Week Three Lecture Notes
Week Three Lecture Notes BIO 227
Popular in Wildlife Conservation Biology
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This 3 page Class Notes was uploaded by Miri Taple on Tuesday February 23, 2016. The Class Notes belongs to BIO 227 at California Polytechnic State University San Luis Obispo taught by Dr. Lisa Needles in Fall 2015. Since its upload, it has received 10 views.
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Date Created: 02/23/16
(Continued from 10/5/15) Lecture Notes c) incidental exploitation • Fisheries by catch • Usually more in # and biomass than targeted species in by catch o Bottom trawl o Dredge o Gillnet o Longline o Purse seine • Terrestrial by catch o Wire snares (elephants and zebras caught in poaching snare) d) commercial harvest • Seafood: $85 billion/yr o Top predators o Fishing down the food chain, can change the whole system o Annual shark harvest- 100 million/yr o Shark finning, shark fin soup used for celebratory feast, big problem in Asian countries • Timber: $400 billion/yr o Provides habitat o Increases structural complexity o Could be habitat for specialists • Bushmeat- subsistence or commercial trade o Bushmeat stew, lemur heads, Madagascar e) market hunting • Sea otter harvest and consequences: o Used for pelts by 1900 only 1000-2000 left from 300,000 • Garret Hardin’s “Tragedy of the Commons” • Rhinos o Highly endangered o Product of commercial harvesting • Recreational Value: o As species become too rare it becomes too difficult o Ceases to be “fun” then people switch to another animal o Populations will recover from sport hunting but not from subsistence hunting • Commodity Value: o As object becomes rarer people are unwilling to pay more o Extraction becomes more difficult and less profitable o Leads to supply switching • Collector Value: o As object becomes rarer people are willing to pay more o Creates market incentive, rarity leads to greater prices/ greater profits o Can easily lead to extinction 10/5/2015 Endangerment and Overexploitation External factors that cause species to become endangered • Evil quartet o Habitat destruction o Exotic species introduced/ disease o Overexploitation o Ecological linkages/ cascading effect Intrinsic factors that cause species to become endangered • Species that are a resource for humans or compete with humans for a shared resource o Fisheries with by-catch o Ex. Turtles an humans utilize the same beach habitat o Changes of one system to another (ex. Prairie to agriculture) • Specialists o Have a particular resource that they utilize and cannot survive without (not generalists) o Ex. Pandas are reliant on bamboo o Ex. Vernal pools: have to be a specialist to survive there • K-selected o Slow life history strategy • Endemic to islands o “ecological naiveté” o many island birds are flightless due to the lack of predators that have gotten to the island • Small and/ or restricted population o Caveat: just because a species is abundant doesn’t mean it is out of danger (ex. American bison, passenger pigeon) o Small, highly localized populations are very vulnerable § Close to the brink of extinction- can’t withstand much impact § Vulnerable to many stochastic (random) factors § Genetic inbreeding and genetic drift can reduce individual’s fitness § Population persistence and evolutionary potential Case study: genetic rescue of Florida panther • Evidence of inbreeding: kinked tail (heritable physical defect), deformed sperm, and cryptorchidism (undescended testes) • They were bread with Texan panthers and it increased genetic diversity of the population • Road kills are primary causes for endangered Florida panthers • Environmental changes very specific habitat, demographic problems such as unbalanced sex ratio, and genetic problems Why are some species rarer than others? • Restriction to uncommon habitats • Species restricted to vernal pools • Limited to a small geographic range • Occur at low population densities Species in general don’t do as well when… • Limited adaptability and resilience • Ecological overlap • Human attention • Large home range requirements Overexploitation • 13 % birds, 25 % mammals, 41 % amphibians threatened • overexploitation: increase in direct human caused mortality of a species to an extent that threatens its viability • types of exploitation of resources o subsistence o recreational o incidental o commercial a. subsistence o ex. Bushmeat (meat from non-domesticated animals, natural resources used for food, medicine, etc.) o can lead to local extinctions o large animals, slow to reproduce affected the most o common in developing nations b. recreational o consumptive, non-essential for survival o usually is an expenditure of funds o hunting, fishing o hunting can aid conservation in the following ways: i. creates a “user group” interested in conserving the species as a resource, the carrying capacity of some populations is aided by hunting to keep it under control and stabilized ii. “user pays” for licenses in which the funds go to conservation iii. habitat protection for game species
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