T16 - Conservation biology Flashcards
What kinds of populations are prone to extinction and why?
Small populations (maybe those going through a bottleneck) because they are vulnerable to inbreeding and genetic drift
What is an extinction vortex?
Further reduction in population size as a result of lower fitness due to inbreeding (inbreeding depression), the reduction of genetic variability prevents the population from adapting to its changing environment
Positive feedback loop; survival rates decrease, fitness is fairly low, lower production
- leads to less and less of a population (exponential decrease to a smaller and smaller population)
- higher genetic diversity allows for a greater ability for indivs in a population to adapt to environment changes
How might one counter the decline in population size?
We can reintroduce some new genetic variability to attempt to increase the survival of populations
populations can quickly rebound out of the extinction vortex
What is the effective population size of a population (Ne)?
the size of an idealised randomly mating population that shows the same level of heterozygosity as the population of interest
- equivalent to a small population in which you have random mating and everyone contributes to the next generation
When does the effective population size = actual population size (Ne=N)?
- if the population has a balanced (1:1) sex ratio
- all indivs contribute equally to the next generation (same number of mating and offspring)
- simultaneous birth of each new generation (no overlapping generations)
- the population size remains constant over time (not inclining nor declining)
Often not all indivs contribut equally to the next generation, what does this imply about the the effective population size and the actual population size?
the effective population size (Ne) will be less than the actual population size
- heterozygosity and genetic diversity will be decreased
- population behaves as if t was much smaller than the census size (drift/inbreeding)
What is the formula for the effective population size?
Ne = (4 x Nf x Nm)/Nf + Nm
where Nm = number of breeding males and Nf = number of breeding females
What isthe minimum viable population (MVP)?
the smallest size at which a population is able to sustain its number and survive
MVP takes into account Ne, indiv range, mortality rate, reprod age…
What are some threats tht may arise regarding biodiversity?
- Habitat loss; changes in habitat can affect species unable to disperse or adapt
- Invasive species; species introduced accidentally can affect communities and native species distributions, increase competition for resources, predation or parasitism
- Overharvesting; extensive exploitation can prevent the populations abiity to rebound (hunting, fishing, harvesting)
- Pollution; accidental or excessive release of nitrogen and phosphate in aquatic habitats can trigger explosive algae blooms that consume the oxygen dissolved in water
- also may prevent sunlight from entering underwater past the large amounts of algae
- Acid precipitation; oxides of sulphur released in the atmosphere (fossil fuels) react with water to form sulphuric acid, acid rain thus decreases the pH of many lakes
- Biomagnification; the increase across trophic levels in the concentration of a toxic substance inside tissues of organisms - may be caused by the very large biomass ingested from the lower trophic levels below
- Global warming; the emission of CO2 and other greenhouse gases causes the solar radiation to reflect back onto the earth’s surface and increase the avg global temperature
- species unable to disperse, adapt or with low genetic variation are at high risk
What are the 3 levels of biodiversity?
Genetic diversity; diversity within and between populations
- can prevent microevolution and limit the adaptive potential of a species
Species diversity; variety of species within an ecosystem or across the biosphere
- loss of a species can be local (extirpation) or global (extinction)
Ecosystem diversity; variety of ecosystems (3 statuses: collapsed, critically endangered and endangered)
What are some reasons we should protect biodiversity?
- The human population relies on biodiversity and natural resources
- wild species can be used for food, fuel, medicine (developing antibiotics)
- provides valuable services to humans (water purification, pollution breakdown)
- formation and maintenance of soils and flood cotrol, pollination of crops, climate regulation, recovery from natural disasters
- these ecosystem functions depend on the integrity of natural communities and ecosystems
- strong emotional, cultural and spiritual connections with nature (appreciation of diversity on earth)
- can be seen as rich genetic heritage froma compex evolutionary history (moral obligation) species are entitled to life and to be preserved/protected
What are biodiversity hot spots?
Relatively small areas containing many endemic species (found nowhere else) and a large number of endangered species
These are often specific to certain taxonomic groups and ignore many invertebrates and microorganisms species (biased to species that are easier to monitor and preserve)
What is conservation biology?
Integrated study of ecology, evolutionary biology, physiology, molecular biology and genetics to sustain biological diversity of all levels
