ORIGINS OF BIODIVERSITY

Important Terms  Important Terms  Evolution: A change in the gene pool of a population over time  Natural Selection: Process by which individuals that are better suited to their environment survive and reproduce more successfully.  Adaptation: An inherited characteristic that increases an organism’s chance of survival.

Charles Darwin

 Proposed the theory of evolution outlined in  The Origin of Species

Evidence of Evolution  Fossil records  Structure of DNA  Mechanisms of mutations

Natural selection as a possible driving force for speciation.  Evolution is the cumulative, gradual change in the genetic characteristics of successive generations of a species or race of an organism, ultimately giving rise to species or races different from the common ancestor.

Natural selection as a possible driving force for speciation.  Evolution reflects changes in the genetic composition of a population over time.

Natural selection as a possible driving force for speciation.  Natural Selection (Evolution) comes down to a species adapting to their surroundings over time.  A species with only plants to eat, will adapt to eating plants.  A species with only animals to eat, will adapt to eating animals.

Darwin's Research Studies 13 species of finches on Galapagos Islands Looked a beak size and shape: Stout beaks for eating seeds Short and sharp beaks for eating insects. Woodpecker-like beak for eating insects from trees, but instead of a long tongue it uses a cactus spine held in its beak to remove its prey.

Natural selection as a possible driving force for speciation.  Darwin’s theory of evolution by natural selection comes down to the following points:  Species show variation.  All species over-produce.  Despite over-production, population levels remain the same.  Over-production leads to competition for resources.

Natural selection as a possible driving force for speciation.  Darwin’s theory of evolution by natural selection comes down to the following points:  The fittest, or best adapted organisms, survive.  The survivors reproduce and pass on their adaptive genes to the next generation.  Over time, the population’s gene pool changes and new species emerge.

Natural selection as a possible driving force for speciation.

What is a species…  Species definition was made by humans, and fails to fully define nature.  These two ants look different are the same species of ant fulfilling different roles in a colony. Pheidole barbata

Species definition is not always black and white Are we the same? +

ZONKEY Photo: Wiki Commons/GNU

Isolation  Geographical, behavioral, genetic, or reproductive factors.  If gene flow between the two sub- populations is prevented, new species may evolve.

This leads to geographic isolation Continental Drift Animation Speciation occurred on the earth over a very long period of time when the continents slowly drifted apart

Isolation  The isolated population is an isolated gene pool since it does not breed with other populations.  The gene pool can therefore change as it adapts to the new conditions by natural selection..

Isolation

Behavioral Isolation  Changes to the appearance or behavior of the populations  No longer attraction among the two types, and therefore no longer breed.

Reproduction Isolation  Two populations can no longer physically breed due to changes to reproductive organs.

Genetic Isolation  Too many genetic differences for the two populations to produce fertile young.

Early fox population Spreads northward and southward and separates Adapted to heat through lightweight fur and long ears, legs, and nose, which give off more heat. Adapted to cold through heavier fur, short ears, short legs, short nose. White fur matches snow for camouflage. Gray Fox Arctic Fox Different environmental conditions lead to different selective pressures and evolution into two different species. Southern population Northern population

Speciation  Read through your packet about Speciation

Plate Tectonics

 PLATE = a portion of the Earth’s crust  TECTONICS = movement

Plate Tectonics  The Earth’s crust (lithosphere) is divided into many different plates.

Plate Tectonics  Plates are carried on the mantle (asthenosphere), which can flow like a liquid on a geological time scale.

Plate Tectonics  Edges of adjacent plates can either move parallel to one another, push one under the other, or collide.

Theory of Plate tectonics  Earth’s crust is broken into large pieces called plates

Theory of Plate tectonics  Plates move over time creating many landforms & geologic events such as earthquakes and volcanoes

Earth Through History  Because Earth’s plates are moving, the continents have not always been in their present location.

Earth Through History  Pangaea – large supercontinent  As continents move apart – physical isolation may occur

Earth Through History  Geologic events – volcanoes & earthquakes can bring about loss of habitat and potential loss of species

Plate Tectonics  The movement of the major and minor plates in relation to one another is called plate tectonics.

Plate Tectonics  Movement of tectonic plates can produce barriers such as mountain ranges, oceans and rift valleys that can lead to isolation of gene pools and then speciation.

Types of Plate Movements  Convergent: pushed together  Divergent: moving apart  Transform: sliding past  What happens at plate boundaries can be constructive: building new land (ie: habitats) or destructive; destroying land

TRANSFORM BOUNDARIES  Plates slide past with friction  EARTHQUAKE ZONES  No new land or habitats

Divergent  Physical separation of the plates  Creates a rift  Rifts on land result in large lakes  Results in the formation of a physical barrier

Convergent  Physical separation  Large changes due to mountains and islands

Convergent Boundaries (colliding)  3 Scenarios:  2 Continents Collide = folded mountains  Could lead to isolation – mountain range separates a population  Creates new habitat  Both constructive (building mountain) and destructive (one plate subducting)

Convergent Boundaries (colliding)  2 Oceanic Plates Collide  More dense plate subducts  Deep sea trench  Oceanic Islands  New Land formation = new habitat Aleutian Island Arc: Possibility of future land bridge?? Affect on evolution & biodiversity?

Plate Tectonics  Land bridges can form from previously unconnected plates allowing species to spread.

Plate Tectonics  The movement of plates through different climatic zones allows new habitats to present themselves, and allow for different adaptations.

APPLY  Explain how plate tectonics has influenced evolution and biodiversity. Give specific examples.

Mass Extinction

Evolution Extinction  Extinction is the process by which a species, genus, or family, becomes extinct — no longer existing and living in the world  99% of all species that were on earth no longer exist

Mass Extinctions  There have been several major extinctions since the beginning of life 3.5 billion years ago

Evolution Extinction  Background Extinction  Not fit for the environment  Mass Extinction  More than ½ of the species extinct in 2 million years

End of Ordovician (440 mya)  2 nd most devestating in Earth’s history  Effecting marine species  Probably due to glaciation Source:

Late Permian (225 mya)  Largest extinction  estimated that as many as 95% of all marine species were lost  Possible causes continents merging to form Pangea global warming caused by volcanic eruptions glaciation Source:

Cretaceous/Tertiary Extinction  All dinosaurs and half of other animals and plants went extinct. Possible asteroid  Brought about the rise of the mammals

Mass Extinction  Plate Tectonics  Super Volcanoes  Climate Changes  Meteorite Impacts

6 th Extinction  There are have been at least 5 in the history of the Earth so far, and it has been well argued that we are currently in the midst of a 6th mass extinction event, the Holocene extinction, or alternately, the Anthropocene extinction

6 th Extinction  Past extinction were geological and extra terrestrial  This is Human Caused.  Must shorter time period  Last year loss is compared to 2-3 million years

Discussion Question  Why does Australia have such strange animals??

Evolutionary Timeline of mammals Platypus (Monotreme) Kangaroo (Marsupial) Dingo (Placental Mammal)