Chapter 20 Community Ecology 20-1: Species Interactions

What’s a community?

5 Comm. Interactions: PREDATION PARASITISM COMPETITION MUTUALISM COMMENSALISM

Predation Predator eats prey Adaptations! Being a good predator: Being a good escaper: Teeth, venom, muscles, etc. Camouflage Mimicry Plants—thorns, toxins, etc.

Mimicry: Avoiding Predation! Batesian Mullerian B – harmless mimics a harmful M-2 or more dangerous sp look similar (bees)

Competition Interspecific Intraspecific

Research in the Lab Gause, 1930s Yeast http://jeb.biologists.org/cgi/reprint/9/4/389.pdf

Research in the Wild Connell, 1960s Barnacles Fundamental niche Realized niche

Competitive Exclusion Principle One species is excluded from a comm. b/c competition for same limited resource No 2 species can occupy same niche at same time/place! Resource partitioning Resource part—similar species avoid competition by using a specific part of the resource

Niche Activity

SYMBIOSIS Parasitism Mutualism Commensalism Symb – close, longterm relship btwn 2 organisms

PARASITISM

MUTUALISM

COMMENSALISM The goby is essentially the 'guardian of the hole' as the shrimp has very limited visual abilities. Because of this, the shrimp, while outside the burrow, holds one antennae on the goby. If the goby sees a potential threat, it will give a slight tail flick. This vibration is picked up by the shrimp who consequently darts into the hole. If the danger approaches further, the goby will shoot into the hole through a quick C-bend of the body and enter the hole.

Concept map in groups http://my.hrw.com/sh2/sh07_10/student/flash/concept_maps/00176.htm

I’m checking today!

Chapter 20 Community Ecology 20-2: Patterns in Communities

Species Richness vs. Evenness Richness-# sp in comm (count) varies w/latitude...more @ equator trop habitats older (ice ages didn’t disturb), more stable climate evenness- abundance of each sp (est pop size of each sp) http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/60359.htm

Latitude & Species Richness Trend? Hypotheses: http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/60360.htm

Area & Sp Richness Trend? Species-area effect Habitat destruction...

Sp Interactions & Richness Predation keeps prey # in check Paine, 1960s Removed sea stars Mussels previously coexisted w/several sp Overabundance  outcompeting for space, etc # sp from 20  <5 !

Richness & Community Stability Tendency of comm to maintain ~constant conditions Response to disturbance More species  more interactions, spread out effects, lessen the blow http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/60362.htm

Brain Break… p. 410—I’m checking it!

Ecological Succession Primary Secondary Gradual, sequential regrowth of a community 1-didn’t support life previously; soil not present 2-did; disturbance, then sequential replacement of sp; soil present

Glacier Bay, AK http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/60363.htm

Pioneer Species 1st on the scene Adapted to new conditions Small, quick growing, reprod quickly http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/60364.htm

Climax Community http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/60365.htm Stable end point Remains constant long pd time Too simple... Disturbances often stop progression (grasslands...fires prevent forest)

p. 410—I’m checking it!

HW Tonight--Ch 20 Review p. 412, quiz tomorrow (THURS)