Ecology Study Guide Exam 1 EVOLUTION Nothing in biology makes sense except in the light of evolution Theodosius Dobzhansky Evolution Microevolution descent with modification o Selection acts on individuals evolutionary change in the traits of individuals population Macroevolution Evolution has nothing to do with religion evolutionary change leads to the formation of new species o Evolution pertains to how life changed once it was on Earth o Creationists care about how life occurred on Earth o Accepting G d and accepting evolution can go hand in hand Birth of Evolution o Erasmus Darwin came up with the idea of evolution Darwin s grandfather o Charles Darwin thought of the theory of natural selection Darwin was the captain s social companion on HMS Beagle as well as the a natural historian Darwin noticed incredible variation on the Galapagos Finches many species each with specialized lifestyles Variability led Darwin to question fixation of species o Alfred Wallace in Malaysia Individually thought of natural selection identical to Darwin s Lyell T H Huxley received Wallace s manuscript promoted Darwin instead and pushed him to publish 1st VP VG VE VG E o VP variation o VG genetic component o VE environmental component o VG E genetic component based on the environment Genetic expression is connected to the environment Natural Selection Natural Selection primary force driving adaptive evolution which requires 1 Variation among individuals 2 Populations produce excess offspring Malthus Essay on Populations 3 Not all offspring survive and reproduce 4 Those that are best adapted to obtain limited resources will survive and reproduce 5 Beneficial traits are heritable Biston betularia peppered moth in UK o Typica white moth o Carbonaria black moth o Coal burning of industrial evolution led to lots of pollution soot killed o Hypothesis by E B Ford H B D Kettelwell black moths were cryptic lichens on soot covered tree trunks o Adaptation is wing color o Wing color can affect thermal physiology affects performance Black moths absorb heat faster and can therefore get warm Peter Boag Peter and Rosemary Grant 1981 quickly allowing them to forage first o Weather changes associated with El Ni o trade winds move East to West because of the high pressure on the East and low pressure in the West 1850 1950 2000 I R Loss of pollution foraging success Used as fertilizer Excrete Guano Big Fish Sea birds Anchovies Phytoplankton Water also goes South to North Happens once in a while Coriolis Effect causes water in the Pacific to move counterclockwise and the water in the Atlantic to move clockwise based on the Earth s rotation cold and nutrient rich water allows for phytoplankton Phytoplankton Water height increases in Indonesia by 40 cm Upwelling growth which provides O2 causing Kelvin waves which brings Indonesia s warm water towards South America El Ni o causes the pressures and wind to switch to West to East single celled algae at the bottom of the food chain o Warm water layer thickens and the cold nutrient water can t reach the sunlight phytoplankton can t thrive entire ecosystem suffers o Peru has major flooding and Galapagos has a drought o Geospiza fortis birds Banded 1500 birds Monitored survival feeding food availability seeds rainfall o Early 1970s normal rainfall 1976 127 mm 1977 24 mm El Ni o year 1978 137 mm o No breeding in 1977 85 decline in population size Nestlings banded in 1976 only 1 of 388 banded survived until 1978 very low I I I I I I I I I o Normal rainfall variation in seed size and hardness o Drought conditions plants that produce small and soft seeds aren t drought tolerant only large and hard seeds available less variation o Birds with small beaks were digging into the soil for small seeds causes balding affects thermoregulation speeds up starvation potentially causes death o There s no 1 gene for bill size but 76 of variation in morphological characteristics in G fortis is x mean heritable o Meets all 5 factors necessary for natural selection o O Donald s w measure of selection intensity Weight 0 49 depth 0 44 o Herman Carey Bumpus 1899 W 0 25 p i h s r o v i v r u S o Directional Selection acts one 1 extreme or the other Doesn t act on trait variance Variance doesn t change Mean shifts could shift in either direction Type of selection that caused change in bill depth Bill Depth t i a r T Normal Post Selection Seeley 1986 o Carcinus maenus predatory green crab sensitive to cold water Before 1900 not present in New England limited to Europe Ship s ballast water 1 transmitter of invasive species used to balance a cargo less ship Historical gradient in invasion history which corresponds with geography longitudinal selection gradient Southern Gulf the crab has been around for 110 years and Northern Gulf the crab has been around for 60 70 years Traits 1 Shell thickness 2 Spire height long spire less sturdy less overlap thinner Both traits influence snail vulnerability to predation Crab predation as an agent of selection of Littorina obstusata 1 Looked at shell samples from museums before the invasion pre 1900 2 collected contemporary specimens in the mid 1980s The 2 traits aren t equally selected for shell thickness is closer to survivorship than spire length Habitat type needs to be consistent High spired populations North in Timber Cove low spired intermediate in Gleason Point No record of differential mortality I o I o I o I o I o I o I o I o Tethering Experiment o o o o o o o o o o o o o o o o Trade off trading one thing for another E g why not have all thick low spired shells Low spire thick shell Costs transportation costs triple with every doubling of body weight Palmer 1988 architectural constraint less internal volume Benefits protection from predators High spire thin shell Costs bad protection against crabs physically Benefits can run and hide from crabs with greater ease o Evolutionary associations evolutionary arms race more internal volume Smith Palmer 1994 Snail shells thicken crabs get stronger thicker shells etc Example crabs claw strength increases when fed with well armored or thick shelled diets within 1 generation within generation change in phenotype in response presence of a predator induces a change in its adaptation is retained throughout an organism s Reproduction is a positive function of body mass o Phenotypic plasticity to an environmental cue Inducible defenses prey s phenotype o Ancestral character state evolutionary history Trussell 1996 Seawater