Population + Community + Behavioral Ecology

Final exam eco evo unit 2

demography

statistical study of population dynamics over time using a series of mathematical tools to investigate how populations respond to changes in their biotic and abiotic environments: birth rates, death rates, life expectancy

survivorship curve

graph of number of individuals surviving at each age interval plotted versus time (usually with data compiled from a life table). allow us to compare the life histories of different populations

type I survivorship

human and most primates exhibit this type of survivorship curve because a high percentage of offspring survive their early and middle years— death occurs predominantly in older individuals. usually have small offspring at once, high parental care to ensure survival

type II survivorship

birds are an example of ___. also known as intermediate survivorship because they die more or less equally at each age interval. relatively few offspring and provide significant parental care

type III survivorship

many trees, marine invertebrates, and fishes exhibit this type of survivorship because very few of these organisms survive their younger years; however, those that make it to an old age are more likely to survive a relatively long period of time. usually have large number of offspring and little parental care needed.

life history

describes the series of events across its lifetime such as how resources are allocated for growth, maintenance, and reproduction. affects the life table of an organism

• genetically determines and shaped by the environment and natural selection

energy budget

species must balance energy intake with their use of energy for metabolism, reproduction, parental care and energy storage (like hibernation)

fecundity

potential reproductive capacity of an individual within a population.

• how many offspring could ideally be produced if an individual has as many offspring as possible, repeating the reproductive cycle as soon as possible after birth of offspring

• typically a trade-off between investment in fecundity vs parental care

• ex: species that produce many offspring usually provide little to no care to offspring since their energy is going to producing them

• usually creates self sufficient animals at an early age

exponential growth

populations with unlimited natural resources grow very rapidly, presenting ____. when population (N) is plotted over time, a J-shaped growth curve is produced. possible only with infinite resources, not very common in real-world

• example: bacteria reproducing with binary fission (only takes about 1hr) in a sample with perfect conditions, after 3 hours there will be an exponential amount of bacteria

• dN/dT= rN ; r values—> 0= no pop growth, neg= decreasing N, pos= increasing N

r is the intrinsic rate of increase

• dN/dT= 𝑟(max)N for maximum growth of species

logistic growth

…and then population growth decreases as resources become depleted, indicating a ___. models the reality of limited resources.

• formula ads carrying capacity (K) as a moderating force in growth rate

• this means that growth of population slows as population size approaches the carrying capacity

• yields an S-shaped curve and is more realistic model fo long-term population growth than exponential.

• dN/dT= 𝑟N [(K-N)/K]

As N approaches K the growth of the population slows.

carrying capacity

when the growth rate model plateaus or levels off, represents the maximum population size that a particular environment can support

• represented by letter K

S-shaped curve

produced by logistic growth and is composed fo three sections":

1. growth is exponential (few individuals and ample resources)

2. growth rate decreases (as resourced are used up and become limited)

3. growth levels off at carrying capacity of the environment, with little change in population size over time

K-selected species

species selected by stable, predictable environments, tend to exist close to their carrying capacity. same as Type I survivorship

• intraspecific competition is high

• few large offspring, long gestation period, long-term care to offspring

• ex: humans, elephants, plants such as oak trees

r- selected species

species will large number of small offspring. usually in unpredictable or changing environments. same as type III survivorship

• no long-term prenatal care and offspring mature quickly/self-sufficient at birth

• example: marine invertebrates like jellyfish, plants like dandelion

biotic potential

r_max as the maximal potential growth rate of a species

cohort

group of the same age that can be followed through time

density-dependent regulation

regulation of population that is influenced by population density, such as forest fires and volcanic eruptions; usually involves abiotic factors

intrinsic rate of increase

(r): birth rate minus death rate

iteroparity

life history strategy characterized by multiple reproductive events during the lifetime of a species

population cycle

somewhat regular rise and fall in population size

population density

number of population members divided by the area or volume being measured

semelparity

life history strategy characterized by a single reproductive event followed by death

transect

path along which one counts and records occurrences of the objects of study

metapopulation

Species existing as ___ which is a population of

populations, connected by gene flow

population size

number of population members in a habitat at the same time

• modeled by (N)

life table

table showing the life expectancy (and/or other stats) of a population member based on its age

Density-independent regulation

regulation of populations by factors that operate independent of population density, such as forest fires and volcanic eruptions; usually involves abiotic factors

batesian mimicry

a harmless species imitates the warning coloration of a harmful one

• assuming they share the same predators this coloration then protects the harmless ones, even though they do not have the same level of physical or chemical defenses against predation as the organism they mimic

mullerian mimicry

multiple species share the same warning coloration, but all of them actually have defenses

niche

all species have an ecological ___ in the ecosystem, which described how they acquire the resources they need and how they interact with other species in the community

• basically range of resources used and conditions tolerated

competitive exclusion principle

states that two species cannot occupy the same niche in a habitat

• different species cannot coexist in a community if they are competing for the same resources

• this can be avoided is a population evolves to use different resources or different habitats

resource partitioning

when competitive exclusion principle is avoided by animals by making use of a different resource, a different area of the habitat, or feeding during a different time of day

• creates two microniches

intraspecific

competition within same species

interspecific

competition among different species

fundamental niche

theoretical range of environmental conditions that a species can tolerate

realized niche

portion of the fundamental niche that is actually occupied (given limiting factors)

competitive exclusion principle outcomes

since no two species can coexist within a habitat while competing for same resources at same place and time, there will be local extinction of one species or natural selection will favor divergence

local extinction

expected when there is asymmetric competition (one stronger than the other) between two species, one of the two species will no longer exist in that area

character displacement

evolutionary changes in traits that make niche differentiation possible

• happens when animals are sympatric with a competitor (same area)

aggressive mimicry

when a predator mimics a desirable species

mating rituals

mating involves one animal signaling another so as to communicate the desire to mate, the types of energy-intensive behaviors or displays associated with mating are called ___

signals

used by animals to communicate with each other using stimuli

• information containing

• evolved at least in part to convey information, receiver has to modify behavior as response to signal

ex: stickleback fish, red region in lower half of fish signals males to be aggressive and signals females to mate

pheromones

chemical signals

aural

signals by sound or noise, ex: songs by birds, whales and dolphins, crickets

courtship display

types of signals that include visual displays to attract mate. series of ritualized visual behaviors designed to attract and convince a member of the opposite sex to mate

tactile

type of signal that utilizes touch. can include grooming, touching shoulder or root of tail, embracing, lip contact, and greeting contact

pheromones

secreted chemical signal used to obtain a response for another individual in same species. elicits a specific behavior from the receiving individual

axillary steroids

pheromones to which humans respond to, chemicals that influence the perception of other people

aggressive display

visual display by a species member to discourage other members of the same species or different species. display that communicates not only the willingness to fight, but the fighting ability. they signal aggression on the part of the sender, however, they are actually a mechanism to reduce amount of actual fighting that occurs, is it “worth the fight”

distraction displays

designed to attract a predator away from the rest, altruistic behavior; benefits the young more than the individual performing it

deceitful communication

the signaler attempt to exploit the receiver by sending out false signals

negative frequency dependent

successful deceitful signals are usually ___ (discussed in chapter 1)

• when the honest signalers are most common, nat sel will favor the individuals rewarded by behaving normally, hence making deceitful successful

• when the deceitful are most common, nat sel will favor the individuals that can detect and avoid the deceitful

territory

an area that is actively defended and provides exclusive or semi-exclusive use of resources. males control them, to find mates and fitness

• males signal each other, by compressing their body or doing other things like head bobs to signal other males of their territory

• in real life theres a lot of behaviors that ca stop the fight before it happens

ritualized sequential assessment

when two males encounter each other they asses their counterparts, starts with approach, then roaring contest, and either one withdraws due to the loudness of roars or they continue with a parallel walk, if none has drawn yet then they fight (this ends up being less than half of these interactions, one of them usually quits beforehand)

honest signals

their signals have to be real, their roars are honest about their strength.

• displays tend to be honest (cannot be faked)

degree of coordination

usually displays of communication for territoriality involves ___ or cooperation, they have a common interest in obtaining information about each other, theres usually steps they know to follow in order to assess each other

• often a predictable sequence of stereotypical behaviors of increasing intensity

axes of assymmetry

tells you when you should not fight

• one is bigger than the other so bigger will hold more power

value of resource

tells you when/ when not to fight based on how much you value mating, if you already have mated it might no to be as necessary for you.

this can be lower for one of the rivals based on physiology, history, social status therefore he will back out

ownership

tells you when/when not to fight

can motivate you to fight if the territory is already yours and you want to defend it

• non-owners are usually less motivated to fight

foraging

behaviors species use to find food