Exam 4

Question 1

Population size (N)

Answer 1

the total number of individuals

Question 2

Population density

Answer 2

the number of individuals within a specific area or volume

Question 3

Two characteristics used to describe and understand populations

Answer 3

Population size and density

Question 4

Four factors impacting population size

Answer 4

Births
Deaths
Immigration
Emigration

Question 5

Population dispersion patterns

Answer 5

show the spatial relationship between members of a population within a habitat at a particular point in time

Question 6

Three types of population dispersion

Answer 6

Uniform
Random
Clumped

Question 7

Demography

Answer 7

the statistical study of population changes over time: birth rates, death rates, and life expectancies

Question 8

Life tables

Answer 8

Divides the population into age groups and often sexes, and show how long a member of that group is likely to live

May include the probability of individuals dying before their next birthday

Question 9

Cohort

Answer 9

individuals of the same age

Question 10

Factors included in life tables

Answer 10

the probability of individuals dying before their next birthday (i.e., theirmortality rate)

the percentage of surviving individuals dying at a particular age interval

their life expectancy at each interval

Question 11

Survivorship curves

Answer 11

the distribution of individuals in a population according to age

Type I, II and III

Question 12

Type I survivorship curve

Answer 12

death primarily occurs in the older years

Humans and mammals

Question 13

Type II survivorship curve

Answer 13

death at any age is equally probable

birds

Question 14

Type III survivorship curve

Answer 14

very few survive the younger years, but after a certain age, individuals are much more likely to survive

trees

Question 15

Fecundity

Answer 15

the potential reproductive capacity of an individual within a population

Question 16

Fecundity in animals

Answer 16

fecundity is inversely related to the amount of parental care given to an individual offspring

Question 17

Plants with low fecundity

Answer 17

produce few energy-rich seeds (such as coconuts and chestnuts) with each having a good chance to germinate into a new organism

Question 18

Plants with high fecundity

Answer 18

usually have many small, energy-poor seeds (like orchids) that have a relatively poor chance of surviving

Question 19

Early Reproduction - Fecundity

Answer 19

likely produce more offspring, but it is often at the expense of the parent’s lifespan

Question 20

Late Reproduction - Fecundity

Answer 20

to better provide for themselves and their offspring, but they risk not surviving to reproductive age

Question 21

Semelparity

Answer 21

a species reproduces only once during its lifetime and then dies

Question 22

Iteroparity

Answer 22

species that reproduce repeatedly during their lives

Question 23

How does the fecundity of Drosophila
melanogaster differ from that of our own species?

How does the survivorship curve of D. melanogaster differ from that of our own species?

Under what circumstances would a male of D. melanogaster be most likely to choose a large female as a mate?

(Be sure to identify what about the male influences its behavior, as well as the biologically-relevant feature of large females.)

Answer 23

Males have shorter lifespans when they are able to mate allowing more time for mating. Larger females had twice as much fecundity. Limited sperm was spent after repeated sexual encounters.

Mating reduces lifespans which is different than human survivorship curves.

Males typically mate with larger females when they have limited resources (sperm) to increase their likelihood of offspring.

Question 24

Variables in population growth models

Answer 24

N = population size
t = time
r or r(max) = Intrinsic rate of growth
K = carrying capacity

Question 25

Model of exponential growth (equation)

Answer 25

dN
___ = rN
dT

‘d’ refers to ‘derivative’ in reference to a function of calculus

Question 26

Model of logistic growth (equation)

Answer 26

dN (K - N)
___ = r(max) * N ________
dT K

The expression “K – N” indicates how many individuals may be added to a population at a given stage.

Question 27

Comparing the models (J and S shape)

Answer 27

When resources are unlimited, populations exhibit exponential growth, resulting in a J-shaped curve.

When resources are limited, populations exhibit logistic growth.

In logistic growth, population expansion decreases as resources become scarce, and it levels off when the carrying capacity of the environment is reached, resulting in an S-shaped curve.

Response lag can occur when examining species with longer generation times (see next slide)

Question 28

Density-dependent factors

Answer 28

Predation, inter- and intraspecific competition, accumulation of waste, and diseases

Usually, the more dense a population is, the greater its mortality rate.

Question 29

Density-independent factors

Answer 29

Weather, natural disasters, pollution (made by other species), and other chemical/physical conditions.

They occur and influence population growth rate no matter what its density.

Question 30

K-selected species

Answer 30

Adapted to stable, predictable environments.

Whales are considered K-selected species as they live long, mature late, and provide long-term parental care to few offspring.

Question 31

r-selected species

Answer 31

Adapted to unpredictable or changing environments.

Dandelions and jellyfish are both considered r-selected species as they mature early, have short lifespans, and produce many offspring that receive little or no parental care.

Question 32

Categorizing interspecific interactions

Answer 32

competition, exploitation, and positive

Question 33

Competition

Answer 33

(-/-)

Two or more species compete for a resource in short supply

Question 34

Exploitation

Answer 34

(+/-)

One species benefits by feeding upon other species which is harmed

Predation
Herbivory
Parisitism

Question 35

Positive interactions

Answer 35

(+/+ or +/0)

One species benefits while the other benefits or is NOT harmed

Mutualism (+/+)

Commensalism (+/0)

Question 36

Competitive exclusion principle

Answer 36

Two species cannot occupy the same niche in a habitat.

In other words, different species cannot coexist in a community if they are competing for all the same resources.

Question 37

Resource partitioning

Answer 37

Behavioral adaptations in potentially competing species serve to keep them out of competition when members of each species rely on different resources in the habitat

May include food, water sources, light intensity, territory, etc

Question 38

ecological niche

Answer 38

to the sum of living conditions required/adapted to by members of a particular species

Question 39

generalist strategy

Answer 39

broad ecological niche

Question 40

specialist strategy

Answer 40

narrow ecological niche

Question 41

fundamental niche

Answer 41

If you were to experimentally remove all species except one, then you might hypothesize that the remaining species would expand to occupy its fundamental niche, which is only available in the absence of competition.

Question 42

realized niche

Answer 42

how each species present and how they satisfy their needs in a natural habitat

Question 43

‘developmental plasticity’ or ‘phenotypic plasticity’

Answer 43

A variable developmental outcome that shifts in response to external stimuli

the variability is an adaptation

Question 44

Character displacement

Answer 44

different developmental outcomes in the face of competition

Question 45

Herbivory may appear less brutal that predation, and that could have biological consequences. Why?

Answer 45

Organisms exploited by herbivores often survive the interaction, but those exploited by predators do not

Herbivores may serve as vectors of pollen and seed for the organisms they exploit

Question 46

Exploitative interactions and complex adaption

Answer 46

Tend to place very strong selective pressures on one of the species involved. This tends to result in remarkable adaptations that tend to reduce the intensity of exploitation.

Question 47

Defense against predation

Answer 47

Colors may naturally adapt over time (eg: strawberry poison dart frog with red uses aposematic coloration to signify its toxins)

Batesian mimicry occurs when a harmless species mimics the coloration of a harmful species, as is seen with the (a) bumblebee and (b) bee-like robber fly

Several unpleasant-tasting Heliconius butterfly species share a similar color pattern, an example of Müllerian mimicry

Question 48

Parasitism

Answer 48

Exploitation of a host by a parasite. Parasites may be ectoparasites or endoparasites, depending on whether they occur inside or outside the body of the host.

The ideal parasite never causes the death of its host. As a parasite species adapts to its host species, the parasite becomes less likely to kill its host. Pathogens tend to follow this evolutionary trend as well.

Question 49

Suppose two species compete in a shared habitat. One is a generalist, with a relatively broad ecological niche. The other is a specialist, with a relatively narrow ecological niche. Make some informed predictions about the following: a) Which is more likely to have its realized niche match its fundamental niche? b) Which is more likely to exhibit character displacement? c) Why are generalists more vulnerable to competitive exclusion?

Question 50

Keystone species

Answer 50

those that, when present, enhance the overall diversity of a community to a greater degree

Question 51

Foundation species

Answer 51

those that provide/alter the physical structure of the habitat to a greater degree

Question 52

Dominant species

Answer 52

most numerous, or contribute the greatest biomass, in a community

Question 53

Invasive species

Answer 53

those that tend to overtake habitat and competitively exclude others to a greater degree

Question 54

Ecological succession

Answer 54

A community-level process in which species diversity and composition present in a habitat changes over time

Question 55

Primary succession

Answer 55

when new habitat is available for colonization for the first time

Question 56

Secondary succession

Answer 56

habitat is available in response to disturbance that changes an existing habitat

Question 57

Stages of 1st succession

Answer 57

Pioneer
Dryas
Spruce
Alder

Question 58

Stages of 2nd succession

Answer 58

Pioneer
Intermediate
Climax

Question 59

The examples of invasive species are various. One thing they have in common is they are generally not native to the community in which they are invasive. How does such an ecological circumstance enhance their ability to succeed as an invasive species? Thinking beyond ecological circumstance, what is a biological/life-history characteristic(s) that makes an invasive species well-suited to such a role?

Answer 59

Ecological:
–Generalist Adaptations
–Lack of Natural Predators or Competitors
–Optimal Environmental Conditions

Biological and life-history characteristics:
–High Genetic Variability
–Ability to Disperse
–Fast Reproduction and Growth Rates: