Study Guide Chapters 16 26 27 28 Bobbie Alexis Shuttle I Chapter 16 Biological Species Concept a groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups LIMITATIONS Cannot determine species identity when organisms reproduce asexually or when looking at fossils It is also difficult to tell whether or not members of different groups are interbreeding i Phylogenetic Species Concept defines a species as the smallest group of individuals that share a common ancestor Speciation due to Isolation i Gene flow is blocked ii Genetic Divergence Genetic differences are formed among isolated populations preventing interbreeding Differences are either by chance or natural selection Allopatric Speciation Species are geographically separated Ex colonization of mainland species on isolated island Sympatric Speciation Species are isolated ecologically without geographic isolation Ex restricted to different habitats Character Displacement The tendency for characteristics to be more divergent in sympatric populations than in allopatric populations It is driven by competition of species Adaptive Radiation is when there are different adaptations for different niches within a population in an ecosystem i Occurs when population of one species invades a variety of new habitats Ex Finch colonization of Galapagos Islands Cichild fish colonization of Lake Malawi FACTORS LEADING TO EXTINXTION Localized Distribution Affected by environmental changes easier Over specialization Have to live in a specific environment and are at a higher risk of i i i ii becoming extinct iii Competition Among Species The higher the competition rate the less of each needed resource the members can get II Chapter 26 Biotic Potential is the maximum rate at which a population could increase given maximal birth rate b and minimal death rate d i What it is influenced by 1 Age at which organism first reproduces 2 How often reproduction occurs 3 Average number of offspring 4 5 Death rate of individuals in population Individual lifespan ii Environmental resistance places limits on growth potential by setting limitations of living or nonliving populations within an environment that decrease the birthrate and increase the death rate such as predation food or competition Exponential Growth population continuously grows a fixed percentage of its size each time period Temporary exponential growth occurs when food supply increases or predators are reduced Logistic Growth when reproduction growth of a population slows due to a decrease in available resources Boom and Bust Cycle is when there is a rapid growth and the massive die off within a population The Carrying Capacity is defined by what the maximum population size an ecosystem can sustain for extended time WITHOUT damaging the ecosystem If a population goes over the carrying capacity they will damage the environment and eventually cause a decrease in the population number Density Independent Factors limit the populations no matter what the density is they do not depend on the population density because they are usually natural events occurring in the environment that cannot be controlled Density Dependent Factors i Predation predator kills a prey in order to eat it ii Parasitism a parasite lives on or in a host feeding on them but usually not directly killing it iii Competition 1 2 Interspecific between different species Intraspecific within the SAME species a Scramble Competition free for all individuals fight for limited resources b Contest Social animals or chemical plants interactions limit access to important resources Population Distribution i Clumped includes family and social groups 1 Advantages more to search for localized food large numbers confuse predators group hunting is more effective ii Uniform Distribution Constant distance maintained between individuals territorial 1 Advantage helps ensure resources for each individual iii Random Distribution individuals do NOT for social groups Usually occurs in vegetation Human impact on Carrying Capacity i Manipulates environment to increase Earth s carrying capacity through technical and Cultural Revolution agricultural developments and medical advancements Demographic Transition Developed countries have experienced an increase in population that eventually stabilized Replacement Level Fertility is when a populations stabilizes because the adults have enough children to replace them Age Structure Diagrams i Expanding has a wide base due to more children than adults ii Stable relatively even because there are just enough children to replace adults iii Shrinking Reproductive aged adults have fewer children than thy need to replace themselves resulting in narrow base and wider middle III Chapter 27 Coevolution occurs when two species share a close interaction and influence each other evolutionary adaptations i EX Predator Prey Ecological Niche defines a place and role of each species in an ecosystem What is the competitive exclusion principle i States that no two species can inhabit the exact same ecological niche at the same time and continuously Resource Partitioning when two species with similar needs coexist they will both occupy a smaller niche than they usually would It reduces interspecific competition Camouflage renders animals inconspicuous even when in plain sight using evolved colors patterns and shapes to blend into surrounding background Aposematic warning coloration attracts attention of predators advertises that they are either poisonous or distasteful i Ex poison arrow frogs coral snakes yellow jackets Mullerian Mimicry two or more distasteful species may each benefit from a shared warning coloration pattern meaning that once a predator experiences one distasteful species they avoid all others that look similar Batesian Mimicry Harmless prey organisms resemble poisonous species to trick i Bees hornets yellow jackets predators i Hoverfly resembles bee Startle Coloration have spots that resemble large eyes or spots Predatory Aggressive Mimicry predator resembles harmless animal to lure prey i False eyed frog in i Frogfish dangles a false wriggling lure to attract fish Symbiotic Relationships i Commensalism one species benefits and the other is unaffected 1 Ex barnacles on whales ii Parasitism parasite benefits while host is harmed 1 Ex tapeworm iii Mutualism both species benefits 1 Algae and fungi Keystone Species Species that plays a major role in how