Biology Ms. Fezza CHAPTER 15 EVOLUTION Naturalist on the HMS Beagle Traveled the world collecting rocks, fossils, and plants 5 years of observation Collect 5 years worth of data Read Charles Lyells Principles of Geology Proposed earth was millions of years old Galapagos Islands Different islands have animals with slight variations No animals like finches anywhere else Europe The finches of the island resembled the birds of South Americas mainland The populations adapted slightly from their new environment from the mainland to the island CHARLES DARWIN Artificial Selection- the process of directing breeding to produce offspring with desired traits Looked at pigeons due to exaggerated features such as tail shape Ex: Dogs Allows for slow accumulated changes, but humans select which traits will reach the next generation BREEDING The mechanism by which evolution works Darwin was influenced by Malthus Competition for food would limit the population of humans Competition for resources drives natural selection As organisms compete for resources, the animals with traits equipped for survival live to reproduce The traits that are helpful for survival have a higher likelihood of staying NATURAL SELECTION Principles of natural selection: Individuals show variation Variations are heritable More offspring are born than can survive Variations that increase reproductive success will be more common in the next generation FOUR PRINCIPALS OF NATURAL SELECTION Darwin published On the Origin of Species by Means of Natural Selection in Today, scientists use evolution to mean cumulative change in a group of organisms through time. Evolution is NOT the process of an organism acquiring traits Natural selection is not synonymous with evolution it is a mechanism by which evolution occurs. THE ORIGIN OF SPECIES 1840 Darwin had formulated the Hypothesis But he hadnt published it yet 1858 Alfred Russel Wallace Summarized Natural Selection in Origins of species 1859 Darwin published On the Origins of Species Main point was about Natural Selection Only used evolution on the last page Evolution is used to define cumulative changes in groups of organisms through natural selection EVOLUTION Chapter 15 SECTION 2 EVIDENCE OF EVOLUTION Evidence comes from fossils Comparison of fossils to current species Ancestral traits- primitive traits that appear in the ancestral form Derived traits- new traits that do not appear in the fossils of common ancestors EVIDENCE OF EVOLUTION Homologous Structures Anatomically similar structures inherited from a common ancestor Similar looking structures are more likely to be inherited from a common ancestor Similar construction May not have the same function COMPARATIVE ANATOMY Vestigial Structures Structures that are reduced forms of functional structures in other organisms Features that no longer serve a function will become smaller over time until they disappear Ex: Whales have a vestigial hip bone that is leftover from the evolution from a four limbed animal COMPARATIVE ANATOMY Analogous Structures Structures that can be used for the same purpose and can be superficially similar but are not inherited from a common ancestor Functionally similar structures can evolve independently in similar environments COMPARATIVE ANATOMY Embryo: an early, pre-birth stage of an organisms development Vertebrate embryos exhibit homologous structures but become functionally different structures in the adult form Pharyngeal pouches are similar in birds, fish and mammal Fish it becomes gills Reptiles, birds and mammals it becomes part of the head or neck Shows common ancestry COMPARATIVE EMBRYOLOGY Similar DNA and RNA sequences for species that are closely related The more closely related the animal the closer the common ancestor Cytochrome C- an enzyme needed for cellular respiration Highly conserved Slight variations in its amino acid sequences, but the overall molecules is relatively the same COMPARATIVE BIOCHEMISTRY Animals on that are closer together geographically, the more closely related they are in ancestry Ex: Mara and a Rabbit Although they both inhabit a similar niche, they are not closely related GEOGRAPHICAL DISTRIBUTION Biogeography is the study of the distribution of plants and animals around the world. Evolution is linked with CLIMATE and GEOLOGICAL FORCES such as Plate Tectonics Plate Tectonics explain some ancestral relationships and geographic distributions BIOGEOGRAPHY Fitness A measure of the relative contribution that an individual trait makes to the next generation The number of reproductively viable offspring that an organism produces in the next generation ADAPTATIONS Adaptation to blend in with the environment Allows an organism to become invisible to predators CAMOUFLAGE When one species evolves to resemble another species Ex: Coral Snakes and King Snake MIMICRY Antibiotic resistant bacteria Bacteria that is not killed by antibiotics ANTIMICROBIAL RESISTANT Example Humans Babies cannot defend themselves and need help from their parents for a long time This is due to the fact that we have large brains and walk upright To walk upright we need narrow pelvises But a babies head must be small enough to fit through a small pelvis SO Baby brains are small and need a lot of time to grow in order for large brains to be advantageous CONSEQUENCES OF ADAPTATIONS