Biodiversity and Evolution Chapter 4

Core Case Study: Why Should We Care about the American Alligator? Largest reptile in North America 1930s: Hunters and poachers Importance of gator holes and nesting mounds 1967: endangered species 1977: comeback, threatened species

Alligator’s niche Fish, insects, snakes, turtles, birds, etc. live in gator holes during dry weather Old gator nests are used for nesting and feeding sites for herons, egrets, red-bellied turtles Alligators eat gar (fish that eats game fish - bass and bream) Alligators move around and keep open water available and free of vegetation. Keystone species

4-1 What Is Biodiversity and Why Is It Important? Concept 4-1 The biodiversity found in genes, species, ecosystems, and ecosystem processes is vital to sustaining life on earth. The more biodiverse a place is, the more likely its life is to survive changes.  Most important thing you’ll see all semester.

Biodiversity Is a Crucial Part of the Earth’s Natural Capital Vital renewable resource Species diversity – number and abundance of species Ecosystem diversity – variety of ecosystems available Functional diversity – variety of bio and chem processes in ecosystems Genetic diversity – variety of genes and alleles among all species (alleles are versions of genes, remember?)

Natural Capital: Major Components of the Earth’s Biodiversity

Evolution pop quiz Don’t worry, you’ll get an A.

Some student comments about evolution: “I think it is interesting.” “I believe that God made the world to adapt to it’s surroundings.” “It takes a lot of words to get the whole thought.” “It is based in solid science. I do not believe that religion and evolution are mutually exclusive, as I am both religious and supportive of evolution.” “I was raised religiously so evolution is practically a swear word in my house. However, I really enjoy learning about it because it makes sense to me that things change and adapt over time.”

More student comments: “I think that evolution happens to a point but I don’t agree that humans evolved from nothing.” “I don’t like some parts of the study of evolution like people saying we evolved from apes because we didn’t.” “I have a hard time believing we came from monkeys.” “It is interesting, but I don’t believe it. I believe God created all animals and plants.” “I don’t necessarily believe this is how life happened. There have been many ideas contrary to the study.” “It doesn’t answer all of the questions about how the world came about.”

4-2 Where Do Species Come From? Concept 4-2A The scientific theory of evolution explains how life on earth changes over time through changes in the genes of populations. Concept 4-2B Populations evolve when genes mutate and give some individuals genetic traits that enhance their abilities to survive and to produce offspring with these traits (natural selection).

Biological Evolution by Natural Selection Explains How Life Changes over Time Natural selection- (watch on your own time, if you’re interested in who Darwin was.) Charles Darwin Alfred Russel Wallace Tree of Life (By the way, what’s a theory, again??)

Six Major Kingdoms of Species Prokaryotes Eukaryotes Eubacteria Archaebacteria Protists Plants Fungi Animals Cenozoic First humans Mesozoic Extinction of dinosaurs Plants colonize land Paleozoic 500 Origin of multicellular organisms 1,000 1,500 Oldest eukaryotic fossils 2,000 Six Major Kingdoms of Species Millions of years ago Accumulation of O2 in atmosphere from photosynthetic cyanobacterium 2,500 Precambrian Figure 4.3 Overview of the evolution of life on the earth into six major kingdoms of species as a result of natural selection. For more details, see p. S46 in Supplement 7. 3,000 Click here! 3,500 Oldest prokaryotic fossils 4,000 Earth cool enough for crust to solidify 4,500 Origin of Earth Fig. 4-3, p. 81

The Fossil Record Tells Much of the Story of Evolution Fossils Physical evidence of ancient organisms Reveal what their internal structures looked like Fossil record is incomplete: why?

Fossilized Skeleton of an Herbivore that Lived during the Cenozoic Era

Lots of evo this summer: read and watch videos. What can you learn from fossils, really? http://kernfamilysite.com/blog/2014/06/14/ashfall/ What about dinosaur fossils? http://kernfamilysite.com/blog/2014/06/21/stop-3-dinosaur/ Evolution driven by geographic isolation in the Ice Age: http://kernfamilysite.com/blog/2014/07/19/stop-9-yosemite-part-3/ Evolution of really weird trees: http://kernfamilysite.com/blog/2014/07/08/stop-8-ancient-bristlecone-pines-national-forest/

The Genetic Makeup of Population Can Change Populations evolve by becoming genetically different Genetic variations In a population, there is variation among individuals Occurs through mutations in reproductive cells

Individuals in Populations with Beneficial Genetic Traits Can Leave More Offspring Natural selection: acts on individuals Individuals with traits that are beneficial to the conditions are more likely to survive and reproduce (differential reproduction) Over time there is a shift in the most common traits, such that beneficial traits become more common within the population (Populations evolve, individuals don’t!) Genetic resistance – good example When environmental conditions change, populations must: Adapt – have traits which allow survival in new conditions Migrate – move somewhere where conditions are better Or…become extinct http://www.unr.edu/nevada-today/news/2014/devils-hole-pupfish

Evolution by Natural Selection A group of bacteria, including genetically resistant ones, are exposed to an antibiotic Normal bacterium Resistant bacterium Eventually the resistant strain replaces the strain affected by the antibiotic The genetically resistant bacteria start multiplying Most of the normal bacteria die Figure 4.5 Evolution by natural selection. (a) A population of bacteria is exposed to an antibiotic, which (b) kills all but those possessing a trait that makes them resistant to the drug. (c) The resistant bacteria multiply and eventually (d) replace the nonresistant bacteria. Stepped Art Fig. 4-5, p. 83

Case Study: How Did Humans Become Such a Powerful Species? Three human adaptations Strong opposable thumbs Walk upright Complex brain

Adaptation through Natural Selection Has Limits Genetic change must precede change in the environmental conditions. The alleles that are beneficial in the new environmental conditions must already be found within the population before the conditions change. (Populations don’t suddenly sprout new traits as a result of environmental changes.) Reproductive capacity – populations with high genetic diversity and fast reproduction rates are most able to adapt to changes (mosquitos, weeds, rats, bacteria, etc.)

Three Common Myths about Evolution through Natural Selection “Survival of the fittest” is not “survival of the strongest” Fittest = better adapted to the ENVIRONMENT Traits that confer “fitness” in one biome may be detrimental in another (gills are great for aquatic biomes, but useless in deserts!) Organisms do not develop traits out of need or want There is no grand plan in nature for “perfect” adaptation Don’t assume all species are headed in a specific evolutionary direction!

Five Fingers of Evolution https://www.youtube.com/watch?v=5NdMnlt2keE

4-3 How Do Geological Processes and Climate Change Affect Evolution? Concept 4-3 Tectonic plate movements, volcanic eruptions, earthquakes, and climate change have shifted wildlife habitats, wiped out large numbers of species, and created opportunities for the evolution of new species.

Geologic Processes Affect Natural Selection Tectonic plates affect evolution and the location of life on earth Location of continents and oceans Species physically move, or adapt, or form new species through natural selection Earthquakes – fissures can isolate species and cause speciation (geographic isolation) Volcanic eruptions – destroy habitats

Movement of the Earth’s Continents over Millions of Years

Climate Change and Catastrophes Affect Natural Selection Ice ages followed by warming temperatures Collisions between the earth and large asteroids Extinction New ecological roles become available for species that don’t become extinct Go back a slide – when did dinosaurs become extinct? Why? If you’re interested in how we know, read T. Rex and the Crater of Doom!

Changes in Ice Coverage in the N. Hemisphere during the last 18,000 Yrs

Science Focus: Earth Is Just Right for Life to Thrive Certain temperature range H2O = s, l, AND g!! Dependence on water Rotation on its axis – no “dark side/bright side” temp issues Revolution around the sun – not too close or too far Enough gravitational mass to keep atmosphere (why? Well, where else could humans evolve?)

4-4 How Do Speciation, Extinction, and Human Activities Affect Biodiversity? Concept 4-4A As environmental conditions change, the balance between formation of new species and extinction of existing species determines the earth’s biodiversity. Concept 4-4B Human activities can decrease biodiversity by causing the premature extinction of species and by destroying or degrading habitats needed for the development of new species.

How Do New Species Evolve? Geographic isolation Reproductive isolation

Geographic Isolation Can Lead to Reproductive Isolation

Extinction is Forever Extinction Endemic species – species found in only one area, such as on islands Particularly vulnerable – difficult to migrate when changes occur

Extinction Can Affect One Species or Many Species at a Time Background extinction – happens all the time through out history Mass extinction – significant rise above background rate Has happened five times (about once per 20-60 million years). Why? We’re not sure. 250mya 95% of all species became extinct! (OK maybe only 3 times – debated … should we define mass extinction by many species going extinct plus low speciation rate?) Extinctions will happen, but do we have a responsibility to make sure we aren’t causing premature extinctions?

Science Focus: We Have 2 Ways to Change the Genetic Traits of Populations Artificial selection – we’ve been doing this since the dawn of agriculture. Genetic engineering, gene splicing Consider Ethics Morals Privacy issues Harmful effects

4-5 What Is Species Diversity and Why Is It Important? Concept 4-5 Species diversity is a major component of biodiversity and tends to increase the sustainability of ecosystems.

Species Diversity: Variety, Abundance of Species in a Particular Place Species richness - Species evenness - Diversity varies with geographical location Most species-rich communities Tropical rain forests Coral reefs Ocean bottom zone Large tropical lakes

Science Focus: Species Richness on Islands Species equilibrium model, theory of island biogeography Rate of new species immigrating should balance with the rate of species extinction Island size and distance from the mainland need to be considered

Species-Rich Ecosystems Tend to Be Productive and Sustainable Species richness seems to increase productivity and stability or sustainability How much species richness is needed is debatable

4-6 What Roles Do Species Play in Ecosystems? Concept 4-6A Each species plays a specific ecological role called its niche. Concept 4-6B Any given species may play one or more of five important roles—native, nonnative, indicator, keystone, or foundation roles—in a particular ecosystem.

Each Species Plays a Unique Role in Its Ecosystem Ecological niche, niche Pattern of living – how much space? Water? Sunlight? Temp range? What food source? Generalist species Broad niche Specialist species Narrow niche

Specialist Species and Generalist Species Niches

Case Study: Cockroaches: Nature’s Ultimate Survivors Generalists High reproductive rates Giant panda and tiger salamanders Specialists Low reproductive rates When (where) would being a specialist be advantageous?

Specialized Feeding Niches of Various Bird Species in a Coastal Wetland Ruddy turnstone searches under shells and pebbles for small invertebrates Dowitcher probes deeply into mud in search of snails, marine worms, and small crustaceans Black skimmer seizes small fish at water surface Brown pelican dives for fish, which it locates from the air Herring gull is a tireless scavenger Avocet sweeps bill through mud and surface water in search of small crustaceans, insects, and seeds Flamingo feeds on minute organisms in mud Scaup and other diving ducks feed on mollusks, crustaceans, and aquatic vegetation Louisiana heron wades into water to seize small fish Oystercatcher feeds on clams, mussels, and other shellfish into which it pries its narrow beak Knot (sandpiper) picks up worms and small crustaceans left by receding tide Piping plover feeds on insects and tiny crustaceans on sandy beaches Figure 4.13 Specialized feeding niches of various bird species in a coastal wetland. This specialization reduces competition and allows sharing of limited resources. Fig. 4-13, p. 93

Niches Can Be Occupied by Native and Nonnative Species Nonnative species; invasive, alien, or exotic species May spread rapidly – (or may not be able to survive in the new conditions) Not all are villains, but many that are successful in the new habitat outcompete natives.

Indicator Species Serve as Biological Smoke Alarms Can monitor environmental quality Trout Birds Butterflies Frogs

Case Study: Why Are Amphibians Vanishing? Habitat loss and fragmentation Prolonged drought Pollution Increase in UV radiation Parasites Viral and fungal diseases Climate change Overhunting Nonnative predators and competitors

Case Study: Why Are Amphibians Vanishing? Importance of amphibians Sensitive biological indicators of environmental changes Adult amphibians Important ecological roles in biological communities Genetic storehouse of pharmaceutical products waiting to be discovered

Life Cycle of a Frog Adult frog (3 years) Young frog Sperm Tadpole develops into frog Sexual reproduction Tadpole Figure 4.14 Life cycle of a frog. Populations of various frog species can decline because of the effects of harmful factors at different points in their life cycle. Such factors include habitat loss, drought, pollution, increased ultraviolet radiation, parasitism, disease, overhunting by humans, and nonnative predators and competitors. Eggs Fertilized egg development Egg hatches Organ formation Fig. 4-14, p. 94

Keystone, Foundation Species Determine Structure, Function of Their Ecosystems Keystone species Pollinators Top predator Foundation species Create or enhance their habitats, which benefit others Elephants Beavers

Case Study: Why Should We Protect Sharks? Keystone species Eat dead and dying fish in the ocean Strong immune systems Wounds do not get infected Almost never get cancer Could help humans if we understood their immune system For every shark that injures a person, we kill 1 million sharks.