Biological Interactions and the Distribution of Life con’t January 28 th, 2014

Mimicry Mimicry – form of biological interaction in which one species evolves the appearance or behavior of another species Batesian mimicry – one species that is not poisonous or unpalatable has the same coloring or shape as a species that is

Batesian mimicry

Mullerian Mimicry Dendrobates spp.

Aggressive Mimicry Ladybird spider

Automimicry Red mason bees

Disturbance

Disturbance – short-term physical or biological events that significantly alter ecosystems OR, any relatively discrete event in time that disrupts ecosystem, community, or population structure and changes resources, substrate availability, or the physical environment Fire, wind, landslide, floods, ice, avalanche, volcano, pests/disease, humans

Jack Pine (Pinus banksiana)

Fire Every ecosystem on the planet has a natural fire return interval → –Chaparral – 3 to 5 years –Southern yellow pine – 5 to 15 years –Grasslands, cool deserts – 10 to 20 years –Mixed conifer-oak forest – 60 to 75 years –Deciduous forest, Temperate rainforest, Boreal forest – 100 years –Warm desert, Wetlands– 100 to 200 years –Rainforest – 800 years –Tundra – 1000 years

Fire Southern pines evolved to be fire dependent during the last ice age Humans arrived 10,000 BC Native Americans burned: –To prevent catastrophic fires –Eliminate underbrush –Hunting purposes –Religious purposes –Control mosquitoes and snakes near villages

Disturbance Colorado

Wind Fires impact surface vegetation, wind impacts canopy Important in temperate forests, tropical forest, high-elevation forests, at forest edge, and trees on shallow soil Fell old and senescent trees Tree-fall gaps (aka canopy gaps) – when one or more trees fall from the canopy due to senescence, disease, lightning, wind

Tree Gaps Gaps in the canopy create very different microhabitats than those under a canopy Frequency of gaps depends on species, local disturbances, topography, soil

Gap Dynamics Gap Dynamics – cyclic changes in plant distributions involving tree falls and subsequent filling in of gaps in the forest canopy that tree falls create What happens when a gap forms?

Flood Flood – high flow of water that overtops the normal confinements and covers land that is normally dry River and lake flooding Flash floods Coastal floods

Pathogens Pathogen - a biological agent that causes disease or illness to its host Hemlock wooly adelgid Introduced from east Asia in 1920s