Test 44/7- When did the earth form?o 4,500 million years ago- Bacteria and Aracheao Earliest organismso 3.5 billion years agoo Prokaryote- How did earth’s atmosphere change about 2.5 years ago?o Accumulation of atmospheric oxygen from photosynthetic cyanobacteria- First eukaryote organism appearedo 1,500 million years ago- Protisto Both multicellular and unicellularo Eukaryotic- Animals1. Eat other organisms2. Move at some stage in life3. Multicellularo Deuterosomes  Anus formed 1st Bilateral Symetryo Protostomes Mouth formed first Bilateral symmetryo Organs/no organso Radial Symmetry- Chordateso Members that use to be underwatero Characteristics Notochord o Spinal cord Dorsal hollow nerve cord - Spinal cord Pharyngeal sites - Use to have to breathe underwater (gills) Post-anal tailo Includes: Tunicates- Invertebrate Lancelets- Invertebrate  Vertebrates- Have backbone and craniumo Fishes without jaws or paired fins Tail fin propels organism Feed by attaching mouthparts to preyo Fishes with jaw and paired fins Fins provide controlled movement Jaw allows for seizing and chewing prey- Transition of vertebrae’s from water to lando 4 major evolutionary changes1. Respirationa. Transferred from gills to lungsb. Evolved from swim bladder found in ray-finned fish2. Gravitya. Required structural support to resist gravityb. Limbs evolved from jointed finsc. Vertebrae’s modified to transmit body weightd. Example: Amphibian – half in water half on land3. Egg Desiccationa. Required egg that resisted drying outb. Created amniotic eggi. Waterproof egg shellii. Prevented drying out- Ectothermic vs. endothermico Ectothermic Body temperature controlled by external conditions- Ex. Sun Scales Ex. Snakes, lizards, reptiles, dinosaurso Endothermic Body temperature maintained using heat from cellular respiration- Mammalso Endothermic o Have vertebraeo Hairo Produces milko Monotremes Lay eggs Milk young using hairo Marsupials Give birth to immature young Young completes development in pouch Ex. Kangaroo, possumo Placental mammals Placenta nourishes young in uterus Milks young with nipples- Not chordate o Invertebraeo 95% of animals are invertebrates- Arthropodso 75% of animal specieso Characteristics Segmented body- Head- thorax- abdomen Exoskeleton Jointed appendageso Ex. Insects, arachnids, crustaceans, millipedes4/9- Ecologyo Scientific study of interactions between organisms and their environmento NOT same as environmentalismo Two major components1. Abiotica. Non-living componentsb. Ex. Rocks, water, sunlight, wind2. Biotica. Living organismsb. Ex. Trees, insects, fungus- 4 levelso organismal ecology (smallest level) studies adaptions organisms use to survive in their abioticenvironmentso Habitat Place where an organism normally loves Often determined by abiotic factorso 3 types of adaptation allow organisms to adjust to changes in their environment1. Physiological responses (evolution)a. Short-term (Goosebumps)b. Long-term i. called acclimationii. can take days or weeks2. Anatomical responses (evolution)a. Change in body shape or structure3. Behavioral responses (not evolution)a. Most animals move to a new locationo Population Ecology Focuses on factors that influence a populations:- Size- Growth rate- Density The dispersion pattern of a population is the way individuals are spaced within the population’s geographical range- Clumpedo Individuals concentrated in resource-rich areas- Uniformo Occurs when individuals are territorial- Randomo Occurs when no factor is bringing individuals together or pushing them apart Populations increase due to births and immigration Populations decrease due to deaths and emigration Population grows when births and immigration outnumberdeath and emigration Two ways to model population growth1. Exponential growth modela. Growth under ideal conditionsb. The larger the population, the faster it growsc. J-shaped growth curve2. Logistical growth modela. Describes population growth that is gradually reduced as the population nears the environments carrying capacityb. Growth within limitsc. More realistic conditionsd. Environmental factors will cause a population’s growth to level ofe. S- shaped growth curvef. Carrying capacity- Population size at which growth is zero- Varies depending on species and habitat- *At carrying capacity, the population is as large as it can get in its current environment- Density dependent factorso The growth rate slows as it reaches the carrying capacity because of this Food supply Habitat for living and breeding Parasite and disease risk Predation risk- Density independent factorso Include natural disasters such as floods, earthquakes, and fireso Limit population size4/11- Age pyramido Shows number of individuals in each age groupo To determine if population will continue to grow, you have to know how many people are past, before, or in the prime ages to reproduce- Human population crasho Earth’s carrying capacity for humans is unknown Not clear if resources will support our peak population sizeo 1700s Human population on Easter Island outgrew its resources and crashedo One reason carrying capacity for humans is difficult to estimate is that we can increase it in a variety of ways Expanding into new habitats Increasing the agricultural productivity of the land Finding ways to live at higher densities4/14- Frog deformityo Scientist have narrowed down to three causes:1. Increases UV-B radiation2. Chemical pollution (such as pesticide)3. Trematode parasites- Communityo Group of species living close enough together for potential interactions- Niche *o Ways an organism uses the environmento Their complete way of living The space required Type and amount of food Timing of reproduction Temperature/water needs Influence on competitors, etco Species can compete with other species for parts of a nicheo Fundamental niche Full range of environments in which they can live Overlap of fundamental niches leads to competition, with two possible outcomes1. Competitive exclusiona. One species within the niche utilizes resources more effienctly, driving the other species to local extinction2. Resource partitioninga. The species each alter their use of the niche, dividing the resourcesb. Occurs due to character