Evolution Test 1 Study guide Lecture 1 Evolution Evolution is the central unifying concept in biology o Descent with modification Pattern History all species evolved from a common ancestor and Process change within species Lecture 2 Evidence for testing evolution Evidence cid 0 observations that can disprove one or more hypotheses The standard theory of evolution single origination is just one of many possible models Species share virtually every feature with other species especially fundamental features of organization cid 0 homology Repeated concordance among data sets are powerful tests of evolution Evidence of change through time o Theory of special creation cid 224 species once created are immutable Claim was challenged by several lines of evidence supporting the fact that populations change over time Vestigial organs o Vestigial structures cid 224 useless or rudimentary version of a body part that has an important function in other closely allied species Interpreted by theory of evolution Evidence of descent with modification o Evidence shows that species change over time on a small microevolutionary scale when looking at bugs evolving with shorter breaks o Also can evolve on a larger scale when looking at birds evolving form dinosaurs Evidence of common ancestry o Darwin s theory of life history holds that species are not independent but connected by descent from a shared ancestor Species have genealogical relationships analogous to family trees Models of the history of life of individual humans o There are many possible models for the history of life ranging from single origins panspermia standard evolutionary theory to billions or trillions of originations spontaneous generation Each makes some predictions about pattern that can be tested o Evidence Not from perfect function o Homology cid 224 structural similarity in parts shared among species o o o What does evolutionary theory predict basis for all comparative biology evidence of common ancestry because of a process of common inheritance Groups of species sharing a homologous trait will share more homologous traits in common than expected by chance or alternatively homologies will not yield incompatible groups o homologies are not random among species but grouped or nested o Examples tetrapod limbs identical parts in same numbers and positions with respect to other parts Orchids 3 sepals 3 petals middle petal modified male and females parts fused inferior ovary o functionally unimportant parts are consistently shared with related species vestigial organs processed pseudogenes non functional copies of genes genetic code o Thus we see species are built using the same parts as related species whether they are optimal or not and more fundamental aspects are shared more broadly Fossil record one source of evidence for the historical sequences of events o o Evidence from the fossil record o Fossil cid 224 trace of any organism that lived in the past o Fossil record cid 224 total worldwide collection scattered among thousands of different institutions and individuals stratigraphic sequence of fossil species is nearly the same throughout the world features transform through time same sequence in geologic time as in development Transitions through time Mammalian inner ear birds Special example Transformation of jaw articulation from non mammal to mammals 1 Non mammal forms had jaw joint articulation between the articular and the quadrate 2 Some Cynodonts early mammal ancestors relatives exhibit a transitional double jaw articulation between articular and quadrate AND between dentary condyloid process and squamosal Modern mammals have only the dentary squamosal articulation 3 o The articular and quadrate are now the malleus and incus and are involved in hearing 4 Supported not only paleontologically but also embryologically Correspondence to phylogenetic sequence based on living species absolute and relative dates radionucleotide dating corroborates stratigraphy What does evolution predict and what are alternatives Biogeography species sharing structural homologies tend to live near each other Many Hawaiian groups fruitflies spiders silverswords Darwin s finches and giant tortoises on Galapagos Malagasy rats Functionally similar species often do not live near each other relationship is more important Fish eating rats live near relatives not unrelated fish eating rats What does evolution predict and what are alternatives Phylogenetic concordance independent data sets yield the same hypothesis of relationships I use this to test evolution almost every day o Example the flightless ratite birds and the flying tinamous What does evolution predict and what are alternatives Selection and response observed Soapberry bugs and see Selection lectures Speciation observed New species have been observed to evolve in a short time o Three spine stickleback fish Pacific northwest lakes 10 000 years o Reintroduced salmon 50 years o Fruit flies in the lab 6 months o Fossil transition sequences e g Yellowstone diatoms oceanic foraminfera o We can only see a small slice of the speciation process because we have only been looking closely for the last 50 100 years Poor design selection can only optimize a feature that it has to work with with occasional new features often selection works with suboptimal features Many cases of poor design may be due to constraints aspects of the genetic or developmental program or manner of construction that preclude certain traits from evolving o Giraffe neck circulation stapedial artery in mammals passes through middle of stapes in inner ear Summary the proof is in the trash best evidence is found in the functionally unimportant details Drawing from his own work and that of others Darwin marshaled evidence that the pattern of life s history is different than is claimed by special creation o First species change over time o Second species are not derived independently but from common shared ancestors He stated that probably all organic beings which have ever lived on earth have descended from some on primordial form into which life first breathed o Lamarck advanced the notion that all species including humans are derived by gradual evolution from other species cid 224 driven by inheritance of acquired characteristics and by an inherent tendency for all organisms to progress from simple to complex form He suggested they are continuously replenished by spontaneous generation from nonliving matter o Darwin convinced