Evolution PDF

Evolution © 2022, Aakash BYJU'S. All rights reserved Key Takeaway 1 Big Bang Theory Evolution 2 3 Spontaneous Generation Special Creation and Catastrophism 4 Chemical Evolution Enclosing the pre biotic system Origin of Heterotrophs and Autotrophs Chemosynthesis and Photosynthesis © 2022, Aakash BYJU...

Evolution © 2022, Aakash BYJU'S. All rights reserved Key Takeaway 1 Big Bang Theory Evolution 2 3 Spontaneous Generation Special Creation and Catastrophism 4 Chemical Evolution Enclosing the pre biotic system Origin of Heterotrophs and Autotrophs Chemosynthesis and Photosynthesis © 2022, Aakash BYJU'S. All rights reserved 5 Cosmozoic Theory and Biogenesis 6 7 Modern Theory of Origin of Life Key Takeaway Evolution of Life Forms 8 9 Evidences for Evolution Fossils Biological Evolution 10 Morphological and Anatomical Evidences Lamarckism Embryological Darwinism Biogeographical Mutation theory Biochemical © 2022, Aakash BYJU'S. All rights reserved Key Takeaway 11 Artificial selection Natural selection 12 Hardy-Weinberg Principle Factors affecting equilibrium Origin and Evolution 13 14 Speciation and Isolation 15 Barriers to hybridisation Plants Animals 16 Man Summary © 2022, Aakash BYJU'S. All rights reserved Adaptive radiation Evolution Evolution is change in form to another. Biogenesis Special creation Big bang theory 5 Spontaneous generation 1 3 Origin of universe 4 2 Cosmozoic Catastrophism Theories on origin of life © 2022, Aakash BYJU'S. All rights reserved 6 Chemical evolution Big Bang Theory  Single huge explosion, unimaginable in physical terms that gave birth to the universe  Universe is about 20 billion years old  Decrease in temperature led to the formation of Hydrogen and Helium gases  By gravitation, the swirling mass of gases condensed forming galaxies and planets  Earth was formed 4.5 billion years ago approximately  Volcanic eruptions reoccurred and very inhabitable hostile environment on earth was created  Hence, earth was like a black ball with no atmosphere  From the molten mass of volcanic eruptions, water vapour, methane, carbon - dioxide and ammonia released and covered the earth’s surface © 2022, Aakash BYJU'S. All rights reserved Hydrogen Helium Big Bang Theory  The UV rays from the sun broke-up water into hydrogen, oxygen and the lighter H2 escaped.  Oxygen combined with ammonia and methane to form water, CO2 and other molecules.  Oxygen reacted and formed ozone layer (which act as a shield for our present environment) around primitive Earth.  As water vapour condensed, it fell as rain, to fill all the depressions and form oceans.  Life originated approximately 4 billion years ago when it became suitable to support life. © 2022, Aakash BYJU'S. All rights reserved Special Creation and Catastrophism Special Creation  God/supernatural power created Earth and all possible life forms on Earth © 2022, Aakash BYJU'S. All rights reserved  Given byCatastrophism Cuvier  After a gap of certain period (age), the world undergoes a catastrophe (sudden calamity)  Catastrophe : Kills almost all the living organisms  God creates a new generation or new life from inorganic matter Spontaneous Generation / Abiogenesis Life spontaneously emerges from non-living matter present on earth. Life emerges spontaneously from decaying material  No life emerges when material is airtight However, Louis Pasteur disproved spontaneous generation by careful experimentation and demonstrated that life arises only from pre-existing life. © 2022, Aakash BYJU'S. All rights reserved Cosmozoic Theory and Biogenesis Cosmozoic theory  Greek thinkers thought units of life called spores or seeds or sperms were transferred to the earth from outer space through meteorites  The transfer of spores was termed Panspermia  It states that life is present throughout the universe  Cosmozoic theory : Transfer of life from one planet to another Meteorite © 2022, Aakash BYJU'S. All rights reserved Biogenesis  First cellular life form : originated approx. 2000 million years ago  Life from life, (omnis vivum ex. vivo) was proved by Redi, Spallanzani and Pasteur independently  Pasteur gave a definite proof of life arising from pre-existing life using microbes and sterilization methods.  He performed "swan neck flask" experiment. Chemical Evolution Oparin – Haldane Hypothesis  First life emerged from pre-existing non - living organic molecules (E.g., RNA, proteins) Simple organic micromolecules Large complex macromolecules Oparin Origin of life © 2022, Aakash BYJU'S. All rights reserved Haldane Chemical Evolution Oparin – Haldane Hypothesis  Formation of life was preceded by chemical evolution i.e., formation of diverse organic molecules from the inorganic constituents.  The conditions on earth were – high temperature, volcanic eruptions, reducing atmosphere containing CH4, NH3 , etc. Amino acid Fatty acids Nucleotides Polymerisation Proteins © 2022, Aakash BYJU'S. All rights reserved Lipids RNA Miller Experiment   In 1953, S.L. Miller, an American scientist created similar conditions at a laboratory scale. He created electric discharge in a closed flask containing CH4, H2, NH3 and water vapour at 800oC, and observed formation of amino acids.  In similar experiments, others observed formation of sugars, nitrogen bases, pigment and fats.  Analysis of meteorite content also revealed similar compounds indicating that similar processes are occurring elsewhere in space. © 2022, Aakash BYJU'S. All rights reserved Electrodes Network of glassware Water boiling chamber Gas chamber Condenser Stand Burner Enclosing the Prebiotic System  Three conditions needed to fulfill the origin of life : ○ supply of self-replicators i.e., self-producing molecules ○ copying of these replicators - subject to error via mutation ○ system of replicators required a perpetual supply of free energy and partial isolation from the general environment  Protobionts : aggregates of artificially produced prebiotic molecules and separate molecules from the surrounding Protobionts Coacervates Large protein + polysaccharides = Coacervates Does not have lipid outer membrane Do not reproduce © 2022, Aakash BYJU'S. All rights reserved Microspheres Organic compound (artificial) + cool water = Microspheres Have bilipid outer membrane Origin of Heterotrophs and Autotrophs Heterotrophs  The first living organisms originated among organic molecules and in oxygen free atmosphere  Obtained energy by the fermentation of organic molecules  Anaerobic, capable of respiration in the absence of oxygen  Required organic material as food; hence, chemoheterotrophs © 2022, Aakash BYJU'S. All rights reserved Autotrophs  When the supply of existing organic molecules was exhausted, some of the heterotrophs might have evolved into autotrophs  Organisms were capable of producing their own organic molecules by chemosynthesis or photosynthesis Chemosynthesis and Photosynthesis Chemosynthesis Photosynthesis  Organisms – chemoautotrophs  Organisms – photoautotrophs  Anaerobic in nature   Have ability to synthesise organic molecules from inorganic raw materials Use solar energy to synthesise food with the help of chlorophyll  Lacked the biochemical pathways to produce oxygen, anaerobic and utilized hydrogen from sources other than water  E.g., sulphur bacteria, iron bacteria, nitrifying bacteria © 2022, Aakash BYJU'S. All rights reserved Modern Theory of Origin of Life Free atoms H2, H2O, NH3, CO2 H, C, N , O etc Formation of inorganic micromolecules Formation of simple organic micromolecules Polysaccharides, fats, proteins, nucleotides, nucleic acids Formation of complex organic compounds Formation of eobionts Without organised nucleus Coacervates and microspheres are two protobiont models Prokaryotes Eukaryotes © 2022, Aakash BYJU'S. All rights reserved CH4, HCN, simple sugars, fatty acids, glycerol, amino acids, nitrogenous bases (purine and pyrimidines) With well organised nucleus Evolution of Life Forms Darwin’s observation  Every living organism, whether animal or plant, has its own ‘characteristic’  All existing life forms shares similarities to varying degrees and may also share common ancestors  Geological history of the Earth closely correlates with the biological history of Earth Natural selection  Characteristics that enable some organisms to survive better than others in the same environment, are said to be selected by nature  Better fit organism in an environment has higher reproduction rate than others  This capability to survive is called fitness or reproductive fitness © 2022, Aakash BYJU'S. All rights reserved Evidences for Evolution Fossils Morphological and Anatomical Embryological Biochemical Biogeographical © 2022, Aakash BYJU'S. All rights reserved Evidences for Evolution : Fossils  These are preserved remains or traces of hard parts of ancient life-forms like bones, teeth, shells, woods, etc. in rocks ○ ○ Number and nature of fossils in early rocks : Number - less than in later eras Nature - Simple marine invertebrates Younger fossils Distribution in successive strata: Proterozoic era - few fossils Paleozoic era - abundant fossils of invertebrates Mesozoic era - fossils of great reptiles (Dinosaur) Cenozoic era - abundant fossils of mammals © 2022, Aakash BYJU'S. All rights reserved Time Older fossils Evidences for Evolution : Fossils ○ Disparity between the past and present forms of life : Early organisms were very different from their modern forms ○ Missing links (Transitional forms) : Fossil organisms show characters of two different groups (Archaeopteryx) Reptiles © 2022, Aakash BYJU'S. All rights reserved Intermediate Aves Evidences for Evolution : Fossils Timeline of evolution : Epochs Periods Eras Division of earth’s part into large blocks of the time Subdivision of eras into smaller blocks of time Subdivision of periods Fossil parks : ○ Birbal Sahni Institute of Palaeobotany, Lucknow (20 million years old fossil forests) © 2022, Aakash BYJU'S. All rights reserved Pleistocene Recent Evidences for Evolution : Fossils Modern horse Equus Pilocene horse Pliocene Miocene Callipus Merychippus Oligocene Miohippus Intermediate horse Mesohippus Orohippus Hyracotherium © 2022, Aakash BYJU'S. All rights reserved Ruminating horse Parahippus Eocene Evolution of horse Pliohippus Evidences for Evolution : Fossils Radioactive/ Carbon dating  It is a method for determining the age of an object containing organic material by measuring amount of C-14 present. Significance  Gives clues to organisms that are long extinct  Show intermediate forms of species as they underwent speciation  By comparing fossils from different species, scientists figure out which species are related to which others © 2022, Aakash BYJU'S. All rights reserved Evidences for Evolution : Morphological and Anatomical Evidences Homologous structures Vs Analogous structures  Similar in anatomy but different functions  Not similar anatomically but perform similar functions  Common origin  Different origin Tendrils Cucurbita Thorns Bougainvillea Different function - Tendril support and thorns protect plants Same structures - Modified branches © 2022, Aakash BYJU'S. All rights reserved Eagle wing (Aves) Butterfly wing (Arthropods) Same function - Flying Different structures - Wing Evidences for Evolution : Morphological and Anatomical Evidences Vs Homologous structures examples Analogous structures examples Hearts in various vertebrates ( fishes, amphibians, birds and mammals) Similarity in basic plan but varied degree of specialization  Eye of octopus and of mammals : Different internal structures but with common function of vision  Brain of vertebrates : similar in basic structure but progressive complexity  Flippers of penguins and dolphins : Different internal structure and origin but common function of swimming  Biochemical : Proteins found in the blood of man and ape are similar  Sweet potato and potato : Modified underground root and stem respectively but common function of storage of food   © 2022, Aakash BYJU'S. All rights reserved Evidences for Evolution : Morphological and Anatomical Evidences Example of homologous organs in animals Common ancestor Divergent evolution © 2022, Aakash BYJU'S. All rights reserved Evidences for Evolution : Morphological and Anatomical Evidences Analogous structure in birds Eagle Bat Butterfly Common function(flying) Different structures evolved due to adaptation to similar needs: Convergent evolution © 2022, Aakash BYJU'S. All rights reserved Evidences for Evolution : Morphological and Anatomical Evidences Vestigial organs : Remnants of organs which were complete and functional in ancestors Nictitating membrane Appendix Coccyx © 2022, Aakash BYJU'S. All rights reserved Evidences for Evolution : Morphological and Anatomical Evidences Connecting link : Organisms sharing characters of two different groups Mammals Reptiles Duck-billed platypus   © 2022, Aakash BYJU'S. All rights reserved E.g., The duck billed platypus, is a connecting link between reptiles and mammals. Mammal like features are mammary glands, hair, diaphragm, etc, and like reptiles, they lay eggs. Evidences for Evolution : Morphological and Anatomical Evidences Atavism : The reappearance of a trait that had been lost during evolution Appearance of tail © 2022, Aakash BYJU'S. All rights reserved Third nipple Excess body hair Evidences for Evolution : Embryological  Similarity in early development among all multicellular animals from a fertilized egg (zygote) to formation of primary germ layers  Resemblance among vertebrate embryos : Human Pig Chicken Fish Mature stage embryos Early-stage embryos © 2022, Aakash BYJU'S. All rights reserved Evidences for Evolution : Embryological  Resemblance among invertebrates : Trochophore larva of annelids and molluscs  Development of vertebrate organs ( e.g., heart, brain, kidney) is the possible path of evolution  Progressive metamorphosis : Ammocoete larva of Lamprey (presumed that Lamprey has evolved from Branchiostoma)  Retro regressive metamorphosis : Sacculina and Herdmania  Temporary embryonic structure : Bird embryo with tooth buds and gill clefts, Whale embryo with hair and early tadpole of frog with tail Biogenetic law  Proposed by Ernst Haeckel  It states that “each embryo's developmental stage represents an adult form of an evolutionary ancestor”.  E.g., Vestigial gill slits present in the embryos of all vertebrates including humans, but functional organ only in fish  Occurrence of ancestral traits in embryo - Palaeogenesis © 2022, Aakash BYJU'S. All rights reserved Evidences for Evolution : Biogeographical Distribution of animals and plants in different parts of the earth  Discontinuous distribution : of closely related species are widely spread  E.g., Elephants found in Africa and India are not found in similar climate of Brazil Neartic realm Palearctic realm Indomalayan realm Afrotropic realm Australasia realm Neotropical realm © 2022, Aakash BYJU'S. All rights reserved  Restricted distribution : Parts separated from mainland have unique flora and fauna.  E.g., Australia has egg laying mammals and pouched animals Evidences for Evolution : Biochemical  Similarities in proteins and genes performing a given function among diverse organisms give clues to common ancestry.  These biochemical similarities point to the same shared ancestry as structural similarities among diverse organisms. © 2022, Aakash BYJU'S. All rights reserved DNA Information is stored in genes and other DNA sequences GENES Contain recipes for protein PROTEIN MACHINE PROTEINS Proteins act alone or in complexes to perform all cellular functions Biological Evolution : Lamarckism Lamarck’s theory    Given by Jean Bapist de Lamarck, French naturalist Theory was discussed in his book “Philosophie Zoologique” published in 1809 Key point - Organisms change their characteristics and these changes are inherited by offspring © 2022, Aakash BYJU'S. All rights reserved Lamarck’s theory : Postulates  Internal forces - increases size of the body  Doctrine of Appetency/ desires - formation of new organs due to continuous need or want felt by the organism  Development and power of action of an organ ∝ Use  Inheritance - transfer of the acquired changes to the offspring  Use and disuse of organs: If an organ is constantly used it would be better developed whereas disuse of organ results in its degeneration Biological Evolution : Lamarckism Lamarck’s theory : Example  Ancestors of Giraffe had small neck and forelimbs  Due to loss of grass with time, they began to stretch their neck to reach out to eat the leaves from tall trees  Hence, with time this lead to neck and forelimbs elongation. © 2022, Aakash BYJU'S. All rights reserved Biological Evolution : Darwinism Darwin’s theory  Given by Charles Robert Darwin  Darwin was inspired by Thomas Malthus ideas  Darwin asserted that variations which are heritable and which make resource utilisation better for few (adapted to habitat better) will enable to reproduce with more progeny High rate of reproduction Total no. almost constant Natural selection Darwin’s theory for natural selection Survival of the fittest Struggle for existence Variations © 2022, Aakash BYJU'S. All rights reserved Biological Evolution : Darwinism Darwin’s theory : Concept of fitness  Differential reproduction - Some of the survived individual which reach adulthood to reproduce at different rates  Survival of the fittest, in the struggle for existence, will depend on the characteristic trait of the organism.  Survival of the fittest was first used by Herbert Spencer and this was, in the same context, asserted by Darwin as "Natural Selection"  Biotic potential : Ability of an organism with a variation in a population to reproduce and increase in number when compared to the other organisms in the population  Cause of variation: Recombination and intermingling of two widely spread populations © 2022, Aakash BYJU'S. All rights reserved Biological Evolution : Darwinism Darwin’s theory : Branching descent and natural selection Branching descent :  Darwin said, the evolution is a branching process  With time, new life form appear and arise as branches from previously existing life forms  Branching descent points towards the concept of common ancestry Natural selection :  Darwin emphasised that the selection of useful variations by nature is the main (but not exclusive) mechanism for evolution to occur © 2022, Aakash BYJU'S. All rights reserved Biological Evolution : Mutation Theory Mutation theory  Proposed by Hugo de Vries  Observed on wild variety of evening primrose (Oenothera lamarckiana)  According to mutation theory, new species originates as a result of large, discontinuous variation which appears suddenly (saltation) Normal gene or  Main features : ○ Mutations are large, random and directionless Mutations are heritable and establish new species Mutation arise from time to time © 2022, Aakash BYJU'S. All rights reserved Mutated gene Normal protein Abnormal protein No protein Difference Between Variations and Mutations Variations Vs Mutation Small and cannot bring sudden change in life forms Bring change only when the accumulate   Large and bring sudden change even in a span of single generation Do not need accumulation  Directional  Random and directionless  Darwin said evolution is a slow and gradual process  Hugo deVries believed that evolution occurs suddenly. Saltation : Single step large mutation which causes speciation    © 2022, Aakash BYJU'S. All rights reserved Artificial Selection It is a selective breeding of plants or animals for desired traits, which is done artificially using various breeding methods   Cauliflower Animal husbandry : Breeding of cows, buffaloes to increase yield and quality of milk Horticulture : Breeding of various crops to improve yield, nutritional value and disease resistance  E.g., Generations of different vegetables like broccoli, kale, cauliflower etc  For security purpose : Breeding of horses, camels, dogs etc. © 2022, Aakash BYJU'S. All rights reserved Cabbage Brussels sprouts Kohlrabi Broccoli Brassica oleracea (a common wild mustard) Kale Natural Selection A process in which organisms adapted better to their environment tend to survive and produce more offsprings. Industrial melanism : After industrialization, pollution increased and tree trunks became dark due to soot and smoke deposition. As a result, white winged moth could not camouflage themselves and were predated by birds Before industrialization (less air pollution) After industrialization (more air pollution) White winged moth Dark winged moth White winged moth Dark winged moth More in number Less in number Less in number More in number © 2022, Aakash BYJU'S. All rights reserved Natural Selection Antibiotic or drug resistance : Continuous use of drugs and antibiotics against microbes leads to resistance towards drugs Herbicide resistance : Continuous use of herbicide and pesticide against weeds and pests leads to resistance. They survive better, despite the prolonged use of herbicides and pesticides. © 2022, Aakash BYJU'S. All rights reserved Adaptive Radiation When an ancestral species evolves into different species due to competition for food or space and occupy different habitat Darwin’s Finches  Location - Galapagos islands (chain of islands in South America)  Found : Varieties of small black birds  Differed in shape of beaks and feeding habits  Analysis after observation: Varieties evolved from original seed eating ancestor bird present in South America © 2022, Aakash BYJU'S. All rights reserved Insect eating Fruit eating Cactus eating Seed eating Adaptive Radiation Australian marsupials  Location - Island in Australia  Found - Number of marsupials (Koala, Kangaroo, etc)  Differed in morphology due to adaptation to different environments © 2022, Aakash BYJU'S. All rights reserved Marsupial Ancestor Adaptive Radiation Placental mammals : Convergent evolution  Resemblance of placental and marsupial mammals in structure and ways of life due to living in the similar ecological niches Resemble in structure Wolf (Placental mammal) Common ancestor 1 © 2022, Aakash BYJU'S. All rights reserved Lead similar lives Live in similar habitat Tasmanian wolf (Marsupial mammal) Common ancestor 2 Hardy-Weinberg Principle  Proposed by G.H. Hardy and W. Weinberg in 1908  The Hardy- Weinberg equilibrium is a principle stating that genetic variation in a population will remain constant from one generation to other in the absence of disturbing factors.  Main concepts : ○ Allele frequencies in a population = Stable and constant from generation to generation ○ Gene pool (total genes and their alleles in a population) = Constant ○ This is called gene equilibrium ○ Sum total of all the allelic frequencies = 1 © 2022, Aakash BYJU'S. All rights reserved Hardy-Weinberg Principle  Gene migration or gene flow Hardy-Weinberg equilibrium is represented by: (p+q)2 = p2 + 2pq + q2 = 1 ○ where, p2 is the frequency of homozygous dominant genotype ○ q2 is the frequency of homozygous recessive genotype ○ 2pq is the frequency of heterozygous genotype © 2022, Aakash BYJU'S. All rights reserved Factors affecting HardyWeinberg Equilibrium Gene drift Mutation Genetic recombination Natural selection Hardy-Weinberg Principle Factors affecting equilibrium: Migration or gene flow  Gene migration : Migration of genes/alleles due to movement of few individuals from one population to another  It can occur by ○ Migration of section of population from one area to another ○ Interbreeding  Gene pool : Total collection of all genes and its allele in a population  Gene flow : Exchange of genes between two different populations  Thus, gene flow disturbs Hardy-Weinberg equilibrium. © 2022, Aakash BYJU'S. All rights reserved Hardy-Weinberg Principle Factors affecting equilibrium: Mutation  Change in nucleotide sequence of genetic material due to errors in DNA copying or exposure of mutagens  Mutation introduce new genes/ alleles or delete old ones  This, lead to a change in gene and allele frequency.  Mutations are ○ random ○ harmful or with no effect ○ very slow © 2022, Aakash BYJU'S. All rights reserved A G T T G T C A A C Mutation A G T T G T C G A C Hardy-Weinberg Principle Factors affecting equilibrium: Mutation  Lederberg Replica Plating Experiment : o Devised by Joshua Lederberg and Esther Lederberg o Demonstrated on E.coli o Cultivated the bacteria which developed into discrete colonies o Each of the colonies originated from a single bacterium through a large number of cell divisions o Through the master plate, replicas were created With penicillin : Most colonies found on the master plate did not grow on the replica plates ○ Showed that many mutations are random rather than directed ○ Mutations are not induced by penicillin © 2022, Aakash BYJU'S. All rights reserved Hardy-Weinberg Principle Factors affecting equilibrium: Genetic drift  Fluctuation in gene/allele frequencies due to chance of events  Causes change in gene frequency by chance in a small population  It has two ramifications: ○ Bottle neck effect : Drastic reduction in population size due to natural disasters ○ Founder’s effect : Reduction in genetic variation when small subset of a population establishes a new colony with few individuals in a population and act as founders. © 2022, Aakash BYJU'S. All rights reserved Hardy-Weinberg Principle Factors affecting equilibrium: Gene recombination Occurrence of new combination of alleles due to sexual reproduction  Due to crossing over of chromosomes  Recombinants - cross overed offspring with new combination of characters Chromosome  Crossing over Parent cell A © 2022, Aakash BYJU'S. All rights reserved B Segments of DNA get exchanged between sister chromatids Hardy-Weinberg Principle Factors affecting equilibrium: Natural selection  It is a process in which heritable variations enable better survival and produce more progeny.  Organisms which get selected by nature will have better survivability and changes in the allelic frequencies.  Natural selection causes unequal survival and reproductive success of individuals. Its effects on different traits Stabilising © 2022, Aakash BYJU'S. All rights reserved Directional Disruptive Hardy-Weinberg Principle Factors affecting equilibrium: Natural selection Peak gets higher and narrower Number of individuals with phenotype Stabilising Phenotypes favored by natural selection Medium - sized individuals are favored Peak shifts in one direction Directional Two peaks are formed Disruptive © 2022, Aakash BYJU'S. All rights reserved Speciation and Isolation  Speciation : Formation of one or more new species from existing ones Modes of speciation based on geographical relationship of a new species to its ancestral species Sympatric Allopatric  When a continuous population in a range, splits into two or more geographically isolated populations and form new species © 2022, Aakash BYJU'S. All rights reserved  Formation of species within a single population without geographical isolation Speciation and Isolation Species concept Morphospecies concept Biological species concept Evolutionary species concept Reproductive isolation © 2022, Aakash BYJU'S. All rights reserved Species is the basic unit of classification Species are characterized by its morphology Species taxon as a group of organisms that can successfully interbreed and produce fertile offspring Sibling species - almost identical morphologically but distinct due to absence of interbreeding Single lineage of ancestor-descendant populations which has its own evolutionary tendencies, separate from other such lineage Inability of a species to breed successfully with related species due to geographical, behavioural, physiological, or genetic barriers or differences Speciation and Isolation Barriers to hybridisation : Ecological isolation Prezygotic mechanisms Temporal isolation Breeding season or flower time may be different in two species Behavioural isolation Male of one species unable to recognise the females of another as potential mates Mechanical Isolation Structural difference in genitalia interfere with mating Gametic Isolation © 2022, Aakash BYJU'S. All rights reserved Two species live in different habitat and do not meet Sperms and ova of different species of animals are unable to fuse together Speciation and Isolation Barriers to hybridisation : Hybrid unviability Postzygotic mechanisms Hybrid sterility Hybrid breakdown © 2022, Aakash BYJU'S. All rights reserved Hybrid zygotes fail to develop Hybrid adults do not produce functional gametes Offspring of hybrids are unviable or fertile Cenozoic Origin and Evolution of Plants Bryophytes Mesozoic Monocotyledons Tertiary Cretaceous Jurassic Sphenopsids Ginkgos Gnetales Herbaceous lycopods Ferns Dicotyledons Conifers Cycads Triassic Permian Paleozoic Angiosperms Quaternary Arborescent lycopods Carboniferous Seed ferns Devonian Progymnosperms Silurian Chlorophyte ancestors © 2022, Aakash BYJU'S. All rights reserved Zosterophyllum Tracheophyte ancestors Rhynia-type plants Psilophyton Origin and Evolution of Animals Cenozoic Turtles Lizards Snakes Tuataras Crocodiles Birds Mammals 0 Quaternary 50 Tertiary Dinosaurs (Extinct) 100 Mesozoic Cretaceous 150 Jurassic Therapsids (Extinct) 200 Thecodonts (Extinct) Triassic Paleozoic 250 Permian Sauropsids 300 Carboniferous 350 Synapsids Early reptiles (Extinct) Amphibians Fishes © 2022, Aakash BYJU'S. All rights reserved Pelycosaurs (Extinct) Invertebrates Origin and Evolution of Man Dryopithecus Australopithecus Ramapithecus © 2022, Aakash BYJU'S. All rights reserved Homo erectus Homo habilis Neanderthal man Homo sapiens Origin and Evolution of Man............................... 15 million years ago (Ancestors of modern apes and man) The hominids Dryopithecus Hominid evolution Apes Ramapithecus and Sivapithecus The oldest direct ancestor First human like form Small brain size Walked upright 3-5 ft. tall Larger brain Bipedal Used tools...................................................................................................... Cranial capacity 900-1140 cc Used fire and stone tools Bipedal 5 ft. tall Cro-Magnon man................. 34,000 years ago................................................................................................................................ Homo sapiens sapiens Early form of modern humans Has left cave paintings Modern man..................... homo sapiens Large cranial capacity 1400 - 1450 cc Cultivated plants and domesticated animals Has spread all over the earth 10-14 million years ago......................... (Lived in Africa) (Lived in Asia) 3-4 million years ago............................... A-africanus 2 million years ago 1.5 million years ago (Lived in Africa) Australopithecus A-robustus (became extinct)................................................................ Homo habilis Horno erectus............................... includes Java man and Peking man....................................................................................................... Neanderthal man 100,000 to 40,000 years ago Homo sapiens neanderthalensis 10,000 years ago................................................................................................................................ Note : This arrow indicates the possible line of evolution. © 2022, Aakash BYJU'S. All rights reserved Origin and Evolution of Man Arboreal and ate soft fruits and leaves, knuckle walker, arms and legs of same length Dryopithecus Ate hard nuts and seeds, lived on treetops, had small canines and large molars Ramapithecus Bipedal locomotion, omnivorous diet, erect posture, absence of chin Australopithecus Homo habilis Bipedal locomotion, moved erect, tool maker, used stones to make tools, cared for the young ones Homo erectus Homo sapiens © 2022, Aakash BYJU'S. All rights reserved Erect posture, omnivorous, protruding jaws, used fire, ate meat Bipedal locomotion, skilled hunters, buried the dead Summary Origin of universe and life Biogenesis Special creation Big bang theory 5 Spontaneous generation 1 3 Origin of universe 4 2 Cosmozoic Catastrophism Theories on origin of life © 2022, Aakash BYJU'S. All rights reserved 6 Chemical evolution Summary Evidences for evolution Fossils Morphological and Anatomical Embryological Biochemical Biogeographical © 2022, Aakash BYJU'S. All rights reserved Summary Adaptive radiation Darwin finches Australian marsupials Insect eating Fruit eating Cactus eating Seed eating © 2022, Aakash BYJU'S. All rights reserved Marsupial ancestor Summary Hardy-Weinberg principle Gene migration or gene flow Gene drift Factors affecting HardyWeinberg Equilibrium Mutation Genetic recombination Natural selection © 2022, Aakash BYJU'S. All rights reserved