Blueprint of Life Flashcards
what is evolution?
evolution is the change in living things over many generations.
what three things have impacted on the evolution of living things?
- changes in the physical environment
- changes in the chemical environment
- competition for resources
what has resulted from australias seperation from Godwana 25mya?
changes in climate and exposure to fire have led to evolutionary change in Australian flora and fauna. climate has become more seasoned, drier, hotter.
what are some examples in changes occuring in australian flora and fauna as a resulted of the seperation from godwana?
- Eucalpyts, bottlebrushes, tea-trees and lilly-pillies have diversified significantly and have become more prolific. although primitive forms still exis, specialised forms have developed and inhabit the very-dry, high seasonal and fire-prone regions
- more grass land and open woodlands formed with decreases in large forests
-CHANGES TO KANGAROOS
first kangaroos lived in trees, but because of physical changes, many other forms have develpoed that we know of today
previously small and omnivorous, kangaroos become larger, developed multi chambered stomachs and teeth fro grinding and digesting vegetation(high crested molars)
they also developed the bipedal hopping for energy efficient locomotion
how do the moths in england during the industrial revolution demonstrate how changes to the physical environment can effect the evolution of living things?
during the industrial revolution, the environment became polluted and led to dark sooty backgrounds for coloured moths to camoflage against.
- light coloured moths were then easier to see by predators and so they were eaten more often than they could reproduce
- genes expressing dark coloured colour passed on to the next generation
as the pollution in this environment descreased, the environment would become lighter, and then dark coloured moths would become easier to see. thus light moths would dominate
away from industralised cities, trees were light in colour, the lighter coloured moths dominated
how does urey and millers experiment desmonstrate the effects of changes in the physical environment to evolution?
there experiment supported oparin and haldanes theory regarding the formation of oragic compounds through the presence of strong UV radiation, electrical energy from lightning and high temps from volcanic eruptions. —> these are all environmental factors
describe how the increase in oxygen levels in the atmosphere affected evolution?
due to the presence of oxygen, aerobic respiration had become possible, a process which led to organisms becoming more complex.
increases in oxygen also led to the development of the ozone later, which could shield the earth from UV rays from the sun, allowing tesstrial life to be protected and to evolve into many different forms
describe how rabbits and myxomatosis relates to evolution
in the 1950’s, the myxoma virus was introduced to control rabbit numbers in australia. the virus was carried by fleas and mosquitoes and causes the disease of myxomatosis in rabbits
- first few years the virus had a 99% deathrate, over a decade this rate decreased to only 50%!
- the first hundred survivors of the virus carried with them a variation in their genetic code which was passed on through reproduction to the next generation. over the decade half of the population became genetically resistant to the virus
describe how insecticide DDT demonstrates the effect of chemicals to evolution
-the chemical initially killed most of the mosquitoes and insects it was sprayed upon
- those who survived carried a DDT resistive gene
- these individuals then reproduced with one another and produced offspring who were genetically resistant to DDT
how does the situation involving the dingo and tasmanian tiger demonstrate the effect that competition for resources has on evolution?
the introduction of the dingo to the australian mainland led to competition between the dingo and tasmanian tiger for food and other resources
- the dingo was more effective at hunting prey, due to their pack behaviour
- as a result, the tasmanian tiger was left starving and weak and became extinct on the mainland
how do the polar bears on the ice caps demonstrate the effects for the competetion resources in evolution?
melting of the ice caps as a result of global warming is leading to a decline in the numbers of polar bears
-as competition for the remaining ice flows become intense, some polar bears may not be able to reach these ice flows for resting and so they may become exhausted and drown
how to plants battling for light demonstrate the effects for the competition for resouces on evolution?
plants which are battling for light have developed large canopies to establish dominance
-different growth habits such as windes and epiphytes are a response to competition for light
what is paleontology and what is a transtional form?
paleontology is the study of fossils. fossils are the remains or traces of life forms that have been trapped in sediment, ice or amber and preserved. they provide a record over time of how living things have been evolving on earth
a transitional form are Fossils or organisms that show the intermediate states between an ancestral form and that of its descendants. ie, it shows one organism in the transitioning stage between one group to another
how does paleonotological evidence and transitional forms support evolution?
one of darwins major predictions was that the fossil record should yield intermediate forms —> organisms which show transitions from one group to another
for example, if amphibians had evolved from fish, then there must be traces of fossils which show an organism that has both fish and amphibian characteristics
what are some examples of transitional forms that support darwins theory of evolution?
seed ferns to plants
- seed fern fossils have both fern and gymosperm characteristics
- the seed fern resembles a fern in structure but produces seeds, not spores
The Archaeopteryx— reptiles to birds
- the most ancient recognised fossil bird, 150mill years old
- the fossil expresses both reptile and bird characteristics; wings, reptillian teeth, feathers, long jointed tail
The Crossopterygii– fish to amphibian
-the lob finned fish, had bones in their palm fins that may have allowed them to drag themsevles over land from one mud pond to the next, when the environment changed and the land was drying out
what is biogeography?
biogeography is the study of the distribution of living organisms on earth.
whats the relationship between a species uniqueness/location and biogeography?
many organims are unique to different parts of the world. barriers such as mountain rangers, desserts and the sea prevent interbreeding and allow unique species to develop
give one example of the effect of geographical isolation on organisms?
ALFRED WALLACE
the animals and plants of asia and australia are very different, even though the continents are very close together
this phenomenon was first observed by alfred wallace, who suggested a line, now called the wallace line, to seperate the distibution of these organisms
what is the prime example of the effect that biogeographical isolation has on organisms?
flightless birds, which include the emu(australia), kiwi (new zealand), ostrich(africa) and the Rheas(South America)
because of how similar these flightless birds are, and because the continents on which they live all were postulated to be apart of godwana, these birds are believed to have a common ancestor
this common ancestor may have been seperated in groups according to the seperation of the continents of godwana, seperated via the ocean and sea
what is comparative embryology?
comparative embryology is the study of the embyrose of different organisms, looking for similarties and difference between them
How does comparative embryology support the theory of evolution ?
The similarity between embryos of different vertebrate species is quite remarkable and suggests a common ancestor
—> all vertebrate embryos have; gill ornates, noctochords, spinal chords and primitive kidneys. Vertebrate embryos have the same type of skin which develops into fish scales, hair, bird feathers, reptilian scales, claws and nails of mammals
All the features described above are features which are common to aquatic organisms. We know that life originated in an aquatic environment, and it is likely that all these common characteristics have been inherited from a common ancestor
What is comparative anatomy ?
The study of the differences and similarities in structure between different organisms
What is the pentadactyl limb and how does it support the theory of evolution?
Organisms have many structures in common, which is evidence for similar inherited characteristics from a common ancestor
the Pentadactyl limb- five finger like bones, two lower limb bones (radius and ulna)
- most land vertebrates posses pentadactyl limbs
- it is believed that this limb was inherited from an ancient aquatic ancestor, the lob finned fish
How does the xylem of plants support the theory of evolution?
Ferns, conifers and flowering plants all have vascular tissue and xylem
Hence structural similarities between the same plant groups suggests common ancestry
what are homologous structures?
structures or organs which appear in different animals
what are vestigial organs?
vestigial organs are structures found in the body which are no longer used and are greatly reduced. these structures are believed to be from a common ancestor
what are some examples of organisms which have vestigial organs?
whales have parts of the pelvis and leg bones that are remnants of their four legged ancestors, the human appendix is no longer used in digestion
