Ecosystems
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Ecosystems. Chapter 2:. 2.1 Everything is Connected. Scientists don’t yet completely understand how the environment works because it is so complex and interconnected Human actions have unexpected effects on the environment (ex: Borneo in Southeast Asia; pesticide DDT)

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Ecosystems

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Ecosystems

Chapter 2:


2.1 Everything is Connected

Scientists don’t yet completely understand how the environment works because it is so complex and interconnected

Human actions have unexpected effects on the environment (ex: Borneo in Southeast Asia; pesticide DDT)

The unfortunate chain of events on Borneo occured because the living things were connected to each other


What is an Ecosystem?

  • An ecosystem includes all the different organisms living in a certain area, along with their physical evironment (ex: coral reef, wetlands)

  • Ecologists think of an ecosystem as an isolated unit, but ecosystems usually do not have clear, cut boundaries; things move from one ecosystem to another (ex: birds fly from one ecosystem in summer to another in winter)

  • Ecosystems contain both biotic factors (living parts: animals, plants) and abiotic factors (nonliving parts: temperature, sunlight, soil type)

  • All parts work together in an ecosystem, if one part is destroyed, the entire ecosystem can be affected


Organism

  • An organism is one individual living thin)g (ex: an ant, an ivy plant, a gorilla)

  • A species is a group of organisms that are able to produce fertile offspring and share common genes, therefore, resemble each other (ex: all humans, domestic dogs)


Population

  • A population is a group of individuals of the same species living in a particular place (ex: the bullfrog population of a pond, the lion population of a savanna)


Community

  • Organisms don’t exist in isolation, neither does a population, every population is a part of a community

  • Communities are all the living inhabitants of interacting populations of different species living in an ecosystem (ex: a pond community includes the different plants, fish, insects, amphibians, microorganisms the live in and around the pond)


Niche and Habitat

  • Niche is an organism’s way of life (ex: a lion eats other animals (gazelle, zebra); the leftovers are consumed by scavengers (vultures, hyenas, bacteria, insects); the lion itself is also food to ticks, fleas, mosquitoes

  • An organism’s relationship with its environment, both the living and the nonliving

  • Niche includes when and how often it reproduces, how many offspring it has, what time of day it is most active, where it finds food; it’s “lifestyle”

  • Habitat is the actual place on organism lives (ex: lion’s habitat is a savanna, cactus’s habitat is a desert); it’s “address”


2.2 How Species Interact with Each Other

Ecosystems are made up of biotic and abiotic components

The biotic components – organisms – affect one another

The five major types of interactions are: predation, competition, parasitism, mutualism and commensalism


Predation

  • In predation, one organism kills and eats another organism

  • The organism that is eaten is called the prey

  • The organism doing the eating is called the predator

  • Examples: lions feeding on zebras; cougars eating deer; snakes consuming mice; birds eating insects; blue whale feeding on tiny krill

  • Predators tend to feed on young and weak individuals; as prey decline, predators either feed on other organisms or die


Competition

  • Competition occurs when two or more organisms of the same or different species attempt to use the same limited resource

  • Examples: Lions and hyenas fighting over the same carcass; two plants fighting for a limited amount of sunlight

  • Species can fight over the same resource and never see one another, ex: one insect feeding on a certain plant during the day and another who feeds on that same plant during the night; because they use the same food source, the two species are competitors


Parasitism

  • Parasites are organisms that live in or on another organism and feed on it without immediately killing it; parasitism is the relationship between the parasite and its host

  • Examples: ticks, fleas, tapeworms, viruses, blood-sucking leeches, mistletoe

  • Organism the parasite takes nourishment from is known as the host

  • The difference between parasitism and competition is that the parasite does not immediately kill their host; it lives in or on the host most of its life; and the parasite weakens its host making it more vulnerable for predators


Mutualism

  • Mutualism is the cooperative partnership between two species in which both species benefit

  • Examples: clownfish and the sea anemone; bacteria in your intestines; acacia tree covered in ants in Central America (when the ants were removed, the tree suffered)


Commensalism

  • Commensalism is the rarest and strangest type of species interaction

  • It is the relationship in which one species benefits and the other is neither harmed or helped

  • Example: sharks and remoras


2.3: Adapting to the Environment

Organisms tend to be well suited for their natural environment

Ex: Kangaroo rats are suited for areas with very little water (desert): never need to drink water, eliminate very little water, active at night


Evolution by Natural Selection

  • Scientists want to how the close match between organisms and their environment came about. Charles Darwin, 1859, proposed an answer. He observed that members of a population differ from each other in form, physiology and behavior; some differences are due to heredity (passed from generation to generation)

  • Environment influences which individuals have offspring; certain traits allow some individuals to survive and have offspring

  • Natural selection describes the unequal survival and reproduction from the presence or absence of particular traits; over the years, characteristics change over time

  • Evolution is a change in the genetic characteristics of a population from one generation to the next


Evolution by Natural Selection…con’t

  • Ex: a herd of deer live in lowland areas with warm climate; some become separated in the high mountains where the temperatures are cold most of the year; many die in the cold; the survivors might have thicker fur; they go on to reproduce with offspring having the desirable trait; this is an adaptation (an inherited trait that increases and organisms chance of survival and ability to reproduce)


Coevolution

  • An organism’s environment includes both the abiotic and the biotic aspects

  • When two or more species evolve in response to each other, it is called coevolution

  • Can be found between predator (enables them to find, subdue and capture prey) and prey (enables them to avoid, escape and fight off predators); ex: crabs (predator) and marine snails (prey); plants and herbivores


Extinction

  • The irreversible disappearance of a population or a species is called extinction

  • When the last individual of an organism dies, the species is considered extinct

  • This is a natural process but humans are causing species to disappear at an alarming rate


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