ecology and evolution exam 2 Flashcards
What is a population? How are populations measured or assessed?
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.
Compare ubiquitous and endemic species.
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
Population crash
a sudden and dramatic decline in the number of individuals within a population.
Endemic distribution
Narrow geographic distribution ex. Florida jay, shale barren, polar bears
Geographic range
area encompasses all individuals of species
Carrying capacity
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.
Environmental stochasticity
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.
Demographic stochasticity
random fluctuations in population size due to chance events affecting individual births, deaths, or reproductive success, especially in small populations.
Migration
coordinated movement of entire population without change in population size
affects population fitness
Dispersal
movement of individuals through space, movement away from each other, one way ticket, hazy predictability
affects individual fitness
Subpopulation
local groups of organisms of same species
Metapopulation
populations linked by dispersal, gene flow, common climate change
Life history
refers to the set of traits and strategies an organism follows throughout its life, including patterns of growth, reproduction, and survival.
Intraspecies competition
between members of the same species
How does density influence population abundance?
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.
Contrast 3 types of population distributions – uniform, clumped, and random. Recognize each from images of real or theoretical populations.
uni-evenly spaced, negative
interactions - competition, predation,
territoriality
clumped- individuals occur in groups -
patches around resources, ramets
random- positions independent of each
other
Explain three methods for estimating population size.
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.
How is reproduction linked to evolution? To changing population abundance?
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.
What are benefits and costs associated with sexual and asexual reproduction?
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
What are the three trade-offs that must be balanced against current reproduction efforts for any organism?
Balance passing on genes now with future
survival
Balance passing on genes now with future
fecundity
Balance passing on genes now with future growth
Why is bigger size better for reproduction? (2 reasons, at least)
size = more resources
make offspring
* Size = age
* Older more experience
* Survival to older age = fitness
When is early sexual maturation selected for? When is later maturation selected for?
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.
Contrast r, K, and periodic life histories (give an example of each too).
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
What is exponential growth? When does it occur? Understand the exponential growth equation and recognize graphs of it.
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:
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(
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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
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.
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:
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=
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−
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N(t)=
1+(
N
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K−N
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−rt
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Where:
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N(t) = population size at time
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t
𝐾
K = carrying capacity
𝑁
0
N
0
= initial population size
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r = intrinsic growth rate
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e = Euler’s number
Under the logistic growth model, when is a population growing the fastest?
Under the logistic growth model, a population is growing the fastest when it is at approximately half of its carrying capacity (K)
Beside birth and death, how can populations size change?
immigration, emigration, environmental factors, predation, and competition
Give examples of density-independent and density-dependent influencers of population size & growth.
DI- climate change, and natural disasters
DD- competition and predation
How does age structure of population influence population growth? If I give you an age pyramid, can you predict population growth, stabilization or decline?
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.
How can gender ratio of population be informative to ecologists?
ecologists can gain valuable insights into population health, reproductive success, and ecological dynamics, aiding in effective management and conservation strategies.
Interspecies competition
between number of different species
Limiting resource
resource whose scarcity limits population of growth ex: sunlight exposure
Exploitation competition
individuals compete for shared resources and are equally affected by competition
Interference competition
a direct interaction where one individual or species negatively affects another’s ability to access resources, such as food, mates, or territory.
Home range
area used during year for growth and reproduction
Floaters
quickly inhabit open territories
Minimum viable population size
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.
Extinction vortex
a downward spiral where small populations become increasingly vulnerable to genetic, demographic, and environmental factors, leading to further declines and eventually extinction.
Minimum dynamic area
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.
Allelopathy
chemicals released by plants inhibit germination and establishment of others
Complete competitors
one species eliminates another and result is exact same niches
Gause’s Exclusion Principle
two species in same environment with exact same niches
What is a survivorship curve? Define the three types and give example organism with each type of survivorship curve.
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
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.
Compare and contrast dispersal and migration on population and individual organism scales.
What drives dispersal?
often driven by competition
What drives migration?
often driven by conditions and resources such as temp., food availability, and predation
What does Levins metapopulation model allow ecologists to do?
Predict metapopulation dynamics
What are three applications of Levins metapopulation model to real-world population dynamics?
What are five warnings, or caveats, to consider when applying Levins metapopulation model?
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
Define competition. List several limiting resources.
when one organism uses a resource at the expense of another
limiting resource: sunlight exposure, food, water resources, space, shelter, and mates
What are the three consequences of intraspecies competition to individuals? Give an example of each impact from class.
- impacts are density dependent
-individuals - or +
-population sizes - or +
What are the four mechanisms of intraspecies competition – how does competition actually manifest in organisms?
- comp. triggers stress
-comp. increases dispersal
-comp. alters social behaviors
-comp. increases territoriality
What is a territory, what is it good for, and how may it be defended?
defended home range, exclusive access to resources
ex: song calls, intimidation displays, attacks, chases, scent markings
Describe six types of interspecies competition – consumption, preemption, overgrowth, chemical interaction, territoriality & encounter and give an example of each.
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
What is a competition coefficient and how does it modify the logistic population growth model when interspecies competition is present?
look this up
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?
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.
Contrast extinction, competitive exclusion, and resource partitioning. Give an example of each.
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.
Give an example of environmental conditions varying over space or time to allow for species co-existence.
time: Hawks are diurnal and hunt during the day.
space: The Cape May warbler feeds on insects at the top of the tree.
Compare fundamental and realized niches.
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
