some species (generalist feeders) adapt to environmental changes %%better%% than other species (specialist feeders)
^^generalist species^^: thrive in dynamic environments; can adapt well (broad niche)
can live in a variety of environments
%%broad%% range of ecological tolerance (no specific diet or habitat)
usually known for being invasivespecies
ex. raccoons, mule deers, rats, bald eagles
^^specialist species^^: thrive in stable environments; easily struggle or succumb to changes in habitat (narrow niche)
only live in specific conditions
%%narrow%% range of ecological tolerance (limited diet, conditions, and habitat)
ex. giant pandas, mountains gorillas, osprey
3.2 K-Selected & r-Selected Species
^^K-selected species^^: large, quality > quantity in offspring, long life spans, late maturation can reproduce multiple times, specialists, large body types, strong competition in their particular environments
%%high levels of competition%% for resources in the habitat
%%more prone%% to the colonization of invasive species
can %%maintain the population%% at carrying capacity (adjusting population to utilize resources efficiently)
ex. giant pandas, elephants
^^r-selected species^^: small, quantity > quality in offspring, early maturation, reproduce only once, generalists
%%low competition%% for resources in the habitat
prone to %%overpopulation%% by exceeding the carrying capacity
can experience %%population dieback%% due to overpopulation
ex. mosquitos, invasive species
^^biotic potential^^: max ideal reproductive rate of a population (measurement of growth capacity in populations)
ex. 1-2 cubs for giant pandas
many species have characteristics of both K-selected and r-selected species
ex. osprey, frogs, sea turtles
3.3 Survivorship Curves
^^survivorship curve^^: displays the relative survival rates of a group of same-age individuals in a population
^^x-axis^^: max lifespan of organisms from birth to death
^^y-axis^^: percent of surviving organisms in a population (logarithmically)
Types of Survivorship Curves
==Type I==: late loss
a %%large number%% of the population survives throughout their lifespan, reaching old age
dies at the end of their lifespan
adequate care → increasing chances of survival to maturation
represents many ^^K-selected species^^
ex. mountain gorillas
==Type II:== constant loss
death rate %%constant%% from birth to death
organisms die throughout their lifespan
ex. birds, squirrels
@@Type III@@: early loss
surviving rate %%drops immediately%% after birth; few organisms survive to adulthood
little to no care → high infant mortality
represents many ^^r-selected species^^
ex. monarch butterflies
3.4 Carrying Capacity
>=carryingcapacity → resource depletion → famine, disease, and conflict
^^carrying capacity^^: max number of organisms the environment can support without resource degradation
represented as a horizontal dotted line at the top of the graph labeled K
^^population dieback^^: decrease in population as a result of resource degradation caused by overpopulation in species
exceeding carrying capacity → population dieback → within carrying capacity
ex. reindeer of st. matthew island
3.5 Population Growth and Resource Availability
^^environmental resistance^^: factors that limit population growth
emerges after the population goes over carrying capacity
%%exponential growth%% = unlimited resources
occurs in all populations below carrying capacity (competition does not greatly affect population growth)
%%logistic growth%% = limited resources
occurs in populations at or above carrying capacity when competition is a dependent variable
^^fecundity^^: ability to produce offspring
including factors such as maturation age, reproductive rate, biotic potential, and reproductive strategy
Types of Environmental Resistance Factors
^^density-dependent resistance factors^^: biotic, affects organisms when population density is ==high==
ex. competition, predation, parasitism
^^density-independent resistance factors^^: abiotic, affects all populations ==regardless of size or density==
ex. natural disasters or droughts
3.6 Age Structure Diagrams
another name for %%population pyramid%%
shows the distributionofages in a population divided by males and females
shapes represent trends within the population
@@x-axis@@: # of individuals (left side male right side female)
@@y-axis@@: center of the diagram showing age groups
^^reproductive^^: 0-14 years
^^reproductive^^: 15-45 years
^^post-reproductive^^: 46-100+ years
higher proportion of young people = rapid population growth (bottom heavy)
wide base, pyramid shape
indicates %%developing nation%%
ex. india, brazil, nigeria, mexico
higher proportion of middle-aged people: stable population growth (middle heavy)
rectangular shape
similar percentages throughout all age groups
indicates %%more developed nations%%
ex. united states, sweden, canada, austrailia
higher proportion of elder people: declining population growth (top heavy)
inverted pyramid shape
many people in the post-reproductive stage
%%more economic and social development%%, higher education common
long-term impact on social services
ex. japan, germany, italy, russia
3.7 Total Fertility Rate
%%TFR%%: avg # of children a woman has during her childbearing years (15-49)
been lowering in recent years depending on the country
ex. world avg = 2.5
developing countries: ^^TFR > 2.1^^
rapid population growth
ex. niger, congo, uganda
developed countries: ^^TFR <= 2.1^^
stable/declining population growth
ex. united states, japan, united kingdom
@@Societal Factors@@
age of first pregnancy
educational opportunities for women
family planning resources
governmental regulations
access to healthcare resources
3.8 Human Population Dynamics
%%thomas malthus%% → all populations have a carrying capacity
humans are limited by density-independent & density-dependent factors
^^density-independent factors^^: affects population regardless of size or density
ex. storms, fire, heat waves, droughts
^^density-dependent factors^^: affects population based on size or density
arises during overshoot and dieback → decreasing overpopulation
ex. disease transmission, territory size, food availability, access to clean air and water
^^doubling time^^: the amount of time a population takes to double at a constant growth rate
calculated using rule of 70
@@rule of 70@@: 70/r = doubling time
r = growth rate of population (%)
Environmental Problems
density-independent factors
hurricanes → drop in population due to property damage, economic loss, and better opportunities elsewhere
more years a woman is in school = lower TFR
Societal Factors
%%birth rates%%:
high rate = rapid population growth
low rate = slow population growth
^^death rates^^:
high rate = slow population growth
low rate = rapid population growth
^^education of women^^:
high rate = slow population growth
low rate = rapid population growth
i^^nfant mortality^^:
high rate = slow population growth
low rate = rapid population growth
%%age of marriage%%:
early - rapid population growth
late - slow population growth
%%nutrition%%:
better = rapid population growth
worse = slow population growth
3.9 Demographic Transition
%%demographic transition%%: model that shows trends in CBR, CDR, and total population
derived from historical data
moving towards industrialization from agricultural-based economies