GEOGRAPHICAL ISOLATION AND NATURAL SELECTION MAY LEAD TO

GEOGRAPHICAL ISOLATION AND NATURAL SELECTION MAY LEAD TO NEW SPECIES

First, What is a species? group of individual organisms that are capable of interbreeding to produce fertile offspring in nature. Male (Purple) and female purple martin (Progne subis )

What Exactly IS Evolution…. How About What it is NOT! It’s one of the most misunderstood, poorly taught aspect of biology It is NOT a belief but a theory based on FACTS; we see it occurring today (pesticide resistance, bacteria immunity to antibiotics, yeast mutate quickly creating new species) Does NOT reject religion, faith or the existence of a ”higher power”. I know scientists that study evolution of various organisms that sing in their church choir! Although it encompass the origin of life, it’s focus is how life changed, and is changing, after origin; how species branch from common ancestry Individuals do not evolve, populations due. Remember genetic diversity? Human activity can influence it

Evolution. What is it? Small or large genetic change at a population level inherited over several generations. Has to occur at the genetic level Changes in allele frequency in a population over time changes due to mutation and are passed along Changes are seen in phenotypes (physical traits) Descent with modification Suggests common ancestor

More Misconceptions It only occurs over long periods of time Over the past 50 years, we've observed squirrels evolve new breeding times in response to climate change, a fish species evolve resistance to toxins dumped into the Hudson River, and a host of microbes evolve resistance to new drugs we've developed. Many different factors can foster rapid evolution — small population size, short generation time, big shifts in environmental conditions — and the evidence makes it clear that this happened many times.

Natural Selection………… In a nutshell, organisms with favorable phenotypes that allow for adaptation in a particular environment will survive, reproduce, pass their alleles along to their off spring The term “survival of the fittest” doesn’t mean only the best survive, just suitable Environment DOES NOT NECESSARILY MEAN THE WEATHER!!!! It simply indicates those that can withstand selective pressures such as: Selective pressures from competition for mates, for food, for shelter, escaping predators, acclimation to climate. Others may include physical features such as variation in beak size (Darwin’s finches!)

Natural Selection It does NOT produce the perfect organism!! There are still fish that swim too slow and get eaten, not to mention the human genetic diseases out there!! However, there is genetic variation in populations of organisms (Remember genetic recombination in Meiosis? Mutations? Natural selection LEADS to evolution; it isn’t evolution!

Natural Selection Isn’t Random! It “Selects” for, or against, phenotypes as environmental occur. For example, if a new predator is introduced to an area, prey organisms must be quick to get away!

Natural Selection Does Not Occur During an Individual Organism’s Lifetime

Early theories explained changes as if they occur in an individual, like the example below…. NOT TRUE

Example of Natural Selection

• In this fish population, individuals have variations. For example, they may differ in color, size, and speed.

• *Individuals with certain useful variations, (in this case speed) survive in their environment, passing those variations to the next generation.

* Over time, offspring with certain variations make up most of the population and look different from their ancestors.

Peppered Moth Video You Tube Title: Peppered Moth by Mark Drollinger http: //www. youtube. com/watch? v=s. VVldxxb Wig (2 minutes!!)

Fitness? ? **The word fitness describes how well a particular phenotype persists in the next generation relative to how individuals that do not have he phenotype. This does NOT mean the organism is the strongest…just the suited **For example, if brown beetles consistently leave more offspring than green beetles because of their color (possibly less noticeable to predators) you’d say that the brown beetles had a higher fitness. Se say the brown phenotype is selected for. The brown beetles have a greater fitness relative to the green beetles.

Darwin’s Finches, Natural Selection and Fitness

Charles Darwin ~Proposed changes in characteristics of a population of organisms occur over time _Suggested that is humans can manipulate species to get desired traits, why can’t something similar occur in nature? ~”Descent with modification” that occur in populations, not characteristics an individual develops in its lifetime (such as the prior slide) ~Studied organisms on the Galapagos Islands…. . he found some extremely interesting organisms!!

Galapagos Turtles

Galapagos Turtle

Galapagos Finches

Marine Iguana

Blue-Footed Booby

Blue-Footed Booby Dance

Red-Footed Booby

Darwin Develops Theory of Natural Selection • Darwin hypothesized that there was a force in nature that worked like artificial selection where breeders bred organisms for a particular trait (Cattle, dogs, etc. ) • Suggests a Common Ancestor

Selective Breeding/Artificial Selection

Darwin and the Galapagos Finches Video You. Tube Title: Galapagos: the finches (4/7) http: //www. youtube. com/watch? v=l 25 MBq 8 T 77 w (2 minutes long!!)

What’s Up With The Finches? What do You Notice About Their Beaks? How Would You Explain This Observation?

Competition for Food!? hmmm These finches were isolated thus competition for food could have been the driving force (selective pressure) of adaptation to new types of food

A subspecies of this species is also known as the vampire finch as it will occasionally drink the blood of blue-footed booby nestlings!!!!!

Geographic Isolation Individuals population of the same species become separated Mountain formation, river formation, human activity such as deforestation and urbanization just to name a few. After separation, natural selection occurs and eventually become two distinct species that can no longer interbreed to produce viable offspring

Speciation and Geographical Isolation ~Geographical isolation is just what the name implies. A species of organisms becomes separated by a physical barrier such as a stream that develops into a river, mountain formation, lava flow, after deforestation, even when cities are built (urbanization)! ~~ Since they are divided into difference environments, natural selection occurs within each of the two populations forming two distinct species. If they can no longer interbreed and produce fertile offspring, we can say that speciation has occurred.

Another Example of Geographical Isolation and Speciation

Geographic Isolation After Deforestation *We’ll use this population of tree frogs as an example. As of now, they live in a subtropical area.

Geographic Isolation After Deforestation • After deforestation, erosion occurs and a stream is formed. This causes the frog population to become divided. Remember that there is already genetic variation in the frog population!

Geographic Isolation After Deforestation • Notice the difference in phenotypes between the two frog populations. Those that were caught on the side that had trees cut down are now in a new ecological environment…. remember natural selection? ? ? These could be two different species of frogs that can no longer interbreed.

Natural selection not only affects finches, but insects, bacteria and viruses as well!!

In Bacteria!! ~~They multiply like crazy (exponentially!! ). You can visibly see a colony after incubating over night! ~~Mutations occur quickly as well; ~~ Along with overuse, and misuse, of antibiotics many strains have developed immunity

Antibiotics Are Medications Used to Kill, or at Least Slow Down, Bacterial Infections, Like Strep Throat

Antibiotic Resistance

Viruses Although viruses aren’t living, they have a single nucleic acid chain (either DNA or RNA) surrounded by a protein coat and capable of replication but only within the cells of living organisms

Your Immunity Ability to Fight Off Infections and Diseases can be caused by bacteria, viruses, some protists and some fungi These are called pathogens Two basic types of acquired immunity Active Passive

Vaccines Help Guard Against

Antiviral Medications Antiviral resistance means that a virus has changed in such a way that the antiviral drug is less effective in treating or preventing illnesses caused by viruses, such as the flu The drug Tamiflu shortens the duration and severity of the flu Nucleic acids of the virus may change in a way that results in the virus becoming resistant to antiviral drugs

Other Forms of Resistance

Pesticide Resistance

To Summarize…… Disease agents like bacteria, viruses and chemicals can influence natural selection in populations of a species Geographical isolation can lead to speciation Natural selection influences changes in populations over time

Evidence of Evolution

Homologous Structures If a bat, a human, an alligator, and a penguin all evolved from a common ancestor, then they should share common anatomical traits

Vestigial Structures Body parts that seaming have little or no function At one time in evolutionary history, they were needed Such as the pelvis of a whale, pelvic girdle in some snakes, wisdom teeth �Leftovers from evolution �It used to be thought our appendix was vestigial, however, it is thought that when beneficial bacteria in our gut is depleted, the appendix allows them to be re stored;

Fossils Formed when organism dies is in silt, mud, sand, tar or clay soon after death Sometimes an insect will die in tree sap (amber) Not all dead organisms will fossilize The conditions have to be right!!

Example – Evolution of the Camel

Dinosaur National Monument: Fossilized dinosaur skeleton in sandstone

Fossil of a fish: perch

Dinosaur tracks (‘trace fossils’)

Barosaurus (27 m tall herbivore from late Jurassic (140 mya)

Leaf impression: Some fossils are imprints, some actually retain original organic matter

Petrified trees: Minerals dissolved in water seep into tissues of dead organisms, replace its organic material, and turn it to stone

Scorpion in hardened resin from a tree (whole organism preserved

Horseshoe crabs (Limulus polyphemus) “Living fossils” that have changed little in hundreds of millions of years.

Mammoth tusks (whole organism may be preserved in ice)

Biochemical (Molecular) Evidence Organisms that are more related have fewer differences in their amino acid sequences. (Cytochrome C below)