Interactions in Populations Chapter 14 Habitat and Niche

Interactions in Populations Chapter 14

Habitat and Niche Ø Habitat l All the biotic and abiotic factors in an area where an organism lives Ø Niche l All the physical, chemical, and biological factors needed to survive

Habitat and Niche • Competitive Exclusion Principle Two species competing for the same resources l One will be better suited than the other l One species will be pushed into another niche l

Habitat and Niche Ø Secondary Outcomes of Competitive Exclusion l Niche Partitioning • Dividing the niche so two species can share l Evolutionary Response • Divergent evolution could take place to allow two species to survive

Habitat and Niche Ø Ecological Equivalants Similar species with similar niches in different geographical regions l Sign of convergent evolution l Emerald Tree Boa – South America Green Tree Python - Australia

Community Interactions l Competition – when organisms try to use the same ecological resources • Resources – any necessity of life • Interspecific Competition • Intraspecific Competition

Community Interactions l Predation – one organism captures and feeds on another • Predator • Prey

Community Interactions l Symbiosis – any relationship where two species live closely together

Community Interactions • Mutualism – both species benefit

Community Interactions • Commensalism – one species benefits the other is unharmed

Community Interactions • Parasitism – one species benefits and the other is harmed

Population Density and Distribution Ø Characteristics of Populations Geographic distribution – the area inhabited by a population l Population density – the number of individuals per unit area l

Population Density and Distribution ØPopulation Dispersion l The amount populations are spread out in relation to one another • Clumped • Uniform • Random

Population Density and Distribution Ø Survivorship Curves l Number of individuals surviving over time • Type III

Population Density and Distribution Ø Type I Common among large mammals l Low infant mortality l Generally long life l

Population Density and Distribution Ø Type II Birds, small mammals, some reptiles l Constant threat of death l

Population Density and Distribution Ø Type III Invertebrates, fish, amphibians, plants l High infant mortality rate l

Population Growth Patterns Ø Population Growth – birth rate, death rate, or migration Immigration – the movement into an area l Emigration - the movement out of a area l

Population Growth Patterns Ø Exponential Growth – individuals reproduce at a constant rate Ø Under ideal conditions, a population will grow exponentially.

Population Growth Patterns Ø Logistic Growth – populations growth slows or stops following a period of exponential growth l Carrying capacity – the largest number of individuals that the environment can support • Population Crash

Population Growth Patterns Ø Limiting Factors – something that causes population growth to decrease

Population Growth Patterns Ø Patterns of Population Growth l Demography – the scientific study of human populations

Population Growth Patterns l Demographic Transition – a dramatic change in the birth and death rates • U. S. , Europe, and Japan • China and India

Population Growth Patterns l Age Structure • What does it mean if there are lots of older people? • What does it mean if there are lots of younger people?

Population Growth Patterns Ø Future Population Growth Is the human population increasing? l Will the human population continue to increase forever? l What factors will cause the human population to slow? l

Population Growth Patterns Ø Density-dependent factors – limiting factor that depends on population size

Population Growth Patterns Ø Density-independent factors – factors that affect all populations regardless of size Weather l Natural disaster l Seasons l Human activities l