Lecture'16'Bio'200'''Angiosperm'Evolution:'• So'many'traits'unite'the'angiosperms.'• All'of'the'flowering'plants'share'the'same'ancestor'Archaefructus@''o Extinct'o Still'talked'about'today'because'it'may'be'our'window'into'the'origin'of'the'angiosperms.''• Based'on'fossil'record'here'was'a'sudden'appearance'of'modern'flowers'during'the'Mesozoic.''• This'posed'such'a'problem'for'the'theory'of'evolution'that'we'have'talked'about.''• Darwin'referred'to'this'as'an'abominable'mystery.''• We'thought'species'evolved'gradually'over'a'long'period'of'time.'Where'did'these'complex'structures'come'from?'Why'don’t'we'have'any'intermediate'or'missing'lings'to'have'they'appeared?'This'really'challenged'darwin’s'believe'about'the'small'steady'change'of'evolution'in'species'• With'all'these'amazing'things'he'observed.'He'believed'flowers'were'the'most'amazing'species.'Today,'these'questions'are'still'unanswered.''• This'abominable'mystery'shows'how'evolution'is'complitites'and'the'gap'in'our'understanding'in'the'origin'in'the'early'phases'of'angiosperms'in'evolutionary'history'• There'are'some'suggestions'in'the'fossil'record.'We'believe'the'Archaefructus'is'the'sister'taxon'to'the'modern'flowering'plants.'But'we'really'don’t'know'if'it'was'the'first ' flower.'''Archaefructus@'• We'have'fossils'from'several'species'from'this'genus'that'dates'back'from'at'least'125'MYA.''• All'aquatic'plants''• Male'and'female'structures'(pre@flowers)'• Didn’t'have'the'sepals'or'petals'that ' we'see'today'that'serve'the'purpose'of'attracting'pollinators.''• Probably'relied'on'water'to'transport'the'pollen'to'the'stigmas.''• Not'really'quite'flowers'as'we'think'ab ou t'today,'''Angiosperm'Origin@'• Flowering'plants'became'the'dominant'plant'on'earth'about'90MYA'from'looking'at'the'fossil'record.''• Fossils'of'Archaefructus'and'records'of'pollen'fossils'(very'important'tool'in'assessing'what'past'environments'looked'like).'These'fossils'have'estimated'140'MYA'were'when'flowering'plants'evolved.'• Last'year,'new'evidence'from'new'pollen'fossils'that'suggested'flowering'plants'originated'much'earlier'than'we'previously'thought.'In'fact'100'MYA'earlier'than'the'theory'above'(first'dinosaurs'were'born)'• But'It'leaves'a'period'of'100'MY'that'there'are'no'records'of'flowering'plant@like'pollen''Modern'Flowering'Plants:''• Amborella'Trichopoda:''• Aka'Amborella'• Only'has'one'remaining'species'in'the'genus.'Used'to'be'a'much'larger'group.''• Represents'most'ancient'living'angiosperm''• Currently'only'exists'on'a'small'island'on'Australia'called'New'Caledonia.''• Sprawling'shrub,'or'a'small'tree'and'the'flowers'on'the'plant'actually'set'out'as'hermaphroditic.'Both'sexes.'• Only'one'of'the'sexes'develops'fully'and'is'fertilize'on'the'flowers'on'a'individual'plant'• The'structure'of'the'other'sex,'is'unfertile.'• Dioecious@'male'of'female'on'individual'plants'• The'flowers'are'extremely'small.'• Cannot'test'ant'hypothesis'on'this'pl ant@'abominable'mystery'still'continuous'''Basal'Angiosperms:'• Amborella,'Nymphaeales,'and'Austrobaileyales'make'up'this'group.'• First'lineages'branching'off'in'the'phylog en ic'tree'of'the'flowering'plants.''• Paraphyletic@'because'they'do'not'a'MRCA'unless'we'include'the'other'groups''Nymphaeales:'• Water'lilies,'• 80'species'of'them'• Entirely'comprised'of'water'plants'• Very'“showy”'flowers.'• No'vessel'cells@'the'exception'to'the'other'angiosperms.'This'is'because'they'are'aquatic'plants,'they'don’t'need'vessel'cells.'They'aren’t'big'structures.''• Root'and'sediments'under'shallow'water'and'have'extended'leave'and'flower'steams'• The'leaves'(lilly'pads)'can'float'on'the'water'surface'and'photosynthesize'and'the'flowers'can'float'and'be'pollinated'above'water'• The'stomata@'openings'that'allow'for'air'to'come'in'and'water'to'go'out='All'are'found'on'top'of'the'leaves'so'they'are'above'the'water'line'• Water'lilies'are'very'strong,'which'is'why'they'can'support'the'weight'of'frogs'and'even'small'children''Austrobaileyales:'• Comprised'of'star'anise'and'relatives'• Contains'about'100'species'of'wooded'plant s.''• Recently'added'group'of'basal'angiosperms'• Found'in'Australia'and'tropical'and'temperate'regions'of'South@east'Asia'and'the'Caribbean’s.''• Most'popular'member'is'the'spice:'Star'anise.''o Dried'fruit'of'a'small'evergreen'tree'in'china'o One'of'5'species'in'the'traditional'Chinese'5@spice'powder.'''Mesangiosperms:'• Chloranthaceae,'Magnoliids,'Monocots,'Certophyllum,'and'Eudicots'make'up'this'group.'• Monophyletic,'because'they'share'MRCA'• Constitute'by'the'far'the'most'flowering'plants'• Most'of'the'diversity'in'flowering'plants'is'found'here'''Chloranthaceae'&'Ceratophyllum'o Small'clades'• Difficult'to'place'on'the'phylogeny'• Often'been'treated'separately'from'the'major'groups.'• Based'on'the'most'recent'data:'Chloranthaeae'is'believe'to'be'groups'with'Magnoliids'• And'Ceratophyllum'is'believed'to'be'grouped'with'Monocots'and'Eudicots'• Chloranthaceae='several'dozen'species'of'Wooden'species'found'in'the'tropics'and'subtropics.'Not'well'known.''• Ceratophyllum='well'known.'The'plants' u sed' in'fresh'water'aquariums'are'ceratophyllum’s.'6'species'in'this'group.'All'the'plants'float'just'under'the'water'surface.'Offer'excellent'protection'to'fish'spawns/babies'and'to'snails.''• Used'in'fresh'water'aquariums'because'of'their'appearance.'And'also'because'of'their'very'high'oxygen'production.'''Magnoliids@''• Very'large'group'of'plants'with'many'species'that'are'very'economically'important'like'foods,'drugs,'perfumes,'ornamentals'etc.''• Many'known'species'are'found'here'• Ex:'Nutmeg,'avocado,'cinnamon,'magnolias,'black'pepper'• Trimerous'flowers@''Flowers'are'found'in'3'parts,'3'petals,'3'sepals,'3'stamens,'etc.''• They'are'often'in'multiple'numbers'and'spirally'shaped'in'the'flowers.''• Ex:'many'carpels'arrange'spirally'looking'like'a'cone.''One'reason'they'were'thought'to'be'primitive'angiosperms.'Because'of'the'flowers'almost'look'like'cones.''Eudicots@'• Represent'75%'of'all'angiosperms.''• Most'successful'plant'lineage,'containing'many'familiar'plant'species.''• Members'that'have'four'or'five'flowers@'Trimerous.'4/5'petals,'4/5'sepals'etc.'• Coco'trees,'tomato'trees,'Venus'fly'trap'etc.'• We'see'them'fused'•
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