Bio Chapter 15 Darwin and evolution

gradualism

incorporated for natural selection Pulled from how earth develops- these things dont take place over night ***Evolution happens for populations; NOT individuals Individuals dont evolve populations evolve Natural selection acts on individuals in that population Natural Selection involves individual organisms & their environment Generations must pass before evolution can occur-- all relative w diff species generations are diff amnts of time w diff species

comparitive embryology and molecular biology

"ontogeny recapitulates phylogeny" homeobox ("Hox") From fertilization on what kind of stages do they go through as they develop Developmental biology reflects evolutionary history Amniotic fluid for humans- has salt content almost exactly like salt content in ocean Hard to tell diff bw human and other species in really early embryonic stages Like to make sure u are crying-- so you have gotten rid of amniotic fluid All organisms use same basic biochemical molecules- DNA RNA and ATP -- can deduce that these must have been present in first living cells Sequence of amino acids of some proteins is similar across the tree of life - number of differences between amino acid sequences in humans and other org increases w distance in time since they shared a common ancestor Evidence from developmental biology Diversity has come about by a set of regulatory genes that control the activity of other genes involved in development Hox genes orchestrate development of body plan in all animals -- all animals share Hox gene common ancestor but number and type of gene vary among groups molec- Looking at types of proteins they produced- by sequencing DNA

natural selection and adaptation

- mechanism by which evolution takes place differential success in reproduction occurs through an interaction b/n environment & variability among individuals (in a population) "survival of the fittest" reproductive success- bc passing on DNA to next generation is what is important - whether genes and traits gave you advantage or not Not strongest, biggest or fastest- means you are best fit for that particular environment Smaller males frogs would hop in and reproduce w girls when big toads were croaking- women would listen to big croak but little guys would get in to reproduce-- but then population became quieter and quieter bc small ones actually injecting DNA Reproductive success- how much offspring are you able to have Have a bunch and hope some survive- R selection K selection- organisms that spend biologically tremendous amount of energy being pregnant - and then energy raising them Product of Natural Selection: adaptation of a population to its environment Darwin concluded early that species change over time and are not fixed entitities crafted by a creator -- but still didnt knowhow change could happen in existing species and how new species arise By 1842- darwin full developed natural selection idea as mechanism of evolutionary change 1858 Alfred Russel sends essay to darwin in which he proposed similar concept Natural selection first presented to Linnean Society of London in 1858 as a pair of essays by Darwin and Wallace Natural selection is a process based on the following observations Organisms exhibit variation that can be passed from one generation to the next - that is, they have heritable variation -- heritable variation Bf darwin diff ignored bc didnt fit into fixed species Darwin emphasizes that variation is required for process of natural selection Genetic variation can be harmful helpful or neutral Harmful variation eliminated from population through natural selection bc indiv w these char often dont survive or reproduce Beneficial or neutral is maintained - natural selection ignores neutral variation but beneficial mutation increases the probability that an individual w this mutation will have greater reproductive success Natural selection is random and has no goal of improvement in anticipation of future enviro changes Organims compete for available resources Realized that if all offspring born to pop survived there would not be enough resources to support the growing population Overproduction potential of a species often referred to as geometric ratio of increase Individuals within a pop differ in terms of their reproductive success Some individuals have traits that enable them to better compete for limited resources Those w favorable traits acquire more resources than the individuals w less favorable traits and can devote more energy to reproduction -- this is differentiable reproductive success Fitness- repro sucess of an individual relative to other members of a population Most fit capture larger amount of resources and convert resources into larger amount of viable offspring Fitness is influenced by diff factors for diff populations White bears most fit in antartic but black in forest Natural selection occurs bc certain members of pop happen to have a variation that allows them to survive and reproduce to a greater extent than do others Organisms become adapted to conditions as the enviro changes Adaptation-- is any evolved trait that helps an organism be more suited to their environment Many animals manatees penguins and sea turtles alla have flippers to help them swim through water- the adaptation is especially evident bc diff animals in same enviro Adaptations to specific environemnts result from natural selection Differential reproduction generation after generation can cause adaptive traits to increase in frequency in each suceeding generation Natural selection only process of evolution that results in adaptation to environment

Descent with modification

Above term rather than evolution Same trait beneficial in one environment and horrible in another Enviro changes around equator- those animals would be worse off w environment change bc it stays so constant Non random selection of very random events that take place All life descended from common ancestor Over time, organisms moved to new habitats® differences accumulated® new species arose Similar to Linnaen scheme of classification Lot of animals connected and most likely bc similar environmental conditions

Darwin and Wallace

After returning to England, Darwin pieced together ideas of evolution w/ evidence Darwin hesitant to publish, knowing it would create controversy Feared for his families life- origin of species wasnt just publishing theory on natural selection, was saying all life coming from common ancestor- going exactly against bible and seven days etc Once published everyone did kind of freak out In 1858, Alfred Wallace published theory of evolution similar to Darwin's- very similar proposal as darwin- they were in group of scientists going back and forth and talking about biodiversity - both came from natural selection being driving force for evolution In 1859, Darwin published On the Origin of Species

Thomas Malthus

An economist who studied factors that influence the growth and decline of human population (1798) published An Essay on the Principle of Populatulation- darwin definitely read this Was talking about why human pop do well and dont do well - quantity of resources and natural disaster Summary: human population was limited by the quantity of resources (food, water, shelter, etc) & how they are affected by famine, war, epidemics, etc. Darwin applied those principles to animal populations Economist who studied factors that influence growth and decline of human populations -- published essay on principle of population -- proposes size of population is limited only by the quantity of resources(food water shelter) available to support it Famine war and epidemics are relted to populations overtstretching their limited resources Darwin reads this and applies to animals and says Animals tend to produce more offspring then can survive, and comp for limited resources in enviro is element that determines survival -- forms his idea of natural selection

evidence of evolution

Biogeography: world's geographic distribution of species- why some species only found on certain continents, (Biogeography Study of geographical distribution of organisms thorughout world Distribution of species and makeup of species in diff regions provide hints abt past geological events (movement of continents, volcanic islands formins, glaciation, river formation) Darwin compared animals on his trip in south american to ones from his home Noticed that similar environments on each continent had similar animals Saw how similar species replace one another -- so related species could be modified according to enviro differences Galapagos islands Animals there slightly diff than ones on mainland-- also varied from island to island Each island had diff type of tortoise Study of finches Diff than finches from england so didnt recognize them All diff kinds of finches w diff shapes beaks etc as to best adjust to environment Darwin wondered if a finch from south america was common ancestor for all diff types of finches on the islands) Fossil record-- these guys just didnt make it- they are in fossil record but not here now- something must have happened Skeltal structure of flippers look like bone structure- can see that similar to lad animal (Fossil evidence Fossils- remains and traces of past life or any other direct evidence of past life (trails, footprints, burrows, preserved droppings) Most fossils usually shells bones and teeth bc rest decomposed Transitional fossils Bear a resemblance to 2 groups that in the present are classified seperately Represent intermediate forms of life in transition - allow us to retrace evolution of organisms over relatively long periods of time 2004- discovered fishapod bc in transition bw fish and 4 legged animals- has fishlike set of gills and fins but front fins are more like wrist bones and unlike fish had flat head, flexible neck and eyes on the top of its head (these transitional features suggest it could push itself along bottom of shallow rivers- would eventually come in handy in river habitat it lived in) Modern whales still have a vestigal hindlimb consisting of only a few bones that are reduced in size - as ancestors of whales adopted increasingly aquatic lifestyle, location of nasal opening underwent transition from tip of snout to midway bw snout and skull to now top of head) Homologous structures body form ("arm bones")-- number of bones may match but structure may be longer or shorter based on type of organism vestigial organs (snake & whale pelvis?) Biogeography and Pangea homologous structures--Anatomy very similar but different functions Molecular Data and Evolutionary Relationships of Vertebrates Looking at similar antigens- compatibility of blood etc-- how close are proteins are related-- like relating hemoglobin protein - we all have hemoglobin but its slightly diff based on what species we are Fruit flies- huge problem in hawaii - these flies came over bc of humans and their stuff from island to island Evolution of insecticide resistance in insect populations- more we get rid of weak ones-- strong ones left behind and have eliminated comp so they now have better chance at reproducing

The voyage of the beagle

Chart the coastline of South America Collect exotic, diverse fauna & flora Stuffed birds to bring back, brought tortoise shells back Compare unknown species with current knowledge base in western europe Geographical distribution puzzled Darwin; especially at Galapagos Islands 13 sp. of finch Biggest find was actually mockingbird that was lightbulb There are mockingbird here in south america and europe but all so diff- why? no large mammals penguins & seals- had only seen penguins bf in chile and argentina Marine iguanas- exist no where else- they can go into ocean and eat algae- can seperate and snort out salt Started to ask- why so much biodiversity?

Artificial selection

Choose things to keep alive other than traits just needed for environment Activally cross polinating or breeding- then keeping them alive by giving them the nutrients they need domesticated plants animals (dogs, cats, horses, etc.) human personalities, looks, etc. With artificial selection you can see evolution sooner bc we are manipulating Darwin noticed that humans can artficially modify desired traits in plants and animals by selectively breeding certain individuals-- like domestic dogs from humans selectively breeding wolves w desired traits Human controlled breeding to increase frequency of desired traits -- called artificial selection Like natural selection, only possible bc original pop has variety of charectoristics Have done same thing w veggies Beak size of medium ground finch adapts to weather swings of one of galapagos islands- recent study done by Peter and Rosemary grant-- they argue that evolutionary change can be sometimes observed within timefrae of a human lifespan rather than over thousands of years--- bc if this island was not in drought and birds when not in drought have smaller beaks and eat smaller seeds but then all of a sudden becomes dry-- now need to eat larger seeds so those w larger beaks will survive and reproduce- next generation will be generally larger Natural selection in form of female mate choice, favors evolution of males w spotted wings -- slight alteration in genes and some had spot in diff spots- those mutations then will be passed on if favorable Bf industrial revolution light moths more common then dark - w increase in pollution dark moths went from 10 to 80 % of pop then huge legislations about reducing pollution and that number dropped again

Anatomical evidence

Descent from common ancestor can explain Anatomical similarities among organisms Verterbrate forelimbs are used for flight (birds and bats), orientation during swimmin (whales and seals), running (horses), climbing (lizards) swinging from trees (monkeys) but all forelimbs have same set of bones organized in similar way -- shows basic vertibrate must have come from common ancestor Homologous- anatomically similar bc inherited from common ancestor Analogous- serve same function but originated independently in different groups of organisms that do not share a common ancestor (wings of birds and insects) Vestigal structures- fully developed in one group of organisms but reduced and may have no function in related groups. -- some birds have wings but dont use them to fly , wisdom teeth -- occur bc organisms inherit anatomy of their acnestors so will show traces of evolutionary history Homology shared by vertebrates is observable during embryological development New structures or novel functions can originate only through modification of preexisting structures in ones ancestors so all vertebrates inherited same developmental pattern from their common ancestor but each group has specific set of modifications to orginal pattern

James Hutton

Focused on earth evolving and earth gradual change If earth took long time to form then animals plants fungi must also do same, earth giving hint about evolution Proposed the theory of slow, uniform geological change Charles Lyell made Hutton's ideas popular in Principles of Geology (1830) Earth shaped by slow, continuous cycles of rock formation and not catastrophic events Lyell proposed uniformitarianism, which states that all land formation is gradual Hutton explains that extreme geological changes can be explained by slow natural processes given enough time- still accepted today Lyell proposes theory of uniformitarianism States that natural processes witnessed today are the same processes that occured in the past Darwin did agree w the fact that earths massive geological changes are the result of extremely slow processes and that the earth therfore must be very cold

Tiktaalik

Has gills like fish but also has lobes where can take in air from outside - can take in air and store temporarily in this lobe Tricky thing about fossils is that not everything fossilizes (gets stuck in water and preserves)-- why people say there are missing links Body fish like head more flattened like amphibian and fins act more like legs Evolution that makes fins act like legs is a mistake - will actually be hard for your environment but maybe you start using enviro diff or move to diff enviro

Darwinian revolution

Lamarck paved way for evolution: explaining fossil record & Earth's biodiversity Darwin left medical school to study botany Accepted position as a naturalist aboard FitzRoy's HMS Beagle (at just 22 years old) Collected samples & data on round-the-world journey Loved nature since childhood, sent to medical school at 16 didnt like him so then went to school to become clergy man at christs college Christs college Went to lot of lectures on bio and geo Summer of 1831 conducted fieldwork with Adam Sedgewick - one of founders of modern geology Trip ended up taking 5 years and goal was to traverse southern hemisphere --started to gather info on how specied are related through descent with modifcation from a common ancestor -- and adaptation to various environments results in diversity Observations of change over time Observed massive geological changes firsthand Raised beaches w a lot of fossils Darwin collected fossils of an armadillo like animal -- when started looking at shells and fossils and realizing that the earth must be very old begun to state that it is old enough for descent with modification to happen -- so species not fixed but change over time

Important historical perspectives

Many Greek philosophers believed in gradual evolution Plato & Aristotle's beliefs strictly contradicted evolution Aristotle put all life on latter w humans on top bc thought we were most evolved- also he thought you couldnt move from rung to rung- cant change your form - offspring will be what you are 1700's natural theologians (science accepted as long as supports bible) saw adaptations as evidence of a Creator's specific plans **Carolus Linnaeus developed taxonomy (two-part naming system: Genus species) Giving more evidence to darwin that all evolved from common ancestor Georges Cuvier's development of paleontology helped Darwin Catastrophism, catastrophic events lead to loss of life and God creating new sets of species to repopulate the world- creator saying no i need to wipe this out and thats how species would go extinct Fossils, relics or impressions of past organisms, mineralized in rock (a lot of plant material is impressions) Sedimentary rock formed from sand & mud settling at bottom of bodies of water Modern birds legs covered in scales Mid eighteenth century influences Greek philosopher plato-- says every species on earth has perfect or essential form -- and species variation is imperfection of this essential form Aristotle- saw that organisms vary in complexity and can be arranged based on their order of increasing complexity George louis (Count buffon)- naturalist who worked most of his life writing a natural history series - described all known plants and animals-provided evidence of evolution and proposed causes for it -- 2 being enviro influence and struggle for existence -- his support of evolution wavered though Taxonomy (classifying organisms) Carolus Linnaeus- developed binomial system of nomenclature -- system of classification for human organisms -- also believed each species had ideal form -- also believed simplest species occupied lowest rungs and then moving up to humans, god Used comparitive anatomy (evaluation of similar structures across a variety of species) to classify org into groups -- compared fossils to living org -- began to realize that some animals had gone extinct-- no current animals w same fossil structure Erasmus Darwin (charles grandpa) was physican and naturalist -- some of his writing suggested evolution -- based his conclusions based on changes in animals during development , animal breeding by humans, and presence of vestigal structures vestigal structure Structures that apparently functioned in an ancestor but have since lost most or all of their function in a descendant. Late 18 early 19 century influences Baron Cuvier used comparitive anatomy to develop a system of classifying animals Founded science of paleontology Study of fossils His Studies showed that assembly of fossils varieties changed suddenly bw diff layers of sediment or strata within a geographic region Proposed that sudden changes in fossil variation could be explained by local catastrophes or mass distinctions followed by repopulation -- this explanation came to be known as catastrophism

Jean Baptiste Lamarck

One to first publish formally idea on evolution W epigenetics way you can rewrite his theories w understanding in genetics - but he didn't know this Published theories of evolution the year Darwin was born (1809) Evolution of organisms: simple to complex Saying you are literally going to change your instructions by what you do Strectch neck then passes on a little bit longer of neck then offspring stretch and so on -rewrite DNA-- not right but darwin goes off of this, was hitting on something Proposed 2 main theories: 1. Use & Disuse 2. Inheritance of Acquired Characteristics first biologist to offer testable hypothesis that explained how evolution occurs via adaptation to environment He thought more complex org are descended from less complex organisms -- thought increasing complexity was result of natural motivating force( a striving for perfection that is inherent in all living org) Proposed ides of inheritance of acquired charectoristics Enviro can produce physical changes in an org during its lifetime that are inheritable Ex: long neck of giraffes developed over time bc necks grew longer as stretched to grab food higher up in trees-- then this longer neck was passed onto offspring Has never been supported by experimentation Molecular mechanism of inheritance explains why--phenotypic changes aquired during organisms life do not result in genetic changes that can be passed to subsequent generations

History of evolutionary thought

Plato (427-347 BC) perfect or "essential" form Everything created in original form Aristotle (384-322 BC) life can be arranged by increasing complexity (like a ladder) More complex you are "more evolved you are"-- just bc more sophisticated in form does not mean you are more evolved- one of biggest misconcep- everything alive rn is equally evolved Count Buffon or Georges-Louis Leclerc (1707-1788) naturalist who's work actually supported evolution by natural selection **Linnaeus (1707-1778) Taxonomy; Latin 2-part naming system still used today! 2 most specific taxonomic groups Genus and species -- would say these 2 names when describing them Genus always capitalized species always lower case Originally started w kingdoms - even broader than kingdoms, domains (eukaryotic and 2 prokaryotic) E. Darwin (1731-1802) research hinted at evolution; especially existence of vestigial species Cuvier (1769-1832) Founder of paleontology; determined species had gone extinct His work helped darwin w natural selection- using fossil record was able to show that some species didn't make it 1831- Darwin sets sails on british naval vessel HMS beagle -- primary mission was to serve as ships naturalist- to record diversity When set sail thought species remained unchanged since time of creation - formed by religious beliefs-- trip made him change mind about species evolution Proposses a process by which species arise and change Evolution - genetic change occurs in a species over time, leads to their genetic and phenotypic differences -- due to natural forces -- now considered one of unifying theories of biology -- wasnt execpted at first His theory of evolution by natural selection explains unity and diversity of life on earth, how all living animals share common ancestor, how species adapt to various habitats over time

On the origin of species

Published almost 30 yrs after Galapagos Islands It made 2 major points: w/ (tremendous amount- birds, penguins, seals, plants, tortoises) evidence, species not created in present form, but evolved from ancestral species: Descent with Modification (used this term didnt actually use term evolution)- one common ancestor small changes accumulated and had branching diversity - happened bc nature chose organisms that have charectoristics that give them ability to live long enough to reproduce proposed mechanism for evolution: Natural Selection