Introduction to Ecology Part II

Autotrophs vs Heterotrophs What is a producer – Autotrophs like plants, protists, and bacteria that make their own food What is a consumer: – Heterotrophs that cannot make their own food

Species Interactions Predation – An individual of one species eats all or part of an individual of another species – Predator – organism eating – Prey – organism being eaten

Species Interactions Predator Adaptations: – Neutral selection favors the evolution of predator adaptations for finding, capturing, and consuming prey Acute heat sensor to webs to camouflage hair to specialized teeth Ex 1: Rattlesnake have acute sense of smell and heat sensitive pits below their nostrils Ex 2: Sticky webs of spiders to flesh cutting teeth of wolves

Species Interactions Predator Adaptations cont. – Natural selection also favor prey to be able to avoid, escape, or ward off predators – Animal prey adaptations: Hide, camouflage, chemical defense, fake eyes and heads, bright colors, to mimic other dangerous animals – Plant prey adaptations: Defense includes: sharp, thorns, spines, sticky hairs, tough leaves, to being poisonous, irritating, or bad tasting.

Competition Interspecific competition: – Is a type of interaction in which two or more species use the same limited resources – Two populations competing for the same resource may end up reducing/eliminating one of the competitors

Competition cont. Competitive exclusion: – Is where one species uses the limited resources more efficiently than the other species does – Ex: Barnacles off the coast of Scottish coast between Chthamalus stellatus and Semibalanus balanoides The C. stellatus could live high and low on ‘shore rock” but due to competition S. Balanoides out competed it restricted the C. stellas to the upper portion of the shore rock

Symbiosis Symbiosis is a close, long-term relationship between two organisms There are three types of symbiotic relationships: – Parasitism – Mutualism – Commensalism

Symbiosis Parasitism: – In parasitism, the prey is called the host – Predator is called a parasite – One organism is harmed (host) while the other organisms benefit (parasite) – Usually does not result in host death Examples: Aphids, lice, leeches, fleas, ticks, and mosquitoes

Symbiosis Parasitism cont. – Ectoparasites: Live inside their hosts body Ex: Protists; tape, heart, round worms – Parasites have a negative impact on their host’s health – Host defense: Skin, tears, saliva, mucus membranes and the immune system

Symbiosis Mutualism: – Relationship where both (two) species have some benefit from each other – Pollination is the most important mutulistic relationship on Earth – Termites are able to digest cellulose due to a mutulistic protozoa called Trichonympha

Symbiosis Commensalism: – Is an interaction in which one species benefits and the other is not affected – Species that scavenges for leftover food items are often commensal species Best known examples are small tropical fishes in relation to sea anemones

Species Richness: Is the number of species or simple count of species in the community Each species contributes one count to the total regardless of whether the species’ population is one in 1 million

Species Richness Varies with latitude – the closer a community is to the equator the greater the number of species – Species is the greatest in the tropical rain forest Larger areas usually contains more species than smaller ones Species interaction also promotes species richness. (Competition can keep species from overcrowding other)

Succession Ecological succession is a gradual sequential growth of a community of species in an area

Succession Succession Primary Succession: – Development of a community in an area that has not supported life in the past – Bare rocks, sand dunes, or volcanic island – No soil present (can take 200+ years to reach vegetation)

Succession Succession Secondary Succession: – Sequential replacement of species that follows disruption of an existing community – Regrowth of organisms after a severe natural disaster (fire, tornado) or farming, logging, or mining – Soil already present (takes about 100 years)

Succession Pioneer Community: – A community that is actively undergoing succession – Not stable, still changing with time

Succession Climax Community: – A community that reaches a stable end point (redwood forest)