Interaction between Species A closer look…

First, a review  What is carrying capacity? How big a population can get while still being supported, having enough resources How big a population can get while still being supported, having enough resources  How can you increase carrying capacity? Altering ecosystem so more energy, resources are available Altering ecosystem so more energy, resources are available Altering behaviour Altering behaviour

Copy this down  Humans have altered the ecosystems that support us, so the carrying capacity is high  But, modern human societies are still subject to the ecological principle of carrying capacity  Human growth has rapidly accelerated over the past 400 years With a current doubling time of less than 1 human lifetime With a current doubling time of less than 1 human lifetime

Human Population Growth

Ecological Footprint DDDDef: an estimate of how much land and water required to support someone’s lifestyle WWWWhat is your ecological footprint? Mine is 6

Urban Sprawl  A city’s growth as it’s population increases More and more development on the ‘outskirts’ of a city More and more development on the ‘outskirts’ of a city

The Golden Horseshoe West end of Lake Ontario

Interaction Among Species  Resources and abiotic factors are not the only influences on a population  Organisms interact with each other too

Ecological Niche  Species focus on 1. Surviving 2. Reproducing  They do not have jobs, but they do contribute a ‘role’ Provide benefits to the ecosystem Provide benefits to the ecosystem  Def: the role an organism plays within its ecosystem (biotic and abiotic factors)

Ecological Niche  Sample niches Regulation of a population (like insects) Regulation of a population (like insects) Decomposition of dead matter Decomposition of dead matter Cycling of matter Cycling of matter  There are millions of spots on Earth  There are millions of niches too

Carnivorous Plants

Predation and Population Size  Predators and prey influence one another in 2 ways 1. Bottom-up population regulation 2. Top-down population regulation #1

Bottom-up population regulation  Grasshoppers eat grass; shrews eat grasshoppers  Grass  Grasshopper  Shrew  If the grasshoppers eat too much grass, population could decrease due to lack of food.  If the population of grasshoppers decreases, there is not enough food for shrews  their population decreases

Bottom-up population regulation  This is called… … because there is a shortage in the plant resource at the base of the food chain which affects animals in higher trophic levels

Top-down population regulation  Now consider this… What if the population of rabbits increases? What if the population of rabbits increases?  With more rabbits to eat, coyote population increases  But with more coyotes eating rabbits, the rabbit population will decrease  This is top-down regulation because a higher (top) trophic level organism influences the population of a lower trophic level (eventually the # of coyotes would decrease too) (eventually the # of coyotes would decrease too)

Competition  As the population of a species increases, so does the competition for resources Can limit population size Can limit population size The more energy an organism spends competing, the less energy it has for growth and reproduction The more energy an organism spends competing, the less energy it has for growth and reproduction #2

Symbiosis  The interaction between members of 2 different species that live together in close association  2 types of symbiosis 1. Mutualism 2. Parasitism #3

Mutualism  Def: symbiotic relationship between 2 species where both benefit Ex: clownfish and anemones Ex: clownfish and anemones In symbiotic mutualism, the clownfish feed on small invertebrates which otherwise could potentially harm the sea anemone, and the fecal matter from the clownfish provides nutrients to the sea anemone. The clownfish is additionally protected from predators by the anemone's stinging cells, to which the clownfish is immune. clownfishsea anemone

Parasitism  Def: symbiotic relationship between 2 species where 1 organism (parasite) depends on another larger organism (host) Frequently the parasite benefits at the host’s expense Frequently the parasite benefits at the host’s expense These primitive fish attach to the bodies of native fish and feed on the fish's body fluids. This often leads to the death of the native fish. Species at risk in the Great Lakes include prized commercial and recreational species such as lake trout, salmon, rainbow trout (steelhead), whitefish, walleye and catfish.

Brain Worm 1. Worm lays eggs in brain 2. Eggs travel to lungs and hatch 3. Larval worms excreted 4. Eaten by slugs 5. Eaten by deer  White-tailed deer aren’t affected Brain-worm cycle successful Brain-worm cycle successful  Other animals are very vulnerable Moose disease Moose disease Sheep Sheep Elk Elk Caribou Caribou

Human Parasitism A 28-year-old medical resident and a companion returned from hiking in Central America with pruritic, erythematous, single-track linear and serpiginous lesions located predominantly on their lower extremities. A physician clinically examined the skin disorder and diagnosed the two patients with cutaneous larva migrans after learning that they had been walking barefoot on the beach during their vacation. Cutaneous larva migrans (CLM) was first described as "the creeping eruption" and diagnosed by a physician in Today, it is one of the most common hookworm infections acquired from subtropical and tropical regions of the world.