Ecology Exam 3 – Resource Partitioning – Flashcards

ways in which species differ in their use of resources

1. food: size, hardness, and type 2. space (or habitat) -broad (macrohabitat): organisms live in different vegetation types EX: siberian tiger and sumatran tiger -narrow (microhabitat): organisms live in the same vegetation type but eat different places within the habitat EX: some anolis lizards feed on the ground and some feed on trees 3. time -daily: when organisms eat during the day (nocturnal, diurnal) -seasonal: when organisms eat during the year (spring, summer, fall)

the set of environmental conditions within which an organism can maintain a viable population -multidimensional EX: humans = an optimal temperature, humidity, etc.

maps an organisms resource use in several different axes and generates a frequency distribution approximated by a smooth curve 2 types: 1) macarthur and levins = two dimensional plot (resource utilization distribution) EX: frequency by seed size 2) hutchinson = multidimensional plot (AKA n-dimensional hypervolume) EX: food size, temperature, moisture

the total range of environmental conditions that are suitable for existence in the absence of interspecific competition, predator or other interspecific reactions

the part of the fundamental nice actually occupied in the presence of interspecific competition, predation, and other interspecific interactions -smaller than fundamental niche because the biotic entities decrease the number (exception = mutualism) EX: chthamalus barnacle is restricted to realized niche (high intertidal) by competition with balanus barnacle.

the different between fundamental and realized niche

species similar in resource use (i.e. with identical niches) cannot coexist

-ashmole experiences resource partitioning by prety size. Species different in beak size and in body size, the bigger the beak, the bigger the prey. -warblers experience resource partitioning by their microhabitat the conifer tree. The species has very similar beak and body sizes. Even though they appear very similar, different warbler species forage in different parts of the tree -conus mollusks experience resource partitioning by prey type and microhabitat. The mollusks stab their prey with their radula, inject toxins and eat it. Many different species coexist together. Some specialize in a few prey types, other species feed in subtidal vs intertidal. -poison arrow dart frog experiences resource partitioning by prey taxon and food size. The species differ in body sizes and prey types. The bigger frogs eat the bigger prey. Some frogs specialize on ants, other on grasshopper, etc. There are more than one type that specializes on ants, but they eat different size ants.

show resource partitioning by macrohabitat, microhabitat, and food size -different species in the rainforest, scrubby forest, and desert -different species inhabit tree crowns, tree trunks, and ground habitats. Twig dwellers= small lizards and short legs (can't be big and overweigh the twig - body adapts to its niche) -there are also giant anolis species in all of these habitats that specializes in much large prey.

that degree of similarity in resource use that just allows coexistance; any greater similarity would result in one of the species becoming extinct. -measured in units of d/w (it is dimensionless) - d is the distance between the means of the curves -w is the standard deviation, or niche width, roughly the distance from the middle to the side at the inflection point, tells us how "fat" the curves are. A large w means generalist species and a small w means a specialist species. -intraspecific competition tends to increase niche width while interspecific competition decreases niche width

distance between the means of the curves

the standard deviation, or niche width, roughly the distance from the middle to the side at the inflection point, tells us how fat the curves are.

there are certain common resources that everyone needs -if you spread completely apart and there is no overlap another species will get that resource -the balance reflects intra vs. interspecific competition

the bigger the area under the overlap, the bigger the α -overlap is small = more different than limiting similarity d/w >1 -overlap is medium sized = limiting similarity d/w ~ 1 -overlap is large = no coexistance: species are too similar, tend to see competitive exclusion d/w < 1 -the higher the d/w the less the species compete.

1) competitive extinction 2) co-evolution

if species are too similar, one drives the other to extinction

species are initially very similar to each other, but diverge over evolutionary time (thereby reducing similarity)

a shift in the characteristic of a species in an area where there is competition -species are more different from each other when in sympatry (i.e., when geographic ranges overlap, they look different in the same region) than when in allopatry (i.e., no range overlap, look the same in different regions) -interspecific competition leads to character displacement EX: galapagos finches species have similar beak sizes when living alone, but beak sizes differ when living in the same are.

same region, but look different

different region, look the same