Studied by 14 people
dosent include carbohydrates or Lipids yet
Evolution
change in the heritable characteristics of a population over time
Darwin’s Theory
variation exists → nature selects the indivisual with the traits best adapted for survival and reproduction = evolution over time
supoorted by genetics (variation is present in a pop due to the precesne of alleles)
evidence for evolution
Biomolecules, selective breeding, homologous structures and analogous structures
Biomolecules (genetic variation)
same genes are present in organisms which have evolved from a common ancestor. differences in the base sequences of DNA (+RNA n protein) are the result of mutations
closley related species have very similar gene and protein sequences as there will be a samll # of mutations as they diverged from a common ancestor.
Selective breeding
process of choosing animals/plants with desirable traits to breed together and produce offspring with more of those desirable traits
selective breeding e.g: (woof)
Canius lupus - selectively bred them with desirable traits to create the variety of dog breeds we have today (sled dogs)
selective breeding e.g: plant
Brassica oleracea (demonstrates how fast evolution can occur) selective breeding results in changes to the heritable characteristics of oraganisms
turned into cabbage, kale and brussell sprouts
Homologous structures
body parts of different organisms that are similar in structures but different in function
present in organisms that have descended from a common ancestor as a result of evolution (more similar the structure, the more recent common ancestor)
homologous structures e.g.
PENTADACTYL LIMB: humans, dogs, birds, whales with pentadactyl limbs have evolved from a common ancestor
structure is similar, function is modified: (humans-writing, dogs-running, birds-flying, whales-swimming)
Convergent evolution
evolution of similar structures in species NOT RELATED due to a recent common ancestor
Analogous structures
have common function but do not share a common ancestor (evolved by convergent evolution)
Analogous structure e.g.
WINGS: in all 3 groups have the same function (flight), none of the groups of organisms share a common ansector with wings so each one evolved independently
Homologous vs. Analogous
Homologous: from a common ancestor, similar structure, different function (pentadactyl)
Analogous: not from common ancestor, similar function, differing structure (wings)
Speciation
only occurs if a population of a species is reproductively isolated and no longer able to reproduce w/ original pop
occurs as pre-existing species evolve into new species over time
gradual evolution DOES NOT = speciation
Extinciton
occurs when there are no living memeber of a species remaining
speciation increases total # of species on earth, extinction decreases it
Reproductive isolation
when there is a barrier whioch prevents indivisuals from reproducing (fertile offspring)
result of geographical isolation
Geographical isolation
when 2 pops. of the same species are prevented from reproducing due to geographical features → rivers, mountains, different islands
e.g. for reproductive n geographic isolation
CHIMPS & BONOBOS: pop of apes lived in central africa, the pop became geographically isolated into 2 distinct pop as the congo became wider. the 2 pops then became reproductivley isolated as members of each pop were unable to reproduce together.
Selection pressures: different traits were selected to better aid their survival on either side of the river
boring bonobos - more vegetables no competition, aggressive chimps - had to fight gorillas and more meat
Biodiversity (definition)
variety of living organisms (plants, animals, micro-organisms) on earth
genetic diversity (definition)
diversity seen in genes (alleles) within a population of species
species diversity (definition)
ecosystem diversity deinition
variety of ecosystems in a given area
MOAS - case study
flightless birds, native to new zealand
fossil records indicate the polynesians used the birds as a food source (over exploitation), within 100 years birds were hunted to extinction
diseases brought by humans could also be a factor
Caribean Monk Seal
marine mammals found in the carribean sea, fishermans killed 100s of seals every night (fuel lamps, grease machinery)
less thar 600 years the sealsbecame extinct, overfishing in their areaas meant these animals felkl short of food sources like fish (starved to deaath)
Splendid Poison Frog
were trafficked as part of the “pet trade”
outbreak of a fungal disease
habitat was reduced due to logging, conversion of forests for agriculture and expansion of urban areas
Anthropogenic Species Extinction
6th mass extinciton, result of human activity: habitat loss/destruction, exploitation, climate change, invasive species
Tasmanian Wolf case study
INVASIVE SPECIES, OVEREXPLOITATION
large carnivores in Tasmania, colonization by europeans ead to a decrease of an already low pop
europeans offered rewards for killing them as they hunted for fish
dingoes introduced byt the euro’s out competed the wolves
kept as pets or zoos
Ecosystem services
supplying recources → water, food, timber and medicine
provides basic services essential for survival:
decomposition of waste, storage of carbon, climate regulation, water cycle
Ecosystem Loss
human activity has lead to the destruction and decline of ecosystems
when entire species collapse the species dependant on the ecosystems are driven to the brink of extinction
Fall of Dipterocarp Forests
southeast asia there are tropical rainforests
key stone species (important)
food sources (leaves, fruits, seeds)
provide homes
roots hold soil
decomposition of leaves enriches soil
help fight climate change → store and lock co2
under threat by logging, deforestation
the destruction of these forests + already endangered animals to become more vulnerable
Dying Reefs: case study
reefs are one of the earth’s most diverse ecosystems
benefits:
sustaion food webs
sources for new medicine
protect coastlines from erosion and storms
provide food for animals and humans
threats:
pollution - oil spills, plastic
destructive fishing activities - overfishing
unsustainable tourisim - divers damaging them
climate change- rising ocean temp leads to ocean acidification, leading to coral bleaching
Population Explosion
in 200 years it went from 1 billion to 7 billion
as the pop grows, the demand for food, water and space increases
increase pressure leads to over exploitatation of natural rescources and habitat destruction = impacting biodiversity
Hunting & overexploitation
decrease and even extinction of many species
poaching and habitat destruction
countries try to have policies but illeagal poaching still continues
Destruction of Habitats
as the demand for space increases more and more natural habitats are lost
when habitats are changed drastically, species cannot adapt as fast and can no longer survive
Habitat Fragmentation
urbanisation invades on existiing natural habitats and can fragment them into smaller habitats
E.G.
laying of railroads thru a natural habitat makes the area smalller and isolates patches
restricts animal mobility - reduces access to food and increases risk of extinction
SOLUTION: building safe passages for animals
Invasive Species
as humans took over the earth they introduced new species accidentally or on purpose
these species become invasive species
sirupt exisiting food chains, reproduce food chains
spread aggresivley and outcompete the native species
includes plants, animals and microorgansims
Pests and Diseases
global transport has also introduced pests/diseases to native species
global trade in amphibians has led to fungal disease (decrease in pop)
Pollution
leading cause of biodiversity
plastic in oceans is often ingested by marine animals, affecting consumers
dumping of garbage pollutes ocean, also becomes breeding ground for pests
the release of sulfur dioxide and NO2 from industries results in acid rain - detrimental effect on plant and animals
In-situ conservation
way of conserving animals and plants in their natural habitats maintaing the original biodiversity of the area
involves designating, managing and maintaining areas for the protection of the and animals.
less disruptive & cost-efficient
E.g
national parks, wildlife sanctuaries, and marine reserves
allows the species to continue living in the habitat to which they are adapted to - preserves their natural behaviout and revents diruption in the food chain
Ex-situ conservation
plants and animals are conserved OUTSIDE their natural habitats
E.g:
zoos, aquarimes, botanical gardens
sometimes the # are too small to sustain the species or the risk of poaching is high
scientists establish gene banks to store biodiversity + storage of GERMPLASM
Captive breeding
conservation technique for preventiing the extinction of species whoose populations are small and on the verge of extinction
animals in zoos are encouraged to breed and then reintroduced into the wild
ONE DRAWBACK is small pops already have low genetic diversity so the chances of passing unfit genes increases
e.G
Arabian Ox - became extinct in the wild, the antelopes that were in zoos were “trained” for realse and ensured that the species could be realse back into the wild
Rewilding
conservation technique which allows wildlife and natural processes to reclaim areas bringing back biodiversity
habitat is rrestored to what it would have been if humans did not interfeer
plants and animals that have dissapered from the habitat are reintroduced (help build ecosystems)
Reclamation of degraded ecosystems
unsustainable human activity often causes degradation of land and water - loss could be due to erosion of soil, deforestation, salination
land restoration strategies recover and realim degraded ecosystems
help from local communitites and indigenous peoples yeild higher result as they have deep knowledge of the land
EDGE: helps endangered animals, ED - evolutionary distinctivness, GE - globally endangered
Living PLanet Index
measure of the average decline in monitored wildlife populations
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