BIO 401 Exam 2
cal poly spring 2016 dr. perrine
Terms in this set (103)
What 4 processes cause a change in population over time?
births, deaths, immigration, emmigration
3 fundamental patterns that affect population dynamics
1.exponential growth (r; absence of limits). 2. carrying capacity (K; upper limit). 3. negative density dependence (Allee threshold- small populations have lower fitness; lower limit)
λ (conceptual and mathematical definitions)
conceptual: constant proportion population is growing by in exponential growth scenario
mathematical: λ= N t+1 / Nt
N t+1 = population size at next time interval
Nt= population size at current interval
Why are deterministic models not particularly useful for calculating extinction probabilities or time to extinction for critically endangered species?
There are many stochastic events involved with small, vulnerable populations that aren't taken into account with deterministic models
What is PVA?
population viability analysis
How does PVA differ from deterministic models?
It is a demographic model that incorporates stochasticity
How is stochasticity incorporated in PVA?
a vital rate is randomly selected from a probability distribution, rather than being identical every time.
PVA incorporates elements of species characteristics and environmental variability.
Why are multiple runs necessary with PVA?
Since stochasticity is included, each simulated population will have a different trajectory. The culminations of these simulations will create a probability of extinction
Why is PVA a kind of risk analysis?
PVA predicts the outcomes of populations and can be used to assess the probability of a population going extinct over time, over a certain number of simualtions
quasi-extinction: what is it and why is it important?
when a population is at a number that make them functionally extinct, or "doomed for extinction"
Minimum Viable Population (MVP)
minimum population size with a specified probability of remaining alive (extant) for a specified period of time
Higher survival probability and the longer the timeframe, the greater the MVP
Key shortcomings/abuses of PVA (4)
1) PVAs can require lots of data (may not have all data for many endangered species. Better to have simpler models with good, local data instead of complicated model with extrapolated data.)
2) Model assumptions may change over lengthy time periods
3) Managing for the MVP can be risky
4) Models are not reality ("statistically unlikely" does NOT mean "it won't happen")
Demographic phases of extinction (4)
1) Small population
2) Stochastic events
3) reduced fitness
"Deterministic" vs "Stochastic" processes
Deterministic: processes that have outcome directly related to inputs (overhunting and habitat destruction- not random events)
Stochastic: processes with outcomes that are not predictable based on inputs (disease, harsh winter- random events)
4 Main stochastic processes that affect small populations
1) Genetic stochasticity
2) Demographic stochasticity
3) Environmental stochasticity
A region is a locus (or region of DNA that encodes a functional RNA or protein product
An allele is a variant form of a gene.
Genetic expression an organism or individual
Outward expression of genotype. observed in the appearance of individual
Recessive: An allele which has its phenotypic expression masked by the contribution of a dominant allele at the same locus
Co-dominance occurs when contributions of both alleles are visible in the phenotype
Hetero: Diploid organism contains two different alleles of gene.
Homo: Diploid organism contains two of the same alleles of gene
Two sets of chromosomes
One set of chromosomes
Polymorphism vs. heterozygosity
Polymorph-proportion of genes that have multiple forms (alleles) present in population.
Heterozyg-for any given gene, what proportion of individuals are heterozygous?
Hardy-Weinburg equilibrium: 5 key assumptions.
What is the relevance?
Relationship to conservation bio?
1) Non natural selection
2) No random allele frequency changes ("genetic drift")
3) No gene flow into or out of population
4) No mutation
5) Random mating
Allows the use of simple rules of probability to generate expected genotype frequencies given allele frequencies.
Why is genetic diversity relevant to conservation at individual, population, and taxa level?
Individual-fitness level (heterosis, inbreeding)
Population-provides resilience (to disease) and stimulates evolution
Taxa-can reveal the correct units of conservation through study of population-specific gene flow
How does genetic diversity relate to evolution? (evolutionary potential)
Increase in genetic diversity in a population leads to greater evolutionary potential, or potential for genetic change
Sudden reduction in size of population due to stochastic events
reduction in heterozygosity-->less resilience-->increase in probability of extinction
population only has one allele=no genetic diversity
loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population
Difference between fitness of optimal genotype and fitness of observed average genotype in population
change in frequency of an allele in population, cause of loss of variation
Outbreeding/outbreeding depression (textbook)
Breeding with genetically distant individuals can create lower fitness in the progeny
What is it? what is it based on? is it a "hard and fast" rule, why or why not?
Guideline for genetically effective population size. 50 individuals needed for short term (to avoid inbreeding depression, 500 individuals needed for long term (to avoid genetic drift).
Yes, because it is more of a "rule of thumb" and it is not scientifically sound for every species
* Case study: human HLA gene
Case study: sickle-cell anemia
- Heterozygote advantage in malaria zones
- Individuals with both normal and sickle-cell allele (mild anemia) are at an advantage in areas with Malaria because they are immune, they just have to sacrifice the blood health of individual
Case study: domestic banana
The modern "Cavendish" banana crops have all the same genetic material. Panama disease came through and wiped out large portion of population. Bananas have low genetic resilience :(
Case study: Tasmanian devil
Tasmanian devil is a highly localized population of individuals that live in Tasmania. Because of low heterozygosity they Facial Tumor Disease came through and effected many individuals. Reverse quarantine was performed
What is Ne and how does it differ from Nc (census population)? When is Ne relevant?
Ne-effective population size is the number of individuals that a population would need to have to produce self-sustaining population of similar size (breeding population)
- inherited from mother
- Circular molecule rather than a linear strand
- haploid rather than diploid
single nucleotide polymorphism. where a single base pair gene changes in an individual from the population. can derive info from where SNPs are found
Repetitions of a short (2-6 base pair) section of DNA. example: CGCGCGCGCGCG
Case study: Black Rhio (Ashley, Pimm)
What was conclusion from study of Black Rhino mtDNA?
There was virtually no difference among populations or subspecies
Case study: Owl Monkey
Researchers used PCR to examine the chromosomes of owl monkeys and revealed that animals from different parts of their range had remarkably different sets of chromosomes. different sets/ karyotypes of genes. 9 distinct species of owl monkey Aotus genus.
Case study: whalemeat
Which technique was used to identify whether whale meat for sale in Japanese markets was legally-harvested species
PCR and mtDNA sequencing of control region
genetic rescue of Florida Panther
How many panthers were translocated and of what gender?
8 females, 0 males brought to Florida from Texas to enlarge gene pool/ force gene flow
genetic rescue of Florida Panther
What is AIC and what is its significance in the study?
AIC is a statistical measure used to determine which model is the best fit for the data. smaller the AIC score the better the model fits the data.
genetic rescue of Florida Panther
What were the ultimate results of the study?
there was a significant difference between purebred and hybrid kitten survival, with hybrids surviving at 3x the rate of purebreds
genetic rescue of Florida Panther
In addition to being struck by vehicles or shot, what is the other primary form of adult mortality in this population?
being killed by other panthers, in intraspecific aggression, regardless of whether they were hybrid or purebred
non-market based consumption where individual takes only what they need locally to subsist
EX: Bushmeat from Cameroon in Africa
harvesting "for fun" or "for sport"
An extraction method that is no necessary for subsistence
EX: fishing/hunting in America
EX: bycatch of albatross with fish hooks, bycatch of zebras due to wild snares
harvest and exportation on a market-scale
EX: Seafood, timber, breeding plumage of herons
Harvesting something until it is all gone
EX: plumage of herons, hunting of bison
Which is the most relevant to terrestrial vertebrates in USA?
How can hunting benefit a species?
Hunting can be a benefit if proceeds from hunting expenses (tags, license, etc.) go toward conservation.
Managed hunting can raise $10,000 for conservation programs
2 largest international industries in biological products
Seafood: $85 billion/yr
~ 100 million tons
Timber: $400 billion/yr
~ >1 billion cubic meters
What is the example/metaphor of Garrett Hardin's "Tragedy of the Common"?
Tragedy: inevitability caused by an inherent flaw
Commons: common pasture
NEED "social coersions" or restrictions on human behavior to prevent overexploitation. CAVEAT: regulations are essential but are only as good as real-world implementation
- As object becomes more and more rare, people are unwilling to pay more
- Extraction becomes more difficult and less profitable
- Leads to switching to cheaper/easier alternative.
- "Commercial extinction" - depletion but not eradication of resource
EX: rice, paper
Collector Value (conducive of "status objects" -- indicators of wealth, power)
- Object becomes more rare, people are willing to pay more
- Creates market incentive to harvest last available units
- Can lead to eradication and eventually extinction
EX: Ivory trade (no functional use but a mark of status)
management implications: how to address the general network of harvest / transport / end user.
Simple bans are ineffective and often lead to "prohibition effect"
In order to be effective, management must simultaneously address: Local harvesting (limit or prohibit), supply chain and transportation, and end user demand.
Hunt of wild land animals for commercial sale (bison)
Meat caught locally for subsistence
depletion of comercial market for good, but not necessary eradication
Species outside of native range
Species released into the wild
Introduced species that maintains local self-perpetuating populations
Established species with specific ecological characteristics that cause it to expand its range into new areas
Accidental introductions (2-3 examples of possible mechanisms, and example species)
- purple loosestrife: transported from ballast rocks dumped from ships
- Zebra mussels: transported by ballast water dumped from ships
Intentional introductions (4 main categories, and example species)
- Biocontrol (Kudzu introduced in south for erosion control)
- domesticated animals/plants (Feral cats and free-ranging house cats)
- acclimatizing societies (Starlings from Europe compete with cavity-nesters)
- sport animals and fish (Introduced sport fish affect native amphibians in Sierra Nevada
when a domesticated animal becomes wild/ non-domesticated again
biocontrols: traits of successful vs unsuccessful (disastrous) biocontrols
- Specialist to host organism that is trying to be controlled
- Non-generalist (wont go and consume something else after populations have depleted
when societies move to another habitat and move some of their familiar biota to make new place feel more like home. bunnies in australia
Main impacts of exotics on native species (direct and indirect effects). Which is most likely to cause extinction of native species?
- DIRECT EFFECTS upon native species (hybridization, competition, predation..)
- INDIRECT EFFECTS upon native species by changing ecosystem properties (hydrology, nutrient cycling..)
- INDIRECT EFFECTS that facilitate other non-native species
What are the main characteristics of successful invaders / invasions?
- R-selected life history
- associated with disturbance/anthropogenic/early successional habitat
Why are "weedy" species more likely to be invasive?
they are able to more easily outcompete native species and are able to reproduce very fast and occupy niches other other species
How does group size affect likelihood of establishment?
Larger groups are more likely to establish
Know several reasons why islands are particularly susceptible / vulnerable to invasive exotics.
- More endemic species
- Species have less resilience and overall fitness
- species are specialists most likely
Why are island plants susceptible to exotic herbivores? What impact does this have on native herbivores? On other exotic plants?
island plants don't have defenses against exotic herbivores (thorns, toxins, etc.)
native herbivores starve because exotics ate all their food
exotic plants take hold more easily when their native counterparts are being eaten/ killed by exotic herbivores
Why are mammalian carnivores so devastating to island wildlife? (as prey)
They are usually more generalist and will disturb natural food chains (Rattus spp. eating bird eggs)
List of banned species or products
list of approved species or products
application of herbicides (plants)
Tearing up/out invasive species
- Can create disturbance which is a perfect environment for weedy species
Requires a parasite that is physiologically linked to the host (not a generalist)
How does modern biocontrol differ from that practiced 50+ years ago?
We have transitioned to use parasites that are physiologically linked to host (not generalist)
Case study: American Chestnut
Chinese chestnut was introduced to the east coast because they had better fitness in that environment. This tree had a fungus that Chinese chestnut was adapted to but this fungus spread to American Chestnut and almost wiped out entire population.
What is Bd? What disease does it cause, in what kinds of species? How did it arrive?
- Chytridiomycosis caused by Batrachochytrium dendrobatidis (Bd)
- Origins: African Clawed Frog - resistant to Cytrid disease
>Frogs used to be used in hospitals for pregnancy tests (1920s-30s)
>When chemical tests were created, frogs were released into the wild
What kind of disease is primarily affecting native Hawaiian birds? How did it arrive? What other exotic species has/have been important in the transmission of this disease?
Endemic birds in Hawaii - Honey creepers
- When chickens were introduced, they had malaria (vector spread disease)
- Introduction of mosquitos caused spread of avian malaria from chickens to birds
- Wild pigs exacerbated problem of mosquitos by creating wallows for mosquito breeding habitat
- Climate change puts stress on bird habitat
What is "White Nose Syndrome"? What taxa are primarily affected by WNS, and how? Where and when was it first discovered? Why is it usually fatal? How is it relevant to California?
White Nose Syndrome in bats
- During hibernation period, bats have been found dead in the snow and in their caves.
- Caused by fungal pathogen, Pseudogymnoascus destructans (Pd)
>Fungus favors temperature just above freezing and starts digesting the bat and spreads
>Bats become itchy and awaken. Their metabolism is reawakened and they must look for food.
>Bats starve and die
Degradation and the three types
Diminished quality for a given species. Manifests as a reduction in fitness (survival or reproduction)
1) Reduction of key habitat elements (snags)
2) Change in ecological succession or disturbance (fire suppression with Jack pine caused decline of Kirtland's warbler)
3) Pollution, toxins (Albatross chicks consumption of plastic)
Degrading to the point of unusability-->loss
Breaking into discontinuous pieces or parts
What 3 things happen to a habitat as a result of habitat destruction?
reduced habitat area (degradation), increased edge effects and fragmentation
Using the Species Area curve: In general, a 50% loss of area results in __% species loss? How about a 90% loss of area?
50% loss in area --> 10% loss in spp.
90% loss in area --> 50% loss in spp.
What are "edge effects"? (know examples of abiotic and biotic factors) [see textbook]
"interior" vs "edge" species
edge: transition between destructed area and habitat. causes micro-climates, disturbance (wind, temperature, fire), predation from exotic or weedy spp
Key factors determining the intensity of edge effects on a patch (3)
Fragmentation: gaps, expansion of gaps, switching of matrix to be disturbed; remnant patches.
What are the top 3 factors (in order) causing habitat destruction and fragmentation for species listed under the Endangered Species Act?
Why are roads particularly problematic to populations? Know several different factors.
What about dams? Be able to explain how dams alter upstream and downstream habitats.
Be able to explain the characteristics that make certain kinds of species particularly susceptible to habitat destruction and fragmentation.
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