All we have yet discovered is but a trifle in comparison with what lies hid in the great treasury of nature. Antoine Van Leeuwenhoek

Biodiversity and Evolution

Case Study: Why Should We Protect Sharks? More than 400 known species. 6 deaths/yr. 79-97 million sharks killed every year: -Fins, organs, meat, hides, fear, by-catch 32% shark species threatened with extinction. Reasons for protection: cancer resistant, keystone species.

Importance of Biodiversity Biodiversity: the variety of Earth’s species, their genes, the ecosystems where they live, and the sustaining ecosystem processes (nutrient cycling, energy flow). Vital to sustaining life on earth (supplies us with food, wood, fiber, energy, and medicine).

Components of Biodiversity (cont’d) Functional diversity: bio/chemical processes needed for survival of species & communities. -energy flow & matter recycling. Ecosystem diversity: variety of terrestrial and aquatic ecosystems. -storehouse of genetic, species diversity.

Components of Biodiversity Species diversity: Est. 8 million to 100 million species. 1.9 million identified. -insects make up most of known species. -unidentified are mostly in rain forests and oceans. Genetic diversity: variety of genetic material within a population. -enables life to adapt to environmental changes.

FYI: Why You Should Love Insects Bad rep: compete for food, spread disease, bite and sting, invade lawns. Natural capital: pollination (allows flowering plants reproduce sexually). free pest control: insects eat other insects.

E.O. Wilson: Biodiversity Loved bugs as a kid. Specialized in ants. Widened scope to earth’s biodiversity. Theory of island biogeography. First to use “biodiversity” in a scientific paper.

4-2 Evolution of Species Biological evolution: change in the genetic makeup of a species over generations. Theory of evolution: organisms with adaptive traits have an advantage over others. Alfred Russell Wallace Charles Darwin: -studied beak shape in Galapagos finches. -published On the Origin of Species by Means of Natural Selection.

Natural Selection Individuals with advantageous traits are more likely to survive & transmit traits to succeeding generations.

Steps of Selection Genetic variability exists in a population. -mutations (random changes to DNA) are source of variation. -mutations within gametes are inheritable. Environmental factors favor survival of individuals with adaptive trait over others. Adaptive trait may lead to differential reproduction, which enables individuals with adaptation to produce more offspring.

Natural Selection and the Six Kingdoms/Tree of Life

The Geologic Time Scale

Natural Selection & Genetic Resistance Ability of members of a population to resist a chemical designed to kill it.

Evidence of Natural Selection Fossil record: entire collection of preserved species. -represents ≈ 1% of all species on Earth. Homologous structures: -similar structures in dissimilar species. DNA analysis

Limitations to Natural Selection Genetic change must precede change in the environmental conditions. Reproductive capacity: -Species that reproduce rapidly and in large numbers are better able to adapt.

Common Myths about Evolution through Natural Selection “Survival of the fittest” is not “survival of the strongest” . (Fittest is in terms of leaving behind the most offspring ) Organisms do not develop traits out of need or want. No grand plan of nature for perfect adaptation (evolution is not “goal oriented).

Case Study: How Did Humans Become Such a Powerful Species? Three human adaptations: Strong opposable thumbs Walk upright Complex brain: allows for weapon development, creation of protective devices, and technologies that extend our senses.

4-3 Geology and Natural Selection Tectonic plates affect evolution and the location of life on earth. -change the location of continents & oceans. -influences climate & distribution of species. -species became geographically isolated from one another. Earthquakes: shifting of tectonic plates; may isolate populations. Volcanic eruptions: occur near plate boundaries; may wipe out populations.

Movement of the Earth’s Continents over Millions of Years Pangea’s breakup explained: Scrat’s Missing Adventure Video Clip , Video Clip 2

Climate Change and Natural Selection Cyclical climate changes restrict location/ survival of populations. -adapt, migrate or become extinct

Catastrophes and Natural Selection Collisions between the Earth & large asteroids have occurred throughout history. -caused destruction of ecosystems/species. -created opportunities for new species.

4-4 Biodiversity, Speciation and Extinction Biodiversity results from the interaction between speciation and extinction.

Extinction Biological extinction: effects global population. Local extinction: widespread, but not global. Endemic species: found only in one area; particularly vulnerable to extinction. Background extinction: typical low rate of extinction. -1-5 species per million species/year. Mass extinction: above background rate. -3-5 over 500 million years.

Golden Toad of Costa Rica Found in cloud forests 2000 m above sea level. Climatic change, pollution, ultraviolet radiation, and/or fungal skin infections? No one knows why it went extinct.

Mass Extinctions Fig. 4-12, p. 93 Figure 4.12 Tertiary Bar width represents relative number of living species Era Period Species and families experiencing mass extinction Millions of years ago Ordovician: 50% of animal families, including many trilobites. Devonian: 30% of animal families, including agnathan and placoderm fishes and many trilobites. 500 345 Cambrian Ordovician Silurian Devonian Extinction Paleozoic Mesozoic Cenozoic Triassic: 35% of animal families, including many reptiles and marine mollusks. Permian: 90% of animal families, including over 95% of marine species; many trees, amphibians, most bryozoans and brachiopods, all trilobites. Carboniferous Permian 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 Jurassic Cretaceous 250 180 65 Quaternary Today Figure 4.12 Fossils and radioactive dating indicate that five major mass extinctions (indicated by arrows) have taken place over the past 500 million years. Mass extinctions leave many organism roles (niches) unoccupied and create new niches. Each mass extinction has been followed by periods of recovery (represented by the wedge shapes) called adaptive radiations. During these periods, which last 10 million years or longer, new species evolve to fill new or vacated niches. Many scientists say that we are now in the midst of a sixth mass extinction, caused primarily by human activities. Fig. 4-12, p. 93

FYI The Passenger Pigeon - Gone Forever Once the most numerous bird on earth. In 1858, Passenger Pigeon hunting became a big business. By 1900 they became extinct from over-harvest and habitat loss. Figure 11-1

Global Extinction Some animals have become prematurely extinct because of human activities. Figure 11-2

Giant panda Black-footed ferret Whooping crane Northern spotted owl Blue whale Figure 11.3 Endangered natural capital: species that are endangered or threatened with premature extinction largely because of human activities. Almost 30,000 of the world’s species and 1,260 of those in the United States are officially listed as being in danger of becoming extinct. Most biologists believe the actual number of species at risk is much larger. Mountain gorilla Florida panther California condor Hawksbill sea turtle Black rhinoceros Fig. 11-3, p. 224

Speciation species arise: Evolutionary process by which new biological species arise: Geographic isolation: physical isolation of populations for a long period lead to… Reproductive isolation: mutations in geographically isolated populations prevent the production of viable offspring.

Geographic Isolation Can Lead to Reproductive Isolation

Changing Genetic Traits Genetic engineering: alters genes by adding, deleting segments of DNA for desired trait(s). Artificial selection: use selective/crossbreeding Normal mouse (left) vs. Transgenic mouse with Human Growth Hormone

4-5 The Importance of Species Diversity Species richness: number of different species in a given area. Species evenness: the comparative number of individuals of each species in an ecosystem. -low evenness: few individuals of each species. -high evenness: many individuals of each species.

FYI: Species Richness and Evenness Which plot has a higher species richness? Each color represents a different species. Which plot has a greater species evenness?

Variations in Species Richness and Species Evenness High species richness Low species richness Low species evenness High species evenness

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. -small islands have a higher extinction rates. -islands closest to the mainland have greater species richness.

Effects of Species Richness Determined by two factors: -plant productivity (more plant biomass) -enhanced sustainability FYI: Current hypothesis suggests that the more species, the more nutrients, the more pathways for energy flow. Our buddy, E O Wilson says, “There’s a common sense to this: the more species you have, the more likely you’re going to have an insurance policy for the whole ecosystem”.

4-6 Roles of Species in an Ecosystem Ecological niche: role of species & everything needed for its survival.

Generalists Generalist species: broad niches many different locations varied diet tolerate wide range of conditions

Specialists Specialist species: narrow niches restricted habitat restricted diet narrow tolerance of environmental conditions

Five Major Species Roles in Ecosystems Native: normal resident. Nonnative: migrate, introduced into. -AKA invasive, alien, exotic Indicator: provide early warnings of damage to communities. Keystone: role determines types, abundance of other species in community. Foundation: create, enhance habitats for other species.

Invasive Species

Deliberately Introduced Species Purple loosestrife European starling African honeybee (“Killer bee”) Nutria Salt cedar (Tamarisk) Figure 11.11 Threats to natural capital: some of the more than 7,100 harmful invasive (nonnative) species that have been deliberately or accidentally introduced into the United States. Marine toad (Giant toad) Japanese beetle European wild boar (Feral pig) Water hyacinth Hydrilla Fig. 11-11a, p. 234

FYI: Invasive Species The Argentina fire ant was introduced to Mobile, Alabama in 1932 from South America. Most probably from ships. No natural predators. Figure 11-12

Indicator Species

Keystone Species

Foundation Species

Exam Focus Role of top predator in ecosystem. Components of biodiversity Link between biodiversity, speciation & extinction. Most abundant identified species. Steps of natural selection, including the “raw” material that drives it and its result. Basics of geologic time scale/resulting kingdoms. Role of plate tectonics in speciation

Exam Focus (cont’d) Genetic resistance. Importance of fossil record to evolution. Reasons for vulnerability to extinction of endemic and specialist species. Species richness vs evenness. Ecological niche