1. Origins of Biological Diversity
Chapter 15
Page 323

2. Species Concept
Biological Species Concept – A species is a population (group) whose members have the ability to breed with one another in nature and produce fertile offspring.
Ex: Humans and gene flow
**MEMBERS OF ONE SPECIES CANNOT SUCCESSFULLY INTERBREED WITH MEMBERS OF OTHER SPECIES**
Ex: Horses and Cows
Not included: Asexual reproduction (frogs, fish, insects) and fossils.

3. Micro and Macro Evolution
Microevolution – A change in allele (trait) frequencies within a population.
Changes within one family.
Macroevolution – Changes that are much more dramatic and include:
Origin of a species
Extinction of a species
Evolution of major features (wing on a bird)
Speciation – Origin of new species – This leads to Biological Diversity, as new kinds of life is started.

4. Microevolution Example

5. Macroevolution Example

6. Reproductive Barriers
INABILITY TO BREED MARKS SPECIES AS SEPARATE – HOW?
Reproductive Isolation – A barrier that keep species from breeding
Timing – Different breeding seasons
Behavior – Different courtship or mating rituals Ex: bird songs and colors.
Habitat – Different habitats in the same location Ex: Sawgrass birds vs. open waterway birds in the Everglades.
Incompatibility of physical structures
Sperm plug Ex: Hemipenes and certain snakes.
Failure to develop
Infertility
Natural Abortion – Without help (From stress, attack, or low food – may abort to save the genes in bad times).

7. Geographic Isolation
Separation of populations due to geographic change or dispersal to isolated places Ex: Earthquake or Hurricane (Birds) – Even in Everglades or Keys – Key Deer
Depends on species ability to physically move
New “splinter” population may now have their own evolution (genetic drift and natural selection).
Many may die through failure to survive and thrive
See Figure 15-6 and Figure 15-7 in book

8. Geographic Isolation Example

9. Adaptive Radiation
Evolution from a common ancestor that results in diversification of species
See Figure 15-7 in your book (page 328)
1) Colonization of a new island (empty environment)
2) Species evolve and move to other islands in the chain and create entirely new species.
Ex: Hawaiian birds

10. Adaptive Radiation Example

11. Tempo of Speciation Punctuated Equilibrium – Species appears suddenly
Persists for thousands of years and has no changes
Suddenly disappears.
*There are long periods of little change (equilibrium) broken by shorter periods of change and speciation, which can be very rapid.
**Successful species last approximately 5 million years (Man is not successful yet)
Can be a short or long interval.
Natural Selection and adaptation happen during Punctuated Equilibrium when a species is “Young”.

12. Example of Punctuated Equilibrium

13. Refinement of Existing Adaptations
Physical structures are adapted or “changed” over time from simpler structures
Ex: The eye of an animal can range from simple to complex – Eyes are based on food needs, light needs, light access. Deep trench animals in the ocean use fluorescence.

14. Adaptation of Existing Structures
When existing materials or structures start with a certain function, then over time fulfill other functions.
Chitin – forms the exoskeleton of Arthropods (insects, spiders, and lobsters)
In the ocean, chitin helped protect animals from predators
On land, chitin helps to prevent dehydration.
Penguin flippers – Penguins are birds whose flippers are modified wings – they “fly” through the water. They are isolated from land predators, but do have water predators.

15. Evolution and Development
Embryology – The study of processes of multicellular organisms as they devleop from fertilized eggs to adults.
Genes or the Adaptation of body parts based on the geography of their home area.

16. Fossil Records Are created by dead organisms
Some fossils actually retain organic material (plants keep chlorophyll).
Fossils are studied for clues on:
Time period of life for organism
Diet
Breeding
Digestion
**Fossils in ice are slower to decompose than in rock layers.**

17. Fossil Record Example

18. Geologic Time Scale (VIP!!)
Use acronyms to remember all of this.
3 large divisions:
Eras
Periods
Epochs E P

19. Eras
4 Different Eras:
Precambrian
Paleozoic
Mesozoic
Cenozoic P M C

20. Precambrian Era The origin of Earth 4.6 to 543 million years ago
Prokaryotic (no nucleus)
Eukaryotic (nucleus, nuclear membrane, internal organelles) cells
Invertebrates (have no backbone)
4.6 to 543 million years ago

21. Paleozoic Era
Cambrian – Modern animal groups – from 543 to 510 million years ago.
Ordovician – Colonization of land by plants and arthropods – 510 to 439 million years ago
Silurian – Jawless, Jawed fishes, and vascular plants – 439 to 409 million years ago
Devonian – Bony fishes, Amphibians, Insects – 409 to 363 million years ago
Carboniferous – Forests, seed plants (fruits), reptiles, amphibians – 363 to 290 million years ago
Permian – Marine & terrestrial organisms die – newer reptiles, modern insects – 290 to 245 million years ago C O S D P

22. Paleozoic Era

23. Mesozoic Era
Triassic – Cone bearing plants (pine trees) , dinosaurs – 245 to 206 million years ago
Jurassic – Cone bearing plants, dinosaurs – 206 – 144 million years ago
Cretaceous – Flowering plants, ORGANISMS GO EXTINCT AROUND 65 MILLION YEARS AGO (CALLED CRETACEOUS EXTINCTIONS). – from 144 to 65 million years ago.
Dinosaurs lasted for 180 million years (quite successful. T J C

24. Mesozoic Era

25. Cenozoic Era (Tertiary Period)
Paleocene – Mammals, birds, pollinating insects (bees) – 65 to 57 million years ago
Eocene – Flowering plants, modern mammals – 57 to 35 million years ago
Oligocene – Modern primates – 35 to 25 million years ago
Miocene – Modern mammals ,plants – 23 to 5 million years ago
Pliocene – Human ancestors – 5 to 1.8 million years ago P E O M

26. Cenozoic Era (Tertiary Example)

27. Cenozoic Era (Quaternary Period)
Pleistocene – The ice ages, start of modern humans – 1.8 million years ago
Recent – now – recorded time P R
**Boundaries between Eras are marked by:
Major changes in life
Where the oldest appearances happen or extinctions occur **

28. Dating Fossils
Relative Ages – They reflect the order in which groups of species existed compared to each other.
Absolute Ages – Actual ages in years.
Radiometric Dating – Measurement of radioactive isotopes in objects.
Determines the absolute age of a fossil.
Half-Life – the number of years it takes for 50 percent of an isotope to decay.
**Unaffected by temperature, pressure, or other environmental conditions.
Uranium -238 (half-life of 4.5 billion years) - used to date rocks of the Cambrian Period, as is not found in living organisms. Found in lava and volcanic rock. Decays into Lead -206 – When scientists compare the amount ratio between Uranium and Lead, they can date the rocks.

29. Dating Fossils
Carbon-12 and Carbon-14 (radioactive) are used to date elements that accumulated when organisms were alive.
They measure the ratio of Carbon-12 to Carbon-14 to calculate how long an organism has been dead.
Carbon dating only used for current fossils (has a half-life of 5,600 years). If older than 50,000 years, they have to use Uranium-238.

30. Continental Drift and Macroevolution
Continental plates are not locked in plates, but drift on a thin layer of magma.
This causes movement of plates known as Continental Drift, which can cause earthquakes as plates shift against each other.
Scientists feel that the continents started as one massive landmass called Pangaea (all land), then broke apart over time into Gondwanaland and Laurasia, then the current continents over time.

31. Continental Drift and Macroevolution
Scientists feel that Continental Drift supports Evolution, because it is the main way certain animals (marsupials) could have wound up where the are at the current time, as they became geographically isolated.
There were also changes to water levels, inland seas, inland climates, etc…
These changes over time may have caused the mass extinctions that are spoken about

32. Continental Drift Example

33. Mass Extinctions
In earth’s history, there has been Punctuated Equilibrium, in that there were long periods of stability with very short periods of huge species loss. These are known as Mass Extinction periods.
Ex: Cretaceous Extinctions (numerous species), Permian extinctions (marine life loss)
Scientists think that the extinction of the dinosaurs is recorded in a meteor crater located in the Yucatan Peninsula in Mexico – Scientists think the meteor would have thrown a huge ash cloud in the sky that polluted the air for months, which would have changed climate, food (no photosynthesis), breeding, etc…
There have been 5 or 6 periods of extinction over the last 600 million years according to the fossil record.
They affect biological diversity, but also lead to Adaptive Radiation and eventual increases in population due to Natural Selection.

34. Mass Extinctions example

35. What is Taxonomy?
A branch of biology that involves the identification, naming, and classification of species.
To help with this, all species are assigned a Latin, scientific name (Genus, species).
The system most widely used was started by Swedish botanist Carolus Linnaeus, who came up with a system that uses two things:
Two part (binomial nomenclature) Latin naming system
A Hierarchy or ordering system of species into broader and broader groups.

36. Taxonomy (Con’t)
Leopard – Panthera pardus – Genus always capitalized and latin name always in italics.
The breakdown starts from Kingdom down to species:
Kingdom King Largest (broadest)
Phylum Phillip
Class Came
Order Over
Family For
Genus Good
Species Spaghetti Smallest (most specific)

37. Taxonomy Example

38. Classification and Evolution
Darwin did consider Linnaeus’s ideas when coming up with Natural Selection and Evolutional Theory.
A physical diagram that represents evolutionary relationships among species is called a Phylogenetic Tree.

39. Classification and Evolution (Con’t)
Homologous structures are one of the best features to indicate how closely organisms are related.
Ex: Penguin flipper and bird wing – they may look different and have different functions, but they have basic similarities in stucture. Also human and chimpanzee skulls (possibly inherited from a common ancestor).
What about when there are not structural similarities?
Convergent Evolution – the process by which unrelated species from similar environments have adaptations that seem similar (analogous structures).
Ex: The wings of insects vs. the wings of birds (do the same thing, but are built from entirely different physical structures.

40. Example

41. Molecular Data
Scientists are now studying the molcular gene sequences of all species to determine what species come from common ancestors.

42. Phylogenetic Trees The key feature is in the pattern of branches.
Can always be expanded
Splits that occur by the base of the tree are considered “deeper” and represent how the species originally split from a common ancestor.

43. Clades Each “branch” in this tree is called a clade.
Represents a new evolutionary species.
They can “nest” within larger clades
Each item in an actual clade may be an individual species, or part of a larger group.
EVERY clade has an ancestor and ALL descendants.

44. Examples

45. Examples

46. Cladistics
The network of branches in a phylogentic tree can be determined by a method called cladistics.
Key feature: All organisms of a clade must share homologous (same) features that cannot be found outside that clade.
The diagram itself is called a cladogram.
Ex: A cladogram can be based on animals that all have hair from an ancestor, or all have teeth for a certain purpose Ex: carnivores.

47. Surprising finds
Upon testing genetic material, scientists have found some surprising things:
Crocodiles are more closely related to birds than to lizards or snakes (warm vs. cold blooded and reptile vs. mammal)

48. Two vs. Three vs. Five
Linnaeus proposed a 2 kingdom system: Plants and Animals
In 1969, Robert Whittaker propsed a 5 Kingdom classification system: Monera, Protista, Plants, Fungi, Animals
In the last 10 years, scientists have come up with a 3 Domain System (made areas broader): Bacteria, Archea, Eukaryotes.