Unit 4 Biological Population Dynamics Part I Species

Unit 4: Biological Population Dynamics Part I: Species Roles & Interactions AP Environmental Science Drusky Westlake High

What roles do species play in ecosystems? § Ecological Niche: § Each species plays a distinct role in the ecosystem where it is found § Includes everything that affects its survival and reproduction § § § How much water/sunlight it needs How much space it requires What temperatures it can tolerate § Habitat: § Place where a species lives in an ecosystem

Generalist vs. Specialist § Niches classify species as: § Generalists § Broad niches, can live in many different places, eat variety of foods, tolerate a wide range of environmental conditions. § Specialists § Occupy narrow niches § Specific living conditions must be met

Generalist Species

Generalist Species § Cockroach § § § § § 350 million years old (outlived dinosaurs) They have thrived because they are generalists 3, 500 species of roaches Eat almost anything including algae, dead insects, fingernail clippings, electrical cords, glue, soap Can live and breed anywhere except polar regions Can go 1 month without food and one drop of water One species can survive being frozen for 48 hours Each eye has 2, 000 lenses and can see all direction at the same time One roach can produce 10 million babies in a year. Important to food webs as a food source

Specialist Species § Tiger Salamander § Can only breed in fishless ponds where their larvae will not be eaten.

Specialist Species § Red-cockaded Woodpecker § Only carves nest holes in longleaf pines that are at least 75 years old.

Specialist Species § Giant Pandas § Feed exclusively on various types of bamboo.

Is it better to be a generalist or a specialist? § …It depends! § When environmental conditions are fairly constant (tropical rain forest), specialists have an advantage over generalists § Fewer competitors § When environmental conditions are rapidly changing, generalists usually are better off.

Species’ Roles § Niches can also be classified in terms of specific roles that certain species play within ecosystems. § Native § Nonnative § Indicator § Keystone § Foundation

Native Species § Species that normally live and thrive in a particular ecosystem

Nonnative Species § Species that migrate into or are deliberately or accidently introduced into an ecosystem § Also called “invasive”, “alien”, or “exotic” § Not always a bad thing § Chicken, cattle, & fish § Many can crowd out a community’s native species and cause unintended and unexpected results. § Can spread rapidly if they find a new more favorable niche. § Often don’t face predators or disease

Nonnative Species § African Bees: Imported by Brazil to help increase honey supply § Killed domesticated animals and humans

Nonnative Species § Burmese Python: Imported to Florida from Southeast Asia as a pet. § When owners realized they were not good pets, they dumped them in the Everglades § Currently expanding population, damaging ecosystem, and threatening human safety

Nonnative Species § Argentina Fire Ants § 1930 s: Introduced accidently in Mobile, AL § Arrived on shiploads of lumber § No natural predators, fire ants have spread rapidly by land water (they float) throughout the South. § When they invade, they wipe out 90% of native ant populations § Do an estimated $68, 000 of economic damage per hour to crops, phone, and power lines. § Pesticides have helped them by eliminating other ant species and promoting genetic resistance to pesticides through natural selection.

More Nonnative Species § Deliberately Introduced: § Nutria: Severe impact to wetlands of Mississippi Delta; Started with 20 in 1930; 20 million in 20 years § Cane Toad: 1935: 102 toads; Now over 200 million toads § Japanese Beetle § European Wild Boar (Feral Pig)

More Nonnative Species § Accidentally Introduced Species: § Sea Lamprey: Found in Great Lakes; Most likely in construction of Erie Canal § Common Pigeon § Formosan Termite: First seen in 1960 s Texas; From southeast Asia § Zebra Mussel: Arrived in 1988 in the Great Lakes; Carried on the hulls of ships § Asian Tiger Mosquito: Arrived in 1985 in Houston in a shipment of used tires § Over 7, 100 harmful invasive species have been introduced into the United States

Nonnative Species in ATL § Kudzu Vine § Promoted in 1920 s and 1930 s by the United States forage and erosion control. § Imported from China and Japan § Now covers 24 counties in Georgia and 7 million acres of the South § Overgrows and shades out trees § Grows up to 1 foot per day!

KUDZU

For a full list of Invasive Species in Georgia… § http: //www. defenders. org/publications/ge orgia. pdf

Indicator Species § Species that provide early warnings of damage to a community or ecosystem § Typical indicator species: § § § Birds Butterflies Amphibians § “Canary in a Coal Mine”: Coal miners used canaries to detect poison gas in the mines. No singing=time to leave the mine.

Why Are Amphibians Vanishing? § Amphibians (frogs, toads, salamanders) § Live part of their lives in water and part on land § Populations are declining worldwide § Difficulty in adapting to the rapid environmental changes in the air, water, and land § Habitat loss/fragmentation, prolonged drought, pollution, increased UV, parasites, viral and fungal diseases § Show us warning signs of declining environmental health

Importance of Amphibians § Adults play important ecological roles: § Eat more insects (like mosquitos) than birds do § Extinction of amphibian species could mean extinction for other species that feed on them § Amphibians are a genetic storehouse of pharmaceutical products waiting to be discovered § Ex: Secretions of compounds from their skin have been used as painkillers and antibiotics or treatments for burns and heart disease

Keystone Species § A keystone is a wedge-shaped stone placed at the top of a stone archway. § If this stone is removed, the arch collapses

Keystone Species § Have a large effect on types and abundances of other species in an ecosystem. § Roles: § Pollination of flowering plants (Bees, Butterflies, Hummingbirds, Bats) § Top Predators feed on and help regulate populations of other species (Alligators, wolf, leopards, lions, sharks)

Foundation Species § Shapes communities by creating and enhancing their habitats in ways that benefit other species. § Ex: Elephants push over, break, or uproot trees, creating forest openings for grasslands. This promotes growth of grasses that benefit smaller grazing species. § Ex: Beavers build dams that create ponds used by many other species

How Do Species Interact? § 5 basic types of interactions among species that share limited resources such as food, shelter, and space: § Interspecific Competition § Predation § Parasitism § Mutualism § Commensalism

Interspecific Competition § Most common interaction § Occurs when members of 2 or more species interact to gain access to same limited resources. § Ex: Humans compete with many other species for space, food, and other resources. § This competition often leads to adaptations to allow them to use shared resources

Predation § A member of one species (PREDATOR) feeds directly on all or part of a living organism of another plant or animal species (PREY) § The 2 species form a “Predator-Prey” Relationship § At population level, predation plays a role in evolution through natural selection § Predator kills sick, weak, aged and leaves behind individuals more fit for survival to reproduce.

Parasitism § Occurs when one species (PARASITE) feeds on the body of, or the energy used by, another organism (HOST), usually by living on or in the host. § The parasite benefits and the host is harmed § Can live inside (tapeworms) or outside of host (mosquitoes, lampreys)

Mutualism § 2 species behave in a way that benefits both by providing each with food, shelter, or some other resource. § Ex: Honeybees, caterpillars, butterflies, and other insects feed on a male flower’s nectar, picking up pollen in the process, and then pollinate female flowers when they feed on them. § Ex: Cleaner fish on Whales § Ex: Bacteria in Small Intestine

Commensalism § Interaction that benefits one species but has little or no effect on the other.