Origin of Species Where did all the species come from?

Macroevolution The formation of new taxonomic groups The formation of new taxonomic groups Kingdoms to species Kingdoms to species

Microevolution – variations within a “type” genus or group

Speciation Formation of a new species Formation of a new species A species is a population of similar organisms that can reproduce and produce fertile offspring A species is a population of similar organisms that can reproduce and produce fertile offspring

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

Cladogenesis Branching evolution Branching evolution A new species arises from a population that buds from a parent species A new species arises from a population that buds from a parent species Splitting (common ancestor) Splitting (common ancestor)

Barriers that isolate populations

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

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

Geographic isolation Habitat isolation by barrier Habitat isolation by barrier

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

Ex. Blue footed boobies Have very specific mating rituals Have very specific mating rituals

Mating songs differ

Temporal isolation Two species may mate at different times Two species may mate at different times

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

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

Mechanical isolation in plants

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

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

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

Reduced Hybrid fertility Hybrids are infertile Hybrids are infertile

Hybrid breakdown The offspring of hybrids are infertile or dead 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) Other than biological species concept (fertile offspring)

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

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

3) Morphological species concept Based on structural features Based on structural features

4) Genealogical species concept Based on genetic history Based on genetic history

Modes of speciation How species occur How species occur

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

Sympatric speciation No geographic isolation No geographic isolation

Adaptive radiation Diversity among a species with single ancestor Diversity among a species with single ancestor

Polyploidy More than 2 sets of genes for a character More than 2 sets of genes for a character Causes more diversity Causes more diversity

Gradualism Many small changes Many small changes Evolution by creeps Evolution by creeps

Gradualism Many small changes Many small changes Evolution by creeps Evolution by creeps

Punctuated equilibrium Large sudden changes Large sudden changes Evolution by jerks Evolution by jerks Little change after formation Little change after formation

Systematics and Phylogeny Chapter 23 Chapter 23 The evolutionary history of an organism The evolutionary history of an organism

Absolute Time The actual date or age of an object The actual date or age of an object Example Example Tree rings Example Radioactive dating – measuring radioactive particles

Carbon 14 dating is absolute time. When a living thing dies it starts losing carbon 14. (radioactive carbon). When a living thing dies it starts losing carbon 14. (radioactive carbon) When ½ of it is gone it is called its half- life When ½ of it is gone it is called its half- life

Relative Time Determines which rock is older and which is younger. It is Not the actual age Determines which rock is older and which is younger. It is Not the actual age

Geologic time – entire history of life on earth

A fossil can help tell us what geologic time period a rock is from

Law of superposition Older rock is below younger rock Older rock is below younger rock Layer 1 is oldest Layer 1 is oldest Layer 2 is older than 3 Layer 2 is older than 3 Layer 3 is older than 4 Layer 3 is older than 4 Layer 4 is youngest Layer 4 is youngest

Systematics The Science of tracing the Phylogeny The Science of tracing the Phylogeny

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

Vertebrate cladogram Each juncture has a division point Each juncture has a division point

Invertebrate cladogram Similar types will branch from same point

Evolution of bird shown in cladogram

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