Chapter 4: Evolution, Biological Communities, and Species

Question 1

Charles Darwin

Answer 1

Charles Darwin wrote a manuscript called “On the Origin of Species” which outlined the theory of evolution through natural selection

He voyaged the world aboard the H.M.S. Beagle.

Question 2

Adaptation

Answer 2

the addition of traits that better allow a species to survive in its environment

*can occur quickly or over a long period of time

• acclimation
• natural selection

Question 3

Acclimation

Answer 3

an immediate response to a change in the environment Ex. Put a coat on when it gets cold.

an acclimation is not permanent; however, the ability to acclimate is inherited

Question 4

Natural Selection

Answer 4

The process of better-selected individuals passing their genes on to the next generation. This insures a better chance of species survival. (AKA Survival of the fittest)

Question 5

Where are traits encoded?

Answer 5

In the DNA of the species

Question 6

What is the relationship between adaptation, acclimation, and natural selection?

Answer 6

Acclimation and natural selection are just two ways an animal can adapt.

Question 7

What are mutations?

Answer 7

alterations in an organisms chromosomes *Only mutations in gametes (sex cells) matter. *Mutations in body cells, like skin cancer and lung cancer, are not inherited. Many mutations actually have a negative effect.

Question 8

Selection Pressures

Answer 8

factors in the environment that favor successful reproduction; the ability to live is reduced for those individuals not possessing those traits Example: In a dry desert climate, only organisms that can live without water for long periods can survive under this “pressure”

Question 9

What are the limits all species live in?

Answer 9

• 1. physiological stress due to some environmental factor (example: pH, moisture, temperature, nutrients, etc.)
• 2. competition with other species
• 3. predation ( includes parasites and disease)
• 4. luck (sometimes surviving a catastrophe is just luck)

Question 10

Critical Factor

Answer 10

the single environmental factor closest to a tolerance limit for a given species at a given time (proposed by Justus von Liebig in 1840)

Question 11

Tolerance Limit

Answer 11

maximum and minimum levels beyond which a particular species cannot survive or is unable to reproduce (proposed by Victor Shelford)

*In some species, like the pupfish, the tolerance limits are different for adults and young fish/eggs.

Question 12

Indicators

Answer 12

the presence or absence of species can be used to judge environmental conditions Example: lichens are sensitive to sulfur dioxide, therefore if there are no lichens, there is probably sulfer dioxide in the area

Question 13

Habitat

Answer 13

place or set of environmental conditions in which a particular organism lives

Question 14

Ecological Niche

Answer 14

either the role played by a species in a biological community or the total set of environmental factors that determine a species distribution (can be multidimensional)

There are two types of niches:

• fundamental
• realized

Question 15

What is the difference between a fundamental niche and a realized niche?

Answer 15

The fundamental niche is the entire set of conditions that an species could live and reproduce in. The realized niche is the set of condtions that the species actually uses due to reasons like competition or predation.

Question 16

Habitat Specialists

Answer 16

have more exacting habitat requirements, tend to have lower reproductive rates, and care for their young longer

*Less resilient to environmental change

Question 17

Endemic

Answer 17

not found anywhere else; highly specialized to exist in a unique habitat (the Serow of Taiwan)

Question 18

Competitive Exclusion Principle

Answer 18

no two species can occupy the same ecological niche for long; the one that is more efficient in using available resources will exclude the other (proposed by G. F. Gause)

Question 19

Resource Partitioning

Answer 19

a form of niche evolution that allows several species to utilize different parts of the same resource and coexist within a single habitat or even utilize the same part of the habitat, but at different times

Question 20

Speciation

Answer 20

the development of a new species

Question 21

Geographic Isolation (Allopatric Speciation)

Answer 21

this occur when a species becomes separated due to some type of physical barrier or social behavior

Question 22

Sympatric Speciation

Answer 22

the formation of a new species because of chromosomal changes; doubling or quadrupling of chromosome numbers; this is associated with genetic drift

Question 23

Genetic Drift

Answer 23

ensures that DNA of two formerly joined populations eventually diverge

Question 24

What are the types of selection pressures?

Answer 24

• Directional Selection
• Stabilizing Selection
• Disruptive Selection

Question 25

Stabilizing Selection

Answer 25

Narrows the range of a trait. For example, 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, so the plants are maintained at a medium height.

Question 26

Directional Selection

Answer 26

The population’s trait shifts toward one extreme over the other. For example, using the familiar example of giraffe necks, there was a selection pressure against short necks, since individuals with short necks could not reach as many leaves on which to feed. As a result, the distribution of neck length shifted to favor individuals with long necks.

Question 27

Disruptive Selection

Answer 27

In disruptive selection, selection pressures act against individuals in the middle of the trait distribution. For example, imagine a plant of extremely variable height that is pollinated by three different pollinators, one that was attracted to short plants, another that preferred plants of medium height and a third that visited only the tallest plants. If the pollinator that preferred plants of medium height disappeared from an area, medium height plants would be selected against and the population would tend toward both short and tall, but not medium height plants.

Question 28

Vancomycin

Answer 28

evolution is still at work today, especially with germs. Germs evolve rapidly and become resistant to antibiotics. So, vancomycin is the treatment of last resort because if resistance were to become widespread, we would have no protection from infections

Question 29

Taxonomy

Answer 29

the study of types of organisms and their relationships

Question 30

Binomials

Answer 30

last two names for organisms; genus and species; names are in Latin. Ex. Human – Homo sapiens; Corn – Zea mays

Question 31

What are the six kingdoms of life?

Answer 31

There are 6 kingdoms of life: animals, plants, fungi, protists, bacteria and archaebacteria.

Question 32

Competition

Answer 32

an antagonistic relationship within a biological community; resources may be in limited supply requiring organisms to compete for them

Examples of limited resources are:

• energy and matter in usable forms (including food)
• living space
• sites for specific activities.

Question 33

Intraspecific Competition

Answer 33

competition between
organisms of the same species.

Question 34

Interspecific Competition

Answer 34

competition between
organisms of different species

Question 35

What are some ways intraspecific competition is reduced in a species population?

Answer 35

• the young of the year disperse
• species exhibit strong territoriality and force offspring or trespassing adults out of the vicinity
• species accomplish resource partitioning between generations

Question 36

Producers

Answer 36

photosynthetic plants and algae (usually)

Question 37

Consumers

Answer 37

*anything that eats organic matter created by other organisms

include herbivores (plant eaters), carnivores (meat eaters),
omnivores (plant and meat eaters), scavengers (eats only dead animals/plants), detritivores (eats decaying organic material), and decomposers (break down dead or decaying organisms).

Question 38

Predator

Answer 38

any organism that feeds directly on another living organism

*As prey species mature, their predators will change

*predators will change prey is another food source becomes more abundant

Question 39

Predation

Answer 39

one organism benefits through receiving nutrition and there is no benefit to the host or prey.

Question 40

Predator-mediated Competition

Answer 40

a superior competitor in a habitat builds up a larger population than its competing species; predators of the superior competitor take note and increase their hunting pressure on the superior species, reducing its abundance and allowing the other weaker competitor to increase in numbers

Question 41

What are some adaptations that help avoid predation?

Answer 41

• Toxic chemicals
• Body armor
• Extraordinary speed
• Ability to hide (camo)
• Plants may have thorns, spines, thick bark, bad tastes, or secrete harmful chemicals.

Question 42

Coevolution

Answer 42

two species (predator and prey especially) exert selective pressure on each other and gradually evolve new features or behaviors together

Example, predators become better at searching and feeding and prey become better at escaping and avoiding

Question 43

Batesian Mimicry

Answer 43

harmless species may resemble poisonous or
distasteful ones to avoid getting eaten

Example: Monarch Butterfly (bad taste to birds) and the Viceroy Butterfly (which can look like Monarch Butterfly)

Question 44

Mullerian Mimicry

Answer 44

two species look alike and both are unappealing (like dead leaves) or dangerous (like similar looking bright colored poison frogs); both benefit because predators learn to avoid either species

Question 45

Symbiosis

Answer 45

2 or more species living closely together; sometimes the relationship can most of the time be helpful or it can be harmful to at least one of the species. They often enhance the survival of one or both partners.

Question 46

Mutualism

Answer 46

a symbiotic relationship between individuals in which both species benefit from the association

Example: the acacia ant colonies and the acacia tree

Question 47

Commesalism

Answer 47

type of symbiosis in which one member clearly benefits and the other is apparently neither benefited nor harmed

Example: mosses on trees

Question 48

Parasitism

Answer 48

a form of predation that may also be considered symbiosis because of the dependency of the parasite on its host

Question 49

Keystone Species

Answer 49

a species that plays a critical role in a biological community that is out of proportion to its abundance. it is usually the top predator, but it can be anything from plants, to microbacteria, to a kind of fish

Question 50

What is Primary Productivity and where are the highest and lowest levels of it?

Answer 50

rate of biomass production (it indicates the rate of solar energy converted to chemical energy; 1,000 kcal/m²/year)

Highest Levels: tropical forests, coral reefs, and estuaries (marsh regions)

Lowest Levels: deserts, arctic tundra, high up mountains (anywhere where there are low levels of photosysthesis rates)

Question 51

What percent of light is reflected when it reaches a leaf? And how much is used to produce carbohydrates?

Answer 51

25%-75% is reflected

0.1%-0.2% is used to produce carbohydrates

*most of the light absorbed is converted into heat and lost into the environment

Question 52

What is the difference between abundance and diversity?

Answer 52

Abundance is total number of organisms in a biological community.

Diversity is number of different species, niches, and genetic variation present

Question 53

While moving up from the equator, how are diversity and abundance affected?

Answer 53

Abundance and diversity are usually inversely related. So, while moving from the equator toward the poles, diversity decreases and abundance within species increases .

Example:

the Arctic has huge numbers of insects but few species

Question 54

What two factors affect what the abundance and diversity levels are in an area?

Answer 54

Climate and history are important factors. For example, Greenland had such a harsh climate that the need to survive through the winter or escape to milder climates becomes the single most important critical factor that overwhelms all other considerations and severely limits the ability of species to specialize or differentiate into new forms. All in all, because of its history, it hasn’t had enough time to diversify.

Question 55

What is ecological stucture and what are the types of it?

Answer 55

refers to patterns of spatial distribution of both individuals and populations within a community; it also refers to the relation of a particular community to its surroundings

The types of ecological stuctures are distributed randomly, clumped together, or are in highly regular patterns.

Question 56

Complexity

Answer 56

the number of species at each trophic level and the total number of trophic levels in a community

Example:

If species are clustered with few trophic levels and simple food chains, the complexity will not be high

Question 57

Many biological communities tend to remain relatively stable and constant over time. What are the three kinds of stability or resiliency in ecosystems?

Answer 57

• Constancy (lack of fluctuations in composition or functions)
• Inertia (resistance to perturbations)
• Renewal (ability to repair damage after disterbances)

Question 58

In 1955, what did Robert MacArthur propose?

Answer 58

he proposed that the more complex and interconnected a community is, the more stable and resilient it will be in the face of disturbance because if many species occupy the same trophic level, then if one disappears, the others can just fill in for its place

Question 59

Edge Effects

Answer 59

boundary/relationship between one habitat and another. The boundary is usually sharp and distinct.

Examples: Forest to grassland, ocean to shore

Question 60

Ecotones

Answer 60

the name for the boundary itself between adjacent communities

Question 61

What are the two types of ecotones?

Answer 61

There are closed communities where the boundry is sharply divided, and there are open communities where the boundries are gradual or indistinct.

Question 62

What is the Climax Community?

Answer 62

Communities develop, grow, and change over time. The community that developed last and lasted the longest is the climax community. It is complex and stable.

Question 63

What is Primary Succession?

Answer 63

organisms begin to make home to a location that has been barren. Ex.sandbar, volcanic flow, mudslide, etc.

Question 64

What is Secondary Succession?

Answer 64

an existing community is disturbed and a new one develops

Question 65

What is a pioneer species?

Answer 65

the first “colonists” in primary succession. May be microbes, mosses, lichens, etc.

Question 66

What are disturbances?

Answer 66

any force that disrupts the established patterns of species diversity and abundance, community structure or properties; these forces can be natural or man-made.

Disturbances generally benefit species because it sets back supreme competitors and allows less-competitive species to persist.

Question 67

What effects can an introduced species have on an environment?

Answer 67

Introducing non-native species can cause severe disturbances in an ecological community and can alter the community.

Example: Mongooses in Hawaii were brought to control rats but instead killed native birds

Question 68

Discuss the dangers posed to existing community members when new species are introduced into ecosystems.

Answer 68

New species introduced to an ecosystem can disturb the delicate balance that exists between the original inhabitants. These invasive species sometimes end up dominating existing species and wiping them out, reducing overall biodiversity with not just the extinction of that species, but other species dependent on it too.

Question 69

What is productivity measured by?

Answer 69

Biological Activity

Question 70

Which world ecosystems are most productive in terms of biomass? Which are least productive? What units are used in this figure to quantify biomass accumulation?

Answer 70

The most productive ecosystems are tropical rain forests and estuaries. The least productive ecosystems are desert and open ocean. The units to quantify biomass accumulation are 1,000/kcal/m²​/year.