Transcript Evolution
Evolution Natural Selection • Definition • Process by which a particular gene (or set of genes) is reproduced in succeeding generations more than other genes. (INFLUENCED BY ENVIRONMENT) • Adaption • Any heritable trait that enables an organism to survive through natural selection and reproduce better under prevailing environmental conditions • Variation • The characteristics in individuals that differ from the typical characteristics of others of the same species. Mutation creates variation. Alan Alda Beak of Finches-Start at 5:45 Ecological Niches and Adaptations • Ecological niche-way or life or role in community or ecosystem • Fundamental niche-full range of physical, chemical, biological conditions and resources it can theoretically use up if it could avoid direct competition from other species. *Niches of competing species overlap • Realized niche- Occupying only part of its fundamental niche in a community or ecosystem. • Generalist species-live in many places, eat variety of foods, tolerate wide environmental condition ranges • Specialist species-occupy narrow niches (prone to extinction) • Under which conditions is it better to be a specialist?? Is there an organism that you would consider the ultimate generalist? Can you name an example of a specialist or generalist, especially from our canoe trip? SPOTLIGHT Cockroaches: Nature’s Ultimate Survivors • 350 million years old • 3,500 different species • Ultimate generalist • Can eat almost anything. • Can live and breed almost anywhere. • Can withstand massive radiation. Figure 4-A Speciation-What causes new species to arise? • Speciation-two species arise from one • https://www.youtube.com/watch?v=8yvEDqrc3XE 1) Geographic isolation- different groups of the same population of a species become physically isolated from one another for long periods • Barrier can be road, lake, mountains, continental shift, volcano 2) Reproductive isolation-mutations and changes by natural selection occur in gene pools of geographically isolated sexually reproducing species. If these species get together again, try to mate and cannot, you have 2 different species. Geographic Isolation Geologic Processes, Climate Change, Catastrophes-They shape evolution • Geology • Asteroids (catastrophe) • Caused mass extinctions BUT provided opportunities for evolution by natural selection for existing species. Example of sustainability of biodiversity. • Earthquakes • Separate or isolate populations. Can lead to new species. • Volcanoes • Destroy habitats, wipe out populations, lava can yield soil that provides a habitat • Tectonic plate movement-influences climate and determines where plants and animals can live. • Movement allowed species to move, adapt to new environments and form new species. • Joining continents, species can disperse and adapt to new environments • Moving continents-populations must evolve isolated or become extinct. Biodiversity Hotspots • Let’s share some of our findings from yesterday and review why biodiversity is so important. Importance of Biodiversity • Importance of Biodiversity • Economy: Provides food, medicine, textiles (cotton) • Ecological services: controlling weeds and pests, pollination of flowers, cleans water, atmospheric regulation, nutrient cycling • Recreational value: provides recreation activities, encourages tourism ($), high aesthetic value • Scientific value: provides organisms in which to study (humans gain knowledge) What have we done to protect the biodiversity on the planet?? • Endangered Species Act • 1973 signed by President Nixon • Identifies and protects species that are threatened and endangered • Protection of species from: • Poaching, import/export, harassing, harming, trapping, killing, collecting, possessing, selling etc. • • • • Penalizes violators (fine) Designs protection plants Reintroduces species Protecting habitat Extinction: Lights Out • Extinction occurs when the population cannot adapt to changing environmental conditions. • Causes of extinction: The golden toad of Costa Rica’s Monteverde cloud forest has become extinct because of changes in climate. • Habitat loss • Overexpoitation (hunting/fishing) • Invasive species • Climate change Cenozoic Era Period Quaternary Millions of years ago Today Tertiary 65 Bar width represents relative number of living species Extinction Extinction Mesozoic Cretaceous Jurassic 180 Extinction Species and families experiencing mass extinction Current extinction crisis caused by human activities. Many species are expected to become extinct within the next 50–100 years. Cretaceous: up to 80% of ruling reptiles (dinosaurs); many marine species including many foraminiferans and mollusks. Triassic: 35% of animal families, including many reptiles and marine mollusks. Triassic 250 Extinction 345 Extinction Permian Paleozoic Carboniferous Permian: 90% of animal families, including over 95% of marine species; many trees, amphibians, most bryozoans and brachiopods, all trilobites. Devonian: 30% of animal families, including agnathan and placoderm fishes and many trilobites. Devonian Silurian Ordovician Cambrian 500 Extinction Ordovician: 50% of animal families, including many trilobites. Fig. 4-12, p. 93 Effects of Humans on Biodiversity • The scientific consensus is that human activities are decreasing the earth’s biodiversity. Figure 4-13 Human Evolution-What was the driving force? • http://www.pbslearningmedia.org/resource/clim10.sci.ess.watcyc.ev oclimate/climate-and-human-evolution/ • Savannah hypothesis vs. Variability Selection Hypothesis Beaks of Finches-Natural Selection Activity • Objective: To determine which “tool” that represent beaks of finches is best suitable to pick up seeds with. • You are working in groups of 3 • In notebook: Looking at the objective, devise a problem for this lab. • After reviewing the tools, write a hypothesis for your lab. (make sure it is in an IF-THEN-BECAUSE statement) • Read through the lab and in your groups of 3 and create a data table that records number of trials and seeds taken. • Follow directions in lab. I will be time keeper. Keep your tools to yourself, and do NOT attempt to hurt your classmates (although competition in the wild is another thing…)