Human Population and Demographics

• Human population refers to the number of people living in an area.
• The world population is over 8 billion, expected to reach 9 billion by 2037 and potentially 10 billion by 2056.
• Population growth is often described as exponential, with a constant annual growth rate percentage.
• Crude birth rate, crude death rate, and crude growth rate are commonly stated per 1,000 individuals.
• A population is a group of individuals of the same species living and interbreeding in an area.
• Population demographics (demography) involves collecting and analyzing statistical factors influencing population growth or decline.

Demographic Parameters

• Population size
• Density
• Age structure
• Fecundity (birth rates)
• Mortality (death rates)
• Sex ratio

Human Population Growth

• Innovation and industrialization has increased access to energy, food, water, and medical care, leading to rapid population expansion.
• Technological and societal innovation is needed to support the world's population while addressing climate and environmental changes.

Effects of Human Population Expansion on the Earth System

• Increases the extraction of environmental resources, including minerals, plants, water, wildlife, and fossil fuels.
• Leads to the release of waste and toxins that degrade air and water quality, endangering human and species health.
• Increases the use of fossil fuels for electricity, industrial processes, and transportation.
• Increases the use of freshwater for industrial activities, agriculture, recreation, and drinking.
• Increases the environmental impact on ecology by destroying forests and habitats for urban areas and farmland.
• Can reduce species populations, geographic ranges, biodiversity, and change organism interactions.
• Increases fishing and hunting, reducing the numbers of exploited species.
• Increases the spread of invasive species through the import and export of supplies.
• Increases the spread of illnesses due to densely populated areas and easier transportation.

Biodiversity

• Biodiversity is the variety of life on Earth, including all species in a specific area or environment.
• Scientists estimate around 8.7 million species of plants and animals exist, with only approximately 1.2 million identified.
• Species develop unique characteristics over generations, distinguishing them from others.
• Different species can no longer procreate with one another due to their divergent evolutionary paths.
• Tropical regions with warm, humid climates support ecosystems with the greatest biodiversity.
• Some regions, like parts of Mexico, South Africa, Brazil, the southwestern United States, and Madagascar, have greater biodiversity.
• Hotspots are places with exceptionally high biodiversity levels and endemic species.
• All species on Earth cooperate for survival and ecosystem preservation.

Threats to Biodiversity

• Human consumption and activities disrupt or destroy ecosystems.
• Population expansion, pollution, and climate change threaten biodiversity.
• Extinction rates have increased, with scientists predicting half of all species may become extinct in the next century.
• Conservation measures are required to maintain biodiversity and safeguard endangered species and their habitats.

Taxonomy

• Taxonomy is the branch of biology that classifies all living things.
• Carolus Linnaeus developed the system in the eighteenth century.
• Linnaeus invented binomial nomenclature, giving each organism a genus and species name
• He also developed the taxonomic hierarchy with eight ranks: domain, kingdom, phylum, class, order, family, genus, and species

Taxon

• A taxon is a group of organisms classified as a unit (specific or general).
• Examples of taxonomic ranks are species and order.

Biological Communities

• Biological community refers to all the living components in an ecosystem
• biota which refers to all flora and fauna, or plant and animal life, in a particular region.

Predation

• A biological interaction where one organism captures and kills other organisms, its prey.
• Is one of the known modes of feeding behaviors that includes parasitism and micropredation and parasitoids.

Symbiotic Relationship

• Any close and long-term biological interaction between two different organisms.
• The organisms, each termed a symbiont, may be of the same or different species.

Mutualism

• Biological and ecological interaction where both organisms benefit from each other
• One of the known ecological interactions

Parasitism

• A symbiotic relationship between species, where one organism, the parasite, lives on or in another organism, the host
• It causes the host some harm, and is adapted structurally to this way of life.

Keystone Species

• Introduced by Robert T. Paine in 1969
• A species relative to its abundance has a disproportionate effect on its natural environment.

Biological Communities

• A population consists of all individuals of a single species that exist together at a given place and time.
• A species is a single type of organism that can interbreed and produce fertile offspring.
• All of the populations living together in the same area make up a community.
• An ecosystem is made up of the living organisms in a community and the nonliving things, the physical and chemical factors, that they interact with.
• Living organisms within an ecosystem are its biotic factors and the physical and chemical features are abiotic factors.
• Abiotic factors include resources living organisms need, such as light, oxygen, water, carbon dioxide, good soil, and nitrogen, phosphorous, and other nutrients.

An Organism Niche

• A species' way of making a living is called its niche.
• An organism’s habitat is where it lives.
• Important characteristics of a habitat include climate, the availability of food, water, and other resources, and other factors, such as weather.

Biological communities

• A community is the biotic part of an ecosystem
• It consists of all the populations of all the species in the same area.
• It also includes their interactions.
• Species interactions in communities are important factors in natural selection.
• Three major types of community interactions: predation, competition, and symbiosis.

Predation

• A relationship in which members of one species (the predator) consume members of another species (the prey).

Competition

• A relationship between organisms that strive for the same resources in the same place.
• Intraspecific competition occurs between members of the same species
• Interspecific competition occurs between members of different species

Symbiosis

• A close relationship between two species in which at least one species benefits.
• Three basic types of symbiosis: mutualism, commensalism, and parasitism.

Food Chain

• Arrangement of the organisms according to the order of predation in which one uses another as a food source.
• Shows the flow of energy in an ecosystem.
• The trophic level refers to the position of organisms in the food chain.
• A food web shows interlocking food chains.
• Community dynamics are the changes in community structure and composition over time, often following environmental disturbances.
• Communities with a relatively constant number of species are said to be at equilibrium.

Succession

• Describes the sequential appearance and disappearance of species in a community over time after a severe disturbance.
• In primary succession, newly exposed or newly formed rock is colonized by living organisms.
• In secondary succession, apart of an ecosystem is disturbed and remnants of the previous community remain..

Human Impacts

• Human activity is directly responsible for hundreds of extinctions in the last two centuries.
• Human impact on the environment has become one of the main topics all over the world.

Overview of human population dynamics, including size, density, and age structure. Discusses factors influencing population growth such as birth rates, death rates, and sex ratio. Highlights the impact of innovation and industrialization on rapid population expansion.