1 Biology 106 Outline EXAM 1 Ecological niche can be abiotic and biotic factors role food where it lives what it does environment can be organism or resource Fundamental niche Realized niche where it can live ideal suitable habitat and conditions where it does live smaller populations limitations because of competition and dispersal effectively because of lack cost of limiting resource usually only one factors that limit use of other resources which cannot be used ghost of competition s past reduces competition between species Resource partitioning Limiting resources Population group of same species that lives in the same area breed compete Density number of individuals per area volume how many can count or estimate mark recapture method Emigration Migration old individuals leave population new individuals enter population Dispersion how they are spaced organized pattern Clumped Uniform group together patches usually for defense or resources evenly spaced Territoriality individual defends own physical space no pattern unpredictable independent Random Demographics study of statistics of populations and change overtime summaries of population s survival patterns d b life expectancy group of individuals same age life followed from birth to death graph represents life table data plot number of individuals alive in Life tables Cohort Survivorship curves cohort at each age I low d early high d late humans K selected low fecundity high survivorship I II constant III high d early low d late sea life R selected high fecundity low survivorship III Reproductive tables reproductive rates fertility schedule female cohorts age specific summary of Exponential Model population growth in ideal unlimited environment Short term Density independent r doesn t depend on N Per capita birth death rate individual female Equations B bN b d number of individuals produced per unit time by average 2 B number of births D dN D number of deaths r b d r per capita growth rate N t B D Zero population growth Population growth rate r 0 b and d are equal Additions bN Losses dN Change bN dN b d N Nr dN dt when N 0 r max most resources available migrate in rmax max per capita growth rate ideal conditions high b low d r actual per capita growth rate r rmax can be negative dN dt rmaxN or rN Logistic Model population grows slowly near carrying capacity Per capita rate of increase approaches zero as k is reached Ideal Density dependent Carrying capacity dN dt rmaxN K N K or rmax K N K K N K is unused space r gets smaller with higher densities more d less b Intraspecific competition increases overtime k max pop size an environment can withhold sustain Competition abundance and distribution of biotic resources affect where a species can live K 2 ideal harvest difficult to tell because k frequently changes Density dependent factors Competitive exclusion principle 2 species cannot coexist if one have competitive as N increases b decreases stress competition space or d increases predation starvation disease stress advantage at obtaining shared resources MUST share same niche and limiting resources interspecific Must specialize or die Interspecific affects realized niche reduces Intraspecific doesn t affect niche Interspecific changes overtime can affect fundamental niche gets resource first differential abilities to use extract resource directly affects other s ability to get resource Exploitation Interference Symbiosis when 2 individuals of 2 species live in direct intimate long term contact with each other 3 Parasitism not always fatal long term many parasites on one host one benefits at expense of another derives nourishment from host includes diseases ex mosquito Parasitoid specialists lay eggs on in host offspring eat host fatal best bio control agent super parasite Predation Mutualism both organisms benefit coevolution fatal short term 1 predator kills many prey Hyperparasitism parasite of a parasite Herbivore organism eats entire plant predator eats part of plant parasite Obligate at least 1 species cannot survive without the other Facultative both species can survive on own without living in same direct intimate contact biological control agent 0 benefits one but neither harms nor helps the other eat anything omnivores between two above Commensalism Facilitation Generalists Trade off Specialists eat certain things only certain group for competition invasive species species have positive effects on survival and reproduction of other species soil around plant roots has complex root secretions and microbial products Plant Relationships Rhizobacteria Rhizosphere soil bacteria in rhizosphere Chemicals produced to stimulate plant growth Make antibiotics Absorb toxins Nitrogen cycle Ammonifying bacteria Nitrogen fixing bacteria Nitrogen fixation Crop rotation between legumes and non legumes can restore nitrogen concentration bacteria N2 fixation NH3 mutualism Rhizobium monoculture change Mychorrhizae fungi mutualism with plant roots host gives fungus sugar and fungus gives plant more water and minerals antibiotics and stimulates growth with chemicals proportion each species represents of all individuals in a community community s tendency to reach and maintain constant composition of species Diversity variety of different species in a community number of different species in community Species richness Relative abundance Stability Climax community Disturbance changes a community removes organisms alters resources species function as integrated unit Non equilibrium model event storm natural disaster drought overgrazing human activity that communities constantly change after being affect by disturbance 4 moderate levels of disturbance foster greater species disturbed area is colonized by variety of species replace each Ecological succession Intermediate disturbance theory diversity than low high levels open up habitats other Primary lifeless area no soil volcano glacier Secondary existing community cleared soil intact fire Trophic structure feeding relationships between organisms energy passed up levels transfer food energy up trophic levels interconnected feeding relationships in ecosystem length of food chain is limited by inefficiency of energy transfer total mass of individuals in a pop Food chain Food web Energetic hypothesis Biomass Dynamic stability hypothesis Dominant species longer higher photosynthetic production superior avoids predation disease Keystone species Ecosystem engineer Bottom up model Top down model
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