Presentation on theme: "“Each species here today represents a long chain of evolution and plays a unique ecological role (niche) in the earth’s communities and ecosystems.”"— Presentation transcript:
“Each species here today represents a long chain of evolution and plays a unique ecological role (niche) in the earth’s communities and ecosystems.”
5-1 Origins of Life 1) Chemical Evolution – organic compounds and systems of chemical reactions formed the first cells. (took about 1 billion years!) 2) Biological Evolution – change from single celled prokaryotes single celled eukaryotes multicellular organism HOW DO WE KNOW??? Most left behind fossil records that give us physical evidence of past organisms and their internal structures. Records are incomplete, however, and actually only represent about 1% of all species ever lived.
5-2 Evolution and Adaptations Evolution – change in a POPULATION’S genetic makeup over successive generations (not individuals!) Theory of Evolution- all species descended from earlier, ancentral species Macroevolution Microevolution Long-term, large scale changes from 1 ancestral species to another where older species is lost through extinction. Small genetic changes in a population’s gene pool that are past on to offspring.
Natural Selection - When individuals in a population have certain genetic traits that enhance their ability to survive and pass on these advantageous traits to their offspring. Adaptation- heritable trait that enables the organisms to better survive under environmental conditions. When faced with changing environmental conditions a species will either: 1) adapt through natural selection 2) migrate to areas with more favorable conditions 3) become extinct!
Coevolution - Interactions between 2 populations of different species over a long period of time can lead to changes in their gene pools, like a evolutionary contest of who can produce the most offspring. - Example: Bats and moths (echolocation)
5-3 Ecological Niches & Adaptations Niche– specific role in an ecosystem (occupation) Includes: adaptive traits range of tolerance for physical/chemical conditions (temperature/H 2 O availability) Types/amount of resources specie uses (food, space,etc) How it interacts with nonliving/living components in the ecosystem Role specie plays in energy flow and matter cycling in the ecosystem. HABITAT- physical location where organism lives (address)
5-3 Ecological Niches & Adaptations Fundamental Niche – full potential range of physical, chemical, and biological conditions and resources a species could theoretically use if there was no t direct competition from other species. Realized Niche- specie only occupies part of its fundamental niche to survive and avoid competition Broad vs. Narrow niches = Generalists vs. Specialists
Limits to Adaptations Genetic trait that leads to an adaptation to changes in the environmental condition must already be present in the gene pool. If present, adaptation is limited by reproductive rate. (humans would take thousands to millions of years to adapt!) Fitness Fitness = reproductive success, not strongest!
5-4 Speciation, Extinction, and Biodiversity Allopatric speciation Geographic isolation Reproductive isolation (Physical barrier)(no longer produces fertile offspring) Sympatric Speciation Mutation or changes in behavior no longer allows interbreed in close living species (insects)
Extinction 99.9% of all species that ever existed are now extinct. Background extinction- species disappear at a low rate Mass extinction and mass depletion Extinctions create new opportunities for other species. Adaptive radiation sets in as new species adapt to fill vacated ecological niches in changed environments.
Human Activities are Decreasing Biodiversity Richest areas of biodiversity- tropical forests, coral reefs, and wetlands
5-5 What is the future of evolution? Artificial Selection Selective breeding Genetic engineering Genetically modified organisms (GMO’s) or transgenic organisms Gene splicing Biopharming- using genetically engineered animals to produce a product for human use (hormones, vaccines, antibodies, etc.) Bioethics- governmental regulations and control