Biological Diveristy Flashcards
What are some abiotic factors?
- temperature
- pH
- salinity
- tides
- humidity
- precipitation
- soil type
- mineral content
- availability of water
- pollution
What are some biotic factors?
- 5 kingdoms
- predators
- parasites
- competition
- symbiotic relationships
- availability of food
- fouling (wastes)
- human activity
What is ICE AGE?
Mnemonic for natural selection
I - inherited variation exists
C - competiton for finite resources
E - environmental pressure
A - adaptation
↕︎(differential reproductive fitness)
G - genotype frequency changes
E - evolution occurs
What is divergent evolution?
the formation of two or more new species when a species adapts (over time) to suit different environmental conditions
What is convergent evolution?
species evolving to become phenotypically similar without a recent ancestor due to experiencing similar selection pressure
What is are the circled events?
Speciation events
What is adaptive radiation?
- big change in environment causes lots of rapid speciation
- diverges into species occupying separate niches
- e.g. 65mya asteriod hit & killed lots of reptiles (dinosaurs) making way for mammals to evolve without predators
How do the finches on galapagos island suppor the theory of evolution by natural selection?
- during droughts, when small soft seeds are not as abundant, small billed finches begin to die out
- when hard large seeds are abundant, large billed finches will thrive
Why have cane toad populations increased so rapidly?
they are an introduced species and have no natural predators
What happened to cane toad traits over time?
- longer legs
- more speed and endurance for travelling long distances
How has spatial sorting affected cane toads?
- first introduced to QLD, now found in QLD, NT, & NSW
- now increase territory by over 50km/year
- toads further from QLD have longer legs as they are more likely to be eaten by predators and mate with other toads with longer legs
What is spatial sorting?
- characterises changes in allele frequencies across space
- involve traits leading to geographical dispersal, with impacts on mating partner options
- relies on variation in populations, inheritance of traits, and time
- way that evolution can occur
What us the formula for the estimated abundance of species using quadrats?
What is the formula for the population abundance using the mark-release-recapture method?
How has the horse evolved over time and why?
- leg length increased - travel futher distances
- taller - no more selection pressure to be small & nimble in undergrowth
- went from four digits to one - smaller digits became vestigial as main strength shifted to main toe
- higher crowned and flatter teeth - grinding grasses
- longer cheek teeth span
- loss of footpads
- fusion of bones in lower legs - stronger to travel longer distances
- elongation of muzzle
- increase in size & complexity of the brain
What is punctuated equilibrium?
- long periods of no evolutionary change
- ‘puncutated’ by periods of relatively rapid evolutionary changes
- new species can appear suddenly
What is gradualism?
- happens over a long period
- evolutionary changes are constant and consistent
- changes features by removing less fit organisms from the gene pool
How does the comparative anatomy of homologous structures provide evidence of evolution?
- structures are similar in form & embryonic development but are adapted for different functions
- indicates evolutionary relationships through divergent evolution
- e.g. pentadactyl limb
How does the pentadactyl limb provide evidence of evolution?
- similar in form but adapted for different functions
- front forelimb is similar - divergent evolution of mammals
- human limb is for grabbing - long fingers
- cat limb is for walking - thicker & short fingers
- whale limb is for propulsion - thick (strength)
- bat limb is for flying - thin (lightweight) with skin attached between fingers
How does the comparative anatomy of analogous structures provide evidence for evolution?
- similar in function but species are of different origins
- convergent evolution
- similar selection pressures of different species leads to analogous structures
- e.g. sharks & dolphins, and hedghehog, echidna & porcupine
How does the comparative anatomy of vestigial structures provide evidence of evolution?
- organs that have become reduced/non-functional that have important functions in other closely related species
- provides evidence for common ancestry
- e.g. thumbs in spider monkeys, legs in snakes, tailbone in humans
How does comparative embryology provide evidence for evolution?
- discredited due to false evidence
- may give clues to evolutionary link to another organism
- embryonic stages of all vertebrates are very similar - stomach is outside body, eyes, spinal cord, tail
How does biogeography provide evidence for evolution?
- geographically separate areas with similar ecology tend to be inhabited by organisms with similar features
- Ratites on all major land masses in Southern Hemisphere - suggests species slightly changed over time to suit distinct ecological niches as Gondwana split apart
How does the molecular evidence of DNA hybridisation provide evidence for evolution?
- heat is applied to DNA strands of different organisms
- DNA strands separate
- DNA strands cool down and bind together
- the more closely DNA strands bind (less gaps), the more closely related the species - base pairs are almost exactly complementary
What is co-evolution?
- when two (or more) species reciprocally affect each other’s evolution
- likely to happen when different species have close ecological interactions (predation/prey, parasite/host, competition, mutualism)
- e.g. acacia tree & acacia ant, Buff-tailed sicklebill hummingbirds & Centropogon flowers
What are two types of speciation?
- Allopatric - populations become geographically isolated
- Sympatric - populations are in the same area
How does sympatric speciation cause speciation?
Pre-zygotic barriers:
* barriers that occur before fertilisation
* behavioural isolation (different behaviours like diff bird songs)
* temporal isolation (breed at diff times)
* habitat isolation (same environment, diff habitat, e.g. aquatic vs terrestrial in a marsh)
Post-zygotic barriers:
* has a zygote
* offspring are unable to reproduce (species cannot merge)
* offspring are very weak and die quickly after birth
* offspring are unable to develop in utero
