14.1 Habitat and Niche KEY CONCEPT Every organism has a habitat and a niche.

A habitat differs from a niche. 14.1 Habitat and Niche A habitat differs from a niche. A habitat is all aspects of the area in which an organism lives. biotic factors abiotic factors An ecological niche includes all of the factors that a species needs to survive, stay healthy, and reproduce. food abiotic conditions behavior

Resource availability gives structure to a community. 14.1 Habitat and Niche Resource availability gives structure to a community. Species can share habitats and resources. Competition occurs when two species use resources in the same way. Competitive exclusion keeps two species from occupying the same niche.

14.1 Habitat and Niche Competitive exclusion has different outcomes. One species is better suited to the niche and the other will either be pushed out or become extinct. The niche will be divided. The two species will further diverge.

14.1 Habitat and Niche Ecological equivalents are species that occupy similar niches but live in different geographical regions. Madagascar South America

14.2 Community Interactions Predation occurs when one organism captures and eats another.

14.2 Community Interactions There are three major types of symbiotic relationships. Mutualism: both organisms benefit

14.2 Community Interactions There are three major types of symbiotic relationships. Commensalism: one organism benefits, the other is unharmed Human Our eyelashes are home to tiny mites that feast on oil secretions and dead skin. Without harming us, up to 20 mites may be living in one eyelash follicle. Demodicids Eyelash mites find all they need to survive in the tiny follicles of eyelashes. Magnified here 225 times, these creatures measure 0.4 mm in length and can be seen only with a microscope. + Organism benefits Ø Organism is not affected Commensalism

14.2 Community Interactions There are three major types of symbiotic relationships. Parasitism: one organism benefits, the other is harmed Organism benefits _ Organism is not affected Hornworm caterpillar The host hornworm will eventually die as its organs are consumed by wasp larvae. Braconid wasp Braconid larvae feed on their host and release themselves shortly before reaching the pupae stage of development. Parasitism +

14.2 Community Interactions There are three major types of symbiotic relationships. Parasites meet their needs as ectoparasites (such as leeches) and endoparasites (such as hookworms)

14.3 Population Density and Distribution KEY CONCEPT Each population has a density, a dispersion, and a reproductive strategy.

14.3 Population Density and Distribution Population density is the number of individuals that live in a defined area. Population density is a measurement of the number of individuals living in a defined space. Scientists can calculate population density.

14.3 Population Density and Distribution Geographic dispersion of a population shows how individuals in a population are spaced. Population dispersion refers to how a population is spread in an area. Clumped dispersion Uniform Random

14.3 Population Density and Distribution There are three types of dispersion. clumped

14.3 Population Density and Distribution There are three types of dispersion. uniform

14.3 Population Density and Distribution There are three types of dispersion. random

14.3 Population Density and Distribution Survivorship curves help to describe the reproductive strategy of a species. A survivorship curve is a diagram showing the number of surviving members over time from a measured set of births.

14.3 Population Density and Distribution Survivorship curves can be type I, II or III. Type I—low level of infant mortality and an older population common to large mammals and humans Type II—survivorship rate is equal at all stages of life common to birds and reptiles Type III—very high birth rate, very high infant mortality common to invertebrates and plants

14.4 Population and Growth Patterns KEY CONCEPT Populations grow in predictable patterns.

14.4 Population and Growth Patterns Changes in a population’s size are determined by immigration, births, emigration, and deaths. The size of a population is always changing. Four factors affect the size of a population. immigration births emigration deaths

Population growth is based on available resources. 14.4 Population and Growth Patterns Population growth is based on available resources. Exponential growth is a rapid population increase due to an abundance of resources.

14.4 Population and Growth Patterns Logistic growth is due to a population facing limited resources.

14.4 Population and Growth Patterns Carrying capacity is the maximum number of individuals in a population that the environment can support. A population crash is a dramatic decline in the size of a population over a short period of time.

Ecological factors limit population growth. 14.4 Population and Growth Patterns Ecological factors limit population growth. A limiting factor is something that keeps the size of a population down. Density-dependent limiting factors are affected by the number of individuals in a given area.

14.4 Population and Growth Patterns Density-dependent limiting factors are affected by the number of individuals in a given area. predation competition parasitism and disease

14.4 Population and Growth Patterns Density-independent limiting factors limit a population’s growth regardless of the density. unusual weather natural disasters human activities

14.5 Ecological Succession KEY CONCEPT Ecological succession is a process of change in the species that make up a community.

Succession occurs following a disturbance in an ecosystem. 14.5 Ecological Succession Succession occurs following a disturbance in an ecosystem. Succession regenerates or creates a community after a disturbance. a sequence of biotic changes damaged communities are regenerated new communities arise in previously uninhabited areas

14.5 Ecological Succession There are two types of succession. primary succession — started by pioneer species

14.5 Ecological Succession There are two types of succession. secondary succession — started by remaining species