Phylogeny & History Of Life - Topic 1 Flashcards
What is prezygotic reproductive isolation?
A barrier to reproduction preventing members of different species reproducing before fertilisation
Explain why the differently coloured fish living in close proximity may ve reproductive isolated.
The females prefer red or blue males depedning on whichproeuce the fittest offspring for that habitat. So over time the species have diverged into two distinct ones with distinct colouring
What is sympatric speciation?
A new species evolving while both live in the same geographic region, potentially caused by prezygotic reproductive isolation.
What us assortative mating?
Non random mating where individuals tend to mate with others who have similar phenotypes (characteristics). Eg scale colour, feathers colour etc
What is the impact of assortatjve mating and prezygotic reproduction on general flow? Explain
It reduces gene flow. Genes are not carried from one population to another so the combination of genes reduces and genetic differences between the two species grow, eventually leading to them being unable to reproduce (evolution via speciation to 2 different species).
If blue and red fish are in shallow water why can we expect to see more blue fish over the next few generations?
More brightly coloured blue fish as at this depth sensitivity to blue light and coloring is favoured since it could provide more camouflage/be more visible for assortative mating to take place.
If blue and red fish are in deep water, why can we expect to see more red fish over the next generations?
Sensitivity to red light and coloring is favoured due to greater visibility, causing assortative mating, reducing the gene flow of the population. As a result sympatric speciation occurs.
Give an example where the prezygotic reproductive barrier of fish colour fails
In murkey water fish cannot see well enough for assortative mating to occur. So the gene pool doesn’t decrease and speciation doesn’t not occur. This results in hybridisation where the two original species become extinct.
What do phylogenetic represent?
Evolutionary relationships and sometimes the timescale of change
What is a homologous trait?
Traits shared by different organisms due to common ancestry and conservation of said trait
What is an analogous trait?
Traits shared by differen organism as a result of independent evolutionary responses to similar selective pressure, resulting in convergent evolution.
Explain the difference between owl and bat wings as homologous trait and insects wings as an anlagous trait.
Wings evolved from a common ancestor of bats and owls whose limbs were made to glide and eventually evolved for locomotion and flight.
Insect wings evolved independently from limbs involved in swimming
What does the convergent evolution of octopus and human eyes tell us about the eye?
It tells us about its functional organisation and how well suited its structure is for its purpose as species with very different ancestry have very similar eye structures.
What is a clade in a phylogenetic diagram?
A monophyletic group of organisms, including a common ancestor and all of its decendants (both living and extinct)
Label the common ancestors, sister groups and outgroups of this clade
What is a paraphyletic group in a phylogenetic diagram?
A group of organisms with a common ancestor but not all of it’s descendants
Why are reptiles paraphyletic?
The group of reptiles doesn’t include all of their common ancestors lime birds and mammals
How does the fossil record help with reconstructing phylogeny?
Fossils show transitional features like limbs before they evolved into flippers. So we can trave how different characteristics came about.
How do genomic and morphological characteristics help with phylogeny?
DNA sequences of different species being compared to decipher how closely related they are based amount of difference in DNA sequence. Less difference = more closely related as not enough time has passed for the highly conserved DNA sequences to mutate and change.
CD are the most closely related.
EFGH are closely related but GH moreso.
AB are the least related to all of them but most related to eachother
How did the beta-caesin (milk protein) gene suggest relation between whales and hippos? Use the figure to explain
The sequence of DNA for the protein is more similar between whales and hippos than any other species. As DNA is highly conserved, the similarity suggests they have a close common ancestor.
How did the beta-caesin (milk protein) gene suggest relation between whales and hippos? Use the figure to explain
The sequence of DNA for the protein is more similar between whales and hippos than any other species. As DNA is highly conserved, the similarity suggests they have a close common ancestor.
How did the beta-caesin (milk protein) gene suggest relation between whales and hippos? Use the figure to explain
The sequence of DNA for the protein is more similar between whales and hippos than any other species. As DNA is highly conserved, the similarity suggests they have a close common ancestor.
