Transcript Document
Species Interactions Important in determining – • • • • population dynamics community composition landscape spatial pattern ecosystem function T. Kittel, W. Bowman Univ of Colorado General Categories Assigned by effect on the two individual organisms interacting: +, + = mutualism +, 0 = commensalism – , 0/+ = amensalism –, + = parasitism N2 fixation, mycorrhizae Nurse plants Allelopathy herbivory / predation –, – = competition Intra & interspecific Can be more complicated than direct interactions of 2 individuals mediated through a 3rd individual or species • soil microbes, herbivores influence competitive interactions A. Mutualism (+, +) Plant-Microbe • Mycorrhizae • N–fixation • Lichen Plant-Animal • Pollination Rhinoceros Hornbill eating Strangler Fig fruits, Borneo Mucuna holtonii, Central America • Insects • Birds • Hummingbirds • Bats • Fruit dispersal • Defense • Ants Azteca Ants on Cecropai, Panama Rufous Hummingbird “The Forgotten Pollinators” Lesser Long-nosed Bat Long–distance migratory pollinators • Threatened – habitat loss • Keystone species “Nectar corridors” • Sequence of flowering plants Monarch Butterfly White-winged Dove Arizona-Sonoran Desert Museum www.desertmuseum.org/pollination/ B. Commensalism (+,0) Plant-Plant 1) Vines 2) Epiphytes • Bromeliads • Orchids • Cacti • • • • Ferns Lichen Moss Algae moss v. lichen Atlantic Forest, Brazil Staghorn fern Exceptions – Mutualism – Lichen with cyanobacteria: N leaching, benefit to tree Epiphytic commensalism goes bad Detrimental overburden Competition • Strangulation • Overtopping Strangler fig Kudzu – “the vine that ate the south” • Introduced 1876 from Asia • Planted for soil conservation 1930’s Pueraria montana var. lobata Oriental Bittersweet • Vine, introduced from e. Asia • Invasion in eastern US Celastrus orbiculata A. Commensalism – continued 2) Nurse plants • Saguaros under Palo Verde • Desert annuals under shrubs • Piñon pine under Sagebrush Plant-animal commensalism – Habitat • • • • nesting roosting hunting for other animals shelter from other animals Red-footed Booby in Mangrove Galápagos Is. Oropendola nests, Roraima Brazil Iran Jaya's People of the Trees Titi monkey, São Paulo Brazil C. Amensalism (– , 0/+) Allelochemical Interactions • Plant–Plant • Allelopathy Larrea tridentata - Creosote Difficult to show in field • Plant–Animal • Herbivory defenses • Plant–Decomposer Big sagebrush with native bunchgrasses growing under canopy > Litter composition soil pH soil biota: Conifer low pH fungi favored, Temperate Deciduous neutral bacteria D. Parasitism (–,+) Dodder (Cuscuta) – • stem parasite • no chlorophyll = holoparasite Coral root orchid - Corallarhiza maculata root parasite on pines Arceuthobium americanum Carpellate plant on Pinus contorta Mistletoe – • stem parasite • differing degrees of chlorophyll • with chlorophyll = hemiparasite • w/o holoparasite Dwarf mistletoe – holoparasite Arceuthobium cyanocarpum Staminate plant (left) and carpellate plant (right) on Pinus ponderosa Broadleaf (Hairy) mistletoe - hemiparasite Phoradendron tomentosum on hackberry (Celtis laevigata), preferred host More hemiparasites: • Indian paintbrush – Castilleja spp. • Root parasite Inference of species interactions on the landscape • If species interactions are important to plant species – Should be reflected in the spatial patterns of individuals (inter and intraspecific) • if mutualisms among plant species occur, should be a positive association they should occur closer together (clumped) than predicted by chance (random) Landscape spatial patterning (con’t) • if amensalism occurs, should be pushed away from each other giving an even distribution Larrea tridentata - Creosote Landscape spatial patterning (con’t) • Under competition – competitive exclusion leads to • range separation • niche partitioning Non-overlapping geographic ranges of five species of large kangaroo rats Within–canopy distribution Amazonian tree – The long roots dangling from the crown probably belong to Philodendrons On the middle and upper branches cluster groups of orchids, bromeliads, and ferns – including staghorn fern on the trunk are Arums & Philodendrons with heart-shaped leaves Low Keystone species • Presence of a species determines community structure disproportionately to population size Summary – Species Interactions Plants and animals engaged in interactions with wide range of other taxa Positive, detrimental, or neutral effects of one species on another Reflected in spatial patterns – random vs. even vs. uniform Reflected in community structure – Keystone species