Module 1: Evolution MonthDayTopic Sept8Mechanisms of evolution I 11Mechanisms of evolution II 13Speciation 15Macroevolution and phylogenies 18Biodiversity 20The history of plants 22Molecular evolution Exam review First mid-term exam

What controls the rate at which new species form?

Species richness

What controls the rate at which new species form? Species richness Range size and mobility

What controls the rate at which new species form? Species richness Range size and mobility Behavior, especially mate choice

What controls the rate at which new species form? Species richness Range size and mobility Behavior, especially mate choice Environmental change

What controls the rate at which new species form? Species richness Range size and mobility Behavior Environmental change Life history

What controls the rate at which new species form? Species richness Range size and mobility Behavior Environmental change Life history “Empty space”

Hawaiian silverswords

4 th mass extinction 210 mya: ~65% of species 5 th mass extinction 65 mya: ~76% of species Extraterrestrial impact or volcanism?

What controls the rate at which new species form? Species richness Range size Behavior Environmental change Generation time “Empty space” Innovation

Proportional Changes in Skull Chimpanzee Human Figure 19.14b Page 315

Microevolution Change in the frequencies of genotypes in a population The formation of new species Macroevolution

Classifying the diversity of life Systematics

Classifying the diversity of life Systematics Taxonomy Phylogenetics

Bluebells…

Taxonomy Linnaeus (1700s) –System of classification based on morphological similarity

Taxonomy Linnaeus (1700s) –System of classification based on morphological similarity –Binomial nomenclature

Taxonomy Linnaeus (1700s) –System of classification based on morphological similarity –Binomial nomenclature –Hierarchical classification

Binomial nomenclature Homo GenusSpecies sapiens Capitalize Italicize or underline

Hierarchical classification Kingdom: Phylum: Class: Order: Family: Genus: Species:

Hierarchical classification Kingdom:Animalia Phylum: Chordata Class: Mammalia Order: Primates Family: Hominidae Genus:Homo Species: H. sapiens

Hierarchical classification Kingdom:Animalia Phylum: Arthropoda Class: Insecta Order: Diptera Family: Muscidae Genus:Musca Species: M. domestica

Hierarchical classification Kingdom:Plantae Phylum: Anthophyta Class: Monocotyledonae Order: Poales Family: Poaceae Genus:Zea Species: Z. mays

Hierarchical classification Kingdom:Plantae Phylum: Anthophyta Class: Monocotyledonae Order: Asparagales Family: Orchidaceae Genus:Vanilla Species: V. planifolia

Phylogenetics Classification of organisms according to their evolutionary relationships

Phylogenetics Classification of organisms according to their evolutionary relationships A phylogeny is the history of decent of a group of organisms from their common ancestor

Ancestor Sp. 1Sp. 2Sp. 3

Ancestor Sp. 1Sp. 2Sp. 3

Ancestor Sp. 1Sp. 2Sp. 3 Derived traits Ancestral trait

Ancestor Sp. 1Sp. 2Sp. 3 Tail stub SHARED CHARACTER

Ancestor Sp. 1Sp. 2Sp. 3 Tail stub Tail motor control SHARED DERIVED CHARACTER

Ancestor Sp. 1Sp. 2Sp. 3 Prehensile control Tail stub appears Tail motor control DERIVED CHARACTER

JawsLimbsHairLungsTailShell Lamprey Turtle Cat Gorilla Lungfish Trout Human Taxon Traits (Characters)

Homologs Features that have descended from a common ancestral feature

Homologs Features that have descended from a common ancestral feature Use homology to determine phylogenetic relationships

Homologs Traits can be… Morphological Developmental Behavioral Molecular

Homologous features

Difficulty Traits change with evolution

More difficulties… Convergent evolution

More difficulties… Convergent evolution –Similar environments shape features that have different ancestral origins to look very much alike

Arm bones are homologous BUT wings are the result of convergent evolution

Cactus and euphorbs

More difficulties… Parallel evolution

More difficulties… Parallel evolution –Similar developmental processes may make traits in distantly related organisms look similar, even though those traits did not come from a shared ancestor

More difficulties… Evolutionary reversals

More difficulties… Evolutionary reversals –A derived trait may revert back to its ancestral state

Ancestor—Toothy frog Sp. 1Sp. 2Sp. 3 Loss of teeth Teeth regained

More difficulties… Convergent evolution Parallel evolution Evolutionary reversals Traits that are similar due to these processes are called homoplastic traits

Homologous trait versus Homoplastic trait Same because of descent from common ancestor Same because shaped by similar environments

Homologous trait versus Homoplastic trait Used to build phylogenetic relationships Not used to build phylogenetic relationships

Principle of parsimony Choose the simplest hypothesis capable of explaining the pattern.

Principle of parsimony Choose the simplest hypothesis capable of explaining the pattern. Descent from a common ancestor is much simpler than invoking homoplasies.

Principle of parsimony …think of it as the path of least resistance It is “easier” to inherit a trait than to build a new one.

Principle of parsimony The null hypothesis: this trait was inherited from a common ancestor The alternative hypothesis: this trait was built by natural selection

Modern taxonomy

Biological species Versus “taxonomic” species

Modern taxonomy Taxonomic groups should reflect evolutionary relationships

Modern taxonomy Taxonomic groups should reflect evolutionary relationships Taxonomic groups should be monophyletic –They should contain all the descendents of a particular ancestor, and no others

Monophyletic

Evolutionary Tree extreme thermophiles halophiles methanogens cyanobacteria ARCHAEBACTERIA PROTISTANS FUNGI PLANTS ANIMALS club fungi sac fungi zygospore- forming fungi echino- derms chordates annelids mollusks flatworms sponges cnidarians flowering plants conifers horsetails lycophytes ferns bryophytes sporozoans green algae amoeboid protozoans slime molds ciliates red algae brown algae chrysophytes cycads ginkgos rotifers arthropods round- worms chytrids oomycotes euglenoids dinoflagellates Gram-positive bacteria spirochetes chlamydias proteobacteria ? crown of eukaryotes (rapid divergences) molecular origin of life EUBACTERIA parabasalids diplomonads (e.g., Giardia) (alveolates) (stramenopiles) chlorophytes kinetoplastids extreme (e.g., Trichomonas) Figure Page 321

Five Kingdoms BacteriaProtistsPlantsFungiAnimals Earliest organisms

Three domains Bacteria Earliest organisms ArchaeaEukarya