conservation biology Flashcards
what is it
predicting how a species will react to current/future changes, human caused, in its environment./density/distribution- whether it will survive and what to do to prevent extinction
Goals in biodiversity
investigating human impacts on biodiversity
Develop approaches to prevent biodiversity loss
Interconnected levels biodiversity loss occurs at
loss in genetic diversity
loss in species diversity
ecosystem loss
Background extinction patterns
the long pattern of ecosystem change that leads to some species going extinct
Mass extinction patterns
Catastrophic spikes of extinction associated with sudden widespread ecosystem change
Even when species don’t go extinct,
their populations get smaller
-reduction in effective population size
Smaller populations do go extinct
4 major threats most species loss can be traced to
Habitat loss or degradation (incl pollution)
Introduced species (incl disease)
Overexploitation (harvesting/hunting)
climate change
Habitat loss and degradation
largest threat
Land suitable for agriculture has be mostly transformed (98%)
73% species gone endangered or extinct
Fragmentation
Process by which a large continuous area is reduced and divided into 2 or more isolated patches
Causes reduction in pop sizes and genetic diversity, incr likelihood local and eventually global extinction
Habitat degradation
Pollution: land, air and water
Land pollution
release of chemicals leaves vast areas unusable for organisms
Air pollution
Large scale effects leading to widespread complex ecosystem alteration
Water pollution
Eutrophication and dead zones
Why can introduced species be a problem?
displace native species Have fewer predators/pathogens Disrupt ecosystem function Reduce overall diversity Transmit disease (native organisms often have limited resistance to novel pathogens)
Over exploitation
Human taking of wild plants or animals and rates that exceed the system’s ability to replace them
Large organisms with slow reproductive rates are particularly susceptible
Aquatic and terrestrial systems are both susceptible
Overfishing
Most fisheries are overexploited (not sustainable)
‘bycatch’ kills lots of nontarget animals- 25% of catch is returned to the sea to die
climate change
species distribution is limited:
energetic costs
resource availability
Fitness under higher optimal conditions
If climate conditions change, few possible outcomes:
-range shifts
-plastic responses (phenotypic plasticity-e ability of a genotype to express a different phenotype under different environmental conditions,)
-adaptive evolution ( shift in allele frequencies leading to a change
in phenotype in a population)
-extinction
Warming oceans- impact on fish
Marine species moving away from equator to cooler waters, and replacing fish caught in fisheries
Subtropic and temperate ocean: as open temps rise, catch composition in the subtropic and temperate areas changed to include more warm-water species and fewer cool-water species
Tropics: catch composition changed then stabilised, likely because there are no species with high enough temp preferences to replace those declining
Pop extinction is certain if
in the long term, the mortality and/or emigration rates are higher than the birth and/or immigration rate
Extinction mechanisms act by
affecting the migration, mortality and BRs
Extinction mechanisms 3 categories
demographic uncertainty
Environ uncertainty
Loss of genetic diversity
Metapopulations
Fragmented population occupying spatially separate habitat patches
source/sink modelling
source populations provide an excess of individuals which emigrate to and colonise sink subpopulations
Metapopopulation survival depends on
- Local population survival (affected by genetics, patch size and quality)–> incr with patch size
- Unoccupied suitable habitat at suitable distances
- sufficient migration for colonization of unoccupied habitat ot occur- incr with small distances and corridors
Maintenance of dispersal key
Natural habitat corridors particularly important for
large animals
Genetic factors affecting small populations
genetic drift, founder effects, bottleneck effects,inbreeding depression
Genetic drift: significant in, what does it incr likelihood of
Change in allele freq in a pop due to random sampling
Effects significant in small populations (random sampling of poor alleles leads to chance of extinction)
Genetic drift incr likelihood that alleles are lost, reducing genetic variation in a pop
Effective pop size (Ne) estimated by
Ne= (4NfNm)/(Nf + N)
Where Nf and Nm are number of females, number of males that breed together successfully
Founder effect
Occur when few individuals become isolated from larger pop to form a new one
Allele freq in small founder pop can be different from those in the larger parent one
Fragmentation can lead to reduced genetic diversity
Bottleneck effect
Due to sudden reduction in pop size due to change in environment
Resulting gene pool no longer reflective of original pop’s gene pool
If pop remains small, it may be further affected by genetic drift
Factors affecting small populations
Inbreeding depression- relative reduction in fitness of inbred progeny in comparison to equivalent outbred progeny
Mainly cause by concealed recessive deleterious mutations
Link between drift/bottle neck and inbreeding
Reduction in no after drift/ bottleneck will incr likelihood of inbreeding increasing expression of deleterious traits (previously concealed) , causing fitness reduction
