Ecology Chapter 3 Biology 15-16

What is life? In order to consider an organism as living, it must have certain characteristics. Living things are made of cells. Living things reproduce Living things have a genetic code Living things grow and develop Living things obtain and use energy Living things respond to their environment Living things maintain homeostasis Living things, as a group, change over time

Living things are made of cells Unicellular = Living things only consisting of one cell. Multicellular = Living things made of 1+ cell. Cell = A collection of living matter enclosed by a barrier to separate it from the surroundings. Smallest unit of life

Living Things Reproduce Living creatures have to be able to produce new organisms. Sexual Reproduction = Cells from 2 different parents unite to form a new organism Asexual Reproduction = The new organism has a single parent

Living Things Have a Genetic Code All living creatures contain a genetic code Mostly DNA

Living Things Grow and Develop All living things have distinct periods of growth and change. Development = A change in amount and type of cells present.

Every Living Things Needs Energy Every Living Organism needs energy to grow, develop, and reproduce. Plants get energy through photosynthesis Animals get energy from eating other organisms. Metabolism = The reactions that enable an organism to build up or break down materials for life processes.

Living things Respond to their Environment Organisms respond to changing light and temperature in their environments. Plant leaves and stems grow toward light. Roots grow down because of their response to gravity.

Living Organisms Maintain Internal Balance Homeostasis = The process used by organisms to keep their internal conditions relatively stable. When you shiver…. When you sweat…

As Groups, Living Things Must be able to Evolve Evolve = Change over time Most noticeable when looking at large amounts of time.

Levels of Organization To understand how organisms interact, scientists have to look at different groupings of animals. Goes from individual animals to the entire biosphere; all life on Earth.

Levels of Organization 1st Level =Molecule These are groups of atoms These are the smallest units of chemical compounds.

Levels of Organization 2nd Level = Cells These are the smallest unit of life.

Levels of Organization 3rd Level = Groups of Cells (Tissue) Groups of Like Cells Example: Nervous Tissue, Muscle Tissue, etc..

Levels of Organization 4th Level = Organism Individual living thing

Levels of Organization 5th Level = Population Groups of individuals that belong to the same species and live in the same area.

Levels of Organization 6th Level = Communities Community = Different populations that live together in a specific area.

Levels of Organization 7th Level = Ecosystem Ecosystem = A collection of organisms that all live in the same place, together with their nonliving environment.

Levels of Organization 8th Level = Biosphere Biosphere – part of Earth that contains all the ecosystems

Interactions Among Organisms There are three major types of interactions among organisms: Competition Predation Symbiosis

Competition What is competition? Different species can share the same habitat and food requirements. Competition is the struggle between organisms to survive as they attempt to use the same limited resource. In any ecosystem, there is a limited amount of food, water and shelter. Organisms that survive have adaptations that enable them to reduce competition. What is competition? What do organisms have to do in order to reduce competition?

Predation What is predation? Predation is an interaction in which one organism kills another for food. The organism that does the killing for food is the predator. The organisms that is killed for food is the prey. What is the relationship between predator and prey?

Predator-Prey competition relationships help maintain stability within an ecosystem. BUT… If a prey population decreases or is eliminated, predator population decreases. Prey population Predator population Likewise, if a prey population increases, predator population increases

Symbiosis What is symbiosis? Symbiosis – is a close relationship between two species that benefits at least one of the species. There are three types of symbiotic relationships: Mutualism Commensalism Parasitism What is symbiosis? What are the three types of symbiotic relationships?

Symbiotic Relationships A. Mutualism A symbiotic relationship in which both species benefit Exp: ants and Acadia trees. Ants protect the Acadia tree by attacking any animal that tries to feed on tree, tree provides nectar and home for ants. Plants and Pollinating Insects

Mutualism One example of a mutualistic relationship is that of the oxpecker (a kind of bird) and the rhinoceros or zebra. Oxpeckers land on rhinos or zebras and eat ticks and other parasites that live on their skin. The oxpeckers get food and the beasts get pest control.

Mutualism Aphids and ants. The aphids secrete a sugary solution called honeydew. Ants drink the honeydew and, in return, they protect the aphids from predators.

Symbiotic Relationships B. Commensalism Commensalism – Is a relationship in which one species benefits and the other species is neither helped nor harmed.

Commensalism What is commensalism? Example – Exp: orchids, ferns, mosses can live on branches of trees and benefit but tree not harmed or benefited Example – The red-tailed hawks’ interaction with the saguaro cactus . The hawks benefit by having a place to build their nests. The cactus is not affected by the hawks. What is commensalism?

A titan triggerfish (Balistoides viridescens) creates feeding opportunities for smaller fish by moving large rocks too big for them to shift themselves.

Symbiotic Relationships C. Parasitism interactions in which a member of one species benefits at the expense of another. Exp: tick on dog, Exp: bacteria host

Parasitism Parasitism – involves one organism living on or inside another organism and harming it. The organism that benefits is called a parasite. The organism that the parasite lives on or in is known as the host.

Parasitism

What Shapes an Ecosystem? Biotic Factors: The living influences on an organism. Example: Organisms it eats, What it competes with for food. Abiotic Factors: The non-living factors that act on organisms. Example: Temperature, Precipitation, and Humidity.

Niche Every organism has a variety of adaptations that are suited to its specific living conditions. A niche is the role of an organism in its habitat, or how it makes its living. A niche includes: Type of food the organism eats How it obtains its food Which other organisms use the organism for food