McMaster Bio 1M03 Exam Questions & Answer

what is a biological community? - Answer All of the populations of organisms living and interacting in a particular area commensalism - Answer interaction where one species benefits and the other is unaffected competition - Answer interaction where individuals use the same resources, lowering fitness for both -/- consumption - Answer interaction where one organism eats or absorbs nutrients from the other, +/- mutualism - Answer interaction where two species benefit +/+ three key themes in species interactions - Answer 1. Species interactions can affect the distribution and abundance of a particular species 2. Species act as agents of natural selection when they interact 3. The outcome of interactions among species is dynamic and conditional coevolution - Answer pattern of evolution where two species influence each other's adaptations over time intraspecific competition - Answer competition within a species Interspecific competition - Answer competition with individuals from different species (they are using the same limiting resources) symmetric competition - Answer overlap in niches results in reduced fitness for both species asymmetric competition - Answer when niches overlap, one species suffers greater reduction in fitness compared to the other species competitive exclusion principle - Answer two species that have the exact same niche cannot coexist fundamental niche - Answer total theoretical range of environmental conditions that a species can tolerate realized niche - Answer portion of the fundamental niche that a species actually occupies niche differentiation - Answer evolutionary change in resource use, caused by competition over generations character displacement - Answer evolutionary change in species traits that enables species to exploit different resources different types of consumption - Answer herbivory, predation, parasitism parasitism - Answer when a parasite consumes small amounts of tissue/nutrients from host endoparasites - Answer live inside host, usually simple worm-like bodies (tape worm) ectoparasites - Answer live on outside of host (like ticks) parasitoid - Answer free-living as adult, but parasitic as larva, often kills host parasitoidism - Answer when a parasitoid is free living adult but endoparasitic as a larva, usually fatal constitutive/standing defenses - Answer defenses that are always present Batesian mimicry - Answer harmless/palatable species resembles a dangerous/poisonous one Mullerian mimicry - Answer mimicry in which two or more harmful species resemble each other inducible defenses - Answer physical, chemical, or behavioral defensive traits that are induced in the prey in response to the presence of a predator how is consumption an agent of natural selection? - Answer it leads to a coevolutionary arms race between predator and prey that drives evolutionary change Four key attributes of community structure - Answer 1) the total number of species 2) the sum of interactions among all species 3) the relative abundance of those species 4) the physical attributes of the community, which may include abiotic factors and biotic factors food web - Answer overlapping food chains, summary of consumption interactions in a community bottom-up influences on community structure - Answer when abiotic factors determine the abundance of primary producers (nutrients, sunlight, water etc.) top-down influences on community structure - Answer when certain consumers change the species diversity in a community keystone species - Answer species with a greater influence on species diversity than its abundance and total biomass suggest example of top-down control - Answer when a consumer limits prey population trophic cascade - Answer series of changes in abundance of species in a food web, usually caused by the addition/removal of a key predator disturbance - Answer any strong, short-lived disruption to a community, changes the distribution of living/non-living resources examples of disturbances - Answer forest fires, windstorms, floods, fall of a large-canopy tree, disease epidemics, short-term explosions in herbivore numbers what do disturbances alter? - Answer light levels, nutrients, unoccupied space, and other aspects of resource availabiliy three factors contributing to the impact of a disturbance - Answer 1. the type of disturbance 2. its frequency 3. its severity disturbance regime - Answer the characteristic disturbances that affect a given ecological community succession - Answer recovery that follows a severe disturbance When does primary succession occur? - Answer happens when disturbance removes soil and its organisms as well as organisms that live above soil surface When does secondary succession occur? - Answer when a disturbance removes some or all the organisms from an area but leaes the soil intact which is more rapid, primary or secondary succession? - Answer secondary succession successional pathway - Answer specific sequence of species that appears over time species diversity - Answer weighted measure incorporating species' relative abundance species richness - Answer count of how many species are present in a given community behaviour - Answer action in response to a stimulus Behavioural ecology - Answer subset of organismal ecology, focuses on evolved responses to ecological selection pressures two types of biological causation - Answer proximate and ultimate proximate/mechanistic causation - Answer explains how actions occur ultimate/evolutionary causation - Answer explains why actions occur fixed action patterns - Answer highly inflexible, stereotyped behavior patterns innate behaviour - Answer behaviours that are inherited/require no learning migration - Answer long-distance movement of a population associated with a change of seasons kin selection - Answer natural selection that acts through benefits to relatives at the expense of the individual eusociality - Answer social structure where workers sacrifice most or all of direct reproduction to help rear the queen's offspring what is the Anthropocene marked by - Answer decline in biodiversity and ecosystem services we depend on what is the efficiency of biomass transfer from one trophic level to the next - Answer 10% why are larger mammals more efficient at producing biomass - Answer they have a smaller surface-area-to-volume ratio and lose less heat why is biomass production more efficient in ectotherms as compared to endotherms - Answer because ectotherms devote less energy to cellular respiration biomagnification - Answer accumulation of pollutants at higher levels in the food chain where is most groundwater stored? - Answer aquifers what are aquifers? - Answer layers of porous rock, sand, or gravel that are saturated with water when are aquifers considered closed - Answer when nonporous rock layers are on top of them when are aquifers considered open - Answer when they can be recharged by water percolating from the surface water table - Answer upper limit of underground layer of soil saturated with water when is nitrogen usable by organisms - Answer when it is fixed to ammonium or nitrate ions from atmospheric N2 what limits the primary productivity in terrestrial and aquatic ecosystems? - Answer nitrogen what is the main reservoir of phosphorus - Answer rock in the Earth's crust the three main interacting drivers of environmental change - Answer changes in land use, the rapid loss of species, global climate change global warming - Answer the increase in the average temperature of the planet global climate change - Answer the sum of all the changes in local temperature and precipitation patterns that result from global warming greenhouse gas effect - Answer CO2 and other greenhouse gases trap heat in Earth's atmosphere which wavelength of light gets trapped by greenhouse effect - Answer low-energy infrared/long-wavelength radiation how does climate change affect the water cycle - Answer rising temps change where, when and how much water falls as precipitation as well as how quickly it evaporates genetic diversity - Answer total genetic info contained within all individuals of a population/species/group of species what are the two reasons the efforts to catalogue genetic diversity has been advanced - Answer 1. ability to sequence the entire genome of multiple members of the same species 2. the research protocol: environmental sequencing environmental sequencing - Answer researchers take a sample from the soil or water present in a habitat and sequence all or most of the genes present why is genetic diversity important - Answer represents the adaptive capacity of a population/the ability for a group to persist over time despite changes in the environment how is species diversity quantified? - Answer species richness: how many species in an area, species diversity: relative abundance of each species present DNA barcoding - Answer use of well-characterized gene sequences to distinguish species taxonomic diversity - Answer lineages that are extremely species rich when functional diversity is a priority the preservation of what is important - Answer the preservation of species with unique ecological roles horizontal diversity - Answer Number of species at each trophic level vertical diversity - Answer number of trophic levels ecosystem diversity - Answer variety of biotic and abiotic components in a region ecosystem function - Answer sum of biological and chemical processes that are characteristic in a given ecosystem