Genetics Chapter 11 Flashcards
What did Charles Darwin do
- Published book - The Origin of species
- 1859
- Based on observations gathered from travelling the world
- As humans travelled they could discover new environments and try hypothesise how they worked and how the species within the environments came to be
Explain the formation of thhe earth
- Earth condensed about 4.6 billion years ago
- initial atmosphere was made up mostly of H2 - First cell discovered to have its own genetic material was present 3.6 billion years ago
- Photosynthesising bacteria appx 3.4 billion years ago
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Why was photosynthesizing bacteria an important evolutionary step
- Evolution of photosynthesis
- Enabled atmosphere to change from being mostly H2
Explain the oxygen produced by photosynthesis
- Was able to react with UV to create Ozone ( O3 )
- O3 protects life on earth from UV radiation
- Thus photosynthesis is a Fundamental steps in the evolution of our planet was the development of photosynthesis in eukaryotes through the process of endosymbiosis.
What is the first thing to understand about evolution
- Dealing with characteristics that are inherited / passed on from parent to offspring
- Characteristics must have a positive impact on the individual, allowing it to become very successful ; survive; reproduce and pass characteristics on
What is the second thing to understand about evolution
- Offspring are better adapted to survive
- In other words, resources for survival and reproduction are limited
- The capacity for reproduction in all organisms outstrips the availability of resources to support their numbers.
- Thus, there is a competition for those resources in each generation and how well an individual in a population can compete will show its advantage over other individuals
What is the third thing to understand about evolution
Offspring vary among each other in regard to their characteristics and those variations are inherited
Explain Thomas Malthus
- Gave a lot of info on how populations change over time
- Different species have different population trends
- A variety of factors limit populations – resources, diseases
What can we try understand about population trends
- Try understand what environmental factors will determine whether we will have an exponential growth or a stable growth over time
Explain populations fully
- Individual members of a population are not equally equipped to survive
- Those who could not obtain resources or were not resistant to diseases would not survive – genes would die out
- Better equipped individuals would survive and reproduce – pass their genes on to the next generation
What is another form of evidence of evolution
Biogeography
Explain biogeography fully
- Biology of different areas of the planet and what are the similarities between the diversity seen in the different areas
- Broad groups of animals and plants that evolved before the breakup of the supercontinent Pangaea (about 200 million years ago) are distributed worldwide.
- compared to other species that may have evolved after the breakup
Are members of the plant family Proteaceae restricted to South Africa?
- The presence of Proteaceae in Australia, southern Africa, and South America is best explained by the plant family’s presence there prior to the southern supercontinent Gondwana breaking up.
In comparison :
- The marsupials of Australia, the finches on the Galápagos, and many species on the Hawaiian Islands are all found nowhere else but on their island, yet display distant relationships to ancestral species on mainlands ( evolved after breakup and havent been able to disperse widely )
What are the patterns of evolution
- Divergenet evolution
- Convergent evolution
Explain divergent evolution fully
- When two species evolve in different directions from a common point
- May have common ancestor or common traits
eg. In the forms of the reproductive organs of flowering plants, which share the same basic anatomies
- however, they can look very different as a result of selection in different physical environments, and adaptation to different kinds of Pollinators
Explain convergent evolution
- The wings of bats and insects, however, evolved from very different original structures. When similar structures arise through evolution independently in different species it is called convergent evolution.
- The wings of bats and insects are called analogous structures; they are similar in function and appearance, but do not share an origin in a common ancestor.
- Not related in any way but have similar structures
Explain homolgous structures
- The wings of a hummingbird and an ostrich are homologous structures, meaning they share similarities .
- The wings of hummingbirds and ostriches did not evolve independently in the hummingbird lineage and the ostrich lineage—they descended from a common ancestor with wings.
Explain micro - evolution
- Chnages that may occur in a population that arent related to naturall selection; mutation; genetic drift; gene flow and non-random mating
Explsin speciation
Explain allopatric speciation briefly
Meaning speciation in “other homelands,” involves a geographic separation of populations from a parent species and subsequent evolution
Explain sympatric speciation briefly
Meaning speciation in the “same homeland,” involves speciation occurring within a parent species while remaining in one location
Explain allopatric speciation fully
- When populations become geographically discontinuous that free-flow of alleles is prevented.
- When that separation lasts for a period of time, micro evolution acts on poopulatiosn seperately the two populations are able to evolve along different trajectories.
- Thus, their allele frequencies at numerous genetic loci gradually become more and more different as new alleles independently arise by mutation in each population and cant mate
- Typically, environmental conditions, such as climate, resources, predators, and competitors, for the two populations will differ causing natural selection to favor divergent adaptations in each group individually leading to new species being present
