Bio 171 Reading Pg 1 12 Chapter 1 Organism 12 14 2012 A life form living entity made up of one or more cells 5 fundamental characteristics o energy acquire and use energy o cells organisms are made up of membrane bound units called cells The membrane regulates passage of materials between o information process hereditary or genetic information interior and exterior encoded in genes o replication everything a organism does is to replicate o evolution organisms are products of evolution The Cell Theory observations cells Theory explanation for a very general class of phenomena or All organisms are made of cells and all cells come from preexisting The Theory of Evolution by Natural Selection Evolution change in the characteristics of a population over time Natural Selection occurs when two conditions are met o Individuals within a population vary in characteristics that are heritable traits can be passed on to off spring Population is a group of individuals of same species living in the same area at the same time o In a particular environment certain versions of traits help individuals survive better or reproduce more than do other Evolution occurs when heritable variation leads to differential versions success in reproduction Fitness means the ability of an individual to produce offspring high fitness means production of many surviving offspring Adaptation trait that increases the fitness of an individual in a particular environment 2 central unifying ideas 1 The cell is the fundamental structural unit in all organisms 2 All species are related by common ancestry and have changed over time in response to natural selection Speciation natural selection has caused populations of one species to diverge and form new species All species come from preexisting species all species past or present trace their ancestry back to a single common ancestor Should be able to create a Tree of Life Phylogeny actual genealogical relationship tribe source To determine this they used RNA rRNA molecule found in all organisms Eukaryotes cells that have a nucleaus multicellular Prokaryotes no nuclease typically unicellular usually bacteria and archaea Taxonomy effort to name and classify organisms Domains 3 in life bacteria Archaea and Eukarya Phylum is a major branch in the tree of life Scientific name organisms genus and species designation Genus group of closely related species 995 1012 components Ecosystem all organisms in a particular region along with nonliving abiotic nonliving air water soil biologists study how nutrients and energy move among organisms n through surrounding atmosphere and soil or water Conservation biology effort to study preserve and restore threatened populations communities and ecosystems Types of Aquatic Ecosystems Biotic living components are members of the same or different species Abiotic temperature precipitation sunlight and wind Physical factors affecting the distribution and abundance of organisms nutrient availability waterdepth and watermovement Nutrient Availability Nutrients are essiential for the growth of photosynthetic species Ocean upwelling o 1 Wind blows in peru the prevailing winds blow north moving water at the surface o 2 Surface water moves as the earth rotates the moving surface water is forced offshore o 3 Upwelling as surface water leaves it is replaced by nutrient laden water welling up from the bottom with upwelling steady anchoveta fisheries are the most productive o nutirents photosynethic cells small grazing animals feed small fish called anchoveta Lake Turnover o Spring and fall turnovers caused by changes in air temp o Winter Stratification Dense 4degree C water at the bottom becomes nutrient rich while colder water near surface becomes oxygenated o Spring Turnover Surface water warms to 4degrees C and sinks carrying O2 down and driving nutrients up o Summer Stratifcation Dense 4C water at the bottom becomes nutrient rich while warmer water near surface becomes oxygenated o Fall Turnover Surface water cools to 4C and sinks carrying O2 down and driving nutrients up o Without fall or spring turnovers most freshwater nutrients would remain on the bottom of lakes These aquatic ecosystems would be much less productive as a result Water Flow Water Depth Water movement is critical factor in aquatic ecosystems because it presents physical challenge literally sweep organisms off their feet Water absorbs and scatters light so the amount and types of wavelengths available to organisms change dramatically as depth increases Light has a major influence on productivity total amount of carbon fixed by photosynthesis per unit area per year Freshwater Environments Lakes and Ponds ponds are small lakes are large enough that the water in them can be mixed by wind and wave action occur in high lattitudes depressions formed by scouring action of glaciers years before Waterdepth o Littoral zone consists of the shallow waters along the shore where flowering plants are rooted o Limnetic zone is offshore and comprises water that receives enough light to support photosynthesis o Benthic zone is made up of the substrate floor o Photic zone regions of the littoral limnetic and benthic zones that receive sunlight o Aphotic Zone regions of pond or lake that do not receive Water movement is caused by wind and temperature Littoral and limnetic zones are warmer better oxygenated than sunlight benthic zone Benthic zone is nutrient rich Cyanobacteria algae plankton live in photic zone Animals that consume detritus abundant in benthic zone Wetlands part of the year shallow water habitats where soil is saturated with water for atleast only have shallow water emergent vegetation plants that grow above the surface of the water they capture sunlight before it hits bogs are stagnant and acidic oxygen poor nutrient poor marshes have non woody plants typically feature grasses reeds the water nutrient rich swamps have trees and shrubs nutrient rich Streams bodies of water that move constantly in one direction o creeks small streams o rivers large streams o variables speed of current availability of oxygen and o most streams shallow enough sunlight reaches the bottom o slow moving streams are relatively oxygen poor but nutrient nutrients rich o rapids are oxygen rich but nutrient poor Estuaries Where rivers meet the ocean fresh water mixes with salt water Highly productive enviroment Salinity varies with o 1 changes in river flows declines when river loods and increases when river ebbs o