BI 5103 FISIOLOGI TERINTEGRASI (Integrative Physiology) Core Principle 1: EVOLUTION (Konsep Inti I : Evolusi) Semester I 2013/2014 tjandraanggraeni 1 Why Evolution? Evolusi dapat memberikan penjelasan secara scientific pada sejarah kehidupan di bumi dan mekanisme yang menyebabkan terjadinya perubahan pada kehidupan (Evolution provides a scientific explanation for the history of life on Earth and the mechanisms by which changes to life have occurred) Semester I 2013/2014 tjandraanggraeni 2 A flower mantid in Malaysia A leaf mantid in Costa Rica Sub Topik : 1. Evolusi melalui seleksi alam : asal-usul organisme dan fungsi fisiologisnya 2. Evolusi menjelaskan asal hubungan antara struktur dan fungsi 3. Variasi dalam struktur protein yang mendasari fungsi fisiologis pada tingkat molekuler dikendalikan oleh mekanisme evolusi Semester I 2013/2014 tjandraanggraeni 5 1. Evolusi melalui seleksi alam : asalusul organisme dan fungsi fisiologisnya Semester I 2013/2014 tjandraanggraeni 6 EVOLUTION: Natural selection & development of complex life Natural Selection Darwin’s theory Mechanism: Variation in populations Some variation heritable More individuals born than will survive Adaptation The evolution of insecticide resistance is an example of natural selection in action Insecticide application Chromosome with gene conferring resistance to insecticide Additional applications of the same insecticide will be less effective, and the frequency of resistant insects in the population will grow Survivor Terminal bud Lateral buds Cabbage Brussels sprouts Flower clusters Leaves Kale Cauliflower Stem Wild mustard Flowers and stems Broccoli Kohlrabi Dogs varieties CONCEPTS OF SPECIES Linnaeus used physical appearance to identify species when he developed the binomial system of naming organisms ◦ This system established the basis for taxonomy Semester I 2013/2014 tjandraanggraeni 12 But appearance alone does not always define a species – Example: eastern and western meadowlarks (the songs of the two species are different) Semester I 2013/2014 tjandraanggraeni 13 Similarities between some species and variation within a species can make defining species difficult – Humans exhibit extreme physical diversity Semester I 2013/2014 tjandraanggraeni 14 The biological species concept defines a species as – a population or group of populations whose members can interbreed and produce fertile offspring Semester I 2013/2014 tjandraanggraeni 15 A ring species may illustrate the process of speciation 1 OREGON POPULATION Sierra Nevada COASTAL POPULATIONS Yelloweyed Yellowblotched 2 Gap in ring Monterey INLAND POPULATIONS Largeblotched 3 Semester I 2013/2014 tjandraanggraeni 16 2. Evolusi menjelaskan asal hubungan antara struktur dan fungsi Semester I 2013/2014 tjandraanggraeni 17 Semester I 2013/2014 tjandraanggraeni 18 Humerus Radius Ulna Carpals Metacarpals Phalanges Human Cat Whale Bat A mass of other evidence reinforces the evolutionary view of life ◦ Comparative embryology is the comparison of early stages of development among different organisms – Many vertebrates have common embryonic structures, revealing homologies – When you were an embryo, you had a tail and pharyngeal pouches (just like an embryonic fish) Copyright © 2009 Pearson Education, Inc. Pharyngeal pouches Post-anal tail Chick embryo Human embryo A mass of other evidence reinforces the evolutionary view of life Some homologous structures are vestigial organs – For example, the pelvic and hind-leg bones of some modern whales Copyright © 2009 Pearson Education, Inc. Pakicetus (terrestrial) Rhodocetus (predominantly aquatic) Pelvis and Dorudon (fully aquatic) hind limb Pelvis and hind limb Balaena (recent whale ancestor) Mechanisms of respiration : example Aquatic animal : diffusion through skin or gills Terrestrial animal : diffusion through alveolus in lungs tjandra anggraeni 24 se me ster II 07/ 08 Semester I 2013/2014 tjandraanggraeni 25 Semester I 2013/2014 tjandraanggraeni 26 Ikan tjandra anggraeni 27 se me ster II 07/ 08 tjandra anggraeni 28 se me ster II 07/ 08 Serangga tjandra anggraeni 29 se me ster II 07/ 08 Burung tjandra anggraeni 30 se me ster II 07/ 08 Amphibi tjandra anggraeni 31 se me ster II 07/ 08 Mamalia tjandra anggraeni 32 se me ster II 07/ 08 Manusia tjandra anggraeni 33 se me ster II 07/ 08 3. Variasi dalam struktur protein yang mendasari fungsi fisiologis pada tingkat molekuler dikendalikan oleh mekanisme evolusi Semester I 2013/2014 tjandraanggraeni 34 CONTROL OF GENE EXPRESSIONS PROTEIN Copyright © 2009 Pearson Education, Inc. Prokaryotic cells Proteins interacting with DNA turn prokaryotic genes on or off in response to environmental changes Semester I 2013/2014 tjandraanggraeni 36 OPERON Regulatory Promoter Operator gene Lactose-utilization genes DNA mRNA Protein Active repressor Operon turned off (lactose absent) RNA polymerase cannot attach to promoter DNA mRNA RNA polymerase bound to promoter Protein Lactose Inactive repressor Enzymes for lactose utilization Operon turned on (lactose inactivates repressor) Promoter Operator Gene DNA Active repressor Active repressor Tryptophan Inactive repressor Inactive repressor Lactose lac operon trp operon Eukaryotic cells Differentiation results from the expression of different combinations of genes ◦ Differentiation involves cell specialization, in both structure and function ◦ Differentiation is controlled by turning specific sets of genes on or off Semester I 2013/2014 tjandraanggraeni 41 Muscle cell Pancreas cells Blood cells Multiple mechanisms regulate gene expression in eukaryotes ◦ Many possible control points exist; a given gene may be subject to only a few of these – Chromosome changes (1) – DNA unpacking – Control of transcription (2) – Regulatory proteins and control sequences – Control of RNA processing – Addition of 5’ cap and 3’ poly-A tail (3) – Splicing (4) – Flow through nuclear envelope (5) Copyright © 2009 Pearson Education, Inc. Multiple mechanisms regulate gene expression in eukaryotes ◦ Many possible control points exist; a given gene may be subject to only a few of these – Breakdown of mRNA (6) – Control of translation (7) – Control after translation – Cleavage/modification/activation of proteins (8) – Breakdown of protein (9) Copyright © 2009 Pearson Education, Inc. NUCLEUS Chromosome DNA unpacking Other changes to DNA Gene Gene Transcription Exon RNA transcript Intron Addition of cap and tail Splicing Tail mRNA in nucleus Cap Flow through nuclear envelope mRNA in cytoplasm CYTOPLASM Breakdown of mRNA Translation Brokendown mRNA Polypeptide Cleavage / modification / activation Active protein Breakdown of protein Brokendown protein Cascades of gene expression direct the development of an animal ◦ Role of gene expression in fruit fly development – Orientation from head to tail – Maternal mRNAs present in the egg are translated and influence formation of head to tail axis – Segmentation of the body – Protein products from one set of genes activate other sets of genes to divide the body into segments – Production of adult features – Homeotic genes are master control genes that determine the anatomy of the body, specifying structures that will develop in each segment Copyright © 2009 Pearson Education, Inc. Eye Antenna Leg Head of a normal fruit fly Head of a developmental mutant Egg cell Egg cell within ovarian follicle Protein signal Follicle cells 1 Gene expression “Head” mRNA 2 Embryo 3 Cascades of gene expression Body segments Gene expression Adult fly 4 Signal transduction pathways convert messages received at the cell surface to responses within the cell ◦ Signal transduction pathway is a series of molecular changes that converts a signal at the cell’s surface to a response within the cell – Signal molecule is released by a signaling cell – Signal molecule binds to a receptor on the surface of a target cell Copyright © 2009 Pearson Education, Inc. Signal transduction pathways convert messages received at the cell surface to responses within the cell – Relay proteins are activated in a series of reactions – A transcription factor is activated and enters the nucleus – Specific genes are transcribed to initiate a cellular response Copyright © 2009 Pearson Education, Inc. Signaling cell Signaling molecule Plasma Receptor membrane protein 1 2 3 Target cell Relay proteins Transcription factor (activated) 4 Nucleus DNA 5 mRNA Transcription New protein 6 Translation Genes that control development play a major role in evolution Homeotic genes are called master control genes and determine basic features, such as where pairs of wings or legs develop on a fruit fly. Profound alterations in body form can result from changes in homeotic genes or how or where homeotic genes are expressed. © 2012 Pearson Education, Inc. Genes that control development play a major role in evolution Duplication of developmental genes can also be important in the formation of new morphological features. A fruit fly has a single cluster of homeotic genes. A mouse has four clusters of homeotic genes. Two duplications of these gene clusters occurred in the evolution of vertebrates from invertebrates. © 2012 Pearson Education, Inc. Genes that control development play a major role in evolution In the threespine stickleback fish, those fish that that live in the ocean have bony plates and a large set of pelvic spines but in lakes have reduced or absent bony plates and pelvic spines, resulting from a change in the expression of a developmental gene in the pelvic region. © 2012 Pearson Education, Inc. Figure 15.11C Missing pelvic spine Evolutionary novelties may arise in several ways In most cases, complex structures evolve by increments from simpler versions with the same basic functions. In the evolution of an eye or any other complex structure, behavior, or biochemical pathway, each step must bring a selective advantage to the organism possessing it and increase the organism’s fitness. © 2012 Pearson Education, Inc. Evolutionary novelties may arise in several ways Mollusc eyes evolved from an ancestral patch of photoreceptor cells through a series of incremental modifications that were adaptive at each stage. A range of complexity can be seen in the eyes of living molluscs. Cephalopod eyes are as complex as vertebrate eyes, but arose separately. © 2012 Pearson Education, Inc. Figure 15.12 Patch of pigmented cells Eyecup Pigmented cells (photoreceptors) Pigmented cells Eye with primitive lens Complex camera lens-type eye Transparent protective tissue (cornea) Cornea Simple pinhole eye Fluid-filled cavity Lens Eyecup Nerve fibers Limpet Nerve fibers Abalone Layer of pigmented cells (retina) Optic nerve Nautilus Retina Optic Optic nerve nerve Marine snail Squid Adaptations that have evolved in one environmental context may be able to perform new functions when conditions change ◦ Example: Plant species with catch basins, an adaptation to dry environments Semester I 2013/2014 tjandraanggraeni 60 Cactus ground finch Medium ground finch Large ground finch Small Large cactus ground finch ground finch Small tree finch Vegetarian finch Medium tree finch Large tree finch Woodpecker finch Mangrove finch Green Gray warbler finch warbler finch Sharp-beaked ground finch Seed eaters Cactus flower eaters Ground finches Bud eaters Insect eaters Tree finches Warbler finches Common ancestor from South America mainland Semester I 2013/2014 tjandraanggraeni 61 A phylogenetic tree based on molecular data Brown bear Polar bear Asiatic black bear American black bear Sun bear Giant Sloth Spectacled panda bear bear Lesser Raccoon panda Miocene Pleistocene Pliocene Ursidae Oligocene Procyonidae Common ancestral carnivorans Semester I 2013/2014 tjandraanggraeni 62 Paper Discuss the relation between evolution and physiology in : Organismal, structure, and / or molecular level Semester I 2013/2014 tjandraanggraeni 63