Announcements September 6, 2006

Steve “crocodile hunter” Irwin died Monday morning after being attacked by a stingray while shooting a TV program off Australia's north coast.

Evolution and Ecological Interactions Lecture Objectives: 1. Learn basic concepts of Evolution 2. Learn 5 major categories of interactions 3. Understand 2 ways humans alter interactions

Often, there are not enough resources for all individuals in the population Many individuals die before reproducing Some individuals are better at surviving and reproducing than others

What is Evolution? The process of change in the traits of populations over time. Process by which species' characteristics change over generations. Evolution does not occur within an individual. Evolution does not occur within a generation. Traits must have genetic basis.

Evolution occurs primarily through natural selection Natural Selection is the process that determines which individuals within a species will reproduce and pass their genes to the next generation. What is Evolution? Proposed by Charles Darwin in his book “On the Origin of Species” published in 1859

Species— Those organisms potentially capable of reproducing naturally among themselves, and producing viable offspring. Genes— Distinct pieces of DNA that determine an individual’s characteristics. Population—All organisms of the same kind found within a specific geographic region. (have the potential to interact)

Natural selection can occur when: * Individuals within a species show genetically determined variation in traits -this variation makes some individuals better at surviving and reproducing than others *Offspring with a particular trait survive better than do those without that trait *Over several generations, the frequency of that trait increases in the population * More offspring are produced than survive to reproduce

Evolution in action Pepper Moths in England two forms: light and dark Light colored ones could blend in with lichens on trees Prior to 1845, most moths light colored

Evolution in action Pepper Moths in England Light colored moths easy for birds to see on soot-covered tree, dark colored moths harder to see Increasing pollution led to soot-covered trees without lichens By 1950, most moths black

Several generations later Several more generations later Before 1845 Environment changes, now more black moths and fewer white moths survive to adulthood 1950 Several more generations later TIME

Evolution in actionResistance to herbicides

Evolution in actionResistance to antibiotics

Evolution does not just happen on long time scales Evolution is important for real-word issues: agricultural, conservation, health * Disease dynamics * Invasive species issues * Antibiotic and pesticide/herbicide resistance

Coevolution: When two or more species interact closely they can influence each other’s evolutionary direction. In tightly coevolved interactions, evolutionary change in one species will lead to evolutionary change in other or the second species may go extinct. Red Queen Hypothesis Lewis Carroll's Through the Looking Glass: “in this place it takes all the running you can do, to keep in the same place." Example: host / parasite coevolution

Interactions among organisms Abiotic – Non-living factors Biotic – living portion of the environment What are some biotic factors that contribute to this differential survival and reproduction? 1. Predation 2. Competition 3. Parasitism 4. Commensalism 5. Mutualism

1. Predation (positive for consumer, negative for prey) One animal consumes another Interactions among organisms

Types of predators Active predators: chase & overpower prey Sit-and-wait predators: motionless until prey close enough to strike

Sit-and-wait predator Antlion

Cryptic Coloration: blend in with environment Many prey items have traits that reduce predation

Warning Coloration: conspicuous to convey threat Many prey items have traits that reduce predation

Batesian Mimicry: defenseless species (mimic) is protected from predation by its resemblance to a species that is dangerous fly (bee mimic) bumble bee

Mullerian Mimicry: 2 or more distasteful or harmful organisms resemble each other

Interactions among organisms 1. Predation Prey is harmed (-) by being eaten Predator benefits (+) from food Predation is a (+ / - ) relationship

Competition: organisms compete for the same limited resource Ex. light, food, mates, habitat, etc. 2. Competition Competition is a (- / - ) relationship Interactions among organisms

Intraspecific competition — Members of same species competing for resources

Interspecific competition: Members of different species competing for resources May lead to competitive exclusion Photos: Alex Wild

3. Parasitism 1 organism (parasite) living in or on another organism (host), from which it derives nourishment Ex. Tapeworm Interactions among organisms Parasitism is a (+ / - ) relationship

3. Parasitism (+,-) Ectoparasites—Live on host’s surface (e.g., Fleas, lice, some molds)

Endoparasites—Live inside host. (e.g., worms, protozoa, bacteria, fungi) Ex. Heartworm 3. Parasitism (+,-)

Parasitoid

Nest Parasitism Common Yellow-throat Adult cowbirds don’t build nests Cowbird

Malaria carrying mosquito Vectors: animals that carry parasite from one host to another Examples: Malaria, Lyme Disease, West Nile Virus, Bubonic Plague

Interactions among organisms 4. Commensalism —One organism benefits, while the other is unaffected. Commensalism is a ( + / 0 ) relationship Remora and shark

4. Commensalism (+,-)

Interactions among organisms 5. Mutualism - Both species benefit. Acacia and ants *Tree provides sugar solution that the ants eats *Ants defends tree against grazers

5. Mutualism (+,+)

Summary of 5 major Interactions Predation+- Competition-- Parasitism+- Commensalism+ Neutral Mutualism++ Individual 1Individual 2

How have people change these interactions? 1) Introduced species 2) Habitat destruction Introduction of novel predators and parasites can devastate natural communities.

Over 2,000 species of birds have gone extinct on islands as a result of habitat loss and the introduction of predators and parasites. Hawaii: Habitat loss, malaria, rats and mongoose

Points to know: 1.Know what evolution is and how is operates. Understand coevolution. 2.Know the 5 main types of species interactions. 3.Understand who benefits from each type of interaction (one or both participants) 4.Understand how humans may influence these interactions.