Intro to Evolution and Biodiversity Flashcards
What were the first experiments first carried out on pre-biotic synthesis? When did they take place and who by?
- Heating of inorganic molecules such as H and ammonia in the absence of oxygen to generate a wide range of organic products e.g amino acids and sugar
- 1953
- Stanley Miller
What happened 3.8 million years ago?
chemicals + heat (lightning) formed organic molecules such as RNA + phospholipid like molecules which spontaneously organised into membranes
What and when was the Cambrian explosion?
- around 500 million years ago
- colonisation of land
What happened during the Cambrian explosion?
- consumption of O2 and generation of CO2
- Massive explosion in the number of plants followed by massive loss (lacking CO2??) this formed fossil fuels
- pangaea supercontinent formed
What was the permian triassic extinction event (252 million years ago)?
The loss of around 95% marine species and around 70% land based vertebrate species and 83% insect genera
-Dinosaurs evolved from surfing species as well as birds and amphibians
What caused the permian triassic extinction event?
meteor, volcanism, methane release, anoxia, high CO2
When was the cretaceous-paleogene extinction event?
65 million years ago
What caused the cretaceous-paleogene extinction event?
A huge asteroid hit the gulf of Mexico
What were the impacts of the cretaceous-paleogene extinction event?
- dust cloud blocked sunlight out for many years
- acid rain
- increased O2 conc (widespread fires)
- 75% species became extinct
What happened after the cretaceous-paleogene extinction event?
Large divergence into new forms and species within empty ecological niches
What are the phases of human evolution?
- Early (hominid) phase (largely ape-like)
- Australopithecine phase (many species widespread in Africa, early tool use?)
- Human (homo) phase, several species
What happened in the homo phase?
- global spread
- encephalised
- dietary range
- behavioural complexity
What did the Homo sapiens evolve from?
homo erectus
What is the single-origin or ‘out of Africa’ hypothesis?
- Migration H.erectus out of Africa
- Speciation of H.sapiens out of H.erectus in Africa
- A further migration replacing the earlier dispersed H.erectus
Who is Linnaeus and what did he do?
- 18th century Swedish botanist
- Created binomial nomenclature
- Created Linnaean taxonomy (hierarchical rank classification)
- Observation of evolution (grouping according to relation but had no mechanism to explain)
What did Darwin observe on his trip on the Beagle from 1831-1836?
- He noticed selective breeder (fancy pigeons descended from rock pigeon)
- Biogeography-adaption to environment (finches and tortoises in Galapagos
What 2 principles did Darwin discover?
1) all living things are connected - phylogenetic tree
2) A mechanism of selection drives change
Describe the observations Darwin made when working out how a mechanism of selection drives change
- Individuals in a population have many traits that can be heritable
- Populations produce more offspring that can survive to produce offspring of their own
- species are generally suited to their environment
How does a mechanism of selection drive change?
- Individuals whose traits are best suited to survive a given environment produce more offspring
- As time goes on the favourable traits are accumulated in individuals
What forms of evidence do we have that support the theory of evolution?
- palaeontology
- Biogeography
- comparative embryology & embryology
- Anatomical vestiges
- biochem
- endogenous retroviruses (ERVs)
- microevolution
How can palaeontology be used to support evolution?
- fossil record (although can be incomplete) (and need to be carried out under exactly the right conditions)
- transitional fossils (link two groups of organisms)
How does biogeography drive evolution?
- geographical isolation
- continental drift
- unique flora and fauna in Australasia
How does cooperative embryology and anatomy support evolution?
-similar features indicative of a similar ancestor
What are anatomical vestiges?
Features that date back to an ancestor that are non-functional but retained e.g tailbone
How does biochem support evolution?
Common chemicals- amino acids, RNA, DNA
What is DNA homology?
- comparison of DNA sequences
- level of homology correlated with evolutionary distance
- pseudogenes
What is microevolution?
evolution occurring now
e.g increased mosquito resistance to DTT and flu virus
How do endogenous retroviruses help prove evolution?
- remnants in the genome of retroviral infections which are similar to around 5% of the human genome
- found at identical loci of different organisms
- evolution from a common ancestor would explain this
Why can evolution be bad?
-As we evolved quickly so can genetic disorders, meaning that they can arise more commonly and quickly before we have time to select against them
-Old genes exposed to 21st century lifestyle (more calories, less exercise, less vitamins etc)
(mismatch hypothesis)
What is a model organism?
- A non-human species studied to understand biological phenomena and provide insights into the workings of other organisms
- in vivo models
What are the difficulties of using a model organism?
- Information has to be extrapolated from one organism to another
- Ethical issues with using animals in experiments
What can be used as a model organism?
- prokaryotes (E.coli)
- simple eukaryotes (yeasts)
- Invertebrates
- Vertebrates
- Amphibians
- Mammals
What is an advantage + disadvantage of using prokaryotes as a model organism?
- Can be grown and cultured easily and inexpensively in a lab
- Significantly different to large eukaryotes
What’s the advantages of using small eukaryotes as a model organism?
- cheap and easy to grow
- Smaller genome than larger eukaryotes but share characteristics with larger organisms
What are examples of invertebrates used as model organisms?
- fruit fly
- nematode
What is the nematode used for?
Understanding the genetic control of development and physiology because it has been completely sequenced
Why is the zebrafish a good vertebrate to use for a model organism?
- Can track stages of development because its body is nearly transparent in early stages
- easily genetically manipulated
- small and cheap
- short generation time (lots of offspring)
- must human genomes causing developmental diseases have a counterpart in zebrafish genome
- can regenerate damaged parts of their heart
Why are amphibians used as model organisms?
- eggs and embryos used in development biology, cell biology and neuroscience
- large, easily manipulated embryos
Why are mice used as model organisms?
- many different strains that can be selected for particular interests
- few differences between mice and humans
- Small & easy to keep
- mutations usually cause a similar phenotype
- gene knockouts (null mice) provide information about genes and proteins
Why do we need to keep biodiversity levels high?
- need to have access to a wide variety of foods for nutrients for health
- medicinal plant use (loss of biodiversity might limit new discoveries)
- synthetic alternatives may not be available
Why are non human primates good to use as model organisms?
-Strong similarities in physiology, behaviour, immunology and genetics
What extinction event is happening now and why?
Holocene/anthropocene extinction event due to human activity
- overpopulation
- overconsumption
- habitat destruction
Why is climate change happening?
Due to increased levels of CH4 and CO2 in the atmosphere
