Sheena Townsend Flashcards
Lecture 1 - 7
State ONE common misconception about evolutionary biology. Describe the main reason this misconception persists and provide a brief scientifically accurate rebuttal grounded in a sound understanding of how
biological evolution occurs.
A common misconception about evolution is that living things have fantastically intricate features that could not function if they were any less complex or sophisticated. Therefore, evolution cannot be used to explain the existence of these features. This misconception persists because people do not understand or even know the scientific evidence of how evolution occurs. Evolution of traits occurs through gradual changes by combining functional traits through adaptation and natural selection to create something new that also functions. This explains the existence of features and how they did function when they were ‘simpler’ in their own ways before coming together due to evolutionary pressures. This is also proven by fossil records and shown by DNA evidence.
How are natural and sexual selection different? and how are they similar?
They are different because sexual selection is a type of natural selection where mating success and access to mates is what drives it even if it impacts their survival whereas all other components of fitness is what drives natural selection.
They are similar because they both need variability, the variability needs to be inheritable, some need to be more successful than others and successful individuals succeed because the variant traits are passed on to their offspring.
What are Darwins postulates for natural selection and how are they reworked for sexual selection?
Natural selection:
1. Individuals are variable
2. Some variation in heritable
3. Some individuals are more successful
4. Success is non-random
Sexual Selection:
1. Individuals are variable in access to mates
2. Some variation in heritable
3. Some individuals are more successful at reproducing
4. Success is non-random and related to mate access
Explain inter and intra-sexual selection
Intra-sexual selection = members of one sex compete with each other for access to the other sex (low investment mate/usually male competition)
Inter-sexual selection = members of one sex choose which individuals of the other sex to mate with (high investment/usually female mate choice)
What is an example of a trait that may be influenced by sexual selection, is it inter or intra sexual selection and briefly describe a study design to investigate this.
An example of a trait that is influenced by sexual selection is male peacocks size and colour of their tails. It is inter sexual selection because it is the females who are selecting who to mate with. A study design for this would be a experimental study Population selection: Choose a population of peacocks and peahens for the study.
Trait measurement: Measure and record the tail feather length, number of eyespots, and overall tail display quality of all male peacocks in the population.
Experimental groups:
Control group: Allow peahens to mate freely with males of their choice
Experimental group: Artificially manipulate male tail displays (e.g., by trimming feathers or adding artificial extensions)
Mating observations:
Record the number of successful matings for each male in both groups
Note female behaviors indicating preference (e.g., time spent near males, courtship responses)
Offspring analysis:
Track the number and quality of offspring produced by each mating pair
Measure offspring survival rates and future reproductive success
Data analysis:
Compare mating success between males with different tail characteristics
Analyze the relationship between tail traits and offspring quality/quantity
Evaluate differences in female preference between control and experimental groupsThis experimental design allows for direct manipulation of the trait in question and observation of its effects on mating success, which is crucial for establishing a causal relationship between the trait and sexual selection
What are Darwins Tenants?
- Populations change over time - evolution happens
- Evolution happens gradually over millions of years
- Speciation occurs - species split into 2 or more species
- All species share a common ancestry
- Adaptation is caused by a process Darwin described and called natural selection
Explain the prediction of increasing complexity
It relates to Tenant 2 - If populations change very gradually over millions of years, and we consult the fossil record, then we should see organisms starting out simply and evidence of increasing complexity over time.
Explain the prediction of evidence of speciation
It relates to tenant 3 - If evolution occurs within lineages and lineages split then we should see evidence of gradual change of 1 species into 2 over time.
Explain the prediction of transitional forms
It relates to tenant 4 - If all species share common ancestors we should find fossil evidence that connect modern groups to their common ancestors.
Explain the prediction of natural selection
If evolution results largely from natural selection then we should expect to observe evidence of it happening in nature.
What is a retrodiction?
Facts and data that aren’t necasarrity predicted by the theory of evolution but only make sense in the light of the theory of evolution, opposite of prediction (going back in time).
What is adaptive radiation? and an example?
Divergence of a clade into populations adapted to many different ecological niches. An example in cichlid fish.
