Intro to Evolution Flashcards
Mycorrhizae
The critical relationship between plans and fungi-symbiosis. Fungus-facilitates absorption of nutrients and water from soil for the plant. Plant-supplies fungus with sugars.
Shared Derived Characters of Kingdom Animalia
No cell wall, multicellular, tissue level of organization, gap, tight, and adhesion junctions. Heterotrophs with extracellular digestion, mobile in at least one stage of life cycle. Requires muscle and nervous tissue (most, not all).
Ancestral Animal Sister Group
Choanoflagellates-colonial flagellated protists have lower level similarities. Evidence suggests that original ancestral animal lived 1 billion years ago.
Demands made on Animals
Must be mobile, requires muscles and skeleton. Obtain enough oxygen to support an active lifestyle, which requires an exchange surface. Be able to transport digested nutrients to where they are needed, and get rid of wastes. (transport systems).
Animal Cell Demands
Must be able to get rid of wastes and import nutrients and oxygen. All ways of getting material in and out of cells only work at a very short range. All depend on surface area of plasma membrane.
Animal Anatomy
Folding very large membrane surface within a compact volume.
Radial Symmetry
Body has no anterior-posterior axis, can be cut on more than 1 plane to produce mirror image segments. ex) starfish
Oral and Aboral ends
Bag-in-a-bag body plan. (radially symmetric organisms)
Sessile
Don’t do well with rapid movement in one direction or the other. (radial symmetric organisms)
Bilateral Symmetry
Body has anterior-posterior axis, can be cut on one plane to produce two mirror image segments. Tube within a tube body plan.
Cephalisation
Bilaterions tend to have heads with sense organs. Dorsal and ventral sides, tend to be active.
Animal Phylogeny-Phylum
Major systematic grouping of Animalia, distinguishable by unique combo of very basic shared derived characters.
Charles Darwin
Wasn’t the first to come up with the idea that evolution happened-but first to come up with proposed mechanism for evolution. Incremental actions of everyday processes-“descent with modification.” Sparked by observations made on his trip around the world on the Beagle.
Charles Darwin’s theory
Developed through extensive research over next 20 years- Used data from comparative anatomy, fossil record, artificial selection, biogeography. Able to correlate relationships among modern species and their geographic distributions in the Galapagos.
Alfred Russel Wallace
Forced Darwin to publish his work when he threatened to scoop him.
Artificial Selection
Domestic plants and animals had changed greatly from their ancestors under domestification.
Fossil Records
Nature of the fossils in sedimentary rocks and the order in which they are laid down are evidence that living things have been evolving as far back as the fossil record goes-fossil distribution is NOT arbitrary.
Transitional Forms
Transitions from one form to another in fossil record-dinosaurs to birds, mesonychids to whales, lobe-finned fish to tetrapods… etc.
Biogeography
Distribution of many modem and fossil taxa can be correlated with known geographical history. Ex) Ratites lived in Gondwanaland- still live in continents derived from break up of Gondwanaland.
Comparative Anatomy
Homologous organs exemplify descent with modification. Way in which homologous structures differ in related species indicates action of evolution.
Convergent Evolution
Produces similar independently derived analogous structures-not present in common ancestor. Analogous structures have similar functions but different origins.
Embryology
Animals share patterns of development. Ex) vertabrates all pass through an embryonic stage with pharyngeal pouches. Common embryonic structure reflects common evolutionary history.
Phylogenies
Family trees of species (shared derived features enables us to derive phylogenies). Are hypotheses concerning relationship and descent.
Postulates
Individuals in a population vary in some behavioural or physical characters. Variation is heritable, correlation between nature of heritable variation and reproductive success.
Attributes of natural selection theory
Organisms don’t evolve-populations do. Natural selection only works with available variation-does not produce new alleles. Has no foresight-selects adaptations to immediate conditions. Aren’t necessarily universally useful for more than one generation ahead.
Pesticide Resistance
Small proportion of wild insect population likely to have some resistance to any given pesticide-quite possibly due to single allele of a single gene.
Adaptation
Is a result of selection-character produced by action of natural selection, enabling an organism to survive and reproduce in a particular environment more successfully than it would otherwise. Sufficient-not perfect. Trade-offs-not perfected by selection.
Variation
Is random and may not be sufficient.
Organisms
Produced by history and constrained by its effects. Organs frequently have more than 1 function. Biological materials may not allow perfection. Accident plays a large role in evolution.
Early Earth
First 200 million years it was very hostile to life. Even after things settled, conditions were still inhospitable-high UV and vulcanism. Very little oxygen which allowed for existence of very complex organic molecules which would not survive today.
Theoretical Steps of Abiogenesis
1-Abiotic Synthesis of small organic molecules-amino acids, fatty acids, monosaccharides, nucleotides.
- Polymerization of these monomers
- Protobionts- Membrane bound vesicles maintaining an internal environment different from external.
- Incorporation of self-replicating molecules into protobionts, allowing inheritance and selection.
- Energy extraction from environment.
Millers Experiment
Exposed mix of gasses (H20, H2, NH3, CH4), thought to correspond to early Earths atmosphere to repeated electrical discharges, repeated cycle of evaporation and concentration. Began finding amino acids in mix.
What is the atmosphere made up of?
Largely CO2 and N2. May have taken place in more restricted locale (deep sea vents).
Polymers
Lengthened by dehydration. Monomers shown to spontanously polymerize abiotically with concentration through evaporation on hot solid surfaces.
Protobionts
Precurser of cell, membrane (lipid) bound vesicle, selectively permeable bilayer, allow concentration of other biomolecules
RNA World
Short lengths of RNA can self-assemble-polymerase not required. Can also act as a template for self-assembly of complementary strand.
Ribozymes
RNA lengths which carry out enzyme -like functions. Protobionts could have served as reservoirs within which RNA “genes” could replicate generation to generation.
What did early prokaryotes produce?
Stromatolites
Early Prokaryotes
Very diverse biochemically-most forms were anaerobic chemoautotrophs. Tend to exist now where there is no O2.
How did oxygen come into play?
Producing photosynthesizers began leaking oxygen into atmosphere by 2.7 billion years ago. By 2.2 Billion years ago, rising oxygen levels probably caused first mass extinction.
First Eukaryotes
First fossils-2.1 billion years ago. Condition not acheived in single step-incorporation of mitochondria came first.
Multicellular Eukaryotes
First fossils more complex multicellular eukaryote “animals.” Ecliacaran Fauna-600 million years ago. Nobody is quite sure what these were.
Cambrian Explosion
Appearance in rapid diversification of “true” animals-535-525 million years ago.
Colonization of the land
Originally by prokaryotes (bacterial films) 1 Billion years ago. By multicellular eukaryotes- 500 million years ago. First by plants and fungi-symbiotic relationship of animals, anthropods and tetrapods. Vertebrates were the most successful.
Radiometric Dating
Radioactive elements (radioisotopes) decay into other elements at predictable rates. Half life-half a given quantity of radioactive elements will turn into its decay product within a specific time frame.
Radioactive Clock
Age of volcanic rock can be determined by ratio of decay product to remaining radioisotope.
Geological Record
Chronology for much of history of earth-divided into Eons, Eras, Periods. History of life is not directive but consecutive-change through time is not haphazard. Also shows mass extinction.
