A neat transition from Genetics Intro to Evolution A neat transition from Genetics Darwin’s Evolutionary Tree

Evolutionary Tree How do we go from a single form of life to all the diversity we see today?

How does genetics influence a species? Possible jumping off points: Meiosis creating unique sex cells Sexual reproduction making new combinations Different allele combinations

Natural selection “Nature selects” the most fit individuals to survive and reproduce making the next generations Which traits in humans are favorable? Which traits are favorable in farm animals? Are these traits the same as they were 50 years ago? 100 years ago?

Speciation Big question: -How does a new species come to be? -Alternatively, how does a species go extinct?

Variation Differences exist between members of the same species Plant leaves Skin color Dog breeds Puppy size Where do you see variation in nature?

Selection Only the fittest organisms survive. The “fit” organisms pass on their traits to their offspring How does nature “select” The most fit individuals in these pictures?

Darwin Natural Selection- The process whereby organisms are better adapted to their environment, and tend to survive and produce more offspring. The theory of its action was first fully expounded by Charles Darwin and is now believed to be the main process that brings about evolution. Charles Darwin

Jean-Baptiste Lamarck Believed that environment influenced behavior, which in turn influences an organism If an organism is able to fulfill a specific niche, then they will change in order to fulfill the niche completely. If an organism changes within their lifetime, they will be able to pass that trait onto their offspring. Lamarck believed that the long necks of giraffes evolved as generations of giraffes reached for ever higher leaves.

Speciation

It starts with a Population Members of same species Live in same home range Able to reproduce fertile young Evolution is the change in a population of organisms over time Speciation is the formation of a new species over time by natural selection or chance events.

Diverse (but limited)Gene pool Genes in a population Collection for all genes of all traits Gene pools change due to selection of traits Genetic Drift happens when small populations favor an allele that the laws of probability would not. Not an actual pool, but a collection of the diverse alleles that exist in a population

Reproductive Isolation 3 types Behavioral Isolation When two populations are capable of breeding but have differences in courtship

Geographical Isolation When two populations are separated from geographic barriers (rivers, mountains, etc) Grizzly Kodiak Polar Kermode – unrelated, but cute!

When two or more species reproduce at different times. Temporal Isolation When two or more species reproduce at different times. American toad and Fowler’s toad can mate in laboratory settings, but not in the wild

Westies and Easties

Of ligers and men

Interpreting Evolution Vestigial structures have no function and suggest organisms evolved from a common ancestor Snakes and whales – hip bones Humans – appendix Blind mole - eyes Homologous structures same structures with different forms in different organisms Embryology amphibians, reptiles and mammals have gill slits (not real gills) and tails

Vestigial Structures Primary function is lost. Not necessary for human survival. Pelvic bone in whales and wings with flightless birds.

Homologous vs analogous structures Structures Forearms in mammals contain the same bones, just different sizes and lengths. Wings and fins have evolved in separate species, but serve the same function

Co-Evolution snakes and newts (2:25-8:25)

Adaptive Radiation One common ancestor evolves into many different species as they take over new niches Darwin’s finches Hawaiian Honeycreepers Natural Variation is the difference in population characteristics that develop (beak shape, fur color) Founder Effect is the change in allele frequency as a result of migration of a small sub group of a population

Patterns of Evolution Macroevolution refers to the large scale evolutionary changes that take place over long periods of time (mass extinctions) Convergent Evolution the process by which unrelated organisms resemble each other (sharks, dolphins, seals and penguins) Coevolution is the change in two organisms in response to changes in each other (flowers and pollinators)

Speciation: Of Ligers and Men Bozeman: Speciation and Extinction

Taxonomy – organizing in groups not stuffing dead animals Purpose: Classify organisms and give ONE accepted name Binomial nomenclature: two-part scientific name in Latin e.g. Homo sapien System of classification using seven taxonomic categories. They are –from largest to smallest- domain, kingdom, phylum, class, order, family, genus, and species.

One zoom – Tree of life explorer # of identified species on Earth??? # of potential species on Earth? http://www.onezoom.org/