Limiting Factors QQ How are population sizes limited?

QQ#1: Review: Explain the difference between these two graphs in relation to population growth

How Can population Growth be slowed? As a populations carry capacity limits the population’s size based on the amount of resources present. Population sizes can also be limited by two types of factors called limiting factors

QQ#2: what do you think the difference between these two factors are? Two types of limiting Factors Density Independent Factors limiting factors that do not depend upon a population’s size. Density Dependent Factors limiting factors that depend upon the population size. The “density” of a population is determined by how many individuals are living in a set amount of space QQ#2: what do you think the difference between these two factors are?

Density Independent Factors Density Independent Factors are limiting factors that do not depend upon a population’s density. Examples include: Natural Disasters (i.e. earthquakes) Seasonal Variation (i.e. drought) Human activities such as deforestation

Density Dependent Factors Unlike density independent factors, these will play are larger or smaller part in limiting growth depending on how dense the population is. Examples include: Competition Predation Parasitism Disease

Competition When populations become crowded (more dense) organisms compete They compete for food, water, space, sunlight, and other essentials. Competition among members of the same species is a density-dependent limiting factor. QQ#3: what kinds of things do you think individuals of the same species compete for?

Predation Populations in nature are often controlled by predation The regulation of a population by predation takes place within a predator-prey relationship, one of the best-known mechanisms of population control

QQ#4: explain what trends you notice between the predator and prey relationship below in regards to population sizes

Parasitism and Disease QQ#5: Why do you think Disease is considered a density dependent limiting factor? A parasite lives in or on another organism (the host) and consequently harms it Parasites/Diseases can limit the growth of a population by killing their hosts Parasites/disease are more easily spread in highly dense populations

Check for Understanding (you do not need to write these) A limiting factor that affects all populations in similar ways regardless of their size might be drought. disease. predation. crowding.

Check for Understanding Within a limited area, if the population of a predator increases, the population of its prey is likely to increase. decrease. remain about the same. become extinct.

Check for Understanding Which of the following is a density-independent factor affecting populations? predation disease a destructive hurricane parasites