ecology and evolution exam 2

Question 1

What is a population? How are populations measured or assessed?

Answer 1

A group of individuals of the same species living in a specific area, capable of interbreeding.

Direct Observation: Count individuals in a confined area.
Sampling Techniques:
Quadrat Sampling: Count individuals in random plots.
Mark and Recapture: Capture, mark, release, and recapture to estimate population.
Transect Sampling: Count individuals along a set line.
Population Density: Number of individuals per unit area.
Demographic Data: Track births, deaths, immigration, and emigration.
Growth Models: Use exponential or logistic models to predict population changes.
Remote Sensing: Use drones, satellites to track hard-to-reach populations.

Question 2

Compare ubiquitous and endemic species.

Answer 2

ubiquitous- widespread geographic distribution ex. oak and red maple in North America; Disadvantage: no specialized niche

Endemic- Narrow geographic distribution ex. Florida jay, shale barren, polar bears

Question 3

Population crash

Answer 3

a sudden and dramatic decline in the number of individuals within a population.

Question 4

Endemic distribution

Answer 4

Narrow geographic distribution ex. Florida jay, shale barren, polar bears

Question 5

Geographic range

Answer 5

area encompasses all individuals of species

Question 6

Carrying capacity

Answer 6

the maximum number of individuals of a species that an environment can support sustainably over time. It depends on available resources like food, water, and habitat.

Question 7

Environmental stochasticity

Answer 7

random changes in the environment, like weather variations, natural disasters, or resource availability, that impact population size and survival unpredictably. Both types of stochasticity can lead to population instability or extinction.

Question 8

Demographic stochasticity

Answer 8

random fluctuations in population size due to chance events affecting individual births, deaths, or reproductive success, especially in small populations.

Question 9

Migration

Answer 9

coordinated movement of entire population without change in population size
affects population fitness

Question 10

Dispersal

Answer 10

movement of individuals through space, movement away from each other, one way ticket, hazy predictability
affects individual fitness

Question 11

Subpopulation

Answer 11

local groups of organisms of same species

Question 12

Metapopulation

Answer 12

populations linked by dispersal, gene flow, common climate change

Question 13

Life history

Answer 13

refers to the set of traits and strategies an organism follows throughout its life, including patterns of growth, reproduction, and survival.

Question 14

Intraspecies competition

Answer 14

between members of the same species

Question 15

How does density influence population abundance?

Answer 15

influences population abundance by affecting resource availability, competition, and interactions among individuals. In high-density populations, resources like food and space may become scarce, leading to increased competition, higher mortality, and reduced reproduction. In low-density populations, individuals may have more access to resources, leading to higher survival and reproduction rates. This relationship helps regulate population size and growth.

Question 16

Contrast 3 types of population distributions – uniform, clumped, and random. Recognize each from images of real or theoretical populations.

Answer 16

uni-evenly spaced, negative
interactions - competition, predation,
territoriality

clumped- individuals occur in groups -
patches around resources, ramets

random- positions independent of each
other

Question 17

Explain three methods for estimating population size.

Answer 17

Quadrat Sampling: Count individuals in small plots, then estimate for the larger area.
Mark and Recapture: Mark individuals, release, and recapture to estimate total population.
Transect Sampling: Count individuals along a set line to estimate population.

Question 18

How is reproduction linked to evolution? To changing population abundance?

Answer 18

the process of natural selection. Traits that enhance survival and reproductive success are passed on to future generations, leading to adaptations over time. Reproductive rates directly influence population size. Higher reproduction can lead to population growth, while lower rates may cause decline.

Question 19

What are benefits and costs associated with sexual and asexual reproduction?

Answer 19

benefits of sexual: genetic diversity, natural selection: leads to better traits because of genetic diversity
costs: energy and time and reproductive rate: usually produces less offspring

benefits of asexual: rapid population growth, no need for mates

costs: lack of genetic diversity, limited adaptation

Question 20

What are the three trade-offs that must be balanced against current reproduction efforts for any organism?

Answer 20

Balance passing on genes now with future
survival

Balance passing on genes now with future
fecundity

Balance passing on genes now with future growth

Question 21

Why is bigger size better for reproduction? (2 reasons, at least)

Answer 21

size = more resources
make offspring
* Size = age
* Older more experience
* Survival to older age = fitness

Question 22

When is early sexual maturation selected for? When is later maturation selected for?

Answer 22

early sexual maturation is for High Mortality Rates: In environments with high predation or environmental hazards, early maturation allows individuals to reproduce before they potentially die.

Stable Environments: When resources are plentiful, early reproduction can enhance population growth, maximizing the number of offspring produced.

Later maturation: Low Mortality Rates: In safer environments with lower predation, investing more time in growth can lead to larger body size and increased reproductive success.
Resource Scarcity: When resources are limited, delaying reproduction can lead to better survival of fewer, higher-quality offspring, as individuals can allocate more energy to growth and development.

Question 23

Contrast r, K, and periodic life histories (give an example of each too).

Answer 23

r selected: Invest in as many small offspring as possible with rapid growth. Short lived early maturation. Semelparity-reproducce once or twice in life time ex: white lip shark

k selected:* Invest in large, well-developed young with slow growth
* Long lived, late maturation
* Iteroparity – reproduce many times in life
ex: elephant

Periodic life histories: Invest in many eggs that grow into large, robust adults
* Long lived, early age of maturation
* Modest energy & resources per young
ex: salmon and tuna

Question 24

What is exponential growth? When does it occur? Understand the exponential growth equation and recognize graphs of it.

Answer 24

a rapid increase in a population size where the growth rate is proportional to the current population. This type of growth is characterized by a J-shaped curve when graphed.
N(t)=N
0
​
×e
(r×t)

Where:

𝑁
(
𝑡
)
N(t) = population size at time
𝑡
t
𝑁
0
N
0
​
= initial population size
𝑒
e = Euler’s number (approximately 2.71828)
𝑟
r = intrinsic r

Question 25

What is logistic growth? When does it occur? What is the relationship between logistic population growth & K, carrying capacity? Recognize carrying capacity on graph of logistic population growth.

Answer 25

describes a population growth pattern where the growth rate decreases as the population reaches its carrying capacity (K). This results in an S-shaped (sigmoidal) curve when graphed.
Equation: The logistic growth model is often represented by the equation:
𝑁
(
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)
=
𝐾
1
+
(
𝐾
−
𝑁
0
𝑁
0
)
𝑒
−
𝑟
𝑡
N(t)=
1+(
N
0
​

K−N
0
​

​
)e
−rt

K
​

Where:

𝑁
(
𝑡
)
N(t) = population size at time
𝑡
t
𝐾
K = carrying capacity
𝑁
0
N
0
​
= initial population size
𝑟
r = intrinsic growth rate
𝑒
e = Euler’s number

Question 26

Under the logistic growth model, when is a population growing the fastest?

Answer 26

Under the logistic growth model, a population is growing the fastest when it is at approximately half of its carrying capacity (K)

Question 27

Beside birth and death, how can populations size change?

Answer 27

immigration, emigration, environmental factors, predation, and competition

Question 28

Give examples of density-independent and density-dependent influencers of population size & growth.

Answer 28

DI- climate change, and natural disasters
DD- competition and predation

Question 29

How does age structure of population influence population growth? If I give you an age pyramid, can you predict population growth, stabilization or decline?

Answer 29

The age structure of a population refers to the distribution of individuals across different age groups within a population. This structure has a significant influence on population growth due to the varying reproductive potential, mortality rates, and economic roles of different age groups.

Question 30

How can gender ratio of population be informative to ecologists?

Answer 30

ecologists can gain valuable insights into population health, reproductive success, and ecological dynamics, aiding in effective management and conservation strategies.

Question 31

Interspecies competition

Answer 31

between number of different species

Question 32

Limiting resource

Answer 32

resource whose scarcity limits population of growth ex: sunlight exposure

Question 33

Exploitation competition

Answer 33

individuals compete for shared resources and are equally affected by competition

Question 34

Interference competition

Answer 34

a direct interaction where one individual or species negatively affects another’s ability to access resources, such as food, mates, or territory.

Question 35

Home range

Answer 35

area used during year for growth and reproduction

Question 36

Floaters

Answer 36

quickly inhabit open territories

Question 37

Minimum viable population size

Answer 37

the smallest population size at which a species can sustain itself over a long period of time without facing extinction due to environmental fluctuations, genetic drift, inbreeding, or other risks.

Question 38

Extinction vortex

Answer 38

a downward spiral where small populations become increasingly vulnerable to genetic, demographic, and environmental factors, leading to further declines and eventually extinction.

Question 39

Minimum dynamic area

Answer 39

the smallest area of habitat required to support a population that can sustain itself over time, while accounting for natural disturbances and ecological processes that occur within the ecosystem. The concept is particularly important in conservation biology, where habitat fragmentation or destruction threatens the survival of species.

Question 40

Allelopathy

Answer 40

chemicals released by plants inhibit germination and establishment of others

Question 41

Complete competitors

Answer 41

one species eliminates another and result is exact same niches

Question 42

Gause’s Exclusion Principle

Answer 42

two species in same environment with exact same niches

Question 43

What is a survivorship curve? Define the three types and give example organism with each type of survivorship curve.

Answer 43

Compare populations
- age, gender, conditions, resources
Type 1- strongly convex shape ex: humans, elephants and most mammals

type 2: straight line ex: adult birds, rodents, reptiles, perennial plants

type 3: strongly concave shape ex: insects, oysters, fish, trees

Question 44

Given a life table and the appropriate equations, be able to predict population growth, times of greatest fecundity and times of greatest mortality as in life table application quiz. I will always provide equations.

Question 45

Compare and contrast dispersal and migration on population and individual organism scales.

Question 46

What drives dispersal?

Answer 46

often driven by competition

Question 47

What drives migration?

Answer 47

often driven by conditions and resources such as temp., food availability, and predation

Question 48

What does Levins metapopulation model allow ecologists to do?

Answer 48

Predict metapopulation dynamics

Question 49

What are three applications of Levins metapopulation model to real-world population dynamics?

Question 50

What are five warnings, or caveats, to consider when applying Levins metapopulation model?

Answer 50

1: species are interlinked
2: empty habitat patches are key
3: if colonization rate is very high subpopulations aren’t independent
4: habitat quality matters
5: distance matters

Question 51

Define competition. List several limiting resources.

Answer 51

when one organism uses a resource at the expense of another
limiting resource: sunlight exposure, food, water resources, space, shelter, and mates

Question 52

What are the three consequences of intraspecies competition to individuals? Give an example of each impact from class.

Answer 52

• impacts are density dependent
  -individuals - or +
  -population sizes - or +

Question 53

What are the four mechanisms of intraspecies competition – how does competition actually manifest in organisms?

Answer 53

• comp. triggers stress
  -comp. increases dispersal
  -comp. alters social behaviors
  -comp. increases territoriality

Question 54

What is a territory, what is it good for, and how may it be defended?

Answer 54

defended home range, exclusive access to resources
ex: song calls, intimidation displays, attacks, chases, scent markings

Question 55

Describe six types of interspecies competition – consumption, preemption, overgrowth, chemical interaction, territoriality & encounter and give an example of each.

Answer 55

1: consumption: one species inhibits others by consuming shared resources

2: Preemption: presence or occupancy by one species excludes or preempts presence of others ex: sessile organisms compete for space

3: overgrowth: one species grows over another to inhibit access to resources ex: algae

4: chemical interaction: chemicals inhibit or kill other species (alleolopathy) ex: fire ants

5: territoriality: behavior exclusion of one
species by another in specific, defended space ex: wolves, coyotes, lions and hyenas

6: encounter: non-territorial meetings negative for both
ex: jacks and vultures

Question 56

What is a competition coefficient and how does it modify the logistic population growth model when interspecies competition is present?

Answer 56

look this up

Question 57

Consider the predictions of Lokta-Volterra interspecies competition population growth models. What should be the outcome of competition in most instances? How can stable equilibrium be achieved?

Answer 57

competitive exclusion: one species eliminates another and/ or coexistence: each species inhibits it’s own growth more than the other by intraspecific competition.
Equilibrium can be achieved by resource partitioning, density-dependent factors, environmental variability, and balanced competition dynamics, allowing both species to coexist under certain conditions.

Question 58

Contrast extinction, competitive exclusion, and resource partitioning. Give an example of each.

Answer 58

extinction- rarely observed: ghost of competition past
exclusion: restriction in fundamental niche to realized niche
resource partitioning is a vital mechanism that enables species to coexist by reducing competition through the diversification of resource use, contributing to the overall stability and health of ecosystems.

Question 59

Give an example of environmental conditions varying over space or time to allow for species co-existence.

Answer 59

time: Hawks are diurnal and hunt during the day.
space: The Cape May warbler feeds on insects at the top of the tree.

Question 60

Compare fundamental and realized niches.

Answer 60

fundamental: full range of environmental conditions in which an organism can live and reproduce, n-dimensional.

Realized niche: portion of fundamental niche that a species actually exploits