Paradigms In Conservation

Transcription

1 Lecture 17, 20 Oct 2009 Paradigms & Populations Conservation Biology ECOL 406R/506R University of Arizona Fall 2009 Kevin Bonine Mary Jane Epps Readings Primack parts of Ch 5 & 6 Marmontel et al (PVA Manatee) Gilpin 1996 (PVA commentary) 506 meet in BSE129 9am Wed (21 Oct) Sarah P. Lecture Thanks -Adrian Q-M Lab Thanks - Don Swann - Cascabel Crew Lab Friday 23 October BICYCLE (1pm northwest corner BSE) 1 Q4 - Due by noon Friday 23 October to MJ as.doc attachment. What are the relative impacts of invasive species and climate change on the present and future diversity of island ecosystems? How should conservation biologists help mitigate these impacts? The best essays will be organized, well written, define terms, explain and justify points of view, and include citations of literature. 2 Quiz, 20 October 2009 Please be concise. 1. Name and Date (1 pt) 2. What was the leading cause of adult mortality in the manatee paper that you read for today? (2 pts) 3. What was the main point of the Conservation Genetics lectures by Adrian Quijada? (2 pts) Paradigms In Conservation 1- Island Biogeography 2- Metapopulations 3- Habitat Heterogeneity 4- Disturbance 5- Genetic Diversity (MVP, PVA, Small Populations) 3 4 Equilibrium Theory of Island Biogeography Habitat Fragmentation Reserve Design Predictions vs. Observations Missing Factors -Rescue Effect -Habitat Suitability -Sink vs. Source -Habitat Heterogeneity -Species Interactions 5 6 1

2 Adaptive Radiation Galapagos Humboldt Current Pough et al Daphne Major Fernandina Pangaea Laurasia Holarctic Gondwana Zug et al

3 Plate Tectonics not fully accepted until 1960s Alfred Wegener, winter Crustal Plates moving 1-12 cm / year Alfred Russel Wallace ( ) Pough et al Wallace s Line Weber s Line Sulawesi Sunda shelf Sahul Shelf Campbell Dispersal Ability (Isolation by Distance) Dispersal Ability Pough et al Pough et al

4 2. Metapopulation: b vs. d Source Spatially disjunct groups of individuals with some demographic or genetic connection largely independent yet interconnected by migration Sink 1. All local populations must be prone to extinction 2. Persistence of entire population requires recolonization of individual sites. (See p.193 in VanDyke text) Juggling Balls, Oranges, and Mites: Metapopulation: Hydrothermal Vents Lowland Leopard Frogs (thanks to Don Swann)

5 4 km Distribution of Lowland Leopard Frogs in Rincon Mountains, Metapopulation Dynamics

6 Chytrid Fungus Habitat Heterogeneity 4. Disturbances Conserve Bigger Area? -Endogenous -Exogenous Conserve More Diverse Habitats? 33 An SUV is seen covered by sand as residents walk to their homes to inspect the damage by hurricane Ivan Wednesday, Sept. 22, 2004 in Pensacola Beach, Fla. Beach residents were allowed to see their homes for the first time since the hurricane. (AP Photo/Alan Diaz) 34 Habitat Heterogeneity and Disturbance Climax Community vs. Shifting Mosaic Intermediate Disturbance Hypothesis - Tree Fall in Forest -Fire - Beaver Dam on Stream succession reset supercompetitors

7 Species Vulnerability to Extinction, LIST A Populations & Extinction (see Primack Ch 5 & 6 etc.) 1. Small geographic range 2. One or only a few populations 3. Small population size(s) 4. Declining population size(s) 5. Actively harvested by humans Small population size(s) Species Vulnerability to Extinction, LIST B Individuals have large home ranges 2. Individuals have large bodies 3. Poor dispersers 4. Seasonal migrants 5. Low genetic variability 6. Specialized habitat 7. Only in stable, pristine environments 8. Individuals aggregate 9. Evolved isolated from humans 10. Species with threatened/extinct relatives 40 Populations & Population Dynamics PVA (population viability analysis) (thanks to Margaret Evans) 41 Groom, Meffe, & Carroll

8 populations are dynamic, not static populations are dynamic, not static Whales in the Antarctic Lemmings Cause of cyclic change in population not completely understood. Cycle length average 3.8 years. Mass migration in response to high density with decreasing food supply, sometimes swimming involved Population sizes change over time Why? What causes change in population size? What regulates population size? If we can answer these questions, we might be able to make changes that increase populations of declining (endangered) species 45 Many things affect population size population structure chance events demographic genetic habitat attributes quantity, quality, configuration, and connectivity competition within a species among species population size succession or disturbance other interactions predation, herbivory, pollination, etc. environmental variation good years, bad years Exponential growth density-independent, deterministic In a closed population (no immigration or emigration), population growth is a function of birth and death rates dn dt = (b-d)n Ring-necked pheasant on Protection Island 47 exponential growth: an unrealistic model? Humans on planet Earth 48 8

9 2. Logistic growth density-dependent, deterministic Alternatively, The population growth rate may increase with population size (positive density-dependence) dn dt = rn ( ) K-N K intraspecific competition stabilizes population size birth rates go down and/or death rates go up with increasing population size Allee effect carrying capacity (K) 49 minimum viable population size 50 How? Allee effect In animals: -group defense against predators -group attack of prey -mates difficult to find -critical number to stimulate breeding behavior How? group defense against predators Allee effect In plants: -pollinator limitation -self-incompatibility -inbreeding depression