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Home , Community (ecology), Ecological niche

14.1 And Niche

KEY CONCEPT Every has a habitat and 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 includes all of the factors that a needs to survive, stay healthy, and reproduce. – – abiotic conditions – behavior 14.1 Habitat And Niche

Resource availability gives structure to a . • Species can share and resources. • 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

KEY CONCEPT interact as individuals and as . 14.2 Community Interactions

Competition and are two important ways in which organisms interact. • Competition occurs when two organisms fight for the same limited . – Intraspecific competition – Interspecific competition 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. – : both organisms benefit 14.2 Community Interactions

• There are three major types of symbiotic relationships. – : one organism benefits, the other is unharmed

Commensalism Ø Human Our eyelashes are home to tiny that feast on oil secretions and dead skin. Without harming + Demodicids Eyelash us, up to 20 mites may mites find all they need to be living in one eyelash survive in the tiny follicles follicle. of eyelashes. Magnified here 225 times, these creatures measure 0.4 mm in length and can be seen only with a microscope.

Ø Organism is not affected + Organism benefits 14.2 Community Interactions

• There are three major types of symbiotic relationships. – : one organism benefits, the other is harmed

0 Braconid Parasitism wasp + Braconid larvae _ feed on their Hornworm host and caterpillar release The host hornworm themselves will eventually die as shortly before its organs are reaching consumed the pupae by wasp larvae. stage of development.

_ Organism is not affected 0 Organism benefits 14.2 Community Interactions

• There are three major types of symbiotic relationships. – Parasitism meet their needs as ectoparasites (such as leeches) and endopaasites (such as hookworms) 14.3 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 dispersion

Random dispersion 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 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 . • The size of a population is always changing. • Four factors affect the size of a population. – immigration – births – emigration – deaths 14.4 Population and Growth Patterns

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

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

• 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. 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

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

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

• There are two types of succession. – primary succession — started by 14.5 Ecological Succession

• There are two types of succession. – secondary succession — started by remaining species