evolution Flashcards
what are Synergistic effects
interaction of discreate conditions such that total effect is greater than the sum of the individual effects
what 2 possible things can happen to a species in danger
evolve or go extinct
what is genetic diversity
range of genetic variation in a pop
what is a phenotype
the observed state of a trait that is based on genetic makeup and env factors
what is Heritability
a statistic that can be used to determine the likelihood a particular character will undergo directional evolution due to exploitation
how does genetic differentiation change with exploitation
genetic diversity decreases with increasing exploration
what is Directional selection
a mode of natural selection in which an extreme phenotype is favoured over the other phenotype, causing the allele freq to shift overtime in the direction of that phenotype
Obvious characteristic at risk of directional selection
body size, growth rates, age at sexual maturity, body shape
what does characteristics does fishing pressure push populations evolutionarily towards
smaller body size, earlier age at repro, higher rates of repro, away from aggregation
characteristics that make Species more likely to evolve
Short generation
Large pop sizes
Faster rates of evolution
Large – behavioural changes
3 myths of extinction
- myth of immense ranges - what appeared to be a single species was actually multiple distinct species, each genetically different but superficially similar
- “millions of eggs” myth - high fecundity will protect from extinction - wrong
- not being a target of a fishery protects species from extinction - wrong
Factors that will increase risk of extinction
Slow pop turnover
Low repro potential
Low capacity for recovery
Restricted geo range
Small pop size
4 lists that highlight endangered / threatened species
- Endangered species act – ESA (US act)
- Office of protected resources – NOAA
- IUCN – international union for the conservation of nature and natural resources – international (Red list
+ Number of categories - CR, EN, VU) - CITES – convention on international trade in endangered species (international) (3 appendixes)
what are the 3 appendixes in CITES lists
- Appendix 1 – most critically endangered – cannot be traded e.g. turtles, beaked whales
- Appendix 2 – not currently threatened but could be if exploitation is not curtailed – can be traded with proper management plan e.g. giant clams, stony coral
- Appendix 3 – any country can list a species
endangered vs threatened
Endangered = a species in danger of extinction throughout all or a significant part of its range
Threatened = species likely to become endangered in the foreseeable future
how many Species are listed with an endangered or threatened status
2270 species listed
what are some species listed as endangered or threatened
14 whales
5 dolphins
7 seals
6sp sea turtles
9 sturgeon
10 sharks
1 sp of seahorse
5 salmon
what are the 3 types of extinction
- Ecological extinction = pop reduced to such low numbers that species can no longer carry out its role in its native ecosystem
- Economical extinction = pop reduced to such low level that species is not profitable to capture
- Biological extinction = no specimens left
why is extinction bad
- less biodiversity
- everything in an ecosystem is interconnected (trophic cascades, habitats, open niche for invasives etc)
