Bio test 3: deomgraphy, exponential and logistic growth,

population

all individuals of a species that live and reproduce in a certain place at the same time

• fundemental units of evolution

population ecology

the study of how and why the number of individuals in a population changes over time and space

variation, evolve

darwin recognized that understanding ___ in a population is key to understanding how populations ___

population size 

total number of all individuals of all ages present in a population 

range

geographic distribuiton of a population

• oftin dyamic and influx over time

• influenced by environment: abiotc and biotic factors

abiotic factors

chacteristics of the physical environment

• ex: temperature, precipitation, altitude, continental drift

• “nonliving”

biotic factors

due ot the presence of other species

• Ex: influence habitat, food, or competiton

• “living”

population density

the number of individuals per unit area

• not equally/uniformly dispersed

sessile/stationary organisms

how you count these organisms is to count within a section that can be exxtrapolated to the entire habitat in order to estimate the population size

marker and capture

counting strategy of mobile organisms:

1. researchers catch individuals and mark them with bands, ear tags, etc

2. release the marked organisms and allow them to mix with unmarked animals in the population

3. second trapping

second trapping

percent of marked individuals that are recaptured and recorded

demography

the statustical study of population change over time

• measure births, immigration, deaths, and emigration

• helps predict the future of a population 

births and immigration

what adds to the population

deaths and emigration

what removes fromt he population

life history

of an organism encompases the sequence and duration of the stages that an organism passes through from the beginning to the end of its life

• can be qualitative or quantitative

age structure/class

number of living individuals of each age

• can be followed through time

survivorship

number of individuals of each age likely to survive the following year (the number of surviving organisms from birth →life stage)

• l_x

• N_x/N₀

• opposite of mortality

age specific fecundity

average number of female offspring (daughters) produced by a female of each age

• surviving daughters produced by age class/total number of females of age class present

  • m_x

generation time

average time between a mothers first

life table

summarizes survivorship and fecundity data for a population (usually a cohort of females)

• summarize the quantity of life history of a population

  • the probability that an individual will survive and reproduce in any given time interval over the course of its life

net reproductive rate

measure wheather a population is increasing, decreasing, or staying stable

• calculated by adding all the l_xm_x

increases

when the net reproductive rate R₀>1, population will ___

decrease

when the net reproductive rate R₀<1, population will ___

stable

when the net reproductive rate R₀=1, population is ___

average births/year/female

average number of female offspring produced by females during each stage of life

• survivorship x age - specific female: l_xm_x

Type curve 1

survivorship is high at a young age and drops quickly with old age

humans

type curve 2

individuals have a similar change of ding each year of their life

• birds

type curve 3

high mortality at a young age and a higher survivorship at adulthood

• insects/plants

survivorship curve

• used to compare species, populations, or generations (cohorts)

• if survivorship curves of different cohorts are similar through time, they can be generalized to describe the survivorship of a population

• survivorhsips can be drastically different in different environments—not usually considered a property of a species

• shape is affected by: general life history strategy of a species and evironmental biotic and abiotic factors

integrety and maintenance

what is the first priority or organisms to expend time and energy on?

limited

organisms have a ___ amount of time and energy to expend

maintainging their bodies, defending themselves, reproducing, obtaining new resources

what do organisms use their resources for?

principle of allocation

resources cannot be used for 2 functions simultaneously, so they must be divided up among life functions

trade offs

life history traits are the results of fitness ____

high, low

species with ___ fecundity tend to grow quickly, reach sexual maturity at a young age, and produce many eggs/seeds, and have ___ survivorship

• “live fast die young”

• many offspring

• small offspring

• early maturity

• small body size

• low disease resistancee

• low predator resistance

• short lifespan

ex: mustard seed

high, low

species with ____ survivorship tend to grow slowly and invest resources in traits that reduce damage from enemies and increase their own ability to compete in the environment, and have ___ fecundity 

• few offspring

• large offspring

• late maturity

• large body size

• high disease resistance

• high predator resistance

• long life span

Ex: coconut palm

∆N

population’s growth rate

∆t

change in time

N

total number of individuals in a population

r

per capitia rate of increase

• used to represent births-deaths

r>0

• growing population

• more birth than individual death

r=0

• population is not changing in size

• birth=death

r<0

• population is shrinking

• more death than birth

exponential growth

when r does not change overtime

• assumes that resources are unlimited

  • the ideal situation, but not true all the time in nature because they would only be unlimited for a limited amount of time

• characteristic J shaped curve

• population grows faster as it gets larger

instantaneous change in population size

snapshot of growth in a moment of time

growth rate, poluation size

instantaneous change in population size tells ___, but not ___ at a specific time

proportional, increasing

the population growth rate is ___ to the size of the population, so for fast growing populations N is constantly ___ as the population gets larger and larger, even as r stays the same

intrinsic rate of increase

conditions are optimal for a particular species: birth rates are maxed and death rates are as low as possible

• functions of species life history and trats

• r_max

characteristic, does not

each species has a____ r_max that ____ change

lower, rarely 

r ≤ r_max because the r value is usually much ____ because conditions are ____ optimal 

constant, >0

no matter the value of r, if it is ___ and ___, growth increases exponentially when resources are unlimited

density independent

when exponential growth is occurring, the population size does not limit the growth rate

• occurs when

  • colonization of a new habitat

  • recovery after a disaster

decrease, increase, decline

when population density gets very high, birth rate will ___ and death will ___ causing r to _

Carrying capacity 

max number of individuals in a population that can be supported in a specific habitat over a sustained period of time

• in nature, is a ceiling that is broken

  • populations ocillate around an average carrying capacity

density dependent factors

in a logistic curve, population slows because of ____

logistic growth model

a population’s growth rate increases rapidly in the early stage of rapid growth, slows down as N approaches K and eventually approximates 0

density independent factors

abiotic factors

• variation in weather patters, floods, earthquakes

density dependent factors

affect size or growth of a population as a function of population density

• changes in intensity as a function of population size

• biotic

• Ex:

  • competition for resources

  • disease and parasitism

  • predation

  • toxic waste

  • social behavior

• can be intraspecifc or interspecific

• determine carrying capacity 

intraspecifc

a characteristic of density dependent factors that happens within species

• ex: competition for food

interspecific

a characteristic of density dependent factors that happens between species

Ex: predation and parasitism

increase

__predators as increase of prey density 

competition for resources

food, sunlight, water, territory, oxygen, bestingd

disease and parasitism

health decline because of stress, infectious disease, parasitism

social behavior

stress mediated behavior, dominance behavior, mating behavior, parental care behavior, predation avoidance behavior

toxic waste

ammonia, carbon dioxide, alcohol, uric acid

nature

in ___, population may grow exponenitally for a limited time, but will eventually be limited by resource availability

logisitic growth

a population’s per capita growth rate gets smaller and smaller as population size approaches carrying capacity

• characteristic S curve

• maximum population is imposed by limited resources in nature

technological advances

growth rates jumped with ____ that have increased food production and improved health

• rise of agriculture, vaccines, sanitation, antibiotics, green revolution

factors to why women are having fewer children

• frewer deaths in childhood, women having fewer babies

• greater access to contraception

• more women in education and work