Biology Chapter 14: Interactions in Ecosystems

Section One: Habitat and Niche Habitat: all the abiotic and biotic factors in the area where an organism lives Ecological Niche: all the physical, chemical, and biological factors that a species needs to survive, stay healthy, and reproduce. Includes food, abiotic conditions, and behavior Also known as the role a species plays in the community (job)

Section One: Habitat and Niche

Section One: Habitat and Niche Competitive Exclusion: when two species compete for the same resources, one species will be better suited to the niche Happens when different species share the same habitat

Section One: Habitat and Niche Niche Partitioning Dividing the niche based on the needs of each organism Ecological Equivalents: species that occupy similar niches but live in different geographical regions.

Section Two: Community Interactions Competition: occurs when two organisms fight for the same limited resources Predation: one organism captures and feeds upon another organism

Section Two: Community Interactions Symbiosis: a close ecological relationship between two or more organisms of different species that live in direct contact with one another Mutualism Commensalism Parasitism

Section Two: Community Interactions Mutualism: interspecies interaction in which both organisms benefit from each other Both organism benefit Ex: Bees and Flowers

Section Two: Community Interactions Commensalism: a relationship between two organisms in which one receives an ecological benefit and the other is not benefitted or harmed Ex: Shark and Remora

Section Two: Community Interactions Parasitism: one organism benefits and the other is harmed Different from predation because the host is not killed Ex: Humans and Mosquitoes

Section Three: Population Density and Distribution Population Density: a measurement of the number of individuals living in a defined space

Section Three: Population Density and Distribution Population Dispersion: the way in which individuals of a population are spread in an area or a volume Clumped Uniform Random

Section Three: Population Density and Distribution Survivorship Curve: a generalized diagram showing the number of surviving members over time from a measured set of births

Section Three: Population Density and Distribution Types of Survivorship Curves Type I: low level of infant deaths and a population that will generally survive till old age Type II: survivorship is roughly equal at all stages Type III: high birth rate and high infant mortality rate

Section Four: Population Growth Patterns What effects population size? Immigration: movement of individuals into a population Births Emigration: movement of individuals out of a population Deaths

Section Four: Population Growth Patterns Based on available resources Exponential growth: when population size increases dramatically over time Logistic growth: populations begin to grow slowly, then go through exponential growth, then slow down and level off Creates an s-shaped curve Occurs because of carrying capacity Carrying capacity: the max number of individuals of a particular species that the environment can support

Section Four: Population Growth Patterns

Section Four: Population Growth Patterns Population crash: a dramatic decline in the size of the population over a short period of time Occurs when the carrying capacity suddenly drops

Section Four: Population Growth Patterns Limiting Factors: a factor the limits population size Density Dependent: factors affected by the number of individuals in a given area Ex: competition, predation, parasitism, disease Density Independent: factors of the environment that limit population growth no matter how large or small it is Ex: unusual weather, natural disasters, human activities

Section Five: Ecological Succession Succession: the sequence of biotic changes that regenerate a damaged community or create a community in a previously uninhabited area Occurs after a disturbance in the ecosystem Two Types: Primary Succession Secondary Succession

Section Five: Ecological Succession Primary Succession: the development of a new ecosystem where there was none before Ex: Volcanic eruptions caused the formation of the Hawaiian Islands Pioneer Species: the first organisms to live in a previously uninhabited area Secondary Succession: the reestablishment of a damaged ecosystem where the soil was left intact Ex: Forests growing back after wild fires

Section Five: Ecological Succession

Section Five: Ecological Succession