Presentation on theme: "WALLACE RESOURCE LIBRARY"— Presentation transcript:
1WALLACE RESOURCE LIBRARY Lecture 02 – Evolution and Biodiversity in MadagascarThis is an ‘example’ of a lecture that is given to A level students as part of their academic lecture series whilst on their expedition.It has been produced for the exclusive use of the lecturer conducting the series and is solely intended for educational purposes.Most of the material comes from Operation Wallacea sources and any other material that has been used has been credited (as far as is possible) to the appropriate author wherever possible.This lecture is only to be used for EDUCATIONAL purposes.
2WALLACE RESOURCE LIBRARY Lecture 02 – Evolution and Biodiversity in Madagascar
3Madagascar -An extraordinary Island This ‘activity’ lecture is designed to last an hour although it should be ‘flexible’ enough to stretch either way – do not have to do everything – just what might work with your group. As lectures go, this has quite a ‘high’ content of ‘activities’ and ‘discussion’. Hopefully lots of scope for ‘differentiation’!! Sorry for the jargon.3 short video clips (BBC2 – 3.5 mins, Biodiversity 2010 clip (8 mins) , Dreamwork’s King Julian – ‘Move-it’ song (3 mins)Also an optional 12 min video account of evolution on Madagascar – good background if someone wanted more detail.Discussion about meaning of diversity – collected ideas exercise10 question quiz on species.Brief discussion – Madagascar species numbers and endemism V India?Matching cards to explain evolution.Before you begin you will need to make sure that they have pens and paper and that you have enough sets of the’ evolution matching cards’ – one set between 3 or 4 students. There is a ‘word.doc which has extra sets if needed. Ideally using a laminated set would work best (can be re-used) although newly cut sets from the 2 sheets will work.The video clips are ‘embedded’ but you will need to test them – the clips must ALL be in the same folder as the power-point. If they do not work from the presentation, they might need re-inserting or played on their own.Lecture content thoughts/notes.This first slide will allow you to locate Madagascar for them (amazing how many will not really know its geography!) and I think show just how big an island it is – also its proximity to the equator and anything else that might be relevant.Lecture 2: Biodiversity, biogeography and evolution of wildlife in Madagascar
4Summary Introduction Madagascar’s biodiversity The Biogeography of MadagascarEvolution of wildlife on MadagascarAfter a brief introduction the lecture session is split into three sections – Biodiversity, Biogeography and Evolution.Each of the key words is introduced and based around what they should know for their A levels – assuming that they are taking Bio. or Geog. – many will not I expect but they should have some knowledge from their GCSE Science course from year 11. Some students will not have started A levels yet so some terms may need a bit more explaining. Year 13 should be better informed although some A level courses have yet to cover these topics.Assume nothing!
5Introduction400km of the east coast of Africa – In the Indian Ocean with the Mozambique Channel separating the island from Africa.The island is just bigger than France - 581,540 sq km – 4th largest island in the world – nearly 1000 miles long (north to south).About 165 million years Madagascar (with India attached) broke away from Africa and drifted Southeastwards.India eventually broke away leaving Madagascar isolated with all its ‘stowaway’ animals.Humans arrived about 2000 years ago – present population is probably above 19 million.There are many facts about Madagascar ( see below) although I think its size, position and isolation history are the most important points for its unique evolutionary position. The David Attenborough clip puts this all into perspective so you do not have to spend too much time on the background – but well worth picking up on the key points after the video clip.Some facts -Madagascar is an island to the east of the southern part of Africa.It is the world's fourth largest island, with 4,828 km of coastline.The capital city is Antananarivo.The island has a narrow coastal plain getting higher as it gets inland, and there are mountains in the centre.The highest mountain is Maromokotro at 2,876m.Madagascar was part of the African continent but broke off and drifted to where it is now about two million years ago. This means that the plants and animals of Madagascar are unique, and different from those of Africa. More than three quarters of the plants and animals are found nowhere else, including huge tree ferns and palm trees, amazing desert plants, and animals such as the lemur.Madagascar was governed by France from 1895, but became a republic in 1958, calling itself the Malagasy Republic. It remained under French guidance until 1960, when it became a fully independent country. In 1975, the country re-named itself the Democratic Republic of Madagascar. In 1993 it became the Republic of Madagascar.The people elect their government and a President. Citizens 18 years and over can vote.Currency: Malagasy francNatural resources found on the island include graphite, chromite, coal, bauxite, salt, quartz, tar sands,semiprecious stones, fish, hydropower. Industries include meat processing, soap, breweries, tanneries, sugar, textiles, glassware, cement, car assembly plant, paper, petroleum.The Land: About 5% of the land is farmed with crops or pasture. The main products are coffee, vanilla, sugarcane, cloves, cocoa, rice, cassava (tapioca), beans, bananas, peanuts, and livestock products. Almost half the island is covered in forests. Much of these forests are being cut down, and as a result soil erosion is becoming a major environmental problem. Too many animals being grazed on limited land is also a problem. Several kinds of the island's plants and animals are endangered.Madagascar is not a wealthy country. Its people face problems of malnutrition and poor health and education facilities. The demand for products such as coffee has fallen. The government is attempting to improve the economy of the country. Tourism is a growing industry, and contributes to the local economy.
6Madagascar’s Biodiversity Can we define ‘biodiversity?What is a species?How can we measure biodiversity?Is biodiversity important?Biodiversity is an important component of A level Biology and Geography. The depth required varies quite a lot between the various courses e.g. some require a mathematical approach whilst others do not. Also part of the discussion will be defining/discussing the concept of a species.The FOUR topics on this screen should cover the topic fully enough for most students.
7Biodiversity: a definition? Any ideas? Biological DiversityBiodiversity: a definition? Any ideas?‘ Biodiversity includes all the different plant, animal , fungus and microorganism species worldwide, the genes they contain, and the ecosystems of which they form a part.‘‘ Biodiversity is NOT just about the number of different species. It is also represents the degree of nature’s variety. Biodiversity takes into account the number of individuals and in how many places they can be found.’These are definitions from one of the exam boards.D.B. Jensen, M. Torn, and J. Harte, "In Our Own Hands: A Strategy for Conserving Biological Diversity in California," 1990: "Biological diversity, simply stated, is the diversity of life...As defined in the proposed US Congressional Biodiversity Act, HR1268 (1990), "biological diversity means the full range of variety and variability within and among living organisms and the ecological complexes in which they occur, and encompasses ecosystem or community diversity, species diversity, and genetic diversity." Genetic diversity is the combination of different genes found within a population of a single species, and the pattern of variation found within different populations of the same species. Coastal populations of Douglas fir are genetically different from Sierran populations. Genetic adaptations to local conditions such as the summer fog along the coast or hot summer days in the Sierra result in genetic differences between the two populations of the same species. Species diversity is the variety and abundance of different types of organisms which inhabit an area. A ten square mile area of Modoc County contains different species than does a similar sized area in San Bernardino County. Ecosystem diversity encompasses the variety of habitats that occur within a region, or the mosaic of patches found within a landscape. A familiar example is the variety of habitats and environmental parameters that constitute the San Francisco Bay-Delta ecosystem: grasslands, wetlands, rivers, estuaries, fresh and salt water."It would be a god idea to try and get them to volunteer the various parts of the definition and this could be done by writing up key words they think of if you have access to a board of some description. They should be aware of the difficulty of defining the term as it means different things to different people.As the next slide suggests – it should be considered from a umber of different levels – genetic – species and ecosystem.The next slide (thanks Dr Peter Long) illustrates this.
8Biological Diversity Genetic diversity within species Biological diversity occurs at the level of:Genetic diversity within speciesSpecies diversity within an ecosystemEcosystem diversity within a regionAbove thanks to Dr Peter Long.Giving examples for each level would be good plus possibly expanding on how you get hold of the data for each level – much will depend on the research site. Good chance to bring in value of PCR if you have a good set of students. Ideas on different ecosystems have different levels of biodiversity (next slide).Insect Biodiversity -
9Biological Diversity Different ecosystems Two examples for biodiversity – different ecosystems and genetic diversity in anopheline mosquitos uncovers 9 cryptic species in Papua New Guinea (http://www.biomedcentral.com/ /10/392).This slide maybe too much for some students – depends on the group.Will need to distinguish between family and species from a taxonomic viewpoint.Genetic biodiversity in mosquitos
10What is a species and what is it based on? A species is often defined as a group of organisms capable of interbreeding (naturally) and producing fertile offspring.Morphological Species (Wiley 1978)Based on visible characteristicsEasy to measure, most useful in practiceNot most biologically relevantBiological Species (Mayr 1942)Based on reproductive isolationTestable – in theoryAre hybrids fertile?Field Study CouncilBiodiversity requires a knowledge of what a species is – many students will have debated the definition and also discussed the features that it is all based on. The slide covers the brief debate.………….What is a "species"? (http://research.amnh.org)This question is important. The scientific system of naming "kinds" of plants and animals revolves around the species level. A scientific name, such as Turdus migratorius (American robin), is always written in italics, and contains first the genus and then the species names. A name like Pinicola enucleator californica (California pine grosbeak) also contains a subspecies name (= californica). For many species (ones that vary in size and/or color over geography), subspecies names are used for distinctive geographic forms.For a long time, ornithologists almost universally used the biological species concept (BSC). This definition of "species" is based on species being reproductively isolated from each other. Under this definition, distinctive geographical forms of the same "kind" of bird are usually lumped as one species. This is because the geographic forms interbreed (or probably would, if they had the chance) where they intersect on the map. The problem with this definition is slightly different, geographically-isolated, forms rarely present us with "tests" of their willingness to interbreed. According to to adherents of the BSC, if the forms are only slightly different, they would probably interbreed if given the chance. Thus, they should be considered the same species. However, proponents of the BSC also say that because two things rarely interbreed (and produce viable hybrids) doesn't mean they belong to the same species. For example, wolves and coyotes (there's no educated disagreement that these are different species) can mate and have fertile and healthy pups.The phylogenetic species concept (PSC) says that diagnosable geographic forms of the same basic "kind" of bird should be treated as distinct species. This is because these forms have evolved separately, and have unique evolutionary histories. The PSC is gaining favor because there is no worry about whether slightly-different geeographic forms might interbreed. If they don't, for whatever reason (for example, migration to different breeding areas), they are full species. Obviously, the PSC is less restrictive than the the BSC. There would be many more species of birds under the PSC than under the BSC.The debate over how species should be defined will continue as long as people are allowed to think freely. Perhaps the argument is rhetorical, because every kind of organism presents a unique situation. It is possible that neither definition can be applied consistently in nature.Evolutionary Species (Cracraft 1983)Based on evolutionary relationships
11How many species are there? A quick quiz – answer on a sheet of paper.A scientist (Erwin 1982) counted the number of beetle species in one species of tree in Panama (1200) – he used this to estimate how many species there were in the world - how many species did he estimate?30 – 50 millionAnother scientists (Raven 1983) said there are twice as many species in the tropics than in temperate regions – what was his estimate?3 millionIn June 2001 two organisations (Species 2000 and Integrated Taxonomic Information System) decided to work out together to create the catalogue of life. By 2007 how many named species were in the catalogue?species (this is now 1,740,330 in 2010)Many scientists say that this represents what % of the actual total number of species?10%This quiz will give them a short break – introduce it as ‘how much do you think you know’ – then get them to answer on a sheet of paper doing question by question – points will arise as you go along about the method used, reliability etc – the main point of the quiz is to start a debate about why we do NOT know the exact number of world species – they suggest reasons why. Link to the role of OpWall and trying to measure biodiversity! Depending on the group, the discussion could be widened to include ‘is it important’ to know the exact numbers etc.You can make the quiz as competitive as you like – individuals or small groups – simple mark scheme.……………Biodiversity value in theory:identifying a fundamental currency of value to peopleBiodiversity has been seen as the total (and irreducible) complexity of all life, including not only the great variety of organisms but also their varying behaviour and interactions. From this viewpoint, no single objective measure of biodiversity is possible, only measures relating to particular purposes or applications. So for conservationists, for example, a measure of biodiversity should quantify a value that is both broadly shared among the people for whom they are acting and considered as being in need of protection.One of the more broadly shared and economically defensible values for conserving wholesale biodiversity (rather than just the few components or 'biospecifics' with obvious high use value at present) may be seen to lie in ensuring continued possibilities both for adaptation, and for future use by people in a changing and uncertain world (this is not to deny other possible values). Consequently, biologists have argued that this value in biodiversity is likely to be associated with the variety of different genes that can be expressed by organisms as potentially useful phenotypic traits or characters (different chemicals, morphological features, functional behaviour). Because we do not know yet precisely which genes or characters will be of value in the future, first they must all be treated as having equal value, and second, the greatest value for conservation will come from ensuring the persistence of as many different genes or characters as possible, as a form of insurance (ref 2, ref 3).For example, a dandelion and a giant redwood can be seen to represent a richer collection of characters in total, and so greater diversity value, than another pair of more similar species, a dandelion and a daisy (ref 1). This shows how the phenotypic characters (or the genes that code for them) could provide a 'currency' of value for biodiversity. Pursuing this idea, we will then need to maximise richness in the character currency within the conservationists' 'bank' of managed or protected areas.A consequence of this approach to valuing biodiversity is that it provides one possible unified view of the traditional three levels at which biodiversity has been described. In effect it uses genetic diversity as a basis for valuing both species diversity (for their relative richness in different genes) and ecosystem diversity (for the relative richness in the different processes to which the genes ultimately contribute). This provides additional justification for multi-level approaches and biodiversity-surrogate methods.A particular strength of the single currency approach is that it avoids the problems in compound measures of trying to trade-off measures for different properties that really cannot be compared or inter-converted (such as species richness and the relative abundances among species that are combined in the diversity measures used in community ecology), which otherwise can lead to confusion and a loss of accountability. This advantage of accountability in terms of a single currency of value becomes particularly important when faced with the problem of choosing areas for biodiversity conservation, when many other factors may be involved (see the sequential approach to accommodating multiple factors).The difficulty with this single currency approach is that the numbers of genes or characters cannot usually be counted directly, so the problem is how best to estimate them?1. Best estimates: using genealogy to predict genetic or character richness2. Popular estimates: using species richness3. Practical estimates: using higher taxa or environmental variables as surrogates4. Relationship among estimates: a scale of surrogacy for mapping more of biodiversity value at lower cost
12How many species are there? The UK Biodiversity Action Plan has made a list of species for the world and UK – if they estimate above for the world – how many do they estimate for the UK?Rank the following for the greatest number of species for each group – ( 1 is for highest number of species)Protoctista Vertebrates Plants Fungi Invertebrates BacteriaWe have ignored viruses? (should we? Is it worth it?) They suspect there are millions of different types – how many have been described so far?5,000+BacteriaVertebratesFungiProtoctistaPlantsInvertebrates
13How many species are there? The agreed estimates for the total number of species varies greatly – the IUCN Red data List (1996) suggests between 5 million and (upper figure) ???? Million. Many scientists believe the figure to be much much higher.10 millionSuggest a couple of reasons why the estimates differ so much?Difficult to see and find, defining a species, difficult to identify, based on estimates, how they are measured.Which country had the highest extinction rate for animal and plant species (IUCN 2007)?United States of America – 236 animals and 30 plantsWhat does this tell us about estimating biodiversity?
14How do you measure biodiversity? by measuring organisms in the field (such as the work carried out by Operation Wallacea).by using formulae such as:Simpson index (A level) D=1 - [ Σ(n/N)2 ] (n = number of individuals of a species, N = total number of all species)Shannon-Wiener index H’=Σpiln(pi)(pi = proportion of the species)These formulae help to ‘quantify’ biodiversity but there is NO one formulae that truly represents a figure for biodiversity.Some useful terms:Species richness is the number of species in a given area.Species evenness is a measure of the relative abundance of the different species making up the richness of an area.This slide will NOT be popular although some exam boards expect students to apply the Simpson index – brief look ONLY. If a very good group you could discuss why the formulae has such limitations in its use – they learn it is mainly used to compare biodiversity in the same habitat – e.g. pollution effects at different locations on a river .Weakness of Simpson index:Simpson's Diversity Index is a measure of diversity which takes into account the number of species present, as well as the relative abundance of each species. As species richness and evenness increase, so diversity increases.Conclusions: Simpson's D is one of many diversity indices used by biologists. Each of these indices has strengths and weaknesses. An ideal index would discriminate clearly and accurately between samples, not be greatly affected by differences in sample size, and be relatively simple to calculate. Biologists often use a combination of several indices to take advantages of the strengths of each and develop a more complete understanding of community structure.Major problem – To calculate Simpson's Index for a particular area, the area must first be sampled. The number of individuals of each species present in the samples must be noted: when is an individual not an individual? Animals and plants which reproduce asexually can cause terrible problems for the biological sampler! Is a single sprig of moss an individual, or is the whole patch one individual?Terms like species richness and evenness are quoted in many specifications.
15Madagascar biodiversity facts Madagascar is a biodiversity HOTSPOT (Myers 1988) – an area that holds especially high numbers of endemic species.There are 34 world biodiversity hotspots but they only cover 2.3% of the Earth’s land surface.Madagascar and its neighboring island groups have an astounding total of eight plant families, four bird families, and five primate families that live nowhere else on Earth.Madagascar’s more than 50 lemur species are the island’s charismatic worldwide ambassadors for conservation, although, tragically, 15 more species have been driven to extinction since humans arrived.Over half of the world’s chameleon species are found on Madagascar.The natural vegetation of this particular ‘hotspot island’ is very diverse.This is a chance to ‘steer’ the session towards the specific site and could be expanded as necessary. Presumably this will be an overlapping theme in other lectures/talks/discussion.…………………………Madagascar Lemurs (http://www.rainforest-facts.com/madagascar-animals.html)The most famous ones are lemurs - mostly nocturnal primates totally endemic to Madagascar Island. There used to be lemurs in central African rainforests, but they were replaced by higher forms of primates such as gorillas and chimpanzees. Today, lemurs are endangered both because habitat destruction, and because superstitious humans kill some species, such as aye-ayes.Other MammalsOther mammals include mongoose, fossas, civets, fanaloucs, tenrecs (hedgehog-like animals), moles, rats, mice and bats. It is very common on islands that there are no large mammals, and bats and rodents make up a large part (if not all) of native mammal species.BirdsIt is also quite common on islands that there is a large variety of birds. Madagascar's birds include different species of asity, babbler, baza, buttonquail, buzzard, coua, emu-tail, flufftail, flycatcher, fody, goshawk, greenbul, ground-roller, harrier, harrier-hawk, hawk-owl, heron, hoopoe, ibis, jacana, jery, kestrel, kingfisher, lark, magpie-robin, munia, newtonia, nightjar, pelican, plover, rail, rock-thrush, sandgrous, scops-owl, serpent-eagle, shearwater, sparrowhawk, spoonbill, starling, sunbird, swamp-warbler, swift, tetraka, vanga, wagtail and weaver.Chameleon LizardOther classic Madagascar animals are chameleons. Although chameleons are found in many other parts of the world too, the vast majority of species are only found on Madagascar Island. Although some species inhabit deserts and grasslands, most of them live in rainforests, and are, as lemurs, threatened by rainforest destruction.Other ReptilesOther Madagascar reptiles include many species of harmless colubrid snakes, and some boas, such as Madagascar ground boa and Madagascar tree boa; Nile Crocodiles, four species of turtles (including the famous Angonoka, Geochelone yniphora; and many species of skinks, geckoes and iguanids. AmphibiansMadagascar also has about 300 species of frogs and almost all of them are endemic to the island. Madagascar's frogs include the colourful mantella frogs (aka Golden frogs); the less colourful Mantidactylus frogs; many species of tree frogs, and genus Dyscophus (Tomato frogs).Insects and SpidersAnd finally, there are millions of species of spiders and insects. Spiders include orb spiders, thorn spiders, trapdoor spiders, pelican spiders, wandering spiders, sac spiders, wolf spiders, tarantula spiders and many more. As many Madagascar's spiders, many insects (such as butterflies, praying mantids, moths and others) also grow quite large. This is often the case with rainforest insects.NHM
16Madagascar - Species numbers and endemism Taxonomic GroupSpeciesEndemic SpeciesPercent EndemismPlants13,00011,60089.2Mammals15514492.9Birds31018158.4Reptiles38436795.6Amphibians23022999.6Freshwater Fishes1649759.1Some facts and figures to look at –When compared to India and the UK: (http://lntreasures.com/indiaff.html)Species number India Species endemic % endemismPlants 15,MammalsBirdsReptilesAmphibiansFishThe UK has 1 endemic bird species and 16 freshwater fish ONLY.How do you think this compares to India and the UK?
17Madagascar - Species numbers and endemism Taxonomic GroupSpeciesEndemic SpeciesPercent EndemismPlants13,00015,00011,600495089.233Mammals1553501444492.912.5Birds31012241815558.40.04Reptiles38440836718795.645Amphibians23019722911099.656Freshwater Fishes16425469728459.11.1Some facts and figures to look at –When compared to India and the UK: (http://lntreasures.com/indiaff.html)Species number India Species endemic % endemismPlants 15,MammalsBirdsReptilesAmphibiansFishThe UK has 1 endemic bird species and 16 freshwater fish ONLY. Scottish Crossbill.Ideas on why differences? Isolation, unique conditions, no diluting influences from mainland so species develop in ownScottish CrossbillHow do you think this compares to India and the UK? India in REDUK – only has 1 endemic bird and 16 endemic freshwater fish !!!Image - RSPB
18Unique flora and fauna in Madagascar As many as 90% of the species are endemic to MadagascarJust some pretty examples – List top row then bottomIndriTree frog (Boophis)Helmet vangaBoa (species?)Chameleon (species?)Lowland streaked tenrec
19Taken at the Durrell – Jersey 2011 Your thoughts!Some thought provoking images from the Durrell Zoo in Jersey.Fossa on the right.Possible thoughts on sustainability (link to later lecture on conservation and sustainability) – people needing the forests etc, role of zoos?! Link to discussion on in-situ and ex-situ conservation..
20Summary ideas from the 2010 International Year of Biodiversity. This video clip comes form the 2010 Year of Biodiversity site – excellent summary on biodiversity ending up with why it is important. Lasts about 8 minutes.
21Biogeography of Madagascar Madagascar has THREE broad ecosystem types –Dry forests in the northHumid forests in the eastSpiny forests in the southNow a brief look at the Biogeography of Madagascar –Defintion: Biogeography is the study of the distribution of biodiversity over space and time. It aims to reveal where organisms live, and at what abundance. As writer David Quammen put it, "...biogeography does more than ask Which species? and Where. It also asks Why? ...A very diverse island in terms of species distribution and habitat – hence why only certain animals found in specific locations.
22WWF ecosystems of Madagascar Madagascar dry deciduous forests (AT0202)Madagascar lowland forests (AT0117)Madagascar subhumid forests (AT0118)Madagascar spiny thickets (AT1311)Madagascar succulent woodlands (AT1312)Madagascar mangroves (AT1404)Operation Wallacea research sites:Mahamavo - dry deciduous forests (AT0202)Ifotaka - spiny thickets (AT1311)Locate the TWO areas for OpWall
23Evolution of wildlife in Madagascar The last part of the lecture:All will have some idea of how evolution works although it will probably be unclear and lacking in good examples.A good chance to remind them why we are called Operation Wallacea – after Alfred Russell Wallace (1823 – 1913)."...every species comes into existence coincident in time and space with a preexisting closely allied species." (1855)Co-discoverer of the theory of natural selection and key player in the development of biogeography. A self-taught professional natural history collector who had spent years in South America and Asia , he began work on the species problem in the mid-1850's while in the field, publishing little-noticed papers that argued for the fact of evolution on the basis of geographical distributions. In 1858 he suddenly intuited the selection theory without realizing that Darwin already had done so, and ironically wrote to him for help in getting his ideas published. This resulted in the joint paper read before the Linnean Society and published that year. Throughout the rest of his life Wallace graciously gave as much credit as possible to Darwin, and the Darwin circle reciprocated by arranging a government pension and assorted honors for Wallace. Although he was less inclined to neo-Lamarckism than Darwin himself, he later argued that the theory did not apply to the evolution of man.Operation Wallacea in Indonesia –The Wallace Line is an imaginary line in Indonesia between Borneo and the island to its immediate east, Sulawesi. The line has ecological significance because it separates two zoogeological regions that are respectively associated with Asia and Australia. To the west of the line, fauna is more Asian. To its east, it more closely resembles the Australian fauna. The reason for the line is a deep oceanic trench that has preserved the gulf between these two islands for millions of years. Without it, they would have been periodically connected as Ice Ages caused the sea level to lower by as much as 120 meters (394 ft), connecting together Borneo with the Asian mainland and Sulawesi with Australia.Darwin: Charles Robert Darwin FRS (12 February 1809 – 19 April 1882) was an English naturalist.[I] He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory with compelling evidence for evolution in his 1859 book On the Origin of Species.The scientific community and much of the general public came to accept evolution as a fact in his lifetime. However, it was not until the emergence of the modern evolutionary synthesis from the 1930s to the 1950s that a broad consensus developed that natural selection was the basic mechanism of evolution. In modified form, Darwin's scientific discovery is the unifying theory of the life sciences, explaining the diversity of life.Darwin's early interest in nature led him to neglect his medical education at the University of Edinburgh; instead, he helped to investigate marine invertebrates. Studies at the University of Cambridge encouraged his passion for natural science. His five-year voyage on HMS Beagle established him as an eminent geologist whose observations and theories supported Charles Lyell's uniformitarian ideas, and publication of his journal of the voyage made him famous as a popular author.Puzzled by the geographical distribution of wildlife and fossils he collected on the voyage, Darwin investigated the transmutation of species and conceived his theory of natural selection in 1838. Although he discussed his ideas with several naturalists, he needed time for extensive research and his geological work had priority He was writing up his theory in 1858 when Alfred Russel Wallace sent him an essay which described the same idea, prompting immediate joint publication of both of their theories. Darwin's work established evolutionary descent with modification as the dominant scientific explanation of diversification in nature.In 1871, he examined human evolution and sexual selection in The Descent of Man, and Selection in Relation to Sex, followed by The Expression of the Emotions in Man and Animals. His research on plants was published in a series of books, and in his final book, he examined earthworms and their effect on soil.In recognition of Darwin's pre-eminence as a scientist, he was one of only five nineteenth-century non-royal personages from the United Kingdom to be honoured by a state funeral, and was buried in Westminster Abbey, close to John Herschel and Isaac Newton. Darwin has been described as one of the most influential figures in human history. (Wikipedia)
24Evolution of wildlife in Madagascar Why is the Wildlife of Madagascar so different?Working in groups of 3 or 4 - Match the 10 pairs of cards together (Evolution Challenge) – e.g. pair a definition/picture with a KEYWORD – then briefly discuss within your group how the wildlife of Madagascar might have evolved (the cards are clues!).Give out the 20 mini cards and ask them to pair them up then place them in a sequence which could explain how the wildlife of Madagascar evolved. There is no ‘correct’ sequence and some students will be unfamiliar with some of the terms. They can do this in groups of 2-3 people.Should take 4 or 5 minutes and might need your help.Possible sequence:Isolation by continental driftAllopatric speciationGene poolVariationFitnessNatural selectionEvolutionUseful terms or things to know about:EndemicFossilsDarwinWallace
25Why is Madagascan wildlife so different? EndemicNative to or confined to a certain region.FossilsGiant lemur (skull )- 2,000 – 26,000 years ago – 200kg. Gorilla sized.These are the pairs and the sequence should be able to give them an insight into the evolutionary process on Madagascar. There will be a big difference between the groups and you will need to adapt to the situation!!!!Sequence:Outline of the work of Darwin and WallaceWhat is a fossil – useful evidence for evolution – especially for MadagascarDefine the work endemicStart sequence: you will need to keep it as simple as possible as most will not have been much beyond GCSE – possibly those who have been in year 12 will know a lot more.Isolation of Madagascar – idea of break-away with some early forms of life plus possibly others arriving on the island by chance.Concept of speciation by isolation – the word allopatric ( possibly discuss sympatric speciation with a top group)Gene pool concept – not all the possible genes present – limited amount.Darwin’s idea of variation within a population – link to gene poolIdea on ‘fitness’ and competition within a species.Natural selection as the process behind evolution.Definition of evolution – maybe think about lemurs and why they are ONLY found on Madagascar. Ideas on tenrecs.Tenrecs:The island continent of Madagascar was part of a large land mass that broke away from Africa some 165 million years ago. As tectonic plates shifted subtly on the Earth's surface, the land mass moved out slowly into the Indian Ocean. Other chunks of land later floated off to leave the island the size and shape we now know, situated 400 km off the Mozambique coast for the last 80 millions years.At that time the island was probably a mix of habitats much as it is today: thick rain forest on the east coast, deciduous forests in the west, deserts with spiny succulent plants in the south-west, and amid the forests of the high plateau a mosaic of grasslands grazed by giant tortoises and walked upon by 3-4 metre tall elephant birds. Mammals had evolved from therapsid reptiles and were spreading across Africa, but none had appeared on Madagascar, as its reptiles were from a different stock.What happened next is only conjecture, but sometime around 60 million years ago a small mammal - perhaps no more than 5 or 6 g in weight with a primitive body plan and physiology - was washed out to sea from Africa. Perhaps it was on a log that had fallen into a river from the coastal forest of what is now Kenya. Currents and winds moved the mammal across the channel until it arrived on Madagascar. Perhaps the founder was joined by others; perhaps it was a pregnant female. Whatever the case, the animals multiplied. And then evolution kicked in!The mammal was an early tenrec; the island it had arrived on probably had no other mammals and so this early lineage evolved over generations to adapt its body shape to its environment. As a result of a process called "adaptive radiation"(made famous by Darwin's finches on Galapagos) new species appeared, each physically suited for its niche, free of competition.Very few other mammals ever made the same journey. Eventually rodents, a mongoose-like carnivore and a primitive primate crossed the channel and gave rise to species found nowhere else on Earth. A pygmy hippopotamus also crossed but Madagascar never saw cats, dogs or large herbivores.Most tenrecs died out on mainland Africa and are known only from fossil records; all except one small lineage that evolved to fill a specialized aquatic niche - the otter shrews (see section “Tenrecs in Africa – the otter shrews”). However, tenrecs still inhabit Madagascar today in an abundance and diversity not seen in any other mammalian family.Giant lemurs:Skull of the giant lemur, Megaladapis edwardsi, a roughly gorilla-sized mammal that lived as recently as 2,000 years ago. This specimen from southwest Madagascar is part of the Natural History Museum's fossil mammal collections.Dates:Wallace - ( )Darwin - ( )Darwin and Wallace
26Why is Madagascan wildlife so different? Isolation by continental driftAllopatric speciationSpeciation following geographical isolation of subpopulations of the species.VariationThe variety of life on Earth at all its levels, from genes to ecosystems.Gene PoolAll the genes in a particular population at a particular time.FitnessThe success of an individual (or allele or genotype in a population) in surviving and reproducing.Gene Pool image – BiodotEdu -Cartoon on evolution:Continental drift image -Natural selection image -Allopatric speciationb -Natural SelectionA process that explains how organisms with traits and characteristics that are beneficial to survive in their environment are passed down to future generations while less adapted dwindle/shrink.EvolutionAn overall change of a population’s gene pool over time through processes such as mutation and natural selection.
27Summary Introduction Madagascar’s biodiversity The Biogeography of MadagascarEvolution of wildlife on MadagascarJust to round things off nicely, the summary slide from the start of the lecture is repeated.