Test 2 Flashcards
what is the consequence of reduced population size?
reduced K, population growth (r max), and N
how do you restore populations in terms of logistic growth?
reintroduce N, support population growth, and restore K
what are the direct factors of species decline?
- over-exploitation
- direct disturbance
- abiotic stress
- pest/pathogens
what are the indirect factors of species decline?
- habitat destruction
- competition due to invasive species
- loss of mutualists
- hybridization
- loss of genetic diversity
what does species restoration entail?
- there is progressive reduction in numbers
- emergency action must be taken
- benefits must be balanced with risks before translocation
define translocation
human-mediated movement of living organisms from one area, with release in another
what are the different types of species restoration
- introduction: species are not currently present in the site
- reintroduction: reestablishment of species that occurred in the past, but not currently
- augmentation /reinforcement: individual species added to a site where species occur
what are the different types of restoration material?
- resident: specie/populations are native to the site
- translocated: genotypes collected offsite for planting on project site
- introduced: species/popns collected offsite and introduced on project site outside their historical range
what are the goals of species reintroductions/augementations?
- restore species within former natural habitat and range
- establish free-ranging and self-sustaining popns
what are the objectives of reintroductions/augmentation?
- survival of the species
re-establishment of a keystone species - restoration of biodiversity
- new popn in previous unoccupied site
- augment popn size (reinforcement)
- genetic rescue (reinforcement)
what are considerations in species reintroduction/augmentation?
- biotic and abiotic habitat needs, interspecific relationships, and basic biology
- matching habitat to meet the candidate species’ total biotic and abiotic needs through all life stages
- founders must show characteristics based on morphology, physiology, adn behavior similar to the original populations
- life stages and season of release should be optimized in respect to the species natural dispersal age or season
- disease and parasites
- social aspects - human communities
- regulatory compliance
- resources and funding
considerations of the re-introduction site
- eliminate previous causes of decline
- core vs periphery of the range
- founders (captive or wild) should show characteristics based on morphology and behavior similar to the original or remaining population
- the re-introduction program
- diseases and parasites
- social aspects - human communities
- regulatory compliance
- resources, funding
what can we assume about populations on the edge of their range?
less dense, less fit, less genetically variable = prone to extinction
explain founders of a wild population
- preference as the source
- removals should not endanger the source population
- genetic considerations
explain captive breeding
- establish captive program from wild-caught individuals
- knowledge to breed species in captivity
- grow the captive population
- must know the health and well-being
what are the challenges with reintroductions from captive populations
- low genetic diversity
- domestication can lead to behavioral changes
reintroduction program: explain hard release
- direct transport form capture site to release site
- no conditioning or support at release site
- less expensive means they can release more individuals
reintroduction program: explain soft release
- individuals are held for a period prior to release
- provided with food
- allows them to accustomed to the new location
- avoid habituation to humans
- more expensive means fewer individuals
explain the re-introduction program - consideration
- life stage and season of release should be optimized to respect the species’ natural dispersal age or season
- age, size, sex composition, and social relationships of founders
- multiple sites allow the species to spread out
- minimize stress during capture and handling
what are the risks from reintroduction
- ecological risk
- endangering source population during translocation
- disease
- invasion
- gene escape: risk of hybridization lowers fitness of offspring
- socio-economic risks
- financial risks
klop: how was the observational study done?
monitored released population of endangered frog species in a created habitat and conducted surveys of frogs in natural breeding/non-breeding ponds to help explain breeding failure in created habitat
klop: how was it done?
- field surveys to measure frog abundance and abundance of other fauna
- water quality testing
- monitored levels of invasive fish, BD, habitability of location
klop: what was discovered?
- vegetation and invertebrate diversity (food) were low in created habitat
- higher proportion of frogs had Bd compared to the wild species
klop: what’s the significance of this work?
the study informs practices of mitigation and makes recommendations to improve future frog release programs
klop: relationship between intro and references
the reference in the article were closely read by the researchers - identifying the current state of knowledge that researchers want to add to
klop: purpose of the introduction
- introduces the purpose of mitigation and notes that habitat offsetting is difficult and often fails
- explains that translocation is not enough
last: states the study objective - why created habitat is important and why it’s challenging for them to be successful
klop: limitations to the study
the location of the study is close to another set of breeding frogs that are the last populations in AUS
klop: methods
- why they surveyed extant frog populations? compare their released to control populations
- why sample breeding and non-breeding ponds? to try and explain breeding failures in released frogs
- why survey invertebrates? food
- why survey habitat? habitat of their food resources
klop: take home messages
- litoria aurea demography: no breeding, no tadpoles, more female than male, juvenile dominated in the created habitat
- other anurans: higher abundance of heterospecific tadpoles at breeding ponds than non-breeding
- invertebrates: breeding ponds had more invertebrate density and diversity compared to the created ponds
- mosquitofish: not likely as cause for the lack of breeding, but greater amounts in non-breeding than breeding
- Bd screening: prevalence of Bd infected frogs was significantly greater in created habitat than the breeding ponds
klop: habitat structures and vegetation
the riparian zone has the greatest difference between the created habitat and breeding ponds due to plant composition. created habitat had lots of open water
klop: fate of releasing litoria aurea in created habitats
food-limited, no breeding, and susceptible to Bd
klop: recommendations for improving the program
- create ponds with permanent hydro-periods
- place created habitat in closer to extant population
- various plant species in wetland zones
- reduce Bd in the site
- trial artificial call playback to stimulate breeding hormones and behavior
knapp: history of Bd in sierra nevada yellow-leeged frog
- 1800s: non native trout introduced to lakes
- 1900s: Bd spread into the region, stayed in the lakes, habitat fragmentation, isolation, and increase of predatory fish
knapp: objectives of study
- translocating from resistant populations to previously inhabited lakes
- predict into the future if translocated populations would persist
- identify predictors of frog survival
knapp: how was the study conducted
3 donor sites, 24 cohorts of frogs, moved to 12 recipient sites
knapp: what was measured
- counted frogs, tadpoles, juveniles, identify frogs with Bd during cmr
- severity of winter, site elevation, donor populations, and cohor characteristics
knapp: reintroduction of resistant R. sierraae
- 80% of translocated cohorts reproduced successfully
- Bd load was consistent between donor and recipient sites, but low levels
knapp: important predictors of frog survival
- elevation, boulders
- Bd was not a predictor
knapp: persistence of r. sierrae over decades
- reintroduced populations are likely to persist over a 50 year time period
knapp: more successful recovery efforts
- adaptive management
- understanding more about resistance
- future monitoring of genetic structure
