant that is too short may not be able to compete with other plants for sunlight. However, extremely tall plants may be more susceptible to wind damage. Therefore plants exhibit which of the following

Directional selection

Mismatch = Maladaptive

Environments change. Adaptations that were once increased fitness in an old environment, now decrease our fitness. Same is true with behavior -Eating high sugar/fat food -Charitable contributions to far away lands -Calling in transplanted squirrels.

Evolution and Natural Selection

Evolution •a genetic change in the population Natural selection - a means to evolution •individual organisms are born with heritable characteristics that enable them to survive better and reproduce more than the offspring of other individuals in the population

Evolution biology

Evolution makes sense of everything we know about biology Evolution explains patterns of unity and diversity in living organisms

Biogeography: Distribution Reflects history

Ex: Australia is populated mostly by marsupials (like kangaroos) but have species with similar traits with placenta animals on the mainland. All related to each other through a common marsupial ancestor

A fire nearly wiped out a forest of the Western Hemlock tree. Which answer is correct about the current population of Western Hemlock?

It has experienced a population bottleneck.

True or False: The theory of evolution by natural selection is tentative and uncertain.

False?

behaviors are traits that can evolve

Feeding behaviors: Animals should maximize energy consumed and minimize energy used

Mating Behaviors

Female choosiness and male competition increases the likelihood that a female will select males that have plentiful resources or high quality genes (disease resistance or physical traits) causing her to produce more or better offspring (with similar features which will have an increased chance of mating....and so forth....)

Genetic Drift vs. Natural Selection

Genetic drift: The change in allele frequencies is NOT related to the alleles' influence on reproductive success. Natural Selection: The change is all frequencies IS related to the alleles' influence on reproductive success.

Examples of altruistic behaviors

In almost all cases, altruism are not truly altruistic; they have evolved as a consequence of either kin selection or reciprocal altruism. From an evolutionary perspective, altruism is beneficial to the individual engaging in the behavior

Learned Behaviors

Involves behaviors that are altered and modified over time in response to past experiences. Tremendous variation among behaviors that require learning. Some are easy to learn. Others are not

Language is a Complex Form of Communication

Language is a very specific type of communication in which arbitrary symbols represent concepts, and a system of rules, called grammar, dictates the way the symbols can be manipulated to communicate and express ideas. -Honeybees -American Sign Language taught to orangutans -Human language

Investment Influences Mating Systems

Mammals -High female investment (gestation and lactation) -Males tend to be polygamous Birds -Males and females participate in gestation -No lactation -90% of species are monogamous for at least a season -"Love birds"

Differences in Male/Female Investment

Mammals •Gestation internal •Lactation •Female (high) > male •Paternity uncertainty Birds •Gestation external •No lactation •Female (med) = male (med) Amphibians •Gestation external •No lactation •Female (low) = male (low)

Evolution ≠ Natural Selection

Natural selection is one way that evolution can occur, but it is not the only agent of evolutionary change. It is simply one of them, and the only one that leads to adaptation.

Modern Evolution by Natural Selection

Modern biologists condense Darwin's four steps into two statements: Evolution by natural 1. selection occurs when: Heritable variation leads to 2. Differential success in survival and reproduction.

Evolution is Incremental

Natural selection does NOT create different traits and alleles.There must be an existing allele (trait) that changes (due to mutation) creating a new allele. This allele MUST be neutral or beneficial.

Natural Selection and Adaptation

Populations Become Better Matched/Adapted to Their Environment Through Natural Selection Traits causing some individuals to have more offspring than others become more prevalent in the population.

Reciprocal Altruism in Humans

Reciprocal altruism is relatively rare in animals, but very common in humans. Why are humans among the few species to have friendships? Humans can keep track of thousands of faces and keep track of cheaters Cooperators (those who give back) have evolutionary advantages over loners. This advantage disappears if the cooperators are the givers most of the time and rarely get anything in return.

Sexual Dimorphism = Sexes Look Different

Sexual dimorphism is an indicator of mating behavior. •One parent invests more. •Mating tends toward polygamy •One sex chooses mate (female) •One sex competes (male)

Categorical vs Continuous Traits

Some traits are categorical -Either/Or Some traits have a continuous range -Susceptible to directional selection

Revisiting Fitness

The alleles carried by an individual with high fitness will increase their market share in a population over time and the population will evolve.

Factors in Mate Selection: Courtship

The courtship process can go on for several days. If the male passes the time-consuming audition, he can generally be counted on to stick around to see a brood through hatching and early care.

Natural Selection Can Co-opt Traits For New Functions

The key to answering this question is that 1% of a wing doesn't actually need to function as a wing at all to increase an individual's fitness. Often, structures appear because they serve some other purpose.

Factors in Mate Selection: Gifts up Front

The larger the food item, the longer she will mate; and the more she eats, the larger the number of eggs she will lay.

Dating Fossils Using Radioactive Isotopes

The use of radiometric dating helps in further painting a picture of organisms' evolutionary history by telling us the age of the rock in which a fossil has been found.

Sexual Conflict and Behaviors

There are big differences in how much males and females invest in reproduction. The mother's material contribution to the offspring exceeds the father's. - A female produces the larger gamete. - A male produces the smaller gamete. Extent of energetic differences in their reproductive investment

Non-heritable traits

Traits that cannot be passed from one generation to the next generation. Ex: Earrings, scars, and physical skills such as jumping are all acquired after birth.

Arctic hares can run at speeds from 2 mph to 6 mph. What condition of natural selection does this represent

Variation in a trait

True or False: There is lots of evidence that supports evolution by natural selection

True?

molecular biology

We can now sequence DNA very quickly at a low cost. To date we have sequenced the entire genomes of thousands of different species and individuals within species. The more distantly you and another individual are related, the more your DNA differs.

Factors in Mate Selection: Control of Valuable Resources

With greater quality and quantity of resources in his territory, a male is better able to attract females, whose reproductive success is partly a function of the resource richness of the territory.

Can Alleles Disappear From a Population?

Yes -either randomly by genetic drift -or by natural selection if it's a deleterious allele

Mutation

a random error in gene replication that leads to a change For an mutation to affect a population, it must be occur in a germ-line cell (in sexually-reproducing populations). - Spontaneous during DNA replication or caused by radiation of chemicals.

Behavior

any and all of the actions performed by an organism -often in response to its environment or to the actions of another organism. -Behaviors are traits that can evolve

Altruism

behaviors that come at a cost to the individual doing the behavior while benefiting the recipient

disruptive selection

favors individuals at both extremes of the phenotypic range Ex: Salom

stabilizing selection

form of natural selection by which the center of the curve remains in its current position; occurs when individuals near the center of a distribution curve have higher fitness than individuals at either end Ex: Human Babies

gene flow = migration

is the movement of some individuals of a species from one population to another.

sexual monomorphism

males and females are similar in size and strength associated with equality in relationships •Parents invest equally. •Mating tends toward monogamy Sexes have equal choosing

Genetic Drift: Founder Effect

occurs when a few individuals become isolated from a larger population; can affect allele frequencies in a population Ex: Polydactyly is more common among Amish than other communities in the US

directional selection

occurs when natural selection favors one of the extreme variations of a trait Ex: Turkeys now have such large breasts that they cannot mate on their own

Are human males larger than human females? The average body size of modern males compared to females implies that human mating systems in the past tended toward:

polygamy (specifically, polygyny).

Genetic Drift

random change in allele frequencies in a population. Important when traits don't affect fitness Genetic drift is much greater in small populations\ Ex: Cleft Chin

Comparative Anatomy: Analogous Structures

structures all developed from different original structures. Look the same, because of similar environments

Comparative Anatomy: Homologous Structures

structures that appear very similar in form or function and seem to be related. -Natural selection works on traits already present

Factors in Mate Selection: Good Looks

the physical feature serves as an indicator of the relative quality of the male, possibly because the feature is correlated with the male's health.

artifical selection

the selective breeding of organisms by humans for specific characteristics Differential reproductive success is determined by humans rather than by nature Ex: Dogs

Direct fitness

•An individual's total reproductive output

Darwin's Evolution by Natural Selection

•Evolution by Natural selection requires: 1. A population with varied, heritable traits (phenotypes) 2. Competition for limited resources 3. Phenotypes better suited to the environment will outcompete other phenotypes and produce more offspring 4. The genotypes represented by those phenotypes will be more represented in the next generation due to increased reproductive success

Evolution

•Evolution occurs as the unequal reproductive success of individuals in a population Some individuals produce more offspring than others and when they do they pass on their genes

Innate Behaviors and Fixed Action Patterns

•Natural selection does not "choose" to select for traits that increase reproductive success. •An animal doesn't say "I need to improve my reproductive success" •A behavior is already present (due to genetics) that increases reproductive success....passed down to offspring. •Putting egg-looking things into nests has increased fitness of geese in the past

Indirect fitness

•The reproductive output brought about by altruistic behaviors toward close kin

Inclusive fitness

•The sum of an individual's indirect and direct fitness

Monogamy

•most individuals mate and remain with just one other individual

Polygamy

•when some individuals attract multiple mates while other individuals attract none •Polygyny - males have > 1 mate •Polyandry - females have > 1 mate