1 Exam on Monday! (Sept 29)
During lecture period, room assignments are posted on Blackboard 9 AM students must take the 9 AM exam, 10 AM students must take the 10 AM exam Covers lectures 2-13 (14 will be on the Final) Multiple choice, matching, true/false, problem solving, and one essay Write in pen (answers in pencil or corrected with white out are not eligible for regrade) No calculators or cell phones Bring your USC ID card Set your alarms!!!!!!!! 1
Essay Guidelines Essays should be written in complete sentences no bullet points! For midterm 1 there will be one essay worth 20 points (20% of the exam). The point breakdown is as follows: Supportive concepts, 17 points Maximal points will be given for essays that answer the question thoroughly, get the facts correct and do not include additional irrelevant or incorrect information. Presentation, 2 points Maximal points will be given for essays with good organization, well-structured sentences and paragraphs, logical flow and high readability. Original content, 1 point One point will be given for essays that go beyond the material presented in lecture by also including ideas or examples from the textbook, the additional assigned readings, or other sources.
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Conservation Genetics
56.1, 56.2 and R4
Conservation biology is a young field that integrates:
Ecology Behavioral ecology Physiology Molecular biology Genetics Evolution
Conservation Genetics
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Conservation biology has grown rapidly in response the biodiversity crisis Some depressing statistics
Nearly 50% of land surface has been altered by humans About 75% of marine fisheries are fully exploited or overexploited We have increased atmospheric CO2 concentrations by 30% Rate of species loss may be as much as 1000x higher than at any point in the past 100,000 years
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Genetic diversity
Genetic variation within and between populations
Genetic diversity in a vole population
Species diversity
The number and relative abundance of species
Species diversity in a coastal redwood ecosystem
Ecosystem diversity
The diversity of habitats, communities and ecological processes
Community and ecosystem diversity across the landscape of an entire region
Fig. 56.3
Why preserve biodiversity?
1. For its own sake.
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Why preserve biodiversity?
2. For our own sake.
Pacific Yew Tree (Taxus brevifolia)
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We cant afford to lose biodiversity!
Pollination, nutrient cycling, purification of air and water, detoxification and decomposition of wastes, moderation of weather extremes Ecosystem services worth ~$33 trillion a year!
(Costanza et al. 1997)
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What are the greatest threats to biodiversity?
Habitat loss Introduced species Overexploitation
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Habitat Loss
California Gnatcatcher
Coastal sage scrub habitat
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Introduced Species
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Overexploitation
Collapse of wild fish stocks by 2048? (Science 2006)
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How is genetics used to aid conservation?
1. Diagnose populations or species at genetic risk 3. Prioritize populations or species worthy of protection
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1. Diagnose populations or species at genetic risk
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Small populations may be at genetic risk due to:
Inbreeding depression Low genetic variation
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Inbreeding depression
Breeding with close relatives increases the chance the parents will share the same deleterious recessive alleles Deleterious recessives are then exposed as homozygotes in the offspring
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The poster child for inbreeding depression in the wild: cheetahs
QuickTime and a Sorenson Video 3 decompressor are needed to see this picture.
Extremely low genetic variation Accept skin grafts from other individuals Poor mating success Abnormal sperm
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Problems with the cheetah example
Problems with skin graft experiments No non-inbred controls Low mating success in captivity due to poor husbandry Decline in wild due to lion predation?
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Support for the cheetah story from pocket gophers (Sanjayan and Crooks 1995)
Used noninbred controls Inbreds accepted skin grafts
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Other reports of inbreeding depression in the wild
Fish Wolves Ngorongoro Lions Shrews White-footed Mice Golden Lion Tamarins...
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Low genetic variation
Can result in reduced ability to adapt to environmental changes, such as alterations in climate or the introduction of new pathogens
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Species often harbor genetic variation to deal with challenges theyve never experienced
Examples:
Melanic moths Heavy metal tolerance in Pesticide plants tolerance Tolerance of climatic change
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Not all species with low genetic variation are doomed
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However, low genetic variation may drive other species down an extinction vortex
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Extinction vortex: inbreeding and genetic drift interact to make small population progressively smaller
Reduction in individual fitness and population adaptability
Small population
Inbreeding
Genetic drift
Lower reproduction
Higher mortality Loss of genetic variability
Smaller population
Fig. 56.10
Extinction vortex in prairie chickens
Populations of the greater prairie chicken were fragmented by agriculture and later found to exhibit decreased fertility To test the extinction vortex hypothesis, scientists imported genetic variation by transplanting birds from larger populations The declining population rebounded, confirming it had been on its way down an extinction vortex
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200 Number of male birds
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100
50 0 1970 1975 1980 1985 Year 1990 1995 2000
Population dynamics 100 Eggs hatched (%) 90 80 70 60 50 40 197074 197579 198084 198589 Years Hatching rate 30 1990 199397
How large does a population need to be to maintain evolutionary potential?
Maintenance of neutral diversity requires an effective population size of ~500 - 5000
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Effective population size (Ne) is generally lower than actual population size (N)
Factors reducing Ne include:
Fluctuations in population size over time Inbreeding Overlapping generations Unequal family sizes Unequal sex ratios
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How is genetics used to aid conservation?
1. Diagnose populations or species at genetic risk 3. Prioritize populations or species worthy of protection
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Do polar bears deserve high priority for conservation?
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Polar bears are not genetically distinct from brown bears
From Waits et al. 1998
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Does the tuatara deserve high priority for conservation?
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Tuatara phylogenetically unique!
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Do Catalina Bison deserve high priority for conservation?
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QuickTime and a TIFF (Uncompressed) decompressor are needed to see this picture.
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Genetic data shows 45% of Catalina bison have cattle mtDNA!
(Vogel, Tenggardjaja, Edmands, Halbert, Derr & Hedgecock, 2007)
beefalo
Does the San Clemente Loggerhead Shrike deserve high priority for conservation? (see R4)
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San Clemente Loggerhead Shrike
Recognized as a subspecies Found only on San Clemente Island Reduced to 17 wild individuals due to introduced species (pigs, goats, cats, rats) and naval operations Called the rarest vertebrate in North America Listed as Endangered in 1977
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But is the subspecies distinct?
Morphological data show they are not clearly distinct from other subspecies Genetic data show they are divergent from neighboring subspecies, but bear no unique mtDNA haplotypes (combination of alleles at linked loci)
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Does the San Clemente Island Fox deserve high priority for conservation? (see R4)
QuickTime and a Sorenson Video 3 decompressor are needed to see this picture.
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San Clemente Island Fox
Recognized as a subspecies Found only on San Clemente Island Population declined ~60% between 1988 and 2000 due in part to mortality caused by efforts to protect shrikes Four island fox subspecies (Santa Cruz, Santa Rosa, San Miguel and Santa Catalina) listed as endangered in 2004 San Clemente and San Nicolas subspecies still not listed despite similar or higher extinction risks according to IUCN criteria
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But is the San Clemente subspecies distinct?
Morphological data show some evidence for differentiation among the 6 subspecies MtDNA suggests San Clemente subspecies is derived from San Miguel subspecies Nuclear microsatellite data shows alleles unique to San Clemente subspecies
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San Clemente Island Fox being denied protection to save the San Clemente Island Shrike?
R4
Conservation Biology 17(5): 1251-1260
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Should the San Clemente subspecies have lower priority if its non-native?
?
?
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Summary
Conservation Biology and Biodiversity Reasons for conserving biodiversity Threats to biodiversity Diagnosing genetic risk
Problems caused by inbreeding depression and low genetic variation, extinction vortex, effective population size
Prioritizing conservation efforts
High priority for uniqueness, low priority for hybrids, conflicts between species that deserve protection
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If youre interested in Conservation or Genetics, come join us for Spring Semester on Catalina!
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