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influence on environment
organisms had an innate urge to become more complex & perfect therefore they could acquire features to help them have success in their environment
use & disuse of organs
- eg, a h2o-bird acquire longer legs if it wades in deeper h2o looking for food
- eg, if a bird stopped flying, its wings would get smaller (during its lifetime)
lamarack evolution theory - eg giraffes
- the ancestors of giraffes were short-necked antelopes. they stretched their neck continuously to grab the leaves
- neck length was gradually increased in each generation until long enough to reach the high branches
natural selection
- the process by which organisms with variations most suited of their environment, survive to reproduce
- one of the mechanisms of evolution, along with mutations, migration & genetic drift
- darwin used thomas malthus idea (1798) that if unchecked, human populations will grow beyond the space & food needed to sustain it
inheritance of acquired characteristics
traits altered by an individual during its lifetime can be passed onto their offspring, enabling species to change overtime
disproving lamarack's theory
- organisms do not strive to be perfect
- evolution doesn't progress in 1 direction, eg giraffe's neck do NOT get longer & longer
- acquired characteristics are NOT passed down
- eg1, ear piercing is not passed onto kids
- eg2, people who work out do not conceive
- eg3, people who have amputations do not conceive children with missing limbs
variation in traits & adaptation
- adaptation: there is natural heritable variation, characteristics which may increase an individual's chance of surviving & reproducing
- polymorphism: the occurrence of 2 different morphs (alternative phenotypes) of a population of a species
eg, some beetles are green & some are brown
survival of the fittest/differential reproduction
- individuals have variable fitness
- since the environment can't support unlimited population growth, NOT all individuals will reproduce
- eg, brown beetles blend with the trunk & get eaten less than green beetles therefore higher fitness, survival & reproduction rate
jean-bapitise lamarack
1809: suggested that organism change during lifetime by selectively using or not using various parts of their bodies
struggle for existence
organisms produce more offspring than can survive as insurance; only a small fraction survives to reproduce
natural selection/heredity
the surviving brown beetles will pass the brown allele to their offspring
conclusion
brown colour adaption is more advantageous than green. eventually, ALL individuals will be brown
natural selection summary
- fitness in evolutionary bio is the reproductive success of an individual having the best-suited adaptations for that environment
- adaptations do not have to be perfect, just good enough for individuals to reach reproductive maturity
- doesn't move in a fixed direction because it does NOT systematically select for a specific trait
- is a process that enables species to survive & reproduce in a local environment
- selection pressures work at killing off the weak individual's
- if environmental conditions change fast then a specie can adapt, specie become extinct
common descent with modification
what does natural selection suggest about living & extinct species?
- Darwin proposed that over many generations adaptations can cause successful species to become NEW species
- he proposed that living species are descended with modifications for common ancestors
- evidence for this came from fossils
- eg, tigers, panthers, & cheetahs had a common ancestor, looking farther back these felines had common ancestors with dogs, horses, & bats
- all mammals had a common ancestor with birds, alligators, & fish
- he proposed that a single "free of life" linked ALL living things
biography
- the study where organisms live now & where they live in the past; patterns in the distribution of living & fossil specie
closely related but different environments
closely related specie differentiate in slightly different climates
- eg, galapagos tortoise varieties evolved from a common mainland specie
distantly related but similar environments
similar habitats throughout the world are home to distantly related PLANTS & animals
- eg, ground-dwelling birds inhabit flat grasslands in Europe, Australia, Africa, & South America
- the birds had diff body structures implying they evolved from diff ancestors
divergent evolution
- is when difference between groups (w/ a common ancestor) compound/add up over time; eventually, the groups separate (physically, biologically) & evolve into diff specie
- usually happens when a specie spreads out into totally diff environments
- eg darwins finches have evolved into 15 diff species over 2 mill yrs
convergent evolution
- describes unrelated specie without a common ancestor (unlike divergent evolution) that ended up with similar body forms colouration, organs & adaptations
- caused by different species living in similar climates environments etc, which makes them face similar selections pressures
- the process by which unrelated or distantly related organisms evolve similarly
- natural selection can result in evolutionary convergence under several diff circumstances
- eg1, rattle group flightless birds, including the emu, ostrich, & rhea fill very similar ecological niches on diff continents. DNA evidence suggest that these "ratites" do NOT share a common ancestor but have evolved independently
- eg2, fish & cetaceans (whales) are very diff specie but they look superficially similar
- body shape is highly streamlined, have fins & tail
- evolution appears to have repeated itself in producing 2 animals that are alike in form
coevolution
when the process of adapting to their environment, mountains 2+ organisms can make use of other organisms by living on or in them, eating them &/or working with them
- organisms can coevolution with other species at the same time, because an environment includes many diff types of orgs
- creates symbiotic relationships
predator/prey
- the prey population decreases as the predators eat the prey
- then the predator population decreases as available prey runs out
- decreases # of predators allow more prey to survive, & the prey population increases
- prey population increases then the predators ear the prey starting the cycle over again
- usually a lag exists for predators in terms of response time to prey population levels
mutualism
- a relationship in which both species obtain some benefit from the interaction (win-win)
- eg1, lichens are a composite org made up of a fungus & a photosynthetic green alga; the fungus grows around the alga, protecting the alga which makes sugar for the fungus photosynthetically
- eg2 corals are made up of an animal & a photosynthetic protist called zooxanthellae
- the coral provides the protist with a protected environment & compounds for photosynthesis
- the protist produces O2 & helps the coral to remove wastes. Most importantly, zooxanthellae supply coral w glucose (sugar), glycerol & amino acids to make carbs, fats, proteins & produce CaCo3 (calcium carbonate) for the skeleton
commensalism
- an interaction in which one org benefits, while the other is unaffected
- eg barnacles live on the hide of the whale & feed passively from the H2O passing by, while there is no apparent benefit or harm to the grey whale
parasitism
- when one org live & feeds on, or, in the body of a host org
- host is harmed by the relationship because the parasite get its nutrients from the host; host may not be able to carry out life functions
- death means loss of habitat for the parasite; so death comes slowly for the host
- controls populations --> survival of the fittest
- invertebrate parasites have a hook/sucker for latching onto host
