Where did all the species come from? Origin of Species Where did all the species come from?

1) Macroevolution The formation of new taxonomic groups Over immense time, organisms develop completely different body systems and physiology

2) Microevolution – variations within a “type” genus or family Minor changes within similar body systems and physiology

3) Speciation Formation of new species of similar organisms that can reproduce with fertile offspring

4) Anagenesis Linear evolution The accumulation of changes in a population, transforming the population into a new species

5) Cladogenesis Branching evolution Two new species arises from a single species population Both species have same Common ancestor

Barriers that isolate populations

6) Prezygotic barriers Hinder or impede the formation of a zygote (sperm united with egg that starts to divide)

7) Habitat isolation – (Ecological) Two species live in different habitats even in the same area Ex. Water snake and land Snake

8) Geographic isolation Habitat isolation by barrier River Mountain

9) Behavioral isolation 2 species may differ in signals used to attract a mate Ex. albatross

Ex. Blue footed boobies Have very specific mating rituals

Mating songs differ

10) Temporal isolation Two similar species may mate at different times

Cicadas can have different mating cycles of 13 years or 17 years The different cycles can’t mate

11) Mechanical isolation 2 species may be stopped from mating because they are anatomically incompatible

Mechanical isolation in plants

12) Gametic Isolation The egg and sperm of different species may not recognize each other

13) Post Zygotic isolation Prevent the hybrid zygote from developing into a viable, fertile adult

14) Reduced hybrid viability The hybrid fails to develop or to reach sexual maturity Mules Zorse

15) Reduced Hybrid fertility Hybrids are infertile

16) Hybrid breakdown The offspring of hybrids are infertile or dead

Some times “some” of the hybrid offspring are viable

Alternate species concepts Other than biological species concept (fertile offspring)

17) Ecological species concept Based on an ecological niche Includes asexual organisms

18) Pluralistic species concept Looks at all factors for different species

19) Morphological species concept Based on structural features

20) Genealogical species concept Based on genetic history

Modes of speciation How species occur

21) Allopatric speciation Populations are geographically isolated Different environmental pressures cause variation and selection Ex. squirrels in grand canyon

22) Sympatric speciation No geographic isolation Populations together but diverge

23) Adaptive radiation Diversity among a species with single ancestor

24) Polyploidy More than 2 sets of chromosomes for a character Causes more diversity

25) Gradualism Many small changes Each small change builds up to a major change over millions of years

26) Punctuated equilibrium Large sudden changes drastically change the population over relatively short time This is followed by long period of very little change

27) Phylogeny, Systematics and Cladistics Traces the evolutionary history of an organism

28) Absolute Time The actual date or age of an object Example Tree rings Carbon 14 dating dating – measuring radioactive particles

29) Relative Time Determines relative age of fossil by the rock it is in comparing younger and older rocks in layers It is Not the actual age Ex law of superposition

30) Geologic time – entire history of life on earth

31) fossils Evidence of life in rock can help tell us what geologic time period a rock is from

32) Systematics The Science of tracing the Phylogeny

33) Cladististics - Uses a cladograms for phylogeny – A branching diagram to show evolutionary relationships

34) Vertebrate cladogram Each juncture has a division point Out group – The First group to separate. Most like the common ancestor

Invertebrate cladogram Similar types will branch from same point

Evolution of bird shown in cladogram

Formation of Clads Clads are formed based on fossil evidence and suppositions by scientists In some cases the common ancestor exists. In many it has not been found so is inferred.

How did a four chamber heart evolve How did a four chamber heart evolve? Use to analyze two models of evolution A) bird/mammal homologous Clad immediate common ancestor, Reptiles _______ B) Bird/mammal analogous Clad, Reptiles ________ distant common ancestor Mammals and birds have 4 chambered heart. Reptiles have 3 ½ chambers