Bio 3401 Exam 1 Study Guide Lecture 1 Intro I Symbiosis an interaction between different species a Often distantly related b Allow the organisms involved to address some type of challenge c Engine for innovation both evolutionary and ecologically d Relation is seen through trees II Trees a Created by systematists b Used because we want to know the direction and pattern of change for organismal features i Changes occur in time which moves in one direction ii Changes occur in a species and are then transmitted to offspring creates a hierarchic pattern c Tree terms i Branch length amount of change ii Terminals species iii Nodes ancestors iv Root base d Describe relationships in respect to common ancestors e Most recent common ancestor is the least inclusive ancestor that the two taxa share f Two taxa are said to be more closely related to each other than to another if they share an ancestor that is not shared with the other taxon III Characters a Attributes that exhibit different states among the study group b Must be transmitted c Should be constant within taxa i Morphology DNA Sequence behavior chemistry ontogeny i Most parsimonious solution is one most corroborated by data d Parsimony IV General Procedure a Define study group ingroup and ext reference points outgroups i Outgroup a taxon outside of study group ii Often use more than one iii Does assume you know something about relationship of ingroup to outgroup b Specify character data propose homologies c Calculate most parsimonious solution d Interpret evolutionary patterns on cladogram i Cladogram tree we reconstruct based on character changes 1 Network of characters and taxa 2 No real ancestors nodes are hypothetical ancestors V Homology a Calling two things the same is a statement of homology b Common ancestry c If two things look the same hypothesize homology rather than convergence most interpretive step i Characters are tested against each other ii Falsification of a hypothesis is based on weight of evidence d DNA sequence homology alignment VI Synapomorphy shared derived character a As characters transform it is innovations that will mark groups b Shared primitive states to not mark groups although they can distinguish assemblages Lecture 2 Symbiosis Intro Symbiosis I a History i Some idea of parasitism known by ancient Greeks ii Worms that live in human gut known iii During 1800 s much progress was made on understanding these associations Instances of spontaneous generation were disproved iv v Complex parasite life cycles were described b Pierre Joseph van Bened n i French biologist in 1875 ii Distinguished mutualists from commensals iii Commensalists and Parasites of the Animal Kingdom c Heinrich Anton de Bary i German botanist in 1879 ii Considered founder of modern mycology iii Often credited with the term symbiosis iv The Phenomenon of Symbiosis d What symbiosis is not i Interactions among individuals within a species 1 Parental care is not symbiosis ii General interaction among species of an ecosystem 1 A fern growing in the shade of a maple tree is not symbiosis e What do organisms need i Energy we call it food ii Environment proper place to live iii Reproduction the next generation f What types of symbiosis are there i Mutualism both parties benefit ii Commensalism one benefits other is neutral iii Parasitism one benefits the other suffers g Factors to consider i Specificity what associates with what 1 Phylogenetic concept 2 Which lineages are involved ii Degree of dependence 1 Obligate facultative 2 Are they in physical contact If so how long 3 Can one or both partners live apart a Do they form a new organism 4 Whole lifespan or just some stages h Dynamic symbiosis arms race i A host species and its parasite species can wage an ongoing battle in which the host develops defenses and the parasite overcomes them i More and more cases are being discovered with 3 4 or 5 i Complex symbioses symbionts j Organismal interactions i Some are superficial external interactions maybe not even physically touching each other ii Other more intimate meaning clear cell cell communication Lecture 3 Mutualism and Commensalism I Mutualism a For some this IS symbiosis b Both partners receive benefit c Does it have to be equal benefit d Can a mutualism fall apart e What maintains a mutualism II Altruism a b Explanations of kin selection helping relatives or regular natural It may not really exist in nature selection for social systems honeybees c The key is that such associations benefit the organisms or species III Lichens an extreme mutualism a An alga usually a green alga and a fungus usually an ascomycete b Name and classify them as organisms c The name is tied to the fungal partner because that is the more variable one d Algae can be free living but fungi are not e Reproduction i No sexual reproduction of lichens as a whole since their genetic material does not fuse ii The fungal biont undergoes sexual and asexual reproduction iii The algal biont only reproduces asexually iv Two ways to reproduce lichen 1 Asexual reproduction by fragmentation with both partners present 2 Following sexual reproduction of fungus symbiosis has to be re established IV Mycorrhiza a Partnership between plant and fungus b 95 of plant species belong to families that are characteristically mycorrhizal c 80 of land plants surveyed shown to be mycorrhizal d Various different kinds of mycorrhiza exist e Typical pattern is for mineral nutrition to go fungus to plant and for carbon compounds to go plant to fungus f Earliest land plants did not have roots and have been shown to have mycorrhizal connections g Arbuscular mycorrhiza V Lead cutter Ants and Fungi i Appear to be most ancient type 400 mya a Attine ants Atta and Acromyrmex b From South America to Southern US c Fungus is a basidomycete d Fungus has never been found outside of an ant nest and has been in cultivation for at least 45 million years e Ants tend the fungus and harvest it for food gongylidia f Queens found new colonies by carrying bits of fungus to a new site g Cultivated fungus is transmitted vertically by queens h Example of obligate association i Escovopsis is a fungus that parasitizes the cultivated fungus j Also not known outside of Attine nests k Attine ants carry bacteria Pseudonocardia on their bodies that secrete anti fungal compounds that are used to fight the Escovopisis VI Prisoner s Dilemma a Cooperate or cheat b Matters whether is a one time or continuing decision VII