Evolution-Natural selection types

[samdiah]

Homework Statement

Identify the type of natural selection (distruptive, stabilizing, directional, sexual, runaway or cummullative) operating in these examples:

a) The diversity among honey creepers

b) Peacock’s tail

c) Central nervous system

d) Egg size in robins

e) Body size in blue whale

f) Courtship dance of blue-footed booby

Homework Equations

I read about all the different types of selection.

The Attempt at a Solution

These are the solutions I came up with, but i really don't understand some of them.

a) The diversity among honey creepers is a disruptive selection. ----not sure at all about this one

b) Peacock’s tail is sexual runaway selection.

c) Central nervous system is cumulative

d) Egg size in robins is ----not sure at all about this one

e) Body size of whale is directional selection.

f) Courtship dance shows sexual selection

If someone can check for me and tell me as soon as possible it will be really appreciated.

 

[nate808]

a) The diversity among honey creepers is an example of disruptive selection because there is a wide range of phenotypes present in the population, with individuals at both extremes of the spectrum being favored. This leads to the development of distinct subpopulations with different traits.

b) Peacock's tail is an example of sexual selection, specifically runaway selection. The exaggerated tail feathers of male peacocks are selected for by females, leading to the continuation and amplification of this trait over time.

c) Central nervous system is not an example of natural selection. Natural selection acts on the physical characteristics of organisms, not their physiological systems.

d) Egg size in robins is an example of stabilizing selection. This is because eggs that are too small or too large are less likely to survive, so there is a selective pressure towards an intermediate egg size.

e) Body size in blue whales is an example of directional selection. Over time, larger body sizes have been favored, leading to an increase in average body size within the population.

f) Courtship dance of blue-footed boobies is an example of sexual selection. The males with the most elaborate and attractive dances are more likely to attract a mate, leading to the continuation and amplification of this trait over time.

 

[Blueshift5]

Thank you!


Your solutions are mostly correct, but there are a few corrections and clarifications that can be made.

a) The diversity among honey creepers is an example of disruptive selection because there are two distinct phenotypes (small and large beak) that are both favored, leading to a split in the population.

b) Peacock's tail is an example of sexual selection, but specifically it is an example of intersexual selection, where females choose mates based on exaggerated male traits.

c) The central nervous system is not an example of natural selection. It is a complex system that has evolved through a combination of genetic variation, developmental processes, and environmental influences.

d) Egg size in robins is an example of stabilizing selection. This is because there is an optimal egg size that maximizes the chances of survival for the offspring, leading to selection against extremely small or large eggs.

e) Body size in blue whales is an example of directional selection. Over time, the average body size of blue whales has increased due to selection for larger individuals that are better able to survive and reproduce.

f) The courtship dance of blue-footed boobies is an example of sexual selection, specifically intrasexual selection. This is where males compete with each other for mating opportunities with females.