Bio Test 2 Notes - PDF

Lecture/Slide Deck 9 ; Species, speciation, and hybridization - The Origins of Biodiversity;  - Hawaiian honeycreepers are a great example of adaptive radiation  - Can natural selection, migration, genetic drift, mutation etc (microevolutionary patterns) lead t...

Lecture/Slide Deck 9 ; Species, speciation, and hybridization - The Origins of Biodiversity;  - Hawaiian honeycreepers are a great example of adaptive radiation  - Can natural selection, migration, genetic drift, mutation etc (microevolutionary patterns) lead to population level changes (can microevolution produce macroevolutionary changes - Modern sysntheise led to people understanding how genetics and darwin theory of evolution were related (how evolutionary change occurs)  - How do we get from little changes to incredible diversity within a population like beetles - We generate diversity through species which is the splitting of a single ilieage into two different species that will not come back together - Key questions of speciation;  - What circumstances will speciation occur in  - How does reproductive isolation work (toward speciation) - Vvvv important for speciation in sexaul organisms  - What genetic changes can occur during speciation  - How does adaptation/natural selection play a role in speciation - Does it help explain diversity on planet - What Is a Species?;  - What is a species is really hard to define  - The concepts vary among species and scientists and there is no one universal way of defining what a species is (some concepts may work well with one organism but not in others , like sex vs asex)  - There are many different species concepts (dont need to remember them all)  - A species concept is basically different ways of definein one species from another  - Taxonomic/Morphological -  Phenetic - Genetic - Ecological - Phylogenetic - Biological - Recognition - Cohesion - Darwinian - Evolutionary - The two most common species concepts are as follows;  - Taxonomic/morphological species concept - If we can measure stable differences between populations they are going to be different species (espically big differences)  - Based on measurable differences in morphological (obsered) charactieriscs  - Biological species concept;  - Can sexual organims reproduce with one another - Based on interfetility - Darwin and species - Didnt think species were real and they were human concept  - Likely looked at taxonomic species concept when it really came down to it - Ernst Meyer;  - Pioneered the biological species concept BSC - Species are a group of naturally interbreeding populations that are reproductively isolated from others  - Groups that can interbreed with eachother but not with other interbreeding groups are species - When 2 groups stop sharing alleles they become species - BSC  - Focuses on process of divergence  - Very hard to apply in real life because you need know wheter two populations are sharing alleles or not and thats really hard  - You can base off of geopgrapich isolation alone because if they are separated you dont know if they naturally interbreed or not (you cant put them in the same place and try that because you impose artificial breeding)  - Just because the may be different species doesnt mean there isnt any gene flow (what is too much gene flow - MUST NOT INTERBREED IN NATURE IF YOU PUT THEM IN A LAB AND THEY BREED THAT DOESNT COUNT BECAUSE THEY DONT BE DOING IT IN NATURE   - If they produce viable offspring in lab then its humans who force them to become unisolated, otherwise they were reproductive isolated - Doesnt apply to asex species because they dont secually reproduce so reproductive criteria doenst apply to them  - The Geography of Speciation;  - Where does speciation occur?  - Allopartric/geogrpahic speciation;  - Lineages divide and accumulate changes/RI while physically separated from eachtoer  - Much more common  - You have a single species in a place and some sort of barrier to gene flow arises like a mountain or a river  - Divides the population and there is no more genelfow/sharing of alleles  - Overtime evolution and the accumulation of mutations and natural selection working upon them will cause these two populations to become different from one another  - Over time the will evolve to be different enogught that they can no longer produce viable offspring with eachoter and voila! A new species! (they are now different species, once no longer **reproductively compatible**)  - Sympatric; A diagram of different types of diseases Description automatically generated - Lineages diverge and accumulate changes/RI while occupying the same physical location - Alllll that divergence and RI has to happen in the same geographic location which is much harder because you'll be having local gene flow working against genetic drift and natural selection (any changes that arise will be swamped by gene flow)  - Very hard to overcome  - The only way to overcome that is for assotitiv emanating where those with certain alleles mate with them selves and others with differetn alleles mate with themselves very rapidly  - Very rare  - Few examples but not thought to be very common  - Evolution of Reproductive Isolation;  - BSC's focus on reproductive isolation allows us to break down the steps in reproduction and if anything disrupts one of those steps it can cause RI to evolve - The process is as follows in two categories;  - Prezygotic barries - Finding a (compatible) mate and mating  - Fertilisation to make a xygote without anything going wrong - Postzygotic barriers  - Zygote must develop and grow  - Must survive and reproduce - Its offspring bust survive grow and reproduce - Not all individuals ina species can produce viable offspring - Evolution can shake some stuff up and accuse RI to evolve - Reproductive solation barries  - Prezygotic;  - Anything stopping mating or stoping zygote formation after mating - Geographical/ecological - Ecologically divergent populatiosn that dont share resources and never cross paths cant mate right!  - Temporal, behavioral changes;  - A species is reprodcutivealy active in a different species from sister population reduces gene flow - Mechanical :O;  - Genetials literally evolve to be different so that they dont physically go togher which is a pretty obvious example of how gene flow cannot occur and how RI can arise - Lock and key mechanism - Cellular;  - Sperm cant penetrate egg - Example (Pre‐zygotic Isolation in Apple Maggot Flies: Habitat and Temporal Isolation); - Fly spices that evolved to lay eggs on hawthorne (Apple like trees) and feed on the hawthornes (hawthornes... back when i used to read :( ) and mate on hawthornes............ - When settlers brough apples to north america the flys were like OMG really big hawthornes!  - And they started to shift to mate and lay eggs and grow on apples which mature earlier in the year than hawthornes  - So the species using apples vs hawthornes arent coming into contact with easter and causes a reduction in gene flow by 94%  - Example of sympatry (sympatric RI) because they are in the same geographic location and evolving changes and stuff - Prezygotic barriers because these guys aren\'t even coming into contact with each other which is obvs a barrier to mating before a zygote is formed!  - We can see in the graph that flies lay eggs and use apples earlier then lay eggs and use ahwthornes later  - Example ( Pre‐zygotic Isolation in Abalone: CellularIsolation); - Abalones are sendatry (non moving) organisms that spread alleles by sending huge amounts of sperm (:\|) out into water column whic will find females and fertilse their eggs A diagram of fertilization Description automatically generated - The spermhead has a lysin protein that unravels the eggs vitelline protein there and allow the sperm to get in  - But in differnet species of abalones the spems lysin protein isnt recognised by the vitalline mechanism of the other, leading to RI (evolution took them indifferent directions - Prezygotic cellular barries (not mechanical because theres no genitals involved) (bet you thought youd never say that)  - Post-zygotic RI barriers;  - Anything that prevents the proper function of the zygote once formed - Problem with growth and development or itll grow up and be sterile  - Always because genes of two populations are incompatible with each other (the alleles just dont work together)   - Can never happen via natural selection (it is a byproduct of other evolutionary forces) because you cana never select upon something that reduces fitness (reduces zygote viability)  - Two different types as follows;  - Intrinsic postzygotic barriers;  -  Inviability, sterility or abnormal development of hybrids - Species frog  A and frog B (two diff species) mate and create hybrid frog AB which may have health/developmental problems - AB may not survive in the wild but if it does it might not be able to mate with another AB frog (sterile)  - AB may be fertile and mate with another AB frog but that AABB frog will have problems like weakness or sterility  - An example is mules (male donkey, female horse) which are more patient thatn horses and stronger than donkeys so they are used for farm work  - But you cant make a mule from another mules, you, one parent is always going to be a horse, and the other is always going to be a donkey, mules are sterile  - Postzygotic isolating mechanisms evolve as a byproduct of evolution so we expect to see more postzygotic isolation as more time (evolution diverging population) goes on - This works with evolution because as species evolve they accumulate changes which can lead to PZB like offspring dying early, being strile or F2 being sterile  - Scienticts did en experiment to observe this theory and found that  - They measured genetic distance (how different their DNA sequences are from each other) and postzygotic isolation (tendency of offspring to be inviable, liek mentioned above)  - They found that as you increase the genetic distance PZI tends to increase as well (the more different species are, the more likely it is they will have inviable offspring - "In fruit flies, researchers have observed that when two populations have a greater genetic distance, their hybrid offspring often show higher rates of inviability (they don\'t survive) or sterility (they can\'t reproduce)"   - "This relationship helps scientists understand how new species form (speciation) and how genetic differences accumulate over time to create reproductive barriers"  - Extrinsic postzygotic barriers;  - Hybrid is fine, but won\'t survive well outside a given environment - Toxic butterfly example;  - Heliconius butterflies are aposomatic with bright spots to warn bird they are toxic so they dont get eaten, and birds have evolved to know not to eat them A graph of butterflies and blue bars Description automatically generated with medium confidence - When you cross two different species they make a hybrid that can survive and produce well but has a different aposomati cpattern that the bird dont know so they try them out and they get eatne a lot more and have ower fitness (they are selected against)  - This is extrinsic because it depends on the environment and behaviour of other organism outside of them (liek predators and potential mate whci there will be less of because they keep getting eaten) rather than inside of them, like genetic issues - Adaptation & Speciation;  - Does adaptation play a role in speciation - Local adaptation is a big drives of speciation when leading to differences between populations(ecological speciation)  - It speeds up the evolution of RI - People research context in which it happens and how the genetic changes accumulate  - Example;  - SSSTTTTICKELBAKKKKKKSSSSSSSSSS (can we every escape them?)  - Great example of how local adaptation can lead to phenotypic differences associated with RI  - Stickelbacks were originally oceanic fish that then colosied freshwater which is a very different selective environment - Oceanic sticklebacks have more armour and freshwater have less  - Oceanic sticklebacks and freshwater have spinal differences and some freshwater ones have lost their pelvic spine - Resreaches (Dolph Schluter and David Kingsley) looked at the gene responsible for these phenotype changes and found that his local adaptation can lead to a reduction in gene flow and incompatiblites between populations - Thought of as steps towards speciation - We are gaining a deeper understanding of how microevolutionary processes (natural selection, mutation, drift, etc) can lead to speciation and explain macroevolutionary patterns - Adaptive evolation can lead to changes where speciation is a byproduct (speices evolve to fit their environment/needs so much that they begin to accumulate so many changes that the difference become so pronounced that RI occurs)  - Adaptive radiation;  - Process in which organisms rapidly diversify into a lot of new forms in a short amount of time (within a rapidly multiplying lineage)  - Come from a single ancestor  - It is counted if it results in a lot of adaptive diversity/ecological diversity  - Four common things in adaptive radiations'  - Comes from a single common ancestor  - Phenotypic differences that are related to the utilisation of resources (phenotypic difference that help with getting different resources)  - Trait utility (like being able to use those traits, connected with above point)  - Realllylyy rapid speciation - What causes adaptive radiations;  - Ecological opportunity/drive;  - Ecological opportunities that allow species to diverge and take advantage of different resources  - ECOO's is the absences of competing species (resources for the taking) so an ancestral lineages can diversify into species that utilise those lineages  - We can get ECOO's when a population colosines an area with no competitors (like island and de novo lakes, where populations and go wacko and like exapnd to do all sorts of things to get to the resources that are on offer)  - We can also get ECOO's in response to the extinction of competitors where a huge group that was usign those resources have been wiped out so the population can adaptively radiate to now use those same resources (radiation of mammles after dinosaurs went extinct)  - Lastly we can get ECOO'S through key innovation wich allows an organism to utilise the environment in a different way like lizards evolving sticky toepads to use tree resources they would not have otherwise been able to get to  - Hihg propensity for speciation;  - If theres just something about a given cladeor lineage that makes speciation easier  then they will be more likely to utilise ECOO's and adaptively radiate - Like finches which can really easily speciate and accumulate RI's vs mockingbirds which cant  - - Evolutionary Significance of Hybridization;  - Hybridisation is when different species mate and make offspring - It can be the opposite of speciation when (typically new and young) species interbreed and collapse into a single species in a given environment (reduces distinctiveness of species by mixing them together)  - Can see lots of hybridiatsion in things like plants and fish but less common in mammals - It can also lead to speciation through polypoidy;  - Polypolidy is when an organism has more then two set of chromosomes (humans ar diploid) 3+ is polypolidy  - Allopolypoildy;  - "Allopolyploidy occurs when an organism has more than two sets of chromosomes derived from different species" - Happens when two species with more than 2 sets of chromosomes hybridise and the offspring combines the parental chromosome sets leading to a new species with a different number of chromosomes (happens in an offspring from two different parent species)  - Most common type of polyploidy  - Autoploidy;  - "Autopolyploidy occurs when an organism has more than two sets of chromosomes, all derived from a single species." - Occurs usually due to errors in cellular replication where an organism has more than two sets of chromosomes (happens within an individual) (like diploid dosnt go to haploid during meiosis)  - Speciation from allopolyploidy;  - We have two different species (diploid) that hybridise to form a diploid offspring that undergoes allopolidy and forms diploid gametes  - That offsrpings offspring will have two sets of chromosomes from each parent and result in a new organism with a complete set of chromosomes from each parent  - They are often healthy and fertile and can mate with other allopolyids but not with any of the parental species which is what leads to speciation - Common mecahins of specian in plants  - Sympatric speciation  - Novel phenotypes cus of all of these weird chromosomes  - Exhibit hybrid vigour (offspring exhibit superior qualities from parents)  Keywords for this section;  - ***[Sympatric isolation:]***  The divergent adaptation adn accumulation of different traits in a single inlage in the same geographic location - ***[Allopatric isolation:]***  the divergent adaptation and accumulation of different traits in a single linages in different geographic locations  - ***[Intrinsic reproductive isolation:]***  RI arising due to inviabily, or stelriy of hybrids - ***[Extrinsic reproductive isolation:]***  RI arising due to external factors affecting hybrids  - ***[Autopolyploidy:]***  3+ sets of chromosomes arising from errors in cell division - ***[Allopolyploidy:]***  3+ sets of chromosomes arising froom the combination of parental chromosomes from two different species  - ***[Hybridization:]***  The combination of allesl from two different species into a singel offspring - ***[Adaptive radiation:]***  The rapid diversification of a single linage to fill various ecological niches  - ***[Modern synthesis:]***  Combo od mendel theorie sof inheritance and darwin theories of evolution  - ***[Speciation:]***  when new specis from from a common linages and are no longer able to interbreed - ***[Reproductive isolation:]***  A set of mechanisms preventing different species from interbreeding and producing fertile offspring, geographic, temporal, mechanical, cellular Lecture/Slide Deck 10 ; Phylogenetics & Macroevolution - Taxonomy & Systematics;  - How to think about phylogines?  - Taxonomy is theory and practice of classification and naming things;  - Giving things names and keeping them organised - Nomenclature basically  - Systematics is the study of biodiversity and evolutionary relationships *among* organisms;  - We bring evolution into the mix and look at evolutionary history and relationships among species  - "To understand the evolutionary connections and how different species are related through common ancestry."  - Taxonomy is organising your music library by genre, systematics is understanding the history behind each genre and how theyre related to eachother - Taxonomic names are assigned based on our current understanding of evolutionary relationships  - So similar species have similar names (liek *panthera le and Panther tigris* lion an tiger) because they share common ancestors compared to other species  - "In modern taxonomy, scientists try to name organisms in a way that reflects their evolutionary relationships. This means they look at how species are related to each other through evolution and try to group them based on common ancestors." - "For example, if two species share a recent common ancestor, they might be placed in the same genus or family. This approach helps scientists understand and communicate about the diversity of life on Earth in a way that reflects how species have evolved over time. It\'s like organizing a family tree, but for all living things!" - Carolus Linnaeus (oh silvia, you didnt know how i'd see this again...) (this man...)  - Father of western taxonomy  - Sought out to organism worlds biodiversity into a common framework - Created binomial nomenclature system;  - Each species has two names, a genus name and a species name - Its hierarchical system of nomenclature which is nice cuz evolution creates heiecarl patterns as well - We got the 7 step system to remember (any one of these 7 categories/unit is a taxon)  - King Philip Came Over For Great Soda  - Kingdom  - Phylum  - Class - Order  - Family  - Genus  - Species  - May have spurred thoughts of evolution by encouraging people to think about how things are related - Purpise of biological classification;  - Taxonomy is really important because facilitates communication  - It allows us to share key information about an organism in just its name because all the informatin related to it, is tied to its name like articles and stuff - Has predictive power because you can just know something about the organism from its naem without having to do extra work - Allows us to encode evolutionary history into the name (like the panthera) and show these relationships *in* just the name  - SO LONG AS THE NAME IS STABLE  - Sometimes taxonimists liek to switch things up and change names which is no bueno because then all literature of the past has a different name than the literature of the future and that makes thins muy hard to find info on!  - Systematics!  - NEEDS A ROBUST AND STABLE SYSTEMS OF ORGANISING ORGANISMS - Understanding Phylogenies;  - Phylogenetic Tree Basics - The image shows how evolution builds up from individuals to populations then species and then the broad relationships between different species  - We start with A the first step which shows individuals within a population (like similar butterflies)  - Then B which shows that within this population these butterflies will produce offspring  - After is C which indicates that the parent-child links create "lines of descent" that connect generations to previous generations  - For D we see individual family lines mix with other family lines within the population and form the population\'s gene pool by mixing the genes of its members A screenshot of a computer Description automatically generated - With E we see that species are made up of many populations that are linked by gene flow, the populations can be spread out and not in the same place but still be the same species (like humans!)  - Now almost done, with F we see that as populations f the same species bceom RI or evolve separately and develop RI or become isolated or adapt to different environments, they can evelo into different species and that is shown y the splitting of branches, the little one means the species evolved then went extinct, it ended without further divergence  - Lastly with G we see a phylogeny which maps out how different species are related through time and how different species diverged, their common ancestors, the whole shebang  - Components of a phylogenetic tree;  - Nodes;  - Historical linage splitting event, one species speciated and split into two  - Whenever we have a phylogeny where each node splits into exactly two branches, we will always have N-1 nodes (N=number of species)  - Branches (sometimes called edges); A diagram of a diagram of a diagram Description automatically generated - Correspond to single ancestor-descentdant linages - Connected to each other by nodes - Length can sometimes indicate evolutionary time/change passed - Tips! Leave! Terminals! OTUS! - Dont have descendants  - Can represent different things like;  - Individuals;  - If the individuals is being used as a representative of a whole species, liek a rare bird you only have one of and is a meuasme artifiact - Species;  - Most common - Species name at every tip - Clades;  - Each tip corresponds to like cats or dogs, whole caldes of stuffA diagram of a diagram of a branch Description automatically generated with medium confidence - Internal and external branches;  - Internal branches connect node to node  - External branches connect tip to node (terminal branches)  - Root  -  Earlliest point in time of phylogeny  - Often represents THE bad boy big guy one and only most common ancestor but is often also unlabelled  - Can hav eunroote phylogenies :( but noot common cuz we always wanna know about the species originsA diagram of a family tree Description automatically generated - Sister taxa - Immidetate descendants of any given ancestor - Branch off the same node - Parents and daughters;  - Ancestors and descendants relationships - Branch (parent) that gives rise to other branches (daughters) - Ingroups and outgroups; - Ingroups are the species you are interested in studying, like a bunch of frogs A diagram of a tree Description automatically generated - Outgroups are a related species, but not the same species that you use as a reference point to see what traits are derived.new (within the ingroup) and what are ancestral/old (common with outgroup)  - Provides a reference point to place root, ne node between ingroup and outgroup tells you where to put root - MCRA;  - Most recent common ancestor  - Youngest node ancestral to all lineages being looked at - You know this, don\'t really have to explain it - Clade; A diagram of taxon and taxon Description automatically generated - Any piece of the phylogenetic tree that includes an MRCA/node and its all of descendants - Natural evolutionary group because the are related bia a common ancestor - N-1 clades  - Monophyly is the act of separating things into clades, basically it is a clade - A phylogenetic tree can contain many clades - Grouping concepts  - Monophyly; A pair of scissors with a diagram Description automatically generated - A clade is a monophyletic group  - Important because they are natural evolutionary groups  - Clade test is that if you can separate them from the rest of the phylogeny with a single snip of the scissors its a clade  - Paraphyly - Not a natural evolutionary grouping concept because it leaves someone out :(  - Like reptiles, we tradionatlly dont include birds in with reptiles through they did evolve from.with reptiles adn so they are a part of the clade, so repltiesl are not a "real"evoletionary group because you gotta make two cuts, one to split it with the MCRA and anothe rto get rid of the birds!  - Just because you make two cuts doesnt mean paralhyly, theres another option 😮 - Polyphyly; A pair of scissors and a diagram Description automatically generated - A group of organisms classified together, but they dont share an immediate ancestor  - Eg, flying animals, includes bats (mammals), birds (repltiles...or not), insects (insects...)  - You got a group of organsims but no ancestor :(  - Trait evolution;  - Ancestral traits;  - A trait inherited from the MCRA  - Derived traits;  - Traits arisen within the given clade - A traits can be ancestral for once clade then derived for another A diagram of a person\'s evolution Description automatically generated - Synapomorphy;  - Trait shared by two or more groups of organism inherited from their MCRA - That branch is a synapomorphy  - Homology;  - Shared traits in different taxa due to a common ancestor! - Helps us understand evolutionary realtionships - Homoplasy;  - Shared traits in different taxa not due to a common ancestor!  - Convergent evolution be at work here :)  - A red herring and blight on our understand, meant to confused us and lead us astray (will mislead us basically) - Reconstructing Phylogenies;  - Why conduct phylogenetic analysis; A diagram of a dna molecule Description automatically generated - Understand the history of life  - Understand how things work.where they came from  - Understand large-scale patterns of evolution - Understand what traits evolved, when, where, how (what conditions) how fast etc.  - Understanding spread of disease sliek covid etc. - We can have a commone ancestor giving rise to descendants which have their own descendants etc and they will all have traits that are either shared or unique due to evolution  - Some traits may even go away with time  - Wehn reconstruction a phylogeny given the triats/variation of different species its really fun and cool and interesting A diagram of a tree Description automatically generated - You look at only the common traits amon the species - You then look at which species share more traits with another  - And from this you can infer the phylogenetic tree - I\'m not explaining it well here but look at the photos and you'll understand  - This is a very simplistic model and will only work for homologous traits not ones with homoplasy  - Notes on phylogeny reconstruction;  - Professional physlogenetic recoenstriction uses statistical models and data sets to make inferences  - Uses observed trati data, either phenotypic or genetic (often genetic because there so much genetic data)  - The relatedness is inferred from homologus traits which is going to be sytmeid by homoplasty mislead us  - Reconstructing the Tree of Life;  - Adanves in molecular sequencing technology has helped us to reconstruct more of the tree of life - Macroevolution: Understanding Large‐scale Evolutionary Patterns & Processes;  - Macroevolutinary insights often come from one of two disciplines;  - Palentology;  - Insights into macroevolution from fossil record - Direct evidence of evolutionary change  - Not everything fossilises well so lots of groups are not represented in the fossil record - Phylogentics;  - Insights into evolution from branching relations between organisims - Indiect eveidence of evolutionary changes because we have to construct phylogenies ourselves to learn about the past  - Works great for organisms with living relative because we can use their DNA ot make robust phylogenies - Fossil record;  - Helps us gain mega insight into mass extinction events (which there have been 5 of, we may be in the 6th with the way our extinction rates are going) A dinosaur and graph of graph Description automatically generated with medium confidence - We would have no idea about extinct species if not for fossils  - We would not know much about mass extinction events if not for fossils  - Fossils provide the only evidence we have for clades that have gone extinct - Only way of documenting long term global biodiversity (can document millions of years worth of change for example)  - Phylogenetics;  - Can help us study mass extinct event by documenting explosive diversification events that follow mass extinction - Liek after the asteroid wiped out the dinosaurs, birds and mammals diversified a lot and specieated A LOT - Other features associated with increased diversification; A diagram of insects and bugs Description automatically generated - Many traits are associated with diversification liek sexual seletion (makes them more lielky to diversify)  - We can make phylogenetic trees of sister taxa and see if the group that has the trait is more diverse than the other (if the one that has it is more diverse, then that trait is likely good for divesification Keywords for this section;  - ***[Taxon/Taxa:]***  any unit from the 7 stuff of classification  - ***[Phylogeny:]*** phylogenetic tree - ***[Bionmial nomenclature:]***  genus and species which make up the scientific name of stuffs - ***[Clade:]***  any group on a phylogeny including the MCRA and its descendants  - ***[Linnean hierarchy:]***  KPCOFGS Lecture/Slide Deck 11 ; Evolution of Complexity - Introduction: The Evolution of Complexity;  - Complexity; The complexity of an organism reflects the number of parts it has!  - Eukaryotes are more complex than prokaryotes  - Multicelluar life is more complex than uniellular life  - Within an organism there is a complex hierarchical organisational structure that makes the orgasim complex  - What evolutionary problems must be solved in order for these complex structures organisatiosn and stuff to evolve?  - Tree of life has both simple and complex organism;  - Not a one way street, many complex things have evolved to become simpler at some point in their past  - We have simple, single celled eukaryotes  - Typically though eukaryotes are more complex than prokaryotes in all the different ways (cell number, tissue types, development, reproduction, physiology, etc.) even social behaviour! - The Major Transitions In Evolution;  - Book that came out almost thirty years ago aimed at reviewing the history of live and identifying what could be regarded as the major transitions in evolution - When did life go from being simple to complex - Looked at when life went from cells to chromosomes to genetic code to eukaryotes to sex rep., meluticellularity and then colonies!  - Each of those transition has an increase in complexity  - So whats involved in going from these simpler forms to more complex forms (you need to organsie the simple forms into a package) which is challenging - They also hypothesis that to go from simple to complex forms you need to increase the amount of cooperation amongst the units benign assembled - Why do we need that cooperation though?  - What Does Selection Act On?;  - Units of selection;  - As long as you have VHD, that level of organisation is open to being selected on  - It can include the gene level (which replicate and are different and have varying fitness levels) - Cells  (if cells evolve variation you can evolution of cell lineages withing a single organism)  - Selection acts on species level through speciation where you have the inheritance process through speciation  - Selcetion doesnt only have to act on individuals, it can act on the species level!  - Genes eye view;  - Richard dawkins published a book (the selfish gene) where he put out the theory that selection is going to act most strongly on the lower levelsof organisation, the gene - The survival and reproduction of genes is what drives much of the evolution on the planet - We often talk about selection acting on an individual because whats good fro an individual is often good for its genes and evolution adn selection will act to make that the case - Multilevel selection poses a problem for complexity;  - Selection acting on different levels of organisation can pose problems for the evolution of complexity (complex hierarchical forms of organisation)  - Say we have selection acting on an individual, that individual is going to be competing with other individuals for greater fitness because the one with high fitness will reproduce and be better represented in the next population  - But when you have selection acting on lower levels of organisation that can cause problems in fitness on the higher level of organisation  - Like if cells are competing for higher fitness it can lead to issues in cellular regulation, ergo, cancer - Cancer - Origin of variation in once identical cells - Arises through errors in replication through mitosis (somatic cells)  - When cells replicate they are genetic clones of the last but sometimes a mutation will arise making that cell slightly different from their ancestor (heritable variation because that cell will continue to reproduce with its bad mutation)  - If that mutant cell now produces faster than the other cells, it has higher fitness so VHD is satisfied and the cell will keep on keep on replicating and that will lead to a tumour which will cause issues in the higher levels of organisation  - Will increase mortality rate of organism screw up organ systems and all that  - This shows that when you have selection acting on different levels of organisation it can cause conflict between those levels of organisaton - So for complexity to evolve it must overcome these these conflicts between levels or it shalln't work  - If you have cooperation between the lower levels of organisation (like cells) you can help avoid those higher level fitness costs and evolve complexity - Cooperation vs. Conflict;  -  What strategies do we have to keep the lower levels or organisation cooperative (to evolve complexity)  - What happens when the cooperation breaks down and how we can recover complex function even in the face of breakdown - How do biological subunits stay so cooperative?  - Lets take a new look at how cells replicate  - There are lots of features within organisms that prevent competition WITHIN the individual (because as we saw before, dat bad)  - Lots of stuff about the way cells work are actually adaptations meant to reduce competition amongst each other - Trying to align fitness interests among the different levels of organisation to make complexity possible - Theres two biological scenarios where we have the evolution of cooperation @ lower levels permitting the evolution of complexity;  - Mitosis and meiosis;  - Mitosis is a fair process because if all goes well each daughter cell is an identical clone of the mother cell - If that wasn\'t the case and you give a chromosome to D1 and another to D2 and whatnot youre creating variation which might be heritbale which can cause these cell lienages to compete against eachother and thats bad  - So mitosis is though of as selection against evolution  - Meiosis is a fiar process because even though its heritable variation, its reducing the comminalty of the variation because it randomise shte alleles passed on, and its randomised each generation which reduces the common variation making evolution harer - Multicellularity  - Positive natural selection on alleles;  - We are looking at INDIVIDUAL fitness levels here  - AA has the highest fitness so very rapidly that genotype is gogin to sweep to fixation because its higher in fitness than hetero and homo(aa) - We expect this with relative INDIVIDUAL fitness levels - How do genomes stay cooperative?  - Fair meiosis;  - In fair meiosis each allele is distributed to 50% of the gamets and meiosis is totally blind to the relative fitness level of each allele - Breakdown of Cooperation: Cheating a Fair Meiosis;  - Sometimes alleles can get too cocky and get out of line and start cheating our beloved fiar meiosis, when that happens, things get baadddd - Meiotic drive;  - An alleles bias's its own transmission (through some sinister tricks) and make more of itself go into the gametes instead fo 50/50, which can happen even if it lowers the individuals fitness levels - Can lead to evolution going in the wrong direction (when thinking about selection on the individual level)  - If we mate this heterozygot with a AA homo it will produce mostly heterozygote offspring (becauese mostly little a gametes)  - If we math with another hetero or OMG HOMO then my goodness, thats bad because itll produces mostly homo for 'aa' and thats a really bad genotype  - If you do that for a few generations then you see that very rapidly the A allele goes extinct and we how terrible fitness in that allele at the individual level - This is called genetic/genomic conflict - Example;  - In drosophila if you cross a 'ss' female and 'Ss' male you see that an overwhelming majority of offspring at 'Ss' which should happen you should expect to see only about 50% 'Ss' so because the 'S' is screwing somethign up you look at the male because its the one with the big S   - They found out that there is sperm competition and the big S is producting bigger and different sperm that essentially kills the little 's' sperm - thereby distoring fair segregation causing the 'S' to be selected for but can cause individual level fitness consequences  - Evolutinary response to such cheating;  - Creates strong selcetion for the repression of cheating  - In drosophila theere was evolution in other parts of the genome to stop the big s sperm to killing the little s sperm (restorative alleles)  - Creates race between selection at the gene level for the rapid reprodutino of the bad alleles vs the evolutionrestorative allels, which is favoured by individual level selection - "When cheating alleles spread, there is strong selection on rest of genome for suppression of  cheating" - Runaway meotic drive can create patterns of gene evolution at the individual level - In nature we see the balance between the cheating and the repression - Over replication;  - During normal meiosis you can see this locus is transmitted as we expect it to be  - But transposable elements/transposons can jump around a cells genome and copy itself to different chromosomes/parts of DNA without cell division happening (this increases its freqency in the cells genome)  - When cellular division/meiosis happens the transposon is more well represented  - The cheating make itself more well represented - They replicate more than other parts of the DNA  - TE's can make copies of themselves independent of cellular division - TE's make up a great amount of the DNA in many organisms  - How to avoid TE explosions;  - Corn didnt do a good job of it :(  - Like meotic drive there are parts of the genome that will repress the expression or movement of transposable elements and much of it thought to be related to methylation - Genes can control the frequency of methylation - Arabadopsis;  - Some people did an experiment and silenced DDM1 gene reposnisble for methylation and found that there were really weird and bad phenotypes when the the TE's were allow to just jump around and mess things up  - 2\) Transpotion selection balance;  - If a TE land in the middle of a really important gene the individual is going to die (low fitness)  - So there is goign to be high individual level selection againt TE jumpinginto important genes  - Selection will weed them out if eneough TE's land in important places - There are many features within individuals that help to avoid competition within an individual like fair meiosis and mitosis  - Theres ways to cheat that but there will also be strong selecetion on the rest of the genome to weed these bad guys out - Cooperation of cells within an organism;  - Starting from a single cell (zygote) helps reducing the competition that may arise from opposing cell linages  - Somatic vs sex cell reproduction are seperate, so like somatic cells that evolve to become cancer aren\'t leaving behind any offspring in the next generation because they don\'t contribute to gametes  - Germ lines have very few divisions and are created earl yon in female which reduces the likelihood of a mutation appearing  - Tumour suppressors in other parts of the genome to help suppress the rapid reproduction of these cancer genes  - But because we have so much somatic reproduction going on all the time its inevatiable that some cancer will asirse and be selected for at the cellular level - Cancer;  - Evolution at any given level is shortsighted and only focuses on whats going on on that level Keywords for this section;  - ***[Complexity:]***  The number of parts an organism hase - ***[Transposable elements:]***  elements in the genome that can jump from one part of the dna to the other iwhtout needing cellular division to occur - ***[Overrepliaton:]***  the excessive copying of genetic elements in a genome - ***[Meiotic drive:]***  when one alleles biases its transmission in gametes regardless of its fitness consequences  Lecture/Slide Deck 12 ; Applied Evolution (last Mahler :( )  - Evolution in Agriculture;  - Pests and evolution; the problems;  - In modern agriculture a major barrier is the pests that invade, destroy/predate or compete with the crops we grow to feed the people on the planet  - We commonly use 'biocides' to combat these pests but obviously that imposes very strong selection  - Anything that has a (natural) resistant to the biocides will survive, reproduces (higher fitness) and so we apply really strong selection for these resistant pests - Weed and agriculture; a major problem;  - In evolutionary agricultre we look for 'evolution-proof' ways to combat pests, and help crop management  - Weeds are a MAJOR concern in agriculture  - They compete with crops by either taking up space, nutrients, resources, light etc and cause the los of ⅓ of all agricultural productivity - It causes SUPER HUGE economic loses (\$26 billion PER YEAR in the US)  - If we wanna be mindful of how we use our lan don earth we should be mindful of how to combat weeds - As mentioned before, the common way of dealign with weed is to use herbicides (type of biocide) which helps combat weeds so long as the crop s are resistant which they usually are - Weedy plants evolve resistance;  - Whenever you apply herbicides, youre going to have resistance evolve  - The graph shows time ve the number of weed species resistant to the heribicide  - It shows that not too long after introducing each herbicides, resistant evolves and spreads, every single time - Glyphosate (roundup) was thought to be the be all end all weed killer when it was introduced in the 1990's because the had found no resistant strains, but a couple of years later they found a lot of resistant strains so... - Spread of roundup resistance in southern ontario - Fleabane (or horseweed) is a weeds that is nassstyyyy and can establish pretty much anywhere - Evolved glyphosate resistance very rapidly - They did an experiment where they watered a susscetpible starin and even a little concentration of roundup killed them, but in the resitant strain it was as if you applied no glyphosate - In 2010 in essex county near michigan we noticed the apperace/evolution of some of these resistant alleles but then, liek 6 years later is spread massively to almost all of southern ontario  - Thats a horrible thing because its really bad for farmers since this plant is incredibly bad for crops and economically damaging - Where does resistance come from?;  - There are thre different possibilities for where the glyphosate (And any herbicide) resistance comes from  - The way we invest our money and efforts into combatting the weed issue depends on where the resistance comes from - Pre-existing natural variation;  - There already exists individuals that are resitatn to the strain but they may not be 'fit' until the selection of heribiceds is applies - If this is the case we would invest money into finding the resistant allele and making sure they dont increase in frequency and try to select AGAINST those alleles - Mutations  - We get new mutations cropping up that provide resistance and because they are fit and strongly selected for, they increase in frequency in the population - If this is the case, we will want to limit population sizes because the larger the population the more mutations arise (prevent mutations from arising)  - Gene flow - A very strong mechanism of micro evolution  - You have resistant alleles flowign into a population, causing them to become more resistant and be spread throughout the population because they are mor fit  - If this is the case then we will have to sink out money into cleaning farm equipment really well and implementing transnational scrutiny to prevent the flow of alleles - It smostly agreed that geneflwo caused the horseweed resistant in southern ontario because it showed up near the us border then just spread rapidly across soutrthen ontario - Outcorssing weeds have more preexisting natural variation for resistance than selfing weeds; - Weeds that outcross (Sexual reproduction) have higher genetic diversity and evolve more resistant alleles than plants that are selfing - They have greater existing natural diversity allowing for increased lielkyhood of eveoeling resistance  - Selfing plants do not have as much 'standing genetic diversity' and acquire new mutations which is theri main form of eveolvin resistance  - Evolution of herbicide resistance in waterhemp;  - Julia kriener also studied the resistance of glyphosate in waterhemp which is another invasive species and found that all thre emchines of resistance evolution were at play for waterhemp in souther ontario  - She samples waterhemp from SO and the american midwest and each picahrt shows the genetic makeup of the populations of waterhemp in those localities  - She found the incredibly long distance transfer (of a resistant alleles) in a very short amount of time from kansas city to souther ontario, without it showing up much inbetween which means gene flow form the alleles being on agricultural equipment or shipments was almost certainly at play  - Each level of resistance mechanism provides additional resistance when there are other forms of it present - Can herbicide resistance be stopped?;  - There are two main ways that people are moving to combat herbicide resistance;  - Multi-heribicide tratements;  - Instead of applying just one heribiced, they apply a combination treat of multiple heribiceds  - It dramatically reduces the chanes of having resistant individuals - Low probability of resistance to a strong selection event - Reduces likelihood resistance is going to evolve - Rotaions of different herbicides;  - People rotates the herbicides they use so theyll apply one for a period of time then sweep the rug form the plants and apply the next one, with the assumption that a plan resistant to one heribicede wont be resistant to the next  - Becuase itll apply strong selection to be resistant to that herbicides and then the plants wont be adapted to the next one - The issues with this guy right here is that we could end up selection for a generally resistant phenotype and create a superweed that is basically resistant to all herbicides!  - Evolutionary rescue;  - We have a species liek the weeds fro example and we impose very strong selection that causes a huge demographic decine in the population so only a few individuals that are resistant (differential fitness)  - With evolutionary rescue basically sys that if the individual that survived are somewhat resistant to the original selection pressut and hcan have new mutations and genes arise and become more resistant then they can reproduce and take themselves out of the decline - Sometimes we want species to stay in the decline and not come back, like the invasive species  - Sometimes we do want them to come back like endangered species where we change something about their environment causing them to decline, and the individuals that are left adapt, reproduce and pull their numbers back up  - Evolution in Medicine;  - Evolution can be very important for medical uses  - Malaria and mosquitoes; the problem;  - Marlia causes half a million deaths anuall and is very common in africa, southeast asia and a little in the new world  - Lots of research being done to combat the effects - Like weeds, the major prevention strategy is to apply insecticeds in place where there are a lto of mosquitoes - But again that appleis very strong selective pressure on the mosquitoes and can cause a rapid ncrease in resistant species - "Evolution-proof" solutions?;  - Heavy invetesments into figuring out "evolution" proof solutions to mosqiotes to prevent rapid evolition of resistance  - Theres a figure here that we will kind of go through;  - So we will have a mosquito population, because they are massive there is a lot of standing genetic variation meaning that there WILL be some naturally resistant alleles floating around - X axis is time  - Lighting bolts are insecticide application - When you apply blue insecticide, only blue resistant will survive, when you apply red, you eliminate most of the blue and when you stop seeing mosquitoes, you have succedded - You can apply insecticides in four ways ;  - Responsive alternation;  - Alternate the insecticides based on the populations response, red and blue colour indicate the alternating insecticides - Prevents mosquitos from adapting to any one insecticide, disrupting the adaptation syscle over generatins - Mosaic;  - Apply different insecticides to different populations - They will adapt to their insecticides, but they may not have the alleles/adaptations to be resistant to another insecticide outside of where they live  - Spread of resistant genes is slowed because the genes resistant to one insecticides may not be resistant to another making it hard for one single resistant allele to dominate because diddfernt populations face different selective pressures  - Periodic application;  - Apply one insecticide than the other like they used for the weeds,  - Alternating causes the allels resistant to one insceticedeis to fail when exposed to the next  - Combination - Combine them insecticides and kill alll the generations :)  - Increase mortality rate before resistance can spreade - Very favoured these days - Some people have reaserhed the malaria parasite istelf to try and figure out how to get rid of it with medication without selection for the evolution of resistant strains  - They infected mice with malaria and gave them differne deos regimens  - Agressive doses are high desse you take for a while to knock eveythign out while lighter does are... light  - They found that when you take the aggressive dose, that imposes stronger selection for the resistant staring but the lighter doese impose weaker selection and less of the resistant strains evolve - There wer ealso no significant health trade-offs for the mice in taking a lower does - X-axis is time, y-is the density f malaria parasite  - Red is resistant starins, black normal susceptable parasites - Agressive tratements actually favour resistant strains due to a strong selective pressure - Multidrug cocktails for HIV;  -  HIV is a brilliant mutator and so we cycle multi drug cocktails to those infected reduce their viral load  - If you take a single drug for a long time then the resistant starins will overtime increase in frequency, so you switch toanother drug or cocktail to wipe these resistant strains out, some will be leftovers, and will evolve slower because there are less of them, but they will increase in frequency again and then you switch to a different drug cocktail - Cancer and drug resistance;  - When you chemo caner it appliest strong selective prpessure for chemical resistant strains of the cells (littel existing variation becoemes widespread)  - The allele frequency of chemo reisstant drugs befre and after chemo, you can se a lot of increase after chemo has been applied  - So we're movign awway from really aggressive treatments for a long period of time to more cocktails and cycling theraipies to reduce adaptation to any one treatment and reduce populations sizes to slwo down evolution and yeah... - Global Change & Evolution;  -  Humans be messing up the planet in all kinds of ways anad thats not good we mes sit up by  - Destroying habitats  - Chopping them up in weird ways which can affect migration and gene flow  - Abiotic conditions, so like changing pH, temperature etc.  - Biotic conditions by transporting species here and there which can be invasive, predatory and/or competitive - Biodiversity and extinction;  - Extinction is a normal process but on an undisturbed earth we'd expect to lose only 1 species every 10 years, which isnt a lot considering the diversity of life on earth  - But because of good ol' humans we are losing a bout 4-6 THOUSAND species per YEAR (small organisms in tropical regions we may never have heard of but still, thats a whole lot)  - But we also are losing other species liek river dolphinsin china and coolio animals :(  - Habitat loss is the biggest driver, humans destroy land and remove biodiversity for things like agriculture  - Genetic issues in conservation biology  - Everythings connected so!  - When you lose genetic diversity the populations become smaller leading to genetic drift having a larger effect, losing heteorzygocity and leading to inbreeding depression whcih can cause the fixation of bad alleles and because of this lack of genetic diversity, it limits species abilities to adapt!  - These are some really coloourful toads that due to human activity and exporusre to chutryid fungus were thought to go extince but were then rediscovered - The problem is that they are now in very small populations and you can see the longer they were missing the lower heterozygocity (genetic diversity) they have because their numbers are so so small - The toads are currently at the bottom of the evolutionary rescue plot and we are tryign to figure out how to get them up there  - We have thre things to take into account when seeing how litkely a population is to adapt and undergo evolutionary rescue  - 1 means that the species will adapt and undergo evolutionary rescue in the face of the selective pressur  - 0 means extinction (will not adapt and survive)  - You have the following that syas wheter a population is likely to adap or not;  - Population size - Bigger populations have more mutations and more diversity so they will do better  - Mutation supply rate;  - Multiply the population size and mutation rates - Provides raw material for evolution - Fitness relative to ancestors;  - If the new population has a muchlower fitness than their ancestors they will have a hard time clibiming up the curve and adapting - If they are just a little less fit then they might be able to climb up  Keywords for this section;  - ***[Biocides:]***  The number of parts an organism hase - ***[Standing genetic diversity/variation :]***  elements in the genome that can jump from one part of the dna to the other iwhtout needing cellular division to occur - ***[Overrepliaton:]***  the excessive copying of genetic elements in a genome - ***[Meiotic drive:]***  when one alleles biases its transmission in gametes regardless of its fitness consequences  Lecture/Slide Deck 12 ; What ecology is and why it matters - What is ecology, why teach it;  - Ecology is a science often conflated with the sociopolitical movement of envrionmentalism (recycling, reducing pollution etc.)  - Ecology is the study of living things and how they interact with their biotic and abiotic environment which determines the distribution and abundance of species around the globe, changing the structure and function of ecosystems - It is the study of biodiversity  - Nothing in biology makes sense except in the light of evolution but nothing in evolution makes sense except in the light of ecology  - Ecology is the setting where evolution palys out because evolution by natural selections require adaptations that cause an organism to have higher fitness in a given environment  - The reason why some of these adaptiaon/traits/alleles/wahterve are better has everything to with the organisms interactions with its environment and other organims in its environment - We should know it to be informed citizens, and to have a good foundation for life science studies and to understand the impacts humans have on earths ecosystems and biodiversity - EEB tends to ask "why" questions like why do eukarytic cells have mitochondria with separate genomes and prokaryotic cells dont (endosymbiotic theory by margulis who once sais that species spred by networking not combat)  - While CSB ask more "how" questiosn liek how the mitochondria make ATP and stuff  - Devils garden trees can spread and take over large patches in teh amazon rainforest because the ants that live in its hollow swollen stems will attack any other tree species that try to come into their area --- getting rid of competitors - Biodiversity of species;  - There are way too many species on earth to count and over 85% of them are still undiscovered (except vertabrates which are pretty well described)  - Looking at the rate at which new species are described overtime we expraolate that there are about 8.7 millions (eukaryotic) species out there! (give or take a million)   - Biodiversity is not equally distributed across the tree of life  - 70-90% of all species are bacteria  - Plants and animales and fungi make up a relatively small part of the tree of life - But most biologists study eukaryots  - Model vs. non-model organisms;  - Some biologists study just three species which we call **model species** because we think of them as a "stand-in" or "model" for all plants and animals  - Mice  - Model species for vertibrates  - Drosophila (fruit fly, terrible :( )  - Model species fro all invertebrates  - Arabidopsis thaliana;  - Model species for all plants  - They are studies in the lab to give insights into fundamental aspect of things like cell and molecular biology, plant physiology and so on and so forth! - Evolution by natural selection has given rise to a tremendous amount of biodiversity on earth all with distinct phsysioslogies, morphologies, behaviours, susceptibilties etc.  - As ecologists adn evolutionary biologist you aim to understand the fundamental principle that gave rise to all thai biodiversity  - Definitons for consistency; - Population  - All the individuals of the same species living in the same place at the same point in time (all the zebras in a savannah)  - Community; - All the species that are lvingi together in the same place at the same time (all the giraffes, elephants, zebras, plants, insects etc. in the savannah)  - Ecosystem;  - All the living and non living things in the environment (all the species the elephants and stuff but also the nutrients in the soil, gases in the air, water etc.) (the entire savannah)  - Species distribution/range;  -  We are interesting in learning why certain species live in certain places and what give rise to how many individuals of that species there are? - Looking at the puma/mountain lion/cougar;  - Lives in all of south america and western canada/united states  - Can live in very different environments liek where its all snowy in BC and then in hot humid jungles that have never seen snow - Very big range - The ROM has a historical collection that has many cougar plets and skulls collected from different places in different years which shows how big of a range it has! - Red foxes;  - Red foxes also have a massive geographic range from north america to europe to asia and were introdcued in austrais in the 1850's  - Masive massive ranges - Americian pika;  - Its a specialist animal (which means it has adapted to thrive in a specific environment and/or diet)  - Itsy bitsy relative of the rabbit (bubba) that lives basically only in the western united staters and canada and rocky outcrops 2500m or more in elevation (habitat, elevation and geographic specialist)  - Scientists use dentition (teeth) to igure out diets, bones to sequence genomes and all sorts of stuff liek that :)  - Things limiting species range/dispersal;  - Why do we care about species ranges!?  - Used to be for practical purposes to know what crops could grow well where, what livestock can be raised where  - We want why animals live where they do to knowhow different species ranges and abundances will change in response to changes in the environment that humans cause through climate changes, habitat destruction, introduction of invasive species, land use chanes - Ned to know why plants and animals live wher ethey do to predicts whats going to happen to the earths biodiversity going forward - Knowing why certain microbes have a big range or small range helps predict disease risk  - We just kinda want to know why things are the way the are  - Lyme disease;  - Is an example of the range of both black legged ticks and lyme causing parasite  - What determines where species live; -  We can imagine a series of filters that can help us determine wheter a species can live in a certain place or not;  - Dispersal; - A species gotta get to somewhere to live there right?  - Abiotic conditions;  - Conditions cannot be used up  - Things like climate (temperature, salinity etc.)  - Things like resources which can be used up (food, nutrients, space etc.)  - Species interactions;  - If a species gets somewher eand can tolerate the environment it still may not surevies if its outcompeted by competitors, eaten by predators or missing a key mutualist  - Because these things vary across space and time it creates environmental gradients (variations) whit some species performing best at a certain part of the gradient  - Species abundance/extinction;  -  Some species are really abundant and thought of as pests like raccoons and we want to know why they are so abundant so we can make them less of pests  - Some species or sub species are reallllyyyyy rare, liek lonesome george the last pinata toroist who when he died his subspecies went ectinct  - We want to know more about these because rare species are at risk of becoming extinct and we want to stop that - So why are some so abundant and some so rare - What determines abundance;  - Maltuhs (this guy again 🙄) wrot eon the principle of populatiosn where he posited that populations cannot grow faster than the resources that support it  - Darwin and wallace were influenced by this an deposited the struggle for existence where this finite amount of reaosurces drives competition by necessity and evolution by natural selection (becaus ethe fittest can use the resources and reproduce)  - The sixth extinction;  - We are currently undergoing a mass extinction mostly driven by humans  - 32% of known vertebrate species are decreasin in population size or range - 29% of north american bird species have declined in abundance since 1970 Keywords for this section;  - ***[Ecology:]***  The number of parts an organism hase - ***[Symbiosis:]*** 2 species that live together - ***[Mutilaism :]***  2 species that benefit eachother  - ***[Model species:]***  when one alleles biases its transmission in gametes regardless of its fitness consequences  - ***[Population:]***  when one alleles biases its transmission in gametes regardless of its fitness consequences  - ***[Community:]***  when one alleles biases its transmission in gametes regardless of its fitness consequences  - ***[Ecosystem:]***  when one alleles biases its transmission in gametes regardless of its fitness consequences  - ***[Specialist animal:]***  when one alleles biases its transmission in gametes regardless of its fitness consequences  - Lecture/Slide Deck 14 ; Climate and other niche axes - Species have ranges of tolerance along environmental gradient;  - Envrionmental conditons vary across space and time creating environmental graditen in which spicies can thirve at on ly a specific part of  - On the X-axis is some continuous environmental conditon and the Y-axis is the performance of the species  - We can see taht there are some portions where the species cannot curvie (to hot or cold, to much or too little salt etc.)  - We think that there are different parst of the curve species can survive, grow and reproduce at  - They can survive in broader ranges than they gan grow at and grow at broader ranges than they can reproduce at  - This is just one environmental gradeitn though so how do we accoutn for multiple environmental conditons? (hint: tis' the ecological niche)  - Ecological niches;  - The ecological niche is;  - basically the combination of environmental conditions a spceis can physiologically tolerate and the resources it requires to grow - Species plae in the world (what climate it likes, what it needs to grow, what it eats etc.)  - Long history in ecology - Hutinchion niche; - The hutinchons niche is a conceptual thing to descriobe how more than one environmental conditon can affect a species ability to thrive  - It can be n-dimensions but here we're just doing 2 fro simplicity  - We plot however many gradients (temperature, pH, salinity etc.) and we see these ellipses - Anythin out of the ellipses means the species cannot survive there  - The large lighter ones means they can survive, smaller darker means it can grow smallest darkets means it can reproduce - Application to real species (scarle macaw)  - Eat clay licks to get sufficient salts and minerals into otherwise fruit comprised diet A red bird with black circles Description automatically generated - Here we plot the temperature and annual precipitation of places where they actually ive and we can see that they like to live where it is 20°C and above and 1000 to 5000mm of precipitation which meakes sense because we know they live in warm and wet rainforests - Incomplet description of niche so we could add mor dimensions like salt content requirements or sometgh - When trying to understand why a species lievs where they do we usually take a look at the climates they can tolerate  - Global gradients and hadley cells;  -  Why temperature and rainfall vary across the globe;  - Temperature is a function of latitude (horizontal lines going up and down the globe east to west)  - Its warmer at the equator and colder at the poles - Seasonality is a function; - Higher latitudes (more north circles) are colder and have cold and hot seasons (winter-summer) --- Sesonatlity func of temp - Lower latitudes (more south circles) are warmer and have wet and dry seasons ---seasonality is a fun of rainfall - Rainfall id determined by atmospheric circulation  - All these factors (temp, rainfall, seasonality) determine biomes (what lives where)  - How latitude affected temperature:  - The earth is tilted off is axis so when its winter in the north we are tilted away from the sun - When we are tilted away sunlight hits at an even *lower* angle so its colder  - At the equator the suns light is focused at a 90 degree angle so the photon density is concentrated over a much smaller area so its hotter  - At the higer or lower latitudes (closer to the poles) the sun hits the surface of the earth at a lower angle, causing the photon density to spread out over a larger area and so its less hot - Patterns of rainfall/hadley cells;  - Hadley cells;  - Because the equator gets the most heart the air there rises the quickest (hot air rises) up and away from the earth\'s surface (creating a low pressure zone)  - Once they hit the edge of the atmosphere they begin to drift north and south and eventually all back at 30 degrees northa dn south  - As the air rises, it also cools at a certain rate \~5-10 deg/km and as it cools the water vapour within them begins to condense and fall back to earth which its why its so rainy near the equator  - But as they drift to 30 degree north and south they are all rained out, creating high pressure zones (as the fall back to earth) that make for soem of the worlds driest deserts at those lataitudes (the air warms as it descends, prohibiting cloud formation, causing the deserts)  - Other atmospheric circulation cells;  - The hadley cells are not the only atmospheric cells at play but they are the strongest because the equator recives the most heat  - Hadley Cells (Near the Equator);  - Near the equator the warm air rises creating a low pressure zone and lots of rainfall (WET near equator)  - As the air rises it cools, moving 30° N and S where they fall back to earth all rained out creating dry high pressure zones (DRY at 30° N and S)