APES Unit IV: Evolution and Biodiversity Chapter 5: Evolution and Biodiverstiy

I: Genetics 101-Understanding How Populations Change Evolution: Change in genetic composition of a population over time population: all individuals of the same species occupying the same area. gene: unit of heritable information -usually associated (at the molecular level) with a specific region located on the chromosome. allele: - one of two or more slightly different forms, or "variants" of a given gene. genotype: a selection of the genes that make up an individual. phenotype: the consequence(s) of all the allelic interactions that give rise to a visibly   determinable "type".

I: Genetics 101-Understanding How Populations Change gene pool: all the genotypes within a population. Mutation: mistake in copying of genetic code; if mutation in sex cells it is inherited. Recombination: during cell division part of one chromosome breaks off and attaches to another, which leads to new gene combinations and thus genetic diversity Evolution by Artificial Selection: Breeding dogs, horses, pea plants Unintended consequence of agricultural breeding is pesticide/herbicide resistance http://evolution.berkeley.edu/evolibrary/article/evo_14

II.Understanding Biodiversity HHMI: 2014 Lectures 2 and 3 Biodiversity: variety of earth’s species, or varying life forms, the genes they contain, the ecosystems they live in and the ecosystem processes of energy flow and nutrient cycling that sustain life. Ecosystem Diversity Species Diversity Population Diversity Genetic Diversity

III. Mechanisms: The Process of Evolution Evolution is the process by which modern organisms have descended from ancient ancestors; responsible for both remarkable similarities in life forms and amazing diversity of life Charles Darwin-On the Origin of Species by Means of Natural Selection. Change in populations (not individuals) genetic makeup over successive generations.

Natural Selection Individuals produce an excess of offspring and not all offspring can survive Individual differ in their traits (Genetic Variability ) as a result of mutation, gene flow and sex. Mutations are random and not all mutations matter. Since the environment can't support unlimited population growth, not all individuals get to reproduce to their full potential.(differential reproduction)

Traits are passed to offspring (Heredity) The more advantageous trait allows some organisms to have more offspring, the trait becomes more common in the population. Eventually, all the individuals in the population will have the trait. (Natural Selection)

Natural Selection acts on individuals but occurs in populations Limitations to adaptation through natural selection Change in enviro condition can lead to adaptation only for genetic traits already present in a population’s gene pool or for traits resulting from mutations, which occur randomly Ability to adapt limited by reproductive capacity Natural Selection at work: Genetic Resistance=ability of one or more organisms in a population to tolerate a chemical designed to kill it. Antibiotic Resistance/Pesticide Resistance

Evolution by Random Processes Genetic Drift: Change in allele frequency in a population due to random sampling. Some organisms, by chance, leave behind more offspring genetic drift with marbles

Population Bottleneck: an evolutionary event in which a significant percentage of a population or species is killed or otherwise prevented from reproducing; some genotypes will be lost and genetic composition of survivors will differ from original group The founder effect is a special case of a population bottleneck, occurring when a small group in a population splinters off from the original population and forms a new one, taking with it only limited alleles from the original population

Co Evolution Two species reciprocally affect each other's evolution; an evolutionary change in the morphology of a plant, might affect the morphology of an herbivore that eats the plant, which in turn might affect the evolution of the plant, which might affect the evolution of the herbivore... Coevolution is likely to happen when different species have close ecological interactions with one another. These ecological relationships include: Predator/prey and parasite/host Competitive species Mutualistic species Case study of co-evolution The term coevolution is used to describe cases where two (or more) species reciprocally affect each other’s evolution. So for example, an evolutionary change in the morphology of a plant, might affect the morphology of an herbivore that eats the plant, which in turn might affect the evolution of the plant, which might affect the evolution of the herbivore...and so on. Coevolution is likely to happen when different species have close ecological interactions with one another. These ecological relationships include: Predator/prey and parasite/host Competitive species Mutualistic species Bats and moths: Bats use echolocation and hunt at night for moths./Some moths have evolved larger ears to avoid predaton/bats can switch frequency. Plants and insects that pollinate them

IV. Measuring Biodiversity Diversity and Abundance Species Richness: Number of different species Species Evenness: abundance / proportion of individuals within the species. Are all species represented by similar numbers of individuals?

V. Speciation and Extinction Determine Biodiversity Process of Speciaition- Two Phases Geographic Isolation: groups from same population become physically isolated Reproductive Isolation: When sexually reproductive organisms becomes so genetically different they cannot mate  Geographic isolation: Separated by river, mountain Reproductive Isolation: The evolution of different mating location, mating time, or mating rituals Lack of “fit” between sexual organs, Offspring inviability or sterility: All that courting and mating is wasted if the offspring of matings between the two groups do not survive or cannot reproduce.

Pace of Evolution Hundreds to millions of years Average global rate 1 species every 3 million years. If populations cannot adapt quickly enough they go extinct To survive a rapid environmental change, a population must evolve quickly.

Ecological Niche includes adaptations acquired through evolution, range of tolerance, types and amounts of resources the species uses and interactions with other organisms. Limits to Adaptation-ability to adapt limited to gene pool and how fast it can reproduce. Fundamental Niche: full potential range of conditions if there were no competition Realized Niche: the portion of niche fulfilled Combination of abiotic conditions fundamentally determines whether a species can persist there-this set of conditions is the fundamental niche of the species. Because biotic conditions further limit population, realized niche includes all abiotic and biotic conditions.

Competition Limits Niche!! All species has an optimal environment in which it performs particularly well-a range of tolerance or limit to abiotic conditions they can tolerate. Fundamental Niche: full potential range of conditions if there were no competition Realized Niche: the portion of niche fulfilled due to competition or other species interactions Competition Limits Niche!! B) C) Bad News is that most individuals would have to die off or become sterile so that individuals with desireable trait could dominate. Resource Partioning: Some species competing for same resource develop special adaptations: hunt day vs. night D) Generalists have broad niches-they are more able to survive if environment changes. Broader range of tolerance, less specific eating habits: mice, deer, catfish, humans Specialists-narrow niches: one type of habitat, limited food source or specific requirement. PANDA-they are prone to extinction or E) No grand design-all random Survival of fittest-fitness is a measure of reproductive success, leaving the most descendients-not strength

A generalist species: Broad Niches able to thrive in a wide variety of environmental conditions and can make use of a variety of different resources (r-strategist) A specialist species: Narrow Niches can only thrive in a narrow range of environmental conditions or has a limited diet. Often prone to extinction.(K-Strategist) Most organisms do not all fit neatly into either group

VI. Environmental Changes-Physical Evolution Movement of tectonic plates has determined location of continents and ocean basins Location/latitude of continents determines climate and thus where plants and animals live Movement of continents has allowed species to move, adapt to new environments and form new species. Movement of tectonic plates has allowed species to move, adapt to new climates and form new species

Volcanic Eruptions: Mt Volcanic Eruptions: Mt. Saint Helens: Destroy habitat and wipe out populations Earthquakes: create fissures that separate and isolate populations Climate Change and Natural Selection: Grizzly and Polar Bear

Divergence: One species becomes two Convergence: The evolution of species from different taxonomic groups toward a similar form. Extinction: Species ceases to exist. They can be ecologically extinct-number are so small they cannot fulfill their role. Over 99 % of all species that have ever lived are now extinct.

Background Extinction Extinctions are normally occurring in nature Endemic Species: found only in one area; are most vulnerable to extinction Background Extinction Extinctions are normally occurring in nature Mass Extinction Extinction of large percent of species across the genera Background Extinction: Mass Extinction:

Summary Earth’s biodiversity is the product of evolution, a change in the genetic composition of a population over time Evolution below the species level is microevolution-variety of apples or potatoes Genetic changes that give rise to new genera, families, classes in macroevolution Extinction and speciation are what leads to biodiversity