Unit 5 ECOLOGY

Chapter 19 populations

Section 1 understanding populations

Section 1

Understanding populations 2003: human pop ________________ (__________________________________________) 2016: human pop _____________ Caused a _________in many other populations http://www.worldometers.info/world-population/

Properties of populations ________________________________________________________________________________ When studying populations: _______________________________________ ________________________________________

Population size ________________________________________________________________________________ Small area, sessile orgs, can just count Can be difficult to measure if… ________________________________________ Scientists must estimate

Population size Example: population size of oak trees in 10km2 Easiest way: Count 1km2 Estimate the value __________________________________________

Population size The above mentioned method can be used on animals Scientist must assume distribution is the same everywhere Leaves room for error

Population density ________________________________________ ________________________________________________________________________________ Some countries may be more densely populated than others

Facts about thailand The population of Thailand is estimated at _____________________ as of July 1 2014. Thailand's population is equivalent to ______of the total world population. Thailand ranks number _______ in the list of countries by population. The population density in Thailand is _______________________________________

Dispersion ________________________________________________________________________________ Clumped distribution: _____________________ _______________________________________ Uniform distribution: ______________________ ________________________________________ Random distribution: _____________________ ________________________________________

dispersion

dispersion Clumped distribution Uniform distribution Random dispersion ____________________________________________________________________________________ __________________________________________ Uniform distribution Random dispersion

Population dynamics Change in size and composition over time Birth rate is important Death rate is important (______________rate) Life expectancy is important __________________________________________ Thailand 2012: LE = __________________________ USA 2012 LE: _______________________________

Age structure ________________________________________ Presented in graphs In humans: old indiv do not reproduce If human pop has high % of young indiv, potential for rapid growth is high

Age structure Which country will have a bigger pop growth in the future?

Pattern of mortality Mortality tend to follow one of three curves on a graph _______________________________________

Pattern of mortality Type 1: _________________________________ __________________________________________ Type 2: _________________________________ Type 3: _________________________________

Homework section 1

Section 2 measuring populations

Section 2

Measuring populations How do populations grow? What factors limit population growth?

Population growth rate Demographers: __________________________ _______________________________________ Growth rate: ____________________________ ______________________________________ Depends on four processes: Immigration: ________________________________ ______________ _____________________________________________ Emigration: _________________________________ ________________ ________________________________________________

Population size Large pop are divided into groups of _________ Expressed per capita (____________________) Example: 52 births, 14 deaths per 1000 per year Birth rate: _________________________________ Death rate: ________________________________ Growth rate = ___________________________ _________________________growth per capita

Population size Finding the number of new indiv in a year: __________________________________________ If pop is 50 000: ____________________________ Positive number: _____________________________ Negative number: ____________________________

The exponential model Pattern of increase in number due to _______________________________________ Pop will add a larger number of indiv with each generation ____________________________ ________________________________________________________________________________

The exponential model

Applying the exponential model Exponential model matches observed real life patterns under certain conditions and for limited periods of time ________________________________________ Pop cannot grow indefinitely __________________________________________ These factors are called _____________________

Applying the exponential model As pop grows, competition for resources start, __________________________________ __________________________________ Birth rate __________, death rate __________

The logistic model Birth rates & death rates are NOT constant Logistic model builds on exponential model, but includes __________________: _____________ ________________________________________ Graph shape is _______________________

The logistic model Small pop, birth rates _____, death rates ____, pop grows at ________________________ As pop size reaches Carrying Capacity, pop growth slows When pop size reaches Carrying capacity, growth ____________ Logistic growth Assuming Carrying capacity is ______________

The logistic model

Population regulation Limiting factors that control pop size: Density-independent factors: ________________________________________ _________________________________________ Density-dependent factors: ____________________, (__________________________) Triggered by ________________________ ________________________________________________________________________________________________

Population fluctuations All pops fluctuate (rise and fall irregularly) in size Some are linked to environmental changes, some are not (harder to explain)

Population fluctuations

Perils of small populations Perils: serious & immediate danger Rapid growth of human pop has reduced other pops Small pops are ____________________________ Environmental disturbances can kill the ________ Likelihood of inbreeding (___________________) increases: makes them less likely to adapt to environmental changes due to decreased _________________

Perils of small populations

Homework section 2

Section 3 human population growth

Section 3

Human populations growth

History of population growth Homo sapiens = __________________ From 500 000 y.a. until 12 000 y.a. human pop grew very slowly Humans lived in small, nomadic (___________ _________________) groups, hunted and gathered food = __________________________ Few societies left today Low pop growth rate due to _______________ among infants and children (______________________________________)

The development of agriculture 10 000 - 12 000ya humans started domesticating animals & cultivate food Domesticate: _______________________________ ___________________________________________ Cultivate: ___________________________________ ___________________________________________ This change in lifestyle is called _____________________________________

Agricultural revolution Lead to many changes ________________________________________ Resulting in human pop growing faster 10 000ya: ______________________________ 2 000ya: ________________________________

The population explosion

The population explosion 1347-1352 bubonic plague killed _____ of pop Human pop growth accelerated after 1650, ____________________, better _________and _______, ____________, ______________, ______________________________ 1650: ________, 1800: ______, 1930: _______

The population explosion Mortality rates dropped again after WW2, improvements in _________________in poorer countries In just 27 years (1960 - 1987) the human pop grew from ___________________

Population growth today 20% of world pop live in ___________countries (modern, industrialized countries) US, Japan, Germany, France, UK, Australia, Canada, Russia Pop growth is very low: _____________________ 80% of world pop live in ___________countries Most Asian countries, Central America, South America, Africa Pop growing faster: _________________________

Demographic transition Delete this slide for students, only for teacher

Demographic transition

Homework section 3